( st independently in different lineages ...)How many genes does it take to learn? Lessons from sea slugs

Until now, scientists have been largely in the dark about how genes control the generation of specific brain circuitry and how genes modify that circuitry to enable learning and memory. For that matter, little is known about the genes that distinguish one neuron from the next, even though they may function quite differently.

Molecular analyses of Aplysia neuronal genes are shedding light on these elusive processes. In 2000, senior author Eric Kandel, M.D., of Columbia University in New York shared the Nobel Prize in Physiology or Medicine for his work using Aplysia as a model of how memories are formed in the human brain.

Despite its simple nervous system - Aplysia has about 10,000 large neurons that can be easily identified, compared with about one hundred billion neurons in humans - the animal is capable of learning and its brain cells communicate in many ways identical to human neural communication.

In the new findings, scientists identified more than 175,000 gene tags useful for understanding brain functions, increasing by more than 100 times the amount of genomic information available for study, according to Moroz and 22 other researchers from UF and Columbia University. More than half of the genes have clear counterparts in humans and can be linked to a defined neuronal circuitry, including a simple memory-forming network.

"In the human brain there are a hundred billion neurons, each expressing at least 18,000 genes, and the level of expression of each gene is different," said Moroz, who is affiliated with UF's Evelyn F. and William L. McKnight Brain Institute and the UF Genetics Institute. "Understanding individual genes or proteins is important, but this is a sort of molecular alphabet. This helps us learn the molecular grammar, or a set of rules that can control orchestrated activity of multiple genes in specific neurons. If we are going t
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Source:University of Florida