Research Overview
What regulates brain size? When it comes to brains, size matters. Humans possess an impressive repertoire of mental skills such as the abilities to read, write, and solve intricate problems. These skills are made possible by the cerebral cortex, the thin, layered sheet of neurons on the surface of the brain that underlies our most complex cognitive abilities. Although all mammals have cerebral cortices, the cerebral cortex in primates, especially that of humans, has undergone a vast expansion in size during evolution, and the increase in the size of the cerebral cortex is thought to underlie the growth of intellectual capacity. Despite many hypotheses about how brain size is regulated, few have been tested experimentally.
We are interested in the factors that regulate the production and differentiation of neurons in the brain. The increased size of the cerebral cortex during evolution results primarily from a disproportional expansion of its surface area, with the appearance of folds of the cortical surface (with hills known as gyri and intervening valleys called sulci) providing a means to increase the total cortical area in a given skull volume. This expansion of the length and breadth of cerebral cortex is not accompanied by a comparable increase in cortical thickness; in fact, the one thousand fold increase in cortical surface area between human and mouse is only accompanied by an approximate two fold increase in cortical thickness.
