Mapping the Brain's 'Symphony'

At his new blog, NIH Director Francis Collins discusses the Human Connectome Project.

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According to Dr. Francis

According to Dr. Francis Collins' blog, he claims that "the Human Connectome Project, has set out to map the brain’s neural connections in their ENTIRETY." This sounds like a program that is rather akin to sequencing the "human genome", but is in fact several orders of magnitude more challenging. While there are about 2.9 billion base pairs in the "human genome," the number of neural connections in the adult human brain are in the order of 100 to 500 trillion. It is becoming apparent that individual human genomes may differ with more than 50 million single nucleotide polymorphisms and mutations. The variation in the connectivity of nervous system is highly likely to be vastly more extensive as the environment has a huge impact on brain development and fine structure. As a very plastic organ, whole regions of the brain can wane and expand depending on the sensory inputs, nutrition and exposure to toxic substances.

While I do not criticize, but rather applaud the efforts of scientists to carefully investigate the architecture of the brain down to the level of intercellular connections and deeper, I do think that better care needs to be taken by very public officials such as Dr. Collins about accurately describing the fruits and challenges associated with these kind of programs.

It is intriguing that with the sequencing of the first human genome over a decade ago, led by in large part by Dr. Collins, the functions of about 40% of the genes encoded by less than 3% of the DNA in the genome were unknown. More than 10 years later, the roles and regulation of most of the proteins specified by these "dark" genes still remain obscure. Yet there are now wild claims widely propagated by at least some members of the ENCODE Project that as much as 80% of the entire human genome sequence is important and functional.

It seems to me that the objective of deducing the connections of all of the neuronal connections is like identifying all of the types and placements of trees, shrubs and plants in a vast forest. There are clearly underlying principles at work that influence the general composition and arrangement of the vegetation in a forest and how it functions as an ecosystem. However, when you view more forests over the surface of the planet, it is clear that no two forests are the same despite their initial similarities when viewed from 30,000 feet above. Such an analogy applies to our understanding of the human brain where clearly there are significant differences in cognitive abilities amongst the general population.