Thursday, July 31, 2008

El auge de la fenomenologia en la filosofia analitica.

Via Leiter Reports.

Sean Kelly

In the second volume of her autobiography, La Force de l'age (1960), Simone de Beauvoir describes the evening in the early 1930s during the course of which Jean-Paul Sartre first became passionate about the philosophical method known as phenomenology. Raymond Aron, the young French philosopher, had been in Berlin studying the new philosophical method of Edmund Husserl (1859- 1938). On his return he joined Sartre and de Beauvoir for a drink at the Bec de Gaz in the rue Montparnasse. Beauvoir:
We ordered the specialty of the house - apricot cocktails. Aron pointed to his glass: "You see, mon petit camarade, if you are a phenomenologist, you can talk about this cocktail and make philosophy out of it!" Sartre turned pale with emotion; this was precisely what he had been longing to achieve for years - to describe objects just as he experienced them, and for that to be philosophy.
If this descriptive task really is what undergirds the phenomenological method - and there is much in favour of such a preliminary characterization - then perhaps it is not difficult to explain the notorious rift in the mid to late twentieth century between the so-called analytic and phenomenological camps in philosophy. After all, it is hard to imagine Bertrand Russell paling with emotion before an apricot cocktail. And yet, explanations by way of national character can take us only so far; perhaps we can hope for a more trenchant analysis.
Such an analysis is all the more desirable because the chasm between the camps increasingly seems to have filled itself in. This is no little feat, given how widely it once yawned. By 1958 the situation was so dire that a notorious meeting at Royaumont pitted English-speaking philosophers against their French counterparts in what the young Charles Taylor, then still a prize Fellow at All Souls, described as "a dialogue de sourds".
The determined deafness of that mid- century has now given way to healthy curiosity. Of course, even half a century ago there were books about phenomenology written in English. Herbert Spiegelberg's massive two- volume history of the phenomenological movement was published in 1960, and Fr William Richardson's equally massive volume on Martin Heidegger appeared shortly after, along with a preface by Heidegger himself. But these were attempts to explain the movement - either by a dedicated historical reconstruction of who was saying what to whom, or by an enthusiastic translation of its most prominent oracle. What is notable today, by contrast, is the desire to appropriate phenomenology, to forage among its branches for the tastiest fruit; and along with this desire, the belief - or at least a resolute openness to the possibility - that the phenomenological fruit might offer philosophical nourishment.
Not every recent contribution to the literature, of course, has this admirable, appropriative quality. Indeed, the bookstores seem to be teeming lately with synoptic overviews of Husserl and his method. David Woodruff Smith, in Husserl, one of the most recent contributions, attempts to present the whole of the philosophical work of Husserl at an introductory level. Smith moves briskly, and relatively accurately, through the various aspects of Husserl's thought; but the task he has set himself is Herculean. That is because the real contribution of Husserl's work is not systematic (though Husserl himself certainly had systematic ambitions); it lies rather in the careful and detailed analyses he provides of an enormous range of philosophical domains. The details of these analyses - often shifting over the years, frequently mistaken in interesting ways, but always probing and original - provide one basic source to which contemporary English-speaking philosophers are beginning to turn in their recent discovery of the phenomenological tradition. Despite a brief section on Husserl's legacy at the end of Smith's book, he is unable to prepare the reader for the curiosity about phenomenology that some contemporary analytic philosophers have begun to feel.
From where, then, does this curiosity come? One factor is certainly the lack of unity - or to put a positive spin on it, the pluralism - that now characterizes much anglophone philosophy. Brian Leiter, arguably the reigning sociologist of the discipline, has even announced the "demise of analytic philosophy", on the grounds that the methodological and substantive pluralism of contemporary anglophone philosophy is now so pronounced that it leaves little to demarcate as "analytic" philosophy as such. Perhaps in retrospect it is clear that this lack of unity characterized even the Oxonians at Royaumont. But at least the standard view is that analytic philosophy for much of the twentieth century was unified by the so-called linguistic turn.
There is disagreement, of course, about what the linguistic turn was, but many of the contestants may agree to at least this: that after the linguistic turn philosophy was motivated to resolve, or perhaps to dissolve, or at any rate to address, philosophical problems primarily by analysing the language we have for talking about the domain in question. Consider perception, for example. On the linguistic account, philosophical problems in this domain should be approached not by thinking primarily about the experience of perceiving, but by thinking rather about the language we have for talking about perception. To take one influential instance, Elizabeth Anscombe, writing in the mid-1960s, approached the philosophical study of perception primarily through an analysis of the grammar of verbs used for perceptual report, such as "see". This, surely, is not what paled the emotional Sartre. Indeed, one significant interpretation of the difference between phenomenology and analytic philosophy, defended most prominently by Michael Dummett, formerly Wykeham Professor of Logic at Oxford, is precisely that Husserl's method precludes such a linguistic turn.
I'll explore this claim more carefully in a moment. First, though, it is worth remarking that two distinct, though sometimes related, movements in recent English-speaking philosophy have been predicated on at least an implicit rejection of the linguistic approach. The first is in metaphysics, the second in philosophy of mind. Perhaps it is not surprising that these are the two areas of contemporary anglophone philosophy where scholars have been most eager to explore the phenomenological literature.
In metaphysics, a revival of the pre- Kantian style of a priori argument, along with renewed interest in the modal notions of possibility and necessity, pushed the most prominent English-speaking philosophers beyond the analysis of natural language in the final third of the twentieth century. According to Timothy Williamson, current holder of the Wykeham chair, and one of the leading contemporary metaphysicians, it is, rather, a "subtle interplay of logic and the imagination" that directs most of the best contemporary work. The desire to discover the essential nature of entities in any region of being (material, mental, abstract, mathematical, cultural, and so on), and to do so through thought experiments that test our intuitions about what it takes for an entity to change from what it essentially is, was also at the heart of Husserl's phenomenological method. Such thought experiments are applications of the technique Husserl calls "eidetic variation", and he believed, like many contemporary metaphysicians, that such a technique, when properly applied, gives us the capacity for "rational intuition"; for "seeing", in other words, what things essentially are. Indeed, it was this aspect of Husserl's phenomenology to which the great mathematician and logician Kurt Godel was increasingly attracted towards the end of his life. And it was the application of this technique, among others, that led to Husserl's early work on the metaphysical nature of parts and wholes, work that the eminent contemporary metaphysician Kit Fine has called "perhaps the most significant treatise on the concept of part to be found in the philosophical literature".
If metaphysicians are intrigued by phenomenology, however, it is in the philosophy of mind that it is most likely to make its mark. This is in the first place because one of the primary and most successful objects of phenomenological investigation - as exemplified by Sartre's original encounter - has been our own conscious mental states. But it is not just that phenomenology devoted itself so successfully to describing the subjective character of experience; it is also that, under the influence of the linguistic turn, anglophone philosophy neglected it so much. Indeed, despite its being a central topic of fascination for modern philosophers from Descartes to Kierkegaard, it is only in the past decade or so that the mainstream contemporary English-speaking world has rediscovered the philosophical importance of subjective experience per se.
To be fair, there were notable renegades along the way. In the mid-1970s Thomas Nagel emphasized the significance of the "subjective character of experience", and in the early 1980s John Searle argued that all mental states depend upon a pre-linguistic set of "background" capacities without which they would fail to represent anything at all. In addition, there was challenging work on the phenomenological side from Hubert Dreyfus, the eminent Heidegger scholar and leader of the American phenomenologists. (I worked with both Searle and Dreyfus as a graduate student at Berkeley.) But the decisive split with the linguistic philosophy of the twentieth century didn't enter the main- stream in philosophy of mind until 1996, with David Chalmers's influential book The Conscious Mind. Although Chalmers's work itself focused principally on traditional metaphysical issues concerning the relation between the mind and the body, the ensuing enthusiasm for problems concerning consciousness and perception stimulated an interest, among some philosophers of mind, in various non-traditional problems about the phenomenology of conscious mental states. In this context the classic phenomenological texts by Husserl and such second-generation phenomenologists as Heidegger, Sartre and Maurice Merleau-Ponty have increasingly found their way onto English-speakers'desks.
So what exactly is phenomenology, and what precisely does it have to offer? It is useful to return to Sartre. What excited him so much about the prospect of phenomenology, as we saw, is that it is devoted almost entirely to describing things. Indeed, description is so central to phenomenology in all of its phases that Heidegger could say, in one of his early lecture courses, that "the phrase descriptive phenomenology is, at bottom, tautological". Description stands in contrast to all the other things a philosopher might be doing when engaging philosophically with a given domain: causal explanation, rational reconstruction, transcendental argument, conceptual analysis, theory-building, and so on. The idea behind phenomenology is that simply describing the phenomena, as completely and accurately as possible and without importing into the description unwarranted presuppositions about how the domain described is or must be, is already a devilishly difficult project. And one can see why. If one has tacit presuppositions about what the phenomena of a given domain are like - as one is bound to with any sufficiently interesting domain - then learning to separate out the phenomena as they actually are from one's presuppositions about them will require a certain kind of discipline. The commitment to this discipline was implicit in the famous battle cry of the phenomenologists: "Zu den Sachen selbst!" ("To the things themselves!"). To get a sense for phenomenological description, let us consider again the case of perception.
Recall that perception played a particularly important role in the epistemology of early modern philosophy as it was developed by Descartes, Locke, Berkeley, Hume and others. In one form or another these empiricist philosophers all believed that we get the thoughts and ideas we have about the world directly from our more fundamental sensations of it; the thoughts are simply "less forceful and vivacious" copies of the images we receive in perception. But this epistemological position carries with it an implicit phenomenological presupposition as well. In particular, the traditional empiricist view, descendants of which have continued to be influential in the twentieth century, takes perception to be the presentation of an image before the mind, an image which can later be copied and stored as an idea. In the twentieth century such an image was often called a "sense datum". Notice that the phenomenological commitment involved in sense- datum theory already goes beyond traditional linguistic-philosophical accounts of perception, since these find the central philosophical features of perception to be discoverable through pure linguistic analysis.
Linguistic philosophers such as Wittgenstein or Anscombe needn't have denied that perceptions have some phenomenological character, of course, but their linguistic technique certainly dissuaded one from focusing on its details. And indeed, one recent position in the philosophy of mind goes so far as to deny any phenomenological features to perception at all. The phenomenologist criticizes the sense-datum theory of perception, as we will see, on the grounds that it gets the phenomenology of perception wrong. But it resists the linguistic approach in a stronger sense, along with the approach that denies any phenomenological features to perception at all, for here the disagreement concerns whether description of the detailed phenomenological character has any essential role to play in a philosophical account of perception.
Sense-datum theories did take seriously the detailed phenomenological character of perception, but different theories of sense data ascribe different phenomenological attributes to them. Still, one phenomenological commitment is common to all sense- datum theories: that the distinctive phenomenological features of the visual sense datum correlate with relevant features of the physical image cast upon the retina. Consider, for example, the much-discussed case of the penny seen at an angle. Since it casts an elliptical image upon the retina, the sense datum one is presented with in the experience of a penny at an angle is said to be elliptical. As the penny rotates towards or away from the perceiver, the retinal image of the penny, and therefore the sense datum correlated with it, changes accordingly; it becomes more or less elliptical.
In addition to this phenomenological feature, sense data are traditionally taken to have epistemological attributes as well. On Bertrand Russell's famous version of the sense-datum theory, for example, one's knowledge of sense data is taken to be "incorrigible": if I take myself to be seeing a red sense datum, for example, then I am - whether or not there is a red object in the world that is correlated with it. This incorrigibility thesis tied modern sense-datum theory back to the epistemological concerns of the early modern philosophers, and much of the discussion concerning sense-datum theories in current anglophone philosophy has focused on these kinds of incorrigibility claims. But for phenomenological purposes, the relevant issue is simpler. In particular, the phenomenologist wants to know whether it is a good description of my everyday experience that when I see a penny presented at an angle I have a perception as of ellipticality.
Husserl thought not. Indeed, Husserl observed that there is an important sense in which when I see the penny presented at an angle - at least if the angle is not too acute - it looks to be round. I can, of course, get myself into the frame of mind in which it appears elliptical - by closing one eye, for example, and focusing on the object in the way one does when trying to draw it in perspective. But it takes a special effort to see the penny in this way, and it is a mistake to think that just because the image on my retina is elliptical therefore I always experience the penny that way. It is interesting to note that there may be people who do see the world in this sense-data-like way. There is some evidence, for example, that savant artists - who are able to draw incredibly detailed scenes in perfect perspective from memory - may rely upon visual images of this projective sort. And neuroscientists have argued recently that, because of a natural misalignment of the eyes, many famous painters were unable to see in stereo. But as interesting as these extreme cases may be, they are striking to us precisely because of how unusual they are. If we are interested in the everyday experience of objects by normal perceivers then, arguably at least, Husserl was right to reject the sense-datum account.
Starting from this very simple kind of example, Husserl was able to draw out a variety of increasingly detailed and wonderful observations about the phenomena of perceptual experience. He noticed, for example, that there is an important sense in which we tend to experience objects as fully three-dimensional: in particular, they look as though they extend beyond what we can see of them from here. You can start to see this by noting that nobody is surprised, when walking around a tree, to discover that it has a backside: in some sense or another our experience of the tree from the front already involves a sense of its "voluminousness". The three-dimensionality of visual experience, however, is notoriously difficult to account for on the sense-datum view. Some sense-datum theorists, like Russell, tried to reduce the experience of voluminousness to a series of beliefs that the perceiver has about the object being perceived. But Husserl was rightly keen to resist this move. After all, I could believe that an object is a mere facade (as I might when looking at the "buildings" on a movie set) but still experience it as three- dimensional.
Husserl also highlighted the temporal dimension of experience. His most famous discussion of this phenomenon began by considering the apparently simple experience of a sequence of notes in a melody. Husserl pointed out, as many had before, that the experience of the later notes in the melody takes place (in some sense or another) against the background of an experience of the earlier notes. But he went on to show that it is exceedingly difficult to describe one's current experience of the earlier notes. In particular, one cannot say, as the sense-datum theorist must, that one hears the earlier notes, or that one has them "before the mind as an auditory image". The reason is that such an account has no obvious way to distinguish between hearing the notes in sequence as a melody and hearing them simultaneously as a chord. Husserl's detailed discussion of the sense in which I "retain" the earlier notes in my current auditory experience without actually "hearing" them is deep and important. It moves beyond Kant's idea that temporal experience is a matter of synthesizing a sequence of images, and it lays the groundwork for Heidegger's existential treatment of temporality. There are many places in Husserl's oeuvre that are inviting to the student of phenomenology, but one could do worse than to begin with the lectures On the Phenomenology of the Consciousness of Internal Time (1893-1917). Husserl's fascinating discussion there could be thought of as an extended rumination on the intuition that T. S. Eliot could only gesture at in "Burnt Norton", when he wrote that "Time present and time past / Are both perhaps present in time future, / And time future contained in time past".
Despite his great talent for describing various features of experience, there were important limitations to Husserl's phenomenology that troubled the second generation of phenomenologists. His focus on objects as we experience them led to an idealistic turn in his metaphysics that was strongly resisted by many of his most prominent students. And his related view that we should be able to bracket all our presuppositions about the world in order to focus exclusively on our experience of it - a method he called the "phenomenological reduction" - was seen by many later phenomenologists as naively optimistic. Still, his voluminous output - he produced more than 40,000 pages of detailed phenomenological description - remains a rich source of ideas for philosophers today.
That said, it is important to emphasize again that the real brilliance of Husserl's work lies more in its details than in its grand scheme. Like a talented poet, Husserl at his best is capable of uncovering aspects of human experience that ring absolutely true in his description of them, even though one has never noticed them before. His special skill lies in a kind of detailed self-reflection that is committed to honesty above all else, and perhaps it is not surprising that some of the most dedicated students of his work have found in phenomenology a religious dimension of the sort one finds in Augustine's Confessions or Pascal's Pensees. It is in the experience of working through the details of phenomenology that this religious, or perhaps poetic, dimension is most easily experienced. For phenomenology done properly requires a certain attitude or stance, a kind of preparation for encountering things as they really are. Eugen Fink, Husserl's final research assistant and sometime co-author, characterized this attitude lovingly when he said that phenomenology is "wonder in the face of the world". Merleau-Ponty thought Fink's characterization was particularly evocative, and perhaps it is appropriate to conclude with Merleau-Ponty's own moving and suggestive account:
Phenomenology's task was to reveal the mystery of the world and of reason . . . . It is as painstaking as the works of Balzac, Proust, Valery, or Cezanne - by reason of the same kind of attentiveness and wonder, the same demand for awareness, the same will to seize the meaning of the world or of history as that meaning comes into being. In this way it merges into the general effort of modern thought.

