Archive for January, 2006

An online published paper by John Hyman provides a thorough criticism of two major contributors to the emergent field of neuroaesthetics, V.S. Ramachandran and Semir Zeki.

Art and Neuroscience

From the article:

I want to discuss a new area of scientific research called neuro-aesthetics, which is the study of art by neuroscientists. The most prominent champions of neuro-aesthetics are V.S. Ramachandran and Semir Zeki (fig. 1). They have both made ambitious claims about their work. Ramachandran says boldly that he has discovered ‘the key to understanding what art really is’, and that his theory of art can be tested by brain imaging experiments, although he is vague about the experimental design. And Zeki, who originally coined the term ‘neuro-aesthetics’, claims to have laid the foundations for understanding ‘the biological basis of aesthetic experience’


The main defect in the work I have discussed is that both authors propose extravagant generalizations about art – all art is caricature; all great art is ambiguous – and then discuss a small number of examples, which are chosen to illustrate the generalization they favour and not to test it. Would Zeki or Ramachandran tolerate this procedure in their own subject? I expect they’d laugh at it. How easily we shrug off our academic training when we take the brave step outside the furrows we were taught to plough!

Read the full article.

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There is a most interesting question being posed at the ABC The Science Show:

“What are the implications of the latest advances in neural prosthetics?”

THE SCIENCE SHOW with Robyn Williams – iHuman
Saturday 14 January, Midday, repeat Monday 16 January, 7pm

What are the implications of the latest advances in neural prosthetics, electronic implants and robotics for humankind? It started with attachments to the body – the watch, the hearing aid – now we are working with nerves and the brain, having the brain operate motors and activators. Combining man and machine can be used to save lives, but where does it end?

Download the mp3 file directly here (mp3 file) or get the transcript here.

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While trying to digest the overwhelming yet so short conference on Imaging Genetics in Irvine, I find myself just tapping into some of the latest headlines. This little piece in New Scientist on sexual differences in revenge sounds interesting.

From the New Scientist article:

Tania Singer of University College London and colleagues used a functional magnetic resonance imaging (fMRI) machine to analyse the brain activity of 32 volunteers after their participation in a simple game, called the Prisoner’s Dilemma.

The game allows players to cooperate or double-cross one another, and so fosters camaraderie or enmity between players. Following the game, participants were placed inside an fMRI machine and then saw their fellow players zapped with electricity. The activity in their brain was recorded as they watched.

The scans revealed changes in activity as players who had cooperated got zapped, compared with those who had double-crossed them in the game. The results suggest that men get a much bigger kick than women from seeing revenge physically exacted on someone perceived to have wronged them.

So it seems possible that there are sexual differences in how men and women choose their revenge. It does not show, however, that men are more vengeful. But they seem to react more to see their opponents being punished.

Red the full story here and visit Dr. Tania Singer’s homepage to read more.

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This year it is 150 years ago that miners in the German Neander Valley lucked upon 16 fossils that turned out to belong to a different homo species. The Neanderthals are of special interest to the study of the homo sapiens brain, being bigger in average volume, but (presumably) different in function. Since brains doesn’t fossile there are really only two ways of studying this difference: (1) through comparing the DNA of the two species, and (2) through what has been called cognitive archeology – the deduction of how the Neanderthal mind must have been organized through an examination of archeological evidence such as diet, technology and social structure.

If you happen to read German this article in Die Zeit kicks off the Neanderthal year. In July Bonn will host a big conference on the Neanderthals. Its web-site has a number of interesting papers on-line.

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Mirror neurons

On a hot summer day 15 years ago in Parma, Italy, a monkey sat in a special laboratory chair waiting for researchers to return from lunch. Thin wires had been implanted in the region of its brain involved in planning and carrying out movements.

Every time the monkey grasped and moved an object, some cells in that brain region would fire, and a monitor would register a sound: brrrrrip, brrrrrip, brrrrrip.

A graduate student entered the lab with an ice cream cone in his hand. The monkey stared at him. Then, something amazing happened: when the student raised the cone to his lips, the monitor sounded – brrrrrip, brrrrrip, brrrrrip – even though the monkey had not moved but had simply observed the student grasping the cone and moving it to his mouth.

