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Archive for the ‘people’ Category

trends.jpgI am a sucker for lists, so please bear with me: In a forthcoming editorial, Shbana Rahman, the editor of the great journal Trends in Cognitive Sciences, is celebrating the ten years anniversary of TICS by printing short reflections on what has been the most “exciting discovery or theory of the past ten years” by a number of fat cats in the cognitive neurosciences: John Anderson, Nick Chater, Jon Driver, Jerry Fodor, Marc Hauser, Phil Johnson-Laird, Steven Kosslyn, Jay McClelland, George A. Miller, Lynn Nadel, Steven Pinker, Zenon Pylyshyn, Trevor Robbins, and Vincent Walsh. Naturally, there are as many different answers as people asked: the shift from computational models to probalistic models (Chater), Gergely and Csibra’s experiments on rational imitation in infants (Hauser), research on how intuitions determine judgments (Johnson-Laird), mirror neurons (Nadel), etc., etc. The funniest entry by far is Fodor’s:

What with brain imaging and neural nets, it will be a hard ten years to forget. But I’m working on it. Hopes
for the future: (i) the further erosion of attempts to apply the adaptationist paradigm to the evolution of
cognitive and linguistic phenotypes; concurrently, its replacement by an account that stresses the ‘‘hidden’’
constraints on phylogeny imposed by neurology, genetics, biochemistry, ontogeny and so forth; (ii)
the development of a serious referential/causal semantics for mental representations.

My own suggestions, just of the top of my head, would be:

(1) The rapidly growing understanding of the role played by emotions in various forms of “higher” cognition.

(2) Research on on the interplay between genes, brain processes and the environment in producing behaviour – especially development. Hopefully outdated words such as “innate” will soon dissapear from the vocabulary of cognitive neuroscientists.

(3) Decision-making. By which I mean research on making a judgment, forming preferences for possible choices, neuroeconomics, neuromarketing, and neuroethics.

What would be your choices?

-Martin

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Kandel is optimistic

kandel150.jpgThis year’s annual question at Edge was, “What are you optimistic about?”. Now, Brockman has asked Eric Kandel to outline the four neuroscience breakthroughs made in 2006 that makes him optimistic about our future possibility of understanding the brain. The first breakthrough is research into the role of microRNAs in the formation of synapses. The second is research into the encoding of external space in the hippocampus and the entorhinal cortex. Kandel’s third choice is research into social interaction, including Rebecca Saxe’s imaging studies of Theory of Mind, and Barry Dickson’s discovery that if the male form of the protein fruitless is expressed in female Drosophila, the females will display male courship behaviour. And his fourth is the possibility, through neuroimaging and other new techniques, of understanding the effects of psychotherapy on psychiatric diseases.

All four advances are clearly great causes for optimism. But maybe there are other breakthroughs worth mentioning? What about research into decision-making, or comparative genetic studies casting light on the evolution of the hominid brain? I bet that you readers have your own suggestions. Please share them with us in the comments section.

-Martin

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New books on semiotics

livstegn.jpgSemiotics, as you may or may not know, is a theory of meaning that holds that the worlds presents itself to us through signs. What is a sign? Well, in a basic sense it is the idea that some perceived part of the physical reality surrounding us – let us call this a “signifier” – acquires meaning by being coupled with some mental content; let us call this latter thing the “signified”. In other words, a sign is a function between a signifier and a signified. Take the word “dog”. As you read this word here on your computer screen, the visual input is related to a certain semantic category. As it so happens this semantic category can also be accessed by other signifiers, for instance the French word “chien”, or the Danish “hund”. In order to understand the meaning of “dog”, “chien”, or “hund” you have to know the rules linking signifier with signified.A basic problem in semiotics is how such rules arise and how they are instantiated. A particular branch of semiotics argues that rules are completely arbitrary and the product of social negotiation. That the signifier “dog” signifies a specific semantic category is due to the fact that some group of people collectively have decided to employ this semiotic rule. On the other hand, another group of semioticians argues that such rules are grounded in a basic isomorphism between the forms of the perceived world and our conceptual system. This “ground” is the very prerequisite for the formation of semiotic rules in the first place. How else would they get off the ground?

