Sustained Enhancement of Lateral Inhibitory Circuit Maintains Cross Modal Cortical Reorganization.

Deprivation of one modality can lead to the improvement of other intact modalities. We have previously reported that visual deprivation drives AMPA receptors into synapses from layer4 to 2/3 in the barrel cortex and sharpens functional whisker-barrel map at layer2/3 2 days after the beginning of visual deprivation. Enhanced excitatory synaptic transmission at layer4-2/3 synapses is transient and returns to the base line level a week after the beginning of visual deprivation. Here we found that sharpened whisker-barrel function is maintained at least for a week in visually deprived animals. While increased AMPA receptor-mediated synaptic transmission at layer4-2/3 synapses dropped to the base line a week after the beginning of visual deprivation, lateral inhibitory synaptic transmission onto the neighboring barrel was kept strengthened for a week of visually deprived animals. Thus, transient strengthening of excitatory synapses at layer4-2/3 in the barrel cortex could trigger the enhancement of inhibitory inputs to neighboring barrel, and sustained lateral inhibition can maintain the sharpening of whisker-barrel map in visually deprived animals.