Sonrisas genuinas (sonrisas Duchenne) y la percepcion de la generosidad y la sociabilidad en las caras.

El rostro humano es un sistema simbolico-semiotico que emite señales con informacion social (y no-social tambien, como pistas de salud, enfermedad...) de forma continua.

Interpretando adecuadamente estas señales podemos obtener una gran cantidad de informacion: la edad, el genero, el atractivo, el estado emocional, los deseos, las intenciones, y otros rasgos complejos de personalidad, como la confianza o la generosidad, a partir de la estructura fisica de la cara, aunque todavia desconozcamos en que estructura fisica en concreto de la cara descansa la atribucion de la confianza.

En filosofia hay un problema epistemologico y metafisico que se llama el problema de las "otras mentes".

Este problema versa sobre si es posible conocer la mente de los demas, sus estados mentales (problema epistemologico), y si en realidad hay otras mentes (problema metafisico).

Como es obvio el problema metafisico, no es verdaderamente un problema real. Como ibamos a ser nosotros los unicos que sentimos, pensamos... Hay otras personas que piensan y sienten igual que nosotros. Es un poco solipsista pensar que mas alla de nuestra mente no hay nada.

Pero el problema epistemologico todavia sigue siendo un obstaculo. No podemos conocer que es lo que realmente puede estar pensando otra persona, "leer su mente" con total exactitud y certeza. Pero por un momento piensa en lo dificl que resultaria coordinar, identificar y resolver los probelmas de un grupo o sociedad, si realmente no tuvieramos, por aproximada o cercana que fuera, una minima idea de lo que otros estan pensando: como habria evolucionado el hombre y llegado a donde ha llegado.