Unfortunately, there has not been a great interest among semiticians to test these assumptions through neuroscientific research. Roman Jakobson, one of the greatest semioticians of the 2oth Century, a few years before his death, said that had he been a young man he would have turned to neuroscience. To date, almost no semiotician has heeded this call.

On this note, let me mention two new semiotics publications. The first is an encyclopedia called Livstegn, written by 49 Danish researcers. (Sorry, this book is only available in Danish!) I contributed the entry on “neuroaesthetics”. Curiously it contains two entries on “neurosemiotics”. Curiously because, as I just wrote, there hardly exists any semiotic research taking its departure from neuroscience.

The second book is Frederik Stjernfelt‘s Diagrammatology, the first monograph to really consider the Peircean concept of “the diagram”. (This book is in English and is published by Springer, so everybody should be able to both get it and read it!) The interesting part about Stjernfelt’s book is that he relates Peirce’s idea of the diagram to both Husserlian phenomenology and modern cognitive linguistics – hence integrating a rather obscure semiotic concept into current discussions in cognitive science. I also know that Stjernfelt is interested in looking into the neurobiology of diagrams.

-Martin

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pamuk.jpgA lot of our fellow science bloggers covered this year’s Nobel Prizes in medicine, physics, and economics. So, let me take the opportunity to congratulate Orhan Pamuk, the recipient of this year’s literary prize. The literary prize is often critized for being controversial, and most people agree that not all the recipients over the years have deserved the prize (Pearl S. Buck, anyone?). The criteria for awarding the literary prize is very different from the criteria for awarding the scientific prizes, though. Whereas it is possible to meassure a scientist’s contribution more or less objectively, according to how accepted his findings are, over time, to the scientific community, literary prizes are awarded for the perceived aesthetic value of a book, and aesthetic value is always in the eye of the beholder. We know this not only from the countless top ten lists floating around on the internet, invariably different!, but also from a century of experimental testing. It is simply impossible to find a work of art universally adored by all humans on this planet. (There might be some universal body features, such as facial traits, deemed pleasant or attractive by everybody, but that’s another story.)

Why is this so? Well, a number of imaging studies have begun to cast light on which parts of the brain are involved in attaching aesthetic value to works of art. It turns out that aesthetic value chiefly stems from a network of subcortical, limbic and frontal regions, including the caudate nucleus, amygdala, nucleus accumbens, insula, orbitofrontal cortex, and anterior cingulate cortex. The workings of these structures may be under influence of several factors: personality (cf. the Hariri studies we have been discussing here on the blog), expertise, mood, age, task, stimulus complexity – and, of course, cognitive factors may modulate them in various ways. We don’t know yet how aesthetic values are formed in detail – and, thus, we don’t know yet why people’s taste differ – but the upshot of  the current research is, that a particular aesthetic judgment (Orhan Pamuk is Nobel material!) is the consequence of a rather complex neural process, malleable over time.

Then, why should we give out literary prizes? Some critics have lamented that, since aesthetic values really can’t be determined objectively, aesthetic prizes is really an attempt to impose value. I suppose there is something correct about this view; we fight all the more over aesthetic value because it can’t be settled objectively. This is not always a bad thing, though. As the saying goes, a big prize may attract attention to an underappreciated author or artist. So literary prizes may have a function, even if they are basically without merit. At least, since I think Pamuk is a great novelist, I am happy that he got the Nobel!

A final word on aesthetic value. Many of today’s articles mention Snow as Pamuk’s chef d’oevre, probably because of its political content. To new readers, though, I would recommend starting with The Black Book and My Name is Red. These two books are, according to my reward system, Pamuk’s undisputable masterpieces!

-Martin

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300px-us10dollarbillnew.JPGThe September 18 issue of The New Yorker contains a short introduction to neuroeconomics. It is a nice enough article without to many obvious errors (the fact that the author attributes the striatum to the limbic system instead of to the basal ganglia is probably only of concequence to anatomists!). It tells the now familiar story of how the classical view of homo economicus has been challenged by the experimental work of Kahneman, Tversky and other members of the so-called behavioural economics field. It then goes through some of the recent imaging experiments on risk aversion, punishment of unfair collaborators, and trust, with quotes from several of the key neuroeconomics players: Colin Camerer, George Loewenstein, David Laibson, Jonathan Cohen, Ernst Fehr, and Paul Glimcher.

