The Corpus Callosum

The title of this post is taken from the title of a USC press release, about a topic in neuroscience.  A guy at USC named Irving Biederman is studying the role of opioid (enkephalin) activity in visual perception.

Actually, the title of this post is misleading.  His research is not about beauty.  Rather, it is about recognition, salience and learning.  


In order to understand his theory, it helps to be able to see the brain regions and pathways involved.  Fortunately, there is a nice diagram here. (Open the page, then click on the link by the little diagram in order to see the enlarged diagram.  Ignore the warning about not having access; the diagram will still open.)  

In a nutshell, what he found is that the areas of the brain that process visual information contain mu-opioid receptors.  The most posterior occipital regions have a relatively low density.  That is where the visual information is first processed.

After the initial processing, the information is shuttled to successive areas, moving anteriorly.  As the processing becomes more sophisticated, the density of opioid receptors increases.  

The first areas take the information from the retina and figure out simple things, such as shape and color.  There's not very much opioid activity there.  The next step in processing, is to take the shape/color information and decipher that, to recognize objects and places.  There is more opioid activity there.

Once the brain figures out what it is seeing, the next step is to associate the images with memories.  That is where the brain figures out what the images mean.  

Biederman's hypothesis is that the release of these endogenous opioids is somewhat pleasurable, and that we get more pleasure from looking at things that we are able to place in some kind of meaningful context.  

He extends this hypothesis, going on to speculate that the involvement of opioid activity can explain why novel stimuli are more interesting than overly-familiar ones.  

Biederman said this theory also explains our taste for novelty and why conversely, familiarity breeds contempt. It rests on an additional principle of brain organization called "competitive learning" - the fact that as the cortex gets more familiar with something, it uses fewer cells to "encode," or represent it.

Something novel activates large swaths of the cortex, firing lots of pleasure cells and making a strong bid for our awareness. But as we experience the thing more, fewer cells are devoted to representing it. This results in fewer pleasure cells firing and a consequent lessening of its tug on our conscious attention.

Biederman's theory has a number of other interesting ramifications, such as why we find fast-cutting sequences on MTV and Sesame Street pleasurable: So long as they aren't incoherent, they up the rate at which the association areas are getting stimulated.

So Beiderman's hypothesis explains why some things look more interesting than others.  Now, what I want to know is this: why is neuroscience research more interesting than all other areas of research?