Experience-dependent