To people already acquainted with the field the most interesting parts of the article is probably a section where Laibson and Cohen ponders possible policy implications of neuroeconomics research, and a section where Cohen and Glimcher are reported to nurture opposing views of how “emotion” and “cognition” interacts in decision-making situations. Briefly, Cohen views emotion and cognition as two separate systems that may at times “compete” for control, whereas Glimcher disputes such a clear-cut separation. Personally, I would have loved to hear more about this issue.

Here are two links to some earlier posts on neuroeconomics:

Risk aversion is rewarding!

Neurofinance

-Martin

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Follies of the wise

Frederick Crews‘ new book, with the rather brilliant title Follies of the Wise (Shoemaker and Hoard), appears to be the perfect christmas gift for those friends of yours who work in the humanities!

Jerry Coyne has a nice review of it in The Times Literary Supplement.

-Martin

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Research on the neurocognitive mechanisms underlying human production and experiece of music is one of most rapidly expanding subfields of contemporary neuroscience. You may recall that back in May I noted that both the Annals of the New York Academy of Sciences and Cognition recently has published newly edited special issues on this topic.

A new book by Daniel Livitin, an investigator at the department of psychology at McGill University (and former music producer), presents parts of this exiting research to the general public: This is Your Brain on Music (Dutton 2006). As a teaser, you may first want to hear an interview with Livitin on NPR, which you can find here.

Canada is in many ways the current epicenter of neuromusicology research. Isabelle Peretz, at the University of Montréal, and Robert Zatorre, also at McGill, are perceived by most to be the leaders of the field. Recently, Peretz and Zatorre have established a brand new center for research into the biological foundations of music called BRAMS (Brain, Music and Sound), which is scheduled to host no less than “a core group of seven faculty together with two to three positions for junior investigators, as well as 10 postdoctoral fellows and 20 graduate students,” according to its website. But neuromusicology is also booming in Europe. Starting this year, a project called “Tuning the Brain for Music”, and funded by the EU, will draw together researchers at universities in Finland, Germany, Sweden, Italy, and Canada (again!) in an attempt to “gain a deeper insight into the relationship between music, emotions and brain functions”.

Much of the interest in the neural underpinnings of music stems from a deep-seated interest in the evolutionary origins of music – as this recent article from The Boston Globe testifies. Many deeply speculative hypotheses have been advanced as to why homo sapiens has evolved this curious passion for music. However, in recent years more serious papers considering this question have also been appearing, integrating data from comparative studies in animal cognition, neuroscience, and genetics. Let me especially recommend these two papers:

-Martin

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Jamie Ward on podcast

Cognitive Neuroscience Arena has an excellent interview with Jamie Ward related to his book The student’s guide to cognitive neuroscience. You can either listen to it directly on the webpage, or you can download it from the podcast url using your favourite podcast software.

From the CNA website:

Dr Jamie Ward is a Senior Lecturer at the Department of Psychology, University College London and has researched and taught extensively in many areas of cognitive neuroscience.

He is a leading authority on the subject of synaesthesia and has contributed to a wider understanding of it in both academic and lay circles.

In this podcast we talk to Jamie Ward about the development of cognitive neuroscience, its portrayal in the media, his textbook The Student’s Guide to Cognitive Neuroscience, and the recent debate on the usefulness (or seductiveness!) of the “flickering lights” of fMRI.

This 22 minute interview serves as a general introduction to the subject of Cognitive Neuroscience, and we have released it free of charge on a Creative Commons licence so that professors and lecturers are free to copy & redistribute it on their university’s network/website for the use of their students, or to play it during a lecture.