Para hablar un lenguaje nos tenemos que poner de acuerdo en los referentes de nuestras palabras, para cazar tenemos que coordinar nuestros movimientos y ataques, para resolver los problemas de la comunidad y crear politica tenemos que persuadir, convencer, y esto conlleva el reconocimiento de la diferencia en los intereses, para interactuar socialmente, para enamorarnos... necesitamos hacer hermenutica social constantemente.

Este es el resumen del articulo de Marc Mehu, el experto en ciencia facial Anthony C. Little, y el gran psicologo evolucionista Robin Dunbar.

Although Duchenne smiles have been shown to have a social signal value, there is
limited evidence as to whether this effect generalises to most positive attributes, or whether it is restricted to a particular social domain. As opposed to non Duchenne smiles, Duchenne smiles involve the activity of facial muscles in the eye region (orbicularis oculi). The hypothesis that Duchenne and non-Duchenne smiles produce different responses in receivers was tested in a face perception experiment. People were asked to rate neutral and smiling faces on ten attributes: attractiveness, generosity, trustworthiness, competitiveness, health, agreeableness, conscientiousness, extroversion, neuroticism, and openness to experience. Results showed that the type of smile had a stronger impact on the ratings of generosity and extroversion. The difference between neutral and smiling was larger when faces showed a Duchenne than a non-Duchenne smile, though the effect of smile type on attributions of generosity appeared to be restricted to male faces. Therefore the Duchenne marker shows some specificity to judgements of altruism and sociability.

Articulo aqui.

Cita del dia.

"Para estar bien seguros, debemos sostener lo siguiente: lo que ante mis ojos aparece como blanco, debo considerarlo negro, si la jerarquía de la Iglesia lo considera así"
-Ignacio de Loyola-

Wednesday, July 30, 2008

Antropogenia: lo que nos hace humanos.

La pregunta qué es ser humano, qué nos hace humanos, qué nos hace únicos, o nos diferencia del resto de animales, es una pregunta filosófica arcaica hundida en los albores de aquellos tiempos en los que el ser humano empezo a cuestionarse a si mismo y lo que le rodeaba.

Pero es una pregunta filosofica que esta enredada en la utopia cognitiva de las respuestas sin (dis)solucion.

Hasta ahora.

Para Aristoteles la razon o el logos (lenguaje)y la construccion del espacio social (zoon politikon) es la diferencia, para Platon la inteligencia discursiva que nos libra de las meras apariencias del mundo sensible, de la caverna donde todos estamos encadenados... Descartes penso que era la conciencia del yo, la existencia de nuestra subjetividad mental, un reino mucho mas alla de lo material.

Podriamos recorrer los distintos pasajes de la historia de la filosofia o de las ideas, y darnos cuenta que ninguna de estas respuestas es incorrecta, pero tampaco completa y suficiente, demostrandonos lo complejo que es dar una definicion ultima de lo que hace humano a un ser humano.

No obstante, la capacidad para la cooperacion (la manipulacion del mundo social en favor de nuestros intereses), el uso de herramientas (la manipulacion del mundo fisico en favor de nuestros intereses) y el lenguaje (a veces erroneamente confundido con la racionalidad. Es posible la cognicion y el pensamiento inteligente sin palabras [Bermudez 2003]) son varios fenomenos que ningun psicologo cognitivo negaria como parte de los ingredientes de la receta humana o piezas del puzzle que nos hace ser lo que somos.

El reputado glicobiologo (la glicobiologia es el estudio de los azucares y su rol en las funciones celulares) Ajit Varki tiene una fijacion por el detalle mucho mas fino y preciso que sus predecesores, y sumandose a la larga tradicion filosofica de cuestionarse los orignes del ser humano, Varki tambien nos propone qué nos hace humanos.

Lo que nos hace humanos es la ausencia de una pequeña molecula, una version del acido sialico llamada Neu5Gc. Los seres humanos tenemos otra version, la Neu5Ac.

Esta molecula pequeña es la "GRAN" responsable de que las funciones en el cerebro humano hayan evolucionado del modo en que lo han hecho, en el preciso momento en que lo hicieron y por qué.

Esta molecula esta presente en el linaje mamifero, y por supuesto en todos los primates, excepto en el ser humano moderno.

Pero en su momento, una especie de hominido si que poseyo esta molecula. La mutacion que diferencio a nuestros ancestros comunes del ser humano moderno ocurrio hace unos 2 o 3 millones de años con el H. Erectus.

Varki trabaja con el paleontologo español Juan Luis Arsuaga (miembro del equipo descubridor del H. Antecessor) en el analisis bioquimico de los restos fosiles de Atapuerca para determinar si su teoria es valida, en la medida en que si demuestran que el H. Antecessor no tenia presente esta molecula, la antropogenia (el origen del hombre) quizas se deba a esta "gran" pequeña molecula.

La unica forma de que esta molecula este presente en el organismo humano es mediante la ingesta de carne y productos lacteos.

Pero una de las terribles consecuencias para el organismo humano de tener que tomar prestado de fuera esta molecula es que de la dieta en carne y productos lacteos (rica en esta molecula Neu5gc) nos lleva a la emergencia de tumores, enfermedades cardiovasculares ,artritis, o asma.

La leccion moralizante, o moraleja, es como siempre: una de cal y otra de arena.

Gracias a la revolucion en la dieta somos lo que somos y nuestro cerebro es como es (somos lo que comemos como diria aquel)

Pero tambien nos desprotegimos, y a diferencia del chimpanze que no tiene cardiopatias o dolencias de huesos y articulaciones, nosostros si.

Recientemente, gracias a una donacion, Varki dirigira, junto a otros cientificos (entre ellos Fred H. Gage), el nuevo centro de investigacion y educacion en antropogenia (siglas en ingles CARTA para Center for Academic Research Training in Anthropogeny).

Cita del dia.

"La ideologia politica puede corromper la mente, y la ciencia"
-E.O. Wilson-

Tuesday, July 29, 2008

La historia y destino del Universo segun George F. Smoot.

Neuroimagen transcultural: la cognicion dependiente de la cultura.

Examinando las funciones cognitivas de gente europea y americana (occidentales) y gente de Korea, Japon, y China (asiaticos) los investigadores Shihui Han y Georg Northoff, han encontrado substratos neuronales dependientes de la cultura.

Utilizando un enfoque denominado "neuroimagen transcultural" estos investigadores han demostrado la dependencia cultural explicita de varios de los correlatos neuronales de la cognicion humana, es decir, el bagaje cultural influye en las funciones cognitivas de alto y bajo nivel.

Los occidentales piensan de forma analitica mientras que los asiaticos piensan de forma mas holistica.

Durante una tarea de percepcion visual los americanos fueron mejores detectando estimulos mas salientes (mas llamativos) que los asiaticos, y ademas fueron menos influenciados por informacion contextual.

Estas variaciones en la cognicion y comportamiento tambien se han observado en la cognicion social (los mecanismos cognitivos que median la interacion y el comportamiento en relacion con otros).

Por ejemplo, en un juego de interaccion social, los asiaticos mostraban estar en mejor consonancia con los deseos e intenciones de su pareja de interactuacion que los americanos.

Las variaciones cognitivas y comportamentales tambien se reflejan en la clasificacion de objetos. Los chinos organizan categorias de objetos de una forma relacional. Por ejemplo, agrupan "monos" con "bananas" porque infieren y razonan que los monos comen bananas, luego agrupan "monos" y "bananas" conjuntamente.

De nuevo, las diferencias cognitivas se han podido observar en la representacion numerica, y la autoconciencia o representacion del yo.

En este ultimo campo, psicologos sociales en sus estudios de campo han ido recopilando distintas estrategias de contruccion del "yo" en funcion de la cultura.

Por ejemplo, los asiaticos tienen una nocion del "yo" mas interdependiente mientras que los americanos una nocion del "yo" mas independiente, indivdiualista y autonoma que les lleva a construir sociedades mas comunitarias para el primer caso, y mas individualistas para el segundo.

Estos investigadores con el uso tecnicas de neuroimagen para probar las diferencias culturales en los mecanismos de la cognicion, han confirmado estas observaciones hechas por los psicologos sociales.

Los occidentales son mejores en recordar palabras que describen rasgos personales (palabras que se refeiren a ellos mismos) que palabras que describen rasgos de otras personas (aunque sean cercanos a ellos como familiares, amigos etc.)
Los asiaticos recordaban las palabras para cado caso, igual de bien.

Teniendo en cuenta todos estos resultados los investigadores prueban la existencia de correlatos neuronales de la cognicion dependientes de la cultura y los contextos socioculturales.

Y presentan un nuevo enfoque, la "neuroimagen transcultural", por el cual describen los sistemas neuronales invariantes a la cultura y los sistemas neuronales sensibles a la cultura (cómo la cultura modela la anatomia funcional de multiples niveles de procesamiento cognitivo).

Del mismo modo, aportan mas datos sobre el rol de la plasticidad en la cognicion.

Articulo aqui.

Cita del dia.

"El sentido de la vida es improbabilidad estadistica a escala colosal"
-Richard Dawkins-

Saturday, July 26, 2008

Economia y cerebro.

Via Mind Hacks.


