Friday, July 4, 2014

Human connectome project: lessons from genetics

The number of genes separating humans and other primate is fewer than previously thought and in fact very small. See this piece.  What this means is that phenotypical differences are not primarily a function of protein coding genes themselves:
"The physiological and developmental differences between primates are likely to be caused by gene regulation rather than by differences in the basic functions of the proteins in question."
 I think this is an important lesson for the massive effort(s) to map the structure of the human brain (e.g., connectome project, BRAIN Initiative, etc.).  I support this effort, of course.  It will provide invaluable data and is absolutely necessary.  But I think once complete we will be in a place quite similar to where we are in genetics: Human Genome Sequence--check.  Understanding how to build a human--not even close.

MIT's Sebastian Seung likes to say, "I am my connectome."  I think the connectome will turn out to be something like the genome: fairly generic foundation on which all of the really interesting stuff is built.  In short, mapping the connectome isn't going to tell us how to build a brain, unfortunately.  


William Matchin said...

This has been proven in the case of the nematode - 400 neurons, completely mapped out, and we have no clue how it does what it does.

David Poeppel said...

There was a debate about this at Columbia in 2012, between Sebastian Seung from MIT and Tony Movshon from NYU. I must say that I found my NYU colleague rather more compelling (although Seung makes the edgier sartorial choices ...)

David Poeppel said...

Just to finish the/a thought on this: A map - even a comprehensive one - is not equivalent to an explanation, and certainly not a story about mechanism and function. However ... it seems like wanting to generate a spatial map of phenomena is innate. No matter what field of study one looks, maps are taken to be the key feature. In an older paper I called this the "cartographic imperative" (borrowing shamelessly from Kant).

Poeppel, D. (2012). The maps problem and the mapping problem: Two challenges for a cognitive neuroscience of speech and language. Cogn Neuropsychol, 29(1-2):34-55.

I submit that map-making is innate (but only a small part of any answer) just as empiricism is innate (but wrong) and dualism is innate (but wrong) - here probably stealing from Fodor or someone like that.