Brain weight differences associated with induced focal microgyria

BACKGROUND: Disrupting neural migration with bilateral focal freezing necrosis on postnatal day 1 (P1) results in the formation of 4-layered microgyria. This developmental injury triggers a pervasive neural reorganization, which is evident at the electrophysiological, behavioral, and anatomical levels. In this experiment, we investigated changes in brain weight as an index of global disruption of neural systems caused by focal damage to the developing cortical plate. RESULTS: We found a dramatic reduction in overall brain weight in microgyric subjects. This reduction in brain weight among animals with microgyria is reflected in decreased total brain volume, with a disproportionate decrease in neocortical volume. This effect is so robust that it is seen across varied environments, at variable ages, and across the sexes. CONCLUSIONS: This finding supports previous work suggesting that substantial reorganization of the brain is triggered by the induction of bilateral freezing damage. These results have critical implications for the profound re-organizational effects of relatively small focal injuries early in development to distributed systems throughout the brain, and particularly in the cerebral cortex.