Do economists need brains?
Jul 24th 2008 | NEW YORK
From The Economist print edition

A new school of economists is controversially turning to neuroscience to improve the dismal science

FOR all the undoubted wit of their neuroscience-inspired concept album, “Heavy Mental”—songs include “Mind-Body Problem” and “All in a Nut”—The Amygdaloids are unlikely to loom large in the annals of rock and roll. Yet when the history of economics is finally written, Joseph LeDoux, the New York band’s singer-guitarist, may deserve at least a footnote. In 1996 Mr LeDoux, who by day is a professor of neuroscience at New York University, published a book, “The Emotional Brain: The Mysterious Underpinnings of Emotional Life”, that helped to inspire what is today one of the liveliest and most controversial areas of economic research: neuroeconomics.

In the late 1990s a generation of academic economists had their eyes opened by Mr LeDoux’s and other accounts of how studies of the brain using recently developed techniques such as magnetic resonance imaging (MRI) showed that different bits of the old grey matter are associated with different sorts of emotional and decision-making activity. The amygdalas are an example. Neuroscientists have shown that these almond-shaped clusters of neurons deep inside the medial temporal lobes play a key role in the formation of emotional responses such as fear.

These new neuroeconomists saw that it might be possible to move economics away from its simplified model of rational, self-interested, utility-maximising decision-making. Instead of hypothesising about Homo economicus, they could base their research on what actually goes on inside the head of Homo sapiens.

The dismal science had already been edging in that direction thanks to behavioural economics. Since the 1980s researchers in this branch of the discipline had used insights from psychology to develop more “realistic” models of individual decision-making, in which people often did things that were not in their best interests. But neuroeconomics had the potential, some believed, to go further and to embed economics in the chemical processes taking place in the brain.

Early successes for neuroeconomists came from using neuroscience to shed light on some of the apparent flaws in H. economicus noted by the behaviouralists. One much-cited example is the “ultimatum game”, in which one player proposes a division of a sum of money between himself and a second player. The other player must either accept or reject the offer. If he rejects it, neither gets a penny.

According to standard economic theory, as long as the first player offers the second any money at all, his proposal will be accepted, because the second player prefers something to nothing. In experiments, however, behavioural economists found that the second player often turned down low offers—perhaps, they suggested, to punish the first player for proposing an unfair split.

Neuroeconomists have tried to explain this seemingly irrational behaviour by using an “active MRI”. In MRIs used in medicine the patient simply lies still during the procedure; in active MRIs, participants are expected to answer economic questions while blood flows in the brain are scrutinised to see where activity is going on while decisions are made. They found that rejecting a low offer in the ultimatum game tended to be associated with high levels of activity in the dorsal stratium, a part of the brain that neuroscience suggests is involved in reward and punishment decisions, providing some support to the behavioural theories.

As well as the ultimatum game, neuroeconomists have focused on such issues as people’s reasons for trusting one another, apparently irrational risk-taking, the relative valuation of short- and long-term costs and benefits, altruistic or charitable behaviour, and addiction. Releases of dopamine, the brain’s pleasure chemical, may indicate economic utility or value, they say. There is also growing interest in new evidence from neuroscience that tentatively suggests that two conditions of the brain compete in decision-making: a cold, objective state and a hot, emotional state in which the ability to make sensible trade-offs disappears. The potential interactions between these two brain states are ideal subjects for economic modelling.

Already, neuroeconomics is giving many economists a dopamine rush. For example, Colin Camerer of the California Institute of Technology, a leading centre of research in neuroeconomics, believes that incorporating insights from neuroscience could transform economics, by providing a much better understanding of everything from people’s reactions to advertising to decisions to go on strike.

At the same time, Mr Camerer thinks economics has the potential to improve neuroscience, for instance by introducing neuroscientists to sophisticated game theory. “The neuroscientist’s idea of a game is rock, paper, scissors, which is zero-sum, whereas economists have focused on strategic games that produce gains through collaboration.” Herbert Gintis of the Sante Fe Institute has even higher hopes that breakthroughs in neuroscience will help bring about the integration of all the behavioural sciences—economics, psychology, anthropology, sociology, political science and biology relating to human and animal behaviour—around a common, brain-based model of how people take decisions.

Mindless criticism
However, not everyone is convinced. The fiercest attack on neuroeconomics, and indeed behavioural economics, has come from two economists at Princeton University, Faruk Gul and Wolfgang Pesendorfer. In an article in 2005, “The Case for Mindless Economics”, they argued that neuroscience could not transform economics because what goes on inside the brain is irrelevant to the discipline. What matters are the decisions people take—in the jargon, their “revealed preferences”—not the process by which they reach them. For the purposes of understanding how society copes with the consequences of those decisions, the assumption of rational utility-maximisation works just fine.

But today’s neuroeconomists are not the first dismal scientists to dream of peering inside the human brain. In 1881, a few years after William Jevons argued that the functioning of the brain’s black box would not be known, Francis Edgeworth proposed the creation of a “hedonimeter”, which would measure the utility that each individual gained from his decisions. “From moment to moment the hedonimeter varies; the delicate index now flickering with the flutter of the passions, now steadied by intellectual activity, low sunk whole hours in the neighbourhood of zero, or momentarily springing up towards infinity,” he wrote, poetically for an economist.

This is “equivalent to neuroeconomics’ brain scan,” notes David Colander, an economist at Middlebury College in Vermont, in an article last year in the Journal of Economic Perspectives, “Edgeworth’s Hedonimeter and the Quest to Measure Utility”. Later economists such as Irving Fisher, Frank Ramsey (who proposed a utility-measuring machine called a “psychogalvanometer”) and Friedrich von Hayek would discuss the role of the complex inner workings of the brain. Hayek cited early advances in neuroscience to explain why each individual has a unique perspective on the world.

The reason why economists in the late 19th century and much of the 20th put the rational utility-maximising individual at the heart of their models was not that they thought that economics should avoid looking into the brain, but because they lacked the technical means to do so, says Mr Colander. “Economics became a deductive science because we didn’t have the tools to gather information inductively. Now, better statistical tools and neuroscience are opening up the possibility that economics can become an abductive science that combines elements of deductive and inductive reasoning.”

The big question now is whether the tools of neuroscience will allow economics to fulfil Edgeworth’s vision—or, if that is too much to ask, at least to be grounded in the physical reality of the brain. Studies in the first decade of neuroeconomics relied heavily on active MRI scans. Economists’ initial excitement at being able to enliven their seminars with pictures of parts of the brain lighting up in response to different experiments (so much more interesting than the usual equations) has led to a recognition of the limits of MRIs. “Curiosity about neuroscience among economists has outstripped what we have to say, for now,” admits Mr Camerer.

A standard MRI identifies activity in too large a section of the brain to support much more than loose correlations. “Blood flow is an indirect measure of what goes on in the head, a blunt instrument,” concedes Kevin McCabe, a neuroeconomist at George Mason University. Increasingly, neuroscientists are looking for clearer answers by analysing individual neurons, which is possible only with invasive techniques—such as sticking a needle into the brain. For economists, this “involves risks that clearly outweigh the benefits,” admits Mr McCabe. Most invasive brain research is carried out on rats and monkeys which, though they have similar dopamine-based incentive systems, lack the decision-making sophistication of most humans.

One new technique being used by some neuroeconomists is transcranial magnetic stimulation, in which a coil held next to the head issues a low-level magnetic pulse that temporarily disrupts activity in a certain part of the brain, to see if that changes the subject’s preferences—for example, for a particular food and how much he is willing to pay for it. However, this tool, too, has only limited applicability, as it cannot get at the central temporal node of the brain where much basic reward activity takes place.

Still, Mr Camerer is confident that neuroeconomics will deliver its first big breakthroughs within five years. Likewise, Mr McCabe sees growing sophistication in neuroeconomic research. For the past four years, a group of leading neuroeconomists and neuroscientists has met to refine questions about the brain and economic behaviour. Researchers trained in both neuroscience and economics are entering the field. They are asking more sophisticated questions than the first generation “spots on brains” experiments, says Mr McCabe, such as “how these spots would change with different economic variables.” He expects that within a few years neuroeconomics will have uncovered enough about the interactions between what goes on in people’s brains and the outside world to start to shape the public-policy agenda—though it is too early to say how.

The success of neuroeconomics need not mean that behavioural economics will inevitably triumph over an economics based on rationality. Indeed, many behavioural economists are extremely pessimistic about the chances that brain studies will deliver any useful insights, points out Mr Camerer with regret.

However, Daniel Kahneman, a Princeton University psychologist who in 2002 won the Nobel prize in economics for his contribution to behavioural economics, is an enthusiastic supporter of the new field. “In many areas of economics, it will dominate, because it works,” says Mr Kahneman.

Even so, “we are nowhere near the demise of traditional neoclassical economics,” he argues. Instead, insights from brain studies may enable orthodox economists to develop a richer definition of rationality. “These traditional economists may be more impressed by brain evidence than evidence from psychology,” he says; “when you talk about biology either in an evolutionary or physical sense, you feel they have greater comfort levels than when you start to talk about psychology.”

In this respect, Mr Kahneman’s Princeton colleagues and neuroscience-bashers may be making a mistake in bundling behavioural economics—soft mind science—and neuroeconomics—hard biology—together. “It is far easier to argue for mindless economics than for brainless economics,” he says.