The researchers, led by Giacomo Rizzolatti, a neuroscientist at the University of Parma, had earlier noticed the same strange phenomenon with peanuts. The same brain cells fired when the monkey watched humans or other monkeys bring peanuts to their mouths as when the monkey itself brought a peanut to its mouth.

Later, the scientists found cells that fired when the monkey broke open a peanut or heard someone break a peanut. The same thing happened with bananas, raisins and all kinds of other objects.

“It took us several years to believe what we were seeing,” Dr. Rizzolatti said in a recent interview. The monkey brain contains a special class of cells, called mirror neurons, that fire when the animal sees or hears an action and when the animal carries out the same action on its own.

By now mirror neurons is a well-known story. However, if you are not up to speed Sandra Blakeslee has a nice story in NY Times giving a short run-down of the story so far. (The quote above is from that article.) Afterwards, you will probably enjoy a visit to the homepage of the Physiology Lab at Parma University. That’s the home of many of the pricipal investigators working on the mirror neuron cells, including Giacommo Rizzolatti, Leonardo Fogassi, and Vittorio Gallese. They have a lot of their research papers on-line.

I’m chiefly mentioning this because I’m going to put up the next installment in my little series on the neurobiology of culture in a few days. (See the first part here.) Here, mirror neurons play a vital part, and you may want to get a head start!

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Hardwired Behavior

This book from Cambridge University Press looks interesting. I haven’t actually read it yet, but the new issue of Nature has a rather positive review of it. A brief passage from the review:

Laurence Tancredi’s book Hardwired Behavior powerfully presents science that shows the gross inadequacy of the binary terms we often use to talk about the genesis and character of complex human behaviours. He writes: “Our brain structures are not immutable; they are susceptible to change for the better and change for the worse.” Indeed, much of the research he discusses rests on this neuroplasticity. He reports on research showing that talk therapy can produce neuronal changes. His chapter on gender differences suggests that changing social conceptions of the roles of women “will inevitably affect the biology of their brains over time”. He reports on research showing that rats deprived of nurture at birth fail to express a gene that is correlated with their ability to handle stress. And he refers several times to a fascinating study by Avshalom Caspi and colleagues (Science 301, 386–389; 2002), which found that the likelihood of children becoming antisocial as adults is a function of both their genomes and their experiences. As Tancredi observes, this finding “emphasizes the interactive nature of genes and environment, nature and nurture”.

Tancredei, L. (2005): Hardwired Behavior. What Neuroscience Reveals About Morality. Cambridge University Press.
Publisher’s description.

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Until recently anatomists were convinced that humans are born with all the neurons they are ever going to own. In the first years of life, some of theses neurons are then pruned due to a dynamic selection process. From then on, the only serious change to the brains was thought to come from cell death or inflicted lesions.

Not so. The brain actually continues to rebuild itself throughout life. For instance, new cells are born in the hippocampus. And a new study from a group at MIT demonstrates that adult dendrites of non-pymidal neurons are able to expand their branches. Here’s the abstract:

Despite decades of evidence for functional plasticity in the adult brain, the role of structural plasticity in its manifestation remains unclear. To examine the extent of neuronal remodeling that occurs in the brain on a day-to-day basis, we used a multiphoton-based microscopy system for chronic in vivo imaging and reconstruction of entire neurons in the superficial layers of the rodent cerebral cortex. Here we show the first unambiguous evidence (to our knowledge) of dendrite growth and remodeling in adult neurons. Over a period of months, neurons could be seen extending and retracting existing branches, and in rare cases adding new branch tips. Neurons exhibiting dynamic arbor rearrangements were GABA-positive non-pyramidal interneurons, while pyramidal cells remained stable. These results are consistent with the idea that dendritic structural remodeling is a substrate for adult plasticity and they suggest that circuit rearrangement in the adult cortex is restricted by cell type–specific rules.

The paper was published in PLoS Biology which means it is open-access. Go grap it!

Lee, WCA. et al. (2006): Dynamic remodeling of dendritic arbors in GABAergic interneurons of adult visual cortex. PLoS Biol 4(2): e29.

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