-Thomas

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Avshalom Caspi and Terrie Moffitt [interview with Moffitt here on npr] made quite a splash in 2002 when they published the paper “Role of Genotype in the Cycle of Violence in Maltreated Children” in Science. They reported that maltreated children would differ in the development of antisocial personality and violent behaviour depending upon whether or not their genotype conferred high or low levels of MAOA expression, a neurotransmitter-metabolizing enzyme. Thus, Caspi and Moffitt showed that a genetic variation may moderate the influence of environmental factors on behaviour in a rather dramatic manner, fueling the growing suspicion that the old nature/nurture dichotomy is much too simplistic. Behaviour is most probably not determined by either an innate genetic Bauplan or the ever changing forces of our surroundings. In Caspi and Moffitt’s study, at least, children with a low-level MAOA genotype only developed an antisocial personality if maltreated (if you happen not to be maltreated, a low-level MAOA polymorphism will not cause you to develop an antisocial personality); but, at the same time, maltreatment doesn’t affect children with a high-level MAOA polymorphism, so the maltreatment is not a cause in itself either. Genes and environmental factors interact to produce behaviour, and the real question is how they do so.

In the July issue of Nature Reviews Neuroscience Caspi and Moffitt discuss some important implications of their research. First of all, if you wish to understand how external pathogens can influence the brain, as is all-important for psychiatric treatment, you have to factor in the individual person’s genetic make-up. The ability of environmental factors to alter the nervous system and generate a disordered mind variates with genetic differences at the DNA sequence level. Say Caspi and Moffitt:

Heterogeneity of response characterizes all known environmental risk factorsfor psychopathology, including even the most overwhelming of traumas. Such response heterogeneity is associated with pre-existing individual differences in temperament, personality, cognition and autonomic physiology, all of which are known to be under genetic influence16. The hypothesis of genetic moderation implies that differences between individuals, originating in the DNA sequence, bring about differences between individuals in their resilience or vulnerability to the environmental causes of many pathological conditions of the mind and body.

Secondly, to really understand this interaction of genes and environmental risk factors and pathogens, more epidemiological cohort studies must integrate neuroscience measurements. As Caspi and Moffitt observe:

First, evidence is needed about which neural substrate is involved in the disorder. Second, evidence is
needed that an environmental cause of the disorder has effects on variables indexing the same neural substrate. Third, evidence is needed that a candidate gene has functional effects on variables indexing that same neural substrate. It is this convergence of environmental and genotypic effects within the same neural substrate that allows for the possibility of gene–environment interactions. At present, such evidence concerning environmental and genotypic effects in relation to neural substrate measures is sparse, and therefore gene–environment interaction hypotheses are likely to be circumstantial at best, and flimsy at worst. But this situation is steadily improving. When we were constructing our hypothesis regarding the genetic moderation of the depressogenic effects of stressful life events, we were aided by direct evidence linking the 5-HTT candidate gene to individual differences in physiological responsiveness to stress conditions in three different experimental paradigms, including knockout mice, stress-reared rhesus macaques and human functional brain imaging.

Of course, imaging genomics studies, such as those by Hariri and Weinberger, or Meyer-Lindenberg, give a good idea of how genetics, brain activity and behaviour can be related to each other, using avant-garde research techniques.

Finally, both perhaps most intriguing, Caspi and Moffitt suggest that findings such as theirs indicate that genes react to environmental influences more than cause brain activity and behaviour. This stance is captured in a quote like this one:

[The] gene–environment interaction approach differs fundamentally from the ‘main-effect approaches’,
with regard to the assumptions about the causes of psychiatric disorders. Main effect approaches assume that genes cause disorder, an assumption carried forward from early work that identified single-gene causes of rare Mendelian conditions. By contrast, the gene–environment interaction approach assumes that environmental
pathogens cause disorder, and that genes influence susceptibility to pathogens. In contrast to main-effect studies, there is no necessary expectation of a direct gene-to-behaviour association in the absence of the environmental pathogen.

Clearly, as such experimental work in greater detail furnish us with a more precise view of genes build the molecular structure of the brain, and how these structures underlie behaviour, we will also become better suited to settle long standing philosophical issues, such as what innateness actually is.

Reference

Caspi, A. & Moffitt, T. (2006): Gene-environment interactions in psychiatry: joining forces with neuroscience. Nature Reviews Neuroscience 7: 583-590.

-Martin

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