Sexo y cerebro.

Hay una gran cantidad de rasgos fisicos sexualmente dimorficos en el linaje primate, incluido el ser humano, es decir, rasgos que difieren en tamaño, forma, estructura y fisiologia basica segun que sexo los posea, ademas de diferencias en comportamiento reproductivo, secrecion hormonal, habilidades espaciales, verbales para el caso del ser humano etc.

En neurociencia y otras areas de la ciencia cognitiva es un debate perenne si las diferencias sexuales existentes en la cognicion (atencion, memoria,inteligencia...) se deben a factores medioambientales o geneticos (nature/nurture)

La investigadora Elena Jazin y colaboradores de la Universidad de Uppsala han investigado las diferencias existentes en la expresion genetica de una region del cerebro fundamental para la realizacion de funciones de alto nivel, o procesos cognitivos, la corteza.

Mediante un enfoque evolutivo, comparacion interespecies de cerebros femeninos y masculinos del macaco (macaca fascicularis), titi comun (Callithrix jacchus) y ser humano (homo sapiens),los investigadores, partiendo de la hipotesis de trabajo de la existencia de diferencias en la expresion genetica sexualmente dependiente y que estas diferencias son funcionalmente relevantes y altamente conservadas en la evolucion primate, hallaron en el cerebro (de las tres especies) genes especificos envueltos en la construccion de la arquitectura funcional de la corteza.

Este patron de expresion genica viene a ser seña caracteristica de la corteza cerebral (los genes principales que muestran un dimorfismo sexual en las tres especies son el XIST y el HSBP1) y conservan un paton de expresion sexualmente dimorfico en las tres especies, no encontrandose sobreexpresado en los cerebros femeninos de dichas especies.

Este trabajo, dicen los investigadores, puede arrojar luz a la psiquiatria biologica o el estudio de los genes, moleculas y sus anormalidades vistas como responsables de los desordenes psiquiatricos, porque puede aportar datos sobre la prevalencia y susceptibilidad a padecer condiciones psiquiatricas segun el sexo.

Articulo aqui

Cita del dia.

"El cerebro humano empieza a funcionar desde el momento en que naces y nunca para hasta que te pones en pie para hablar en publico"
-George Jessel-

Friday, July 25, 2008

Pintura y cerebro.

El arte se crea a partir del cerebro. Cualquier disfuncion cerebral influye en la forma en que el artista crea su imagineria y su estilo. A lo largo de la historia de la pintura no ha habido pocos casos de artistas que padeciendo desordenes en las rutas visuales (miopia, cataratas, astigmatismo)o en el cerebro per se a consecuencia de trastornos psiquiatricos (van Gogh), su arte ha alcanzado un estilo peculiar y genuino.

Renoir, Degas, Cezanne, Pissarro, Degas, Dufy, Derain, Braque, Vlaminck, Rodin, Segonzac y Matisse eran miopes (Trevor-Roper, Patrick D. 1988).

Renoir pintaba sus cuadros con mayor detalle en aquellas partes mas cercanas a él que en aquellas mas distantes, y aunqnue esto normalmente se ha interpretado como un compromiso con el manifiesto impresionista, esto realmente se puede ver como un sintoma de miopia que ademas se agudizo con el paso del tiempo. Ademas sabemos que Renoir renego de llevar gafas o lentes toda su vida.

El Greco era astigmatico. El astigmatismo caracterizado por el aplanamiento de la curvatura de las lentes, le hizo pintar sus figuras pictoricas de forma alargada (Marmor y Ravin 1997).

Monet padecia de cataratas y se sabe que las cataratas distorsionan la percepcion del color.

Munch sufio una hemorragia interna en el ojo en 1930, y experimento con drogas para testar los limites de las imagenes, y por supuesto todo ello influyo en su arte.

La pregunta que surge para cualquier aficionado o academico de la historia del arte es: hasta que punto la estragia pictorica, el estilo o la adherencia a una escuela con un manifiesto concreto es fruto deliberado del compromiso teorico o intelectual con las ideas sobre el arte, personales o culturales del momento al que se pertenece, o es fruto de los deficits cerebrales (el componente interpretativo del arte) o visuales (el componente perceptor), en definitiva, de la estructura de tus procesos cognitivos. Mas poeticamente formulada la pregunta: el artista elige su arte, o el arte le elige a él.

La imagen es de un cuadro de Milton Avery.

Habilidad locomotora en animales y robots.

Este es el resumen de un articulo original de investigacion del profesor Auke Jan Ijspeert sobre el desarrollo de patrones centralizados de actividad neuronal oscilatoria capaces de producir patrones coordinados necesarios para la lacomocion, y como del estudio de estos mecanismos biologicos en los sistemas nerviosos de los animales se puede crear robots con propiedades locomotoras biologicamente inspirados.


The problem of controlling locomotion is an area in which neuroscience and robotics can fruitfully interact. In this article, I will review research carried out on locomotor central pattern generators (CPGs), i.e. neural circuits capable of producing coordinated patterns of high-dimensional rhythmic output signals while receiving only simple, low-dimensional, input signals. The review will first cover neurobiological observations concerning locomotor CPGs and their numerical modelling, with a special focus on vertebrates. It will then cover how CPG models implemented as neural networks or systems of coupled oscillators can be used in robotics for controlling the locomotion of articulated robots. The review also presents how robots can be used as scientific tools to obtain a better understanding of the functioning of biological CPGs. Finally, various methods for designing CPGs to control specific modes of locomotion will be briefly reviewed. In this process, I will discuss different types of CPG models, the pros and cons of using CPGs with robots, and the pros and cons of using robots as scientific tools. Open research topics both in biology and in robotics will also be discussed.

Articulo aqui.

Cita del dia.

"Por lo tanto, toda la cognicion humana comienza con las intuiciones, de ahi a los conceptos, y termina en las ideas"
-Immanuel Kant, Critica de la Razon Pura.(A702/B730)-

Thursday, July 24, 2008

Peter Bossaerts sobre la "neurofinance" o neurofinanzas.

Sistemas dinamicos, cognicion y conciencia.

Este es el resumen del articulo introductorio al libro Neurodynamics of Cognition and Consciousness de Leonid I. Perlovsky (Harvard University, University of Memphis) y Robert Kozma (US Air Force Research Laboratory, University of Memphis):


Dynamic aspects of higher cognitive functions are addressed. Dynamical neural networks with encoding in limit cycle and non-convergent attractors have gained increasing popularity in the past decade. Experimental evidence in humans and other mammalians indicates that complex neurodynamics is crucial for the emergence of higher-level intelligence and consciousness. We give an overview of research activities in the field, including dynamic models of consciousness, experiments to identify neurodynamic correlates of cognitive functions, interpretation of experimental findings, development of dynamical neural memories, and applications of dynamical approaches to intelligent system.

Articulo aqui.

Cita del dia.

"Hay billones de neuronas en nuestros cerebros, pero qué son las neuronas. Solamente celulas. El cerebro no tiene conocimiento hasta que las neuronas se conectan entre si. Todo lo que sabemos, todo lo que somos, procede de la forma de conexion de nuestras neuronas"
-Tim Berners-Lee -

Tuesday, July 22, 2008

Free will by P. Read Montague: ¿Qué es el libre albedrio (libertad)?

Current Biology, Vol 18, R584-R585, 22 July 2008

Free will
P. Read Montague

Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030, USA

What is free will?
Free will is the idea that we make choices and have thoughts independent of anything remotely resembling a physical process. Free will is the close cousin to the idea of the soul — the concept that ‘you’, your thoughts and feelings, derive from an entity that is separate and distinct from the physical mechanisms that make up your body. From this perspective, your choices are not caused by physical events, but instead emerge wholly formed from somewhere indescribable and outside the purview of physical descriptions. This implies that free will cannot have evolved by natural selection, as that would place it directly in a stream of causally connected physical events. Consequently, the idea of free will is not even in principle within reach of scientific description.
If free will is not a useful scientific concept, then how can we address the biological substrates of choice?
Instead of getting hung up on the semantics of defining free will, modern biological approaches to the problem of choice have directed their efforts toward understanding how nervous systems: (1) frame the finite choices available; (2) value the choices; and (3) choose an option based on those valuations. This is a very economic rendering of the problem, but the problem of choice for biologically evolved creatures is exactly an economic problem. Viewed this way, it's easy to see why ‘free’ choice is an unconstructive way to conceptualize the way humans choose. Real-world creatures operate on finite energetic resources and so they are never free to choose from an infinite reserve of possibilities. Moreover, even among the finite choices available, some choices are much better than others. Imagine the creature that, upon detecting a fierce predator, has a nervous system that chooses to run straight at the predator. This kind of mechanism doesn't last very long in the real world, and therefore we don't see good examples of such ‘non-escape’ behavior in creatures today.
Much of the best biological work in decision-making has been carried out in bacteria and insects because the genetics of these organisms is better understood and they provide the most physically accessible nervous systems. With the advent of modern imaging and neurophysiological techniques, however, decision-making by human and non-human primates has become a bustling area in the early stages of development. This work has focused largely on the important problem of valuation — the way that nervous systems assign differential value to available behavioral options. And it's this valuation step that appears to provide human decision-makers with an especially developed capacity — the ability to use abstract ideas to control our behavior. It is this capacity that resembles, but is not equivalent to, the older ideas about will.
Is there any mechanism or capacity in the human nervous system that resembles will?
It's well known that abstract ideas can commandeer a person's behavior and often in odd ways. For example, humans routinely go on hunger strikes based on political ideas and can inhibit their drive to take in food — even to the point of death. The capacity for abstractions to veto survival instincts can be seemingly arbitrary and the abstraction does even not have to possess any basis in reality. One need only remember the 1997 mass suicide of the Heaven's Gate cult based on the idea that there was a spaceship hiding in the tail of the comet Hale-Bopp waiting to take believers ‘to the next level’.
The ability to make choices inconsistent with survival is a potent ability to choose and one that brings potential physical danger to its possessor.
Does the capacity to make choices inconsistent with survival demonstrate that humans possess something like free choice?
The dramatic examples above appear on the surface to resemble the old philosophical idea of free will — choosing a course of action against all biological imperatives. As we illustrated above, humans do not possess the traditional notion of free choice; however, they do possess a capacity for flexible choice. One way to understand this flexibility is by hypothesizing that these ‘pathologies’ of choice represent extremes in the normal human capacity for cognitive innovation — the ability to form and pursue novel ideas not directly related to immediate survival needs.
As biological creatures, we are intimately tied to the demands for our survival — breathing, eating, procreating, avoiding trouble, and so on. Cognitive innovation requires (at least) a kind of timeout from these demands, as well as elevation of the value assigned to the innovation, that is, the new idea or behavior. To pursue some idea not directly related to survival our brains would need mechanisms to turn down the importance of survival needs and turn up the value of the idea. This hypothesis makes an important point. Our choices never were free, but they remain rather flexible and they do so by allowing abstractions to be able to commandeer our attention and behavior — at least temporarily. This capacity provides one direct conduit from the culture that we build and further allows this culture to couple rather tightly to our behavior. This is a biological process that we do not understand, but it exposes all sorts of important ramifications for our treasured social institutions — schools, laws, government, and so on.
Are there practical ways in which valuation mechanisms change a human's capacity to choose?
Yes. Consider drug addiction (choose any drug). Modern biological approaches to drug addiction have attacked the problem at numerous levels of description. We now understand a great deal about the neuroanatomy, neurophysiology, and molecular interactions that are influenced by drugs of abuse. Over the last 15 years, however, computational descriptions of reward processing systems have added another perspective to this literature. These models have identified reward-prediction error signals encoded in fluctuations in dopaminergic neuron activity in the midbrain. Midbrain dopamine systems are hijacked or perturbed by every drug of abuse and these systems are intimately tied to the way that the mammalian nervous system values choices available to it.
Such models portray addiction as valuation disease, where the nervous system over-values cues associated with drugs or drug-taking. However, there is a point here: the addicted nervous system is choosing highly valued options, a rational maneuver; but the valuation on the drug-associated cues is pathologically high. So loosely, one might see this as a diminished will — a lowered capacity to choose behavioral options not leading to drugs, but resulting from bad valuations of cues associated with drugs. The mechanisms that make the choice conditioned on the valuation appear intact. So these approaches to addiction have given us a new way to conceptualize what might have been lazily labeled a ‘lack of will’ on the part of the addict. These computational models are growing in sophistication each year and are now being used to direct physiology experiments, neuroimaging experiments, and the assessment of various therapies in this domain.
There are other conditions that can also dramatically affect a person's capacity to carry out normal value-dependent choice. Strokes, traumatic brain injury, coma, and various metabolic conditions can all influence one's capacity to value behavioral acts and mental states, and so will compromise the ability to navigate a ‘normal’ life. Often family members or even the courts must step in and decide whether to turn off life support machinery, yet without any good understanding of what functions might need to recover for this ‘normal life’ to ensue nor how they might recover nor how to make measurements related to these unidentified functions. So we have a lot to learn in this domain, but this is exactly the arena where the best science needs to inform the decision-makers. I say inform here because even once the mechanistic answers are clearer, we will still have to choose what to do with them.

How can I find out more?

[Dennett, 2003] Dennett, D. (2003). Freedom Evolves (Penguin Group: Viking Press).

[Gigerenzer, 2007] Gigerenzer, G. (2007). Gut Feelings (Penguin Group: Viking Press).

[Redish, 2004] Redish, A.D. (2004). Addiction as a computational process gone awry. Science 306, 1944-1947.

[Montague et al., 2004] Montague, P.R., Hyman, S., and Cohen, J.D. (2004). Computational roles for dopamine in behavioural control. Nature 431, 760-767.

[Dayan et al., 2006] Dayan, P., Niv, Y., Seymour, B., and Daw, N. (2006). The misbehavior of value and the discipline of the will. Neural Networks 19, 1153-1160.

[Chiu et al., 2008] Chiu, P.H., Lohrenz, T.M., and Montague, P.R. (2008). Smokers' brains compute, but ignore, a fictive error signal in a sequential investment task. Nat. Neurosci. 11, 514-520.

Cita del dia.

"Los neuroanatomistas bien cultivados, una raza espcial de gente, a menudo compulsivamente, y ocasionalmente semiparanoicamente, numeran pocas cosas en el mundo entero"
-David Hubel-

Monday, July 21, 2008

Comunicacion vocal en los peces: La evolucion del habla desde los peces hasta el ser humano.

La periodista, Lauren Gold, una de las encargadas de informar sobre las noticias cientificas dentro de la comunidad de la Universidad de Cornell, E.E.U.U., dice asi al respecto de los hallazgos del doctor Andrew Bass y colaboradores que han sido publicados en la revista Science:

"Es un largo camino desde los ronquidos del pez sapo hasta las tensiones de las arias de Puccini, o la simple melodia de Celine Dion. Pero la circuiteria neuronal que nos lleva hasta la cancion de amor humana, sin mencionar los cantos de pajaros, la rana como croa y las llamadas de emparejamiento de todo tipo de vertebrado, es muy probable que fuera establecida hace cientos de millones de años en la piscina acogedora del mar"

En el articulo publicado en la revista "Science", Andrew Bass y colaboradores han demostrado como la circuiteria neuronal del pez sapo usada para realizar vocalizaciones se desarrolla en la misma region del cerebro que hace que un ser humana ria, una rana croa, lo cual indica que la capacidad para producir y responder a sonidos se ha conservado en la linea evolutiva de los vertebrados.

Bass dice: "Los peces tienen las mismas zonas y partes cerebrales que tu"

Usando larvas del pez sapo, el grupo de investigacion trazo el desarrollo de un grupo de neuronas localizadas entre la zona posterior del cerebro y la zona anterior de la medula espinal. Esta misma parte en los vertebrados mas complejos, como los seres humanos, tiene una misma funcion,indicando que ha sido altamente selecionada durante el curso de la evolucion.

El pez sapo no es el unico que produce sonidos con significado entre los peces.

Segun Bass "Hay razones para suponer que el uso del sonido en la comunicacion social es comun en los peces".

Pincha aqui.

Cita del dia.

"Tenemos la obligacion y la responsabilidad de invertir en nuestros estudiantes y escuelas. Debemos asegurarnos que la gente que tenga sus titulos, el deseo y la voluntad, pero no el dinero, pueda conseguir la mejor educacion posible".
-Barack Obama-

Sunday, July 20, 2008

Momentos historicos en neurociencia y filosofia (neurofilosofia).

No estan todos los que son, pero son todos los que estan...

4000 a.C. son descritos los efectos euforicos de la planta de la papaveracea en textos sumerios.

4000 a.C. tablas de arcilla de mesopotamia discuten el uso del alcohol en medicina.

1700 a.C. papiro quirurgico Edwin Smith. Primer registro escrito que habla del sistema nervioso y el encefalo.

1400-1200 a.C. se desarrolla el sistema Ayurveda de medicina hindu.

500 a.C. Alcmeon de Crotona disecciona los nervios sensoriales y describe el nervio optico.

500 a.C. Empedocles sugiere que los "rayos visuales" causan la vision y formula la "teoria extromisiva" de la vision (la vision no se produce porque el ojo sea sensible a la luz sino porque el ojo emana o emite rayos de luz)

470 a.C. Socrates padre de la filosofia ateniense, maestro de Platon y principal personaje de sus Dialogos, esta interesado en entender la naturaleza humana (Gnothi Seauton-Nosce te ipsum-Conocete a ti mismo)

460-379 a.C. Hipocrates analiza la epilepsia como un desorden del cerebro, redacta el documento de practica de conducta medica mas importante de la antiguedad, y que ha llegado a nuestros dias, y afirma que es el cerebro la sede de la razon y las sensaciones.

387 a.C. Platon da clases en la Academia, discipulo de Socrates y maestro de Aristoteles, situa en el cerebro muchas de las facultades intelectivas.

335 a.C. Aristoteles uno de los grandes genios de la antiguedad y de la historia de las ideas, hijo de medico, descubridor y sistematizador de las reglas del pensamiento (logica), naturalista y botanico, escribe sobre el sueño pero situa las funciones intelectivas en el corazon (toeria cardiocentrica)

335-280 a.C. Herophilo de Calcedonia filosofo, medico y naturalista, padre de la anatomia cientifica, da nombre a la retina y a la "neurona" (vease, este post)

280 a.C. Erasistratus de Chios se da cuenta de la estructura y divisones del cerebro descubriendo las circunvoluciones y fisuras (Vease, este post)

177 Galeno descubrio que es el cerebro el organo encargado de controlar la voz, describio varios nervios craneales, y que la medula espinal inerva los musculos.

1000 Alhazen compara el ojo con una "camara".

1000 Abulcasis descubre varios procedimientos quirurgicos para tratar desordenes neurologicos.

1025 Avicena escribe sobre la vision y el ojo.

1316 Mondino de'Luzzi escribe el primer texto anatomico europeo.

1410 Primera institucion mental en la cristiandad europea (despues del Hospital Santa Maria de Belen) establecido en Valencia, España, inaugurado por el Padre Jofre. En otras palabras, el primer hospital psiquiatrico del mundo.

Siglo XVII, el cerebro es finalmente aceptado como el substrato de la vida mental mas alla de los ventriculos, espiritus animales y otros fluidos tal y como autores anteriores habian establecido.

1664 Thomas Willis publica "Cerebri Anatome" con ilustraciones del cerebro de Christopher Wren. Es el tratado anatomico mas exsahustivo hasta la fecha.

1791 Luigi Galvani revela la nauraleza electrica de las acciones nerviosas a traves de la experimentacion y estimulacion en los musculos de las extremidades de la rana.

1808 Franz Joseph Gall popone que regiones especificas del cerebro controlan funciones especificas (Frenologia)

1849 Hermann von Helmholtz mide la velocidad del impulso nervioso en la rana.

1859 Charles Darwin publica "El orgien de las Especies".

1861 Paul Broca discute la localizacion cortical de funciones cognitivas como el lenguaje.

1864 John Hughlings Jackson escribe sobre la perdida del habla tras lesiones cerebrales.

1873 Camilo Golgi publica los primeros trabajos sobre el metodo de tincion con nitrato de plata.

1877 Jean-Martin Charcot influye con su obra el curso de la ciencia neurologica.

1879 Wilhelm Wundt funda el primer laboratorio de psicologia cientifica en Leipzig.

1891 Wilhelm von Waldeyer introduce el termino "neurona" (aunque vease, este post)

1895 Wilhelm Konrad Roentgen inventa los rayos X.

1897 Charles Sherrington introduce el termino "sinapsis".

1903 Ivan Pavlov describe el reflejo condicionado como un tipo de aprendizaje.

1903 Santiago Ramon y Cajal recopila numerosos datos sugiriendo la "teoria o doctrina de la neurona" por la cual el sistema nervioso se compone de unidades funcionales genetica, histologica y anatomicamente diferenciadas.

1903 Alois Alzheimer describe la patologia del desorden neurodegenerativo que llevara su nombre.

1909 Korbinian Brodmann describe 52 areas corticlas y crea el primer mapa anatomico con clasificacion alfanumerica.

1909 Harvey Cushing es el primero en estimular la corteza sensoriomotora. Padre de la neurocirugia moderna.

1914 Henry Dale identifica la accion fisiologica de la acetilcolina que luego se demostrara que es un neurotrasmisor.

1919 Cecile Vogt identifica mas de 200 areas corticales.

1935 Constantin von Economo revisa la nomenclatura establecida por Brodman.

1938 Edgar Adrian desarrolla un metodo para registrar la actividad de neuronas indiviudales.

1940 Alan Hodgkin, Andrew Huxley y Bernard Katz explican la actividad de las neuronas a partir de la concentracion de gradiantes de iones y su flujo por los poros de las membranas celulares.

1949 Donald Hebb introduce una regla de aprendizaje sinaptico.

1930-1950 Otto Loewi, Henry Dale, Wilhelm Feldberg, Stephen Kuffler y Bernard Katz establecen las bases quimicas de la neurotrasmision.

1950 Karl von Frisch, Konrad Lorenz y Niko Tinbergen, fundan la ciencia de la etologia (el estudio del comportamiento animal en contextos naturales) y sientan las bases para la neuroetologia.

1950 John Eccles realiza los primeros experimentos sobre la sinapsis que le llevaran a ganar el Premio Nobel en 1963.

1955 Vernon Mouncastle, David Hubel y Torsten Wiesel, son pioneros en la medicion de neuronas individuales en la corteza cerebral.

1956 Rita Levi Montalcini y Stanley Cohen, aislan y purifican el "factor de crecimiento neuronal" (siglas en ingles NGF)

1957 Brenda Milner, realiza el estudio neuropsicologico mas importante sobre el paciente HM que la llevara a descubrir la importancia del lobulo temporal para la memoria.

1957 Arvid Carlsson, encuentra dopamina en el cerebro y la propone como la responsable de desordenes extrapìramidales como el Parkinson.

1960 Simples invertebrados (Drosophila, Aplysia, C. elegans) son introducidos para estudiar fenomenos neurobiologicos.

1963 Roger Sperry, propone un sistema de correspondencia quimica entre celulas (la hipotesis de la qumioafinidad)

1979 Timothy Bliss, y Terje Lomo, descubren el "long-term potentiation" (LTP)mecanismo sinaptico candidato para la memoria en los mamiferos.

1979 Se desarrolla la tomografia por emision de positrones.

1986 H. Robert Horvitz descubre los genes "Ced" criticos en la apoptosis (muerte celular programada).

1986 Segi Ogawa y colaboradores desarrollan la resonancia magenetica funcional (siglas en ingles fMRI)

1986 Mario Capecchi y Oliver Smythies desarrollan la tecnica de supresion genetica (gene knockout technology)que pronto se utilizara en neurociencia.

1998 Rod MacKinnon revela la primera imagen estructural en 3-D de un canal ionico.

2004 Richard Axel, y Linda Buck, comparten el premio Nobel en fisiologia y medicina por sus descubrimientos sobre los receptores olfativos y la organizacion del sistema olfativo.


Post inspirado de Kandel E. y Squire L. (2001), Neuroscience: Breaking down scientific barriers to the study of brain and mind. Annals of the New York Academy of Sciences, 935, 118-135.

Cita del dia.

"La educacion es el arma mas poderosa que puedes usar para cambiar el mundo"
-Nelson Mandela-

Saturday, July 19, 2008

Friday, July 18, 2008

Jonah Lehrer nos habla de Escoffier, el "quinto" sabor umami, Kanye West y la plasticidad de las neuronas dopaminergicas.


Neuromusica es un termino que puede incitar la confusion porque sus dos principales acepciones, aunque conceptualmente relacionadas, tienen significado distinto.

Por un lado, la neuromusica es la "neurociencia de la musica", o el estudio sistematico de las bases neuronales de la percepcion o ejecucion musical.

Por otro lado, la neuromusica es la musica generada a traves del interfaz directo entre un electroencefalograma y un instrmento musical unido a un programa informatico, o por decirlo de otra forma, la musica que se crea de la actividad electrica de nuestro cerebro.

La actividad electrica del cerebro humano fue por primera vez medida de forma sistematica por Hans Berger que le lllevo a desarrollar el electroencefalograma siguiendo los trabajos pioneros de Richard Caton, quien a su vez fue el primero en descubir el flujo ionico (atomos con carga electrica) a nivel intracelular y observar que este es el responsable de que el sistema nervioso tenga actividad electrica.

Los primeros intentos de generar musica a traves de la actividad electrica del cerebro (que redundancia podria pensar uno. Porque la musica convencional, tocar el piano, la flauta o el violin, es gracias a la actividad del cerebro que produce patrones o ritmos oscilatorios de alta o baja frecuencia debido a la actividad de los disparos neuronales, que permiten al musico tocar un instrumento. La neuromusica lo que hace es "tomar" directamente las ondas cerebrales para generar la musica sin que intermedie el instrumento, es decir, toma las ondas cerebrales medidas por un electroencefalograma que adquiere estas ondas las analiza y las filtra a traves de un algoritmo matematico, purifica la señal y esta es enviada a una plataforma robotica que mecanicamente "toca" el instrumento pertinente) se deben a los esfuerzos del musico experimental de origen americano Alvin Lucier que en 1965 a traves de la medicion de los ondas alfa cerebrales y con instrumentos de percusion, compuso "Music for solo performer":

Durante años muchos musicos experimentales y diversos autores han utilizado las ondas del cerebro para generar musica y algunos incluso han dado conciertos ocasionales basados en las ondas cerebrales, como es el caso de Andrew Culver.

Pero la neuromusica no se limita a la medicion de la actividad electrica del cerebro y partir de esta crear musica.

La neuromusica es toda una disciplina cientifica en si misma, que lo que estudia es el fenomeno de la capaciadad para la musica y como esta ha influido en el desarrollo de la cognicion humana. Para ello aplica la tecnologia existente y trata de investigar nuevas formas de expresion musical teniendo en cuenta el bagaje de la reflexion filosofica y humanista entorno a la musica.

Pincha aqui.

Cita del dia.

"No es de la benevolencia del carnicero, del cerevecero o del panadero por lo que esperamos nuestra cena, sino por su propio interes"
-Adam Smith-

Thursday, July 17, 2008

Neuroanecdotas y neuromitos.

Neuroanecdotas verdaderas:

Tenemos 10 elevado a la 11 neuronas ( el cerebro humano y si contaramos una neurona por segundo, tardariamos 3.171 años en contarlas.

Si extendieramos las neuronas del cerebro humano a lo largo teniendo en cuenta su forma y tamaño, tendriamos 1000 kilometros de neuronas.

La medula espinal de un hombre mide aprox. 45 cm y la de una mujer 43cm.

El cerebro humano de un adulto pesa aprox. 1 kilogramo y medio, y el cerebro de un recien nacido entre 300 y 400 gramos

Neuromitos falsos:

Solo usamos el 10% de nuestro cerebro.

El hemisferio izquierdo a diferencia del hemisferio derecho realiza funciones distintas.

Existen distintos tipos y estilos de aprendizaje.

Cita del dia.

"Tengo un sueño que mis cuatro hijos pequeños un dia vivan en un pais donde no sean juzgados por el color de su piel sino por el contenido de su caracter"
-Martin Luther King Jr.-

Wednesday, July 16, 2008

Santa Rita, Rita lo que se da no se quita: la neuroeconomia detras de la aversion a la perdida de las posesiones.

Brian Knutson y colaboradores han mostrado los mecanismos neurofisologicos del cerebro vinculados a la perdida potencial de nuestros posesiones, respondiendo a un fenomeno observado en laboratorios de economia experimental y en contextos naturales durante años:

¿por que nos cuesta tanto desprendernos de nuestras posesiones?

El fenomeno del "endowment effect", o el efecto de la posesion (una traduccion liberrima)consiste en ver como las personas prefieren lo que ya poseen en comparacion con productos similares que no poseen.

Este fenomeno esta en contradiccion con la teoria racional de la decision que arguye que las posesiones no deben influir en las preferencias y decisiones.

Brian Knutson y colaboradores usando tecnicas de neuroimagen (RMf)escanearon los cerebros de varios sujetos durante diversas condiciones diseñadas para producir el "efecto de la posesion" (endowment effect).

Los sujeots fueron instados a que compraran, vendieran, se lo dieran al experimentador, o eligieran entre otros productos y dinero en metalico.

Knutson y colaboradores advirtieron la actividad selectiva de tres regiones cerebrales durante las distintas condiciones experimentales el nucleo acumbens, asociado a la prediccion de la ganancia economica y preferencias sobre cosas, la insula, asociada a la prediccion de la perdida de ganancias economicas, y la corteza prefrontal media, implicada en la actualizacion de nuestras predicciones.

La medicion de la actividad cerebral en estas areas de los sujetos, mostro como el nucleo accumbens se activaba selectivamente durante la venta y compra de productos. La corteza media prefrontal se correlacionaba negativamente con el precio durante la compra y postivamente durante la venta. Es decir, mayor actividad de la corteza prefrontal durante la venta en contraposicion con la compra, lo que explica que la corteza prefrontal vinculada por una ingente cantidad de datos de la la literatura neurocientifica a funciones ejecutivas y la atencion, a si que como otros procesos cognitivo-motivacionales, estaba altamente activa haciendo "calculos" sobre lo que se vendia.

Al mismo tiempo, y los mas interesante segun los investigadores, la insula del hemisferio derecho indicaba diferencias individuales en la susceptibilidad al efecto de la posesion (recordemos que la insula se asocia a la prediccion de perdidas monetarias)

Las conclusiones de los investigadores es que el efecto de la posesion no se produce porque nos sintamos mas atraidos a lo que tenemos sino que nuestras posesiones aumentan el valor de la posible perdida de nuestros productos.

En palabras de Knutson y colaboradores:

"Nuestros resultados favorecen la idea de un mecanismo envuelto en el incremento de la aversion a la perdida de nuestras posesiones durante la venta de los mismos e ilustra que los metodos neurocientificos pueden hacer avanzar la teoria economica no solo por descomponer en elementos un fenomeno aparentemente unitario, como la eleccion, en componentes como la anticipacion de la perdida o ganancia, sino tambien cuando uno de estos componentes entra en juego".

Pincha aqui.

...un poquito de Rock & Roll tampoco viene mal.

Cita del dia.

"La matematica puede ser defnida como el estudio en el cual nunca sabemos de que estamos hablando y si lo que decimos es verdad"
-Bertrand Russell-

Tuesday, July 15, 2008

Horace Barlow sobre el papel de la teoria, el sentido comun y la conjetura en neurociencia.

Cita del dia.

"Creo que hay que ser valiente, enfrentarse a problemas dificiles, especialmente aquellos que al principio parecen irresolubles y desestructurados. Uno no debe tener miedo de intentar cosas nuevas como moverse de una disciplina a otra, o pensar en y desde los limites de diferentes campos de estudio, porque es en los limites donde algunos de los problemas mas interesantes residen"
-Eric Kandel-

Monday, July 14, 2008

La evolucion del ojo segun William Paley.

Charles Darwin en su obra "On the Origin of Species" dedico toda una seccion a las dificultades y problemas de su teoria de la evolucion por seleccion natural.

Entre una de esas dificultades se encontraba la observacion de la existencia de rasgos y organos de extrema perfeccion y complejidad, tales como el ojo humano.

El diseño del ojo humano, con toda su complejidad y precision, no podia ser el resultado del azar.

William Paley fue teologo y filosofo cristiano, afin a la escuela en filosofia moral conocida como Utilitarismo, ademas de profesor en Cambridge.

La obra capital de su produccion literaria (junto con "Principles of Moral and Political Philosophy") fue "Natural Theology; or, Evidences of the Existence and Attributes of the Deity. Collected from the Appeareances of Nature" publicada en 1802.

Esta obra era canonica en el curricumum de estudios de la Universidad de Cambridge, y por supuesto, Darwin que era alumno del mismo College donde Paley era catedratico, de una u otra forma tuvo que leerla.

La Teologia Natural de Paley es la obra de apologetica cristiana mas famosa y de obligada lectura para cualquier filosofo, y podriamos decir biologo, moderno. En su tiempo la "Teologia Natural" de Paley era la cumbre de la ciencia biologica basada en la idea de la creacion especial. El propio Dawkins y otros muchos biologos contemporaneos como Williams no tienen reparos en laudear esta obra y a su autor viendole como un darwinista que no ha salido del armario por ser hijo de su tiempo, o como un pre-adaptacionista, porque por primera vez alguien se maravillo de la complejidad del mundo natural y vio que requeria una explicacion muy especial; solo que Paley se equivoco apelando a la divinidad y no a la seleccion natural.

Pero esta obra canonica del pensamiento occidental tiene una tesis que hoy en dia esta lejos de estar en consonancia con la ciencia: el diseño inteligente o el argumento del diseño, y como ejemplo de ello, el ojo "organo de extrema perefeccion y complicacion" en palabras de Darwin.

Es ya un "locus clasico" las palabras de Paley cuando dice:

"In crossing a health, suppose I pitched my foot against a stone, and were asked how the stone came to be there; I might possibly answer, that, for any thing I knew to the contrary, it had lain there for ever: nor would it perhaps be very easy to show the absurdity of this answer. But suppose I had found a watch upon the ground, and it should be inquired how the watch happened to be in that place; I should hardly think of the answer which I had before given, that, for any thing I knew, the watch might have always been there. Yet why should not this answer serve for the watch as well as for the stone? why is it not as admissible in the second case, as in the first? For this reason, and for no other, viz. that, when we come to inspect the watch, we perceive (what we could not discover in the stone) that its several parts are framed and put together for a purpose, e. g. that they are so formed and adjusted as to produce motion, and that motion so regulated as to point out the hour of the day; that, if the different parts had been differently shaped from what they are, of a different size from what they are, or placed after any other manner, or in
any other order, than that in which they are placed, either no motion at all would have been carried on in the machine

Esta es la "analogia del reloj" que aplica de la naturaleza al hombre, tomando el diseño del ojo, como ejemplo palmario del proposito y diseño de la naturaleza hacia la perfeccion y prueba de la existencia de un diseñador.

No obstante hoy ya sabemos que si la Madre Naturaleza fuera realmente un gran diseñador o ingeniero, no hubiera dado lugar a una pieza como el ojo humano (que aunque realmente exquisita)esta diseñada al reves.

La estructura y anatomia del ojo humano no muestra nada de inteligencia. La luz viaja desde la cornea, las lentes, el humor vitreo, venas, celulas amacrinas, bipolares, y ganglionales, hasta los primeros receptores sensibles a la luz en la retina, situada en la parte trasera del globo ocular, para luego transducir los fotones en impulsos neuronales que seran de nuevo transportados hasta la parte trasera del cerebro, en el lobulo occipital, donde nos crearemos una imagen del mundo.

Por no decir que durante el viaje de la luz en el globo ocular debido a las venas y otros obstaculos existentes hay un punto muerto en el que no vemos nada y que el cerebro (esta vez si, gracias al ingenio de la Madre Naturaleza) tiene que rellenar (el fenomeno del Filling-in en la vision )y completar lo que falta. (Es como si la Madre Naturaleza nos diera la bolsa con los trucos para las soluciones, al mismo tiempo que crea torpenmente.)

Pero, claro, Darwin considero que el argumento de Paley era sobrecogedor y tuvo que dar concesiones en su obra, como hemos dicho al principio, por falta de conocimiento, que solo años mas tarde, la genetica y la neurociencia daria.

Pincha aqui.