Munc13-3 mutation prevents critical period neuronal plasticity in visual cortex

MUNC13-3 MUTATION PREVENTS CRITICAL PERIOD NEURONAL PLASTICITY IN VISUAL CORTEX James G. Morris July 30, 2010 Through differential display PCR, Munc13-3 was identified as a gene whose relative expression in the visual cortex corresponds to critical period plasticity. Expression of the gene was low at the peak of the critical period and expression was high in the weeks near the end of the critical period. Expression of the gene also shifted during dark rearing, a process known to delay the time course of the critical period. Using electrophysiology and monocular deprivation (MD) in mice at different points within the critical period, it is possible to compare normal MD mice's visual evoked potentials to Munc13-3 mutant MD mice's visual evoked potentials to see what effect Muncl3-3 has on visual cortical plasticity. Visual evoked potentials from the eyes contralateral and ipsilateral to the recording electrode in the binocular region of the visual cortex were stimulated and recorded in normal wildtype mice, monocular deprived mice and monocular deprived Muncl3-3 mutants at ages 3.5 weeks and 9 weeks. At 3.5 weeks age the normal wildtype mice showed a large contralateral and smaller ipsilateral response, monocular deprived mice showed the same size ipsilateral (non-deprived eye) response, but a smaller contralateral (deprived eye) response. The monocular deprived Munc13-3 mutant mice showed the same as the normal mouse, large contralateral (deprived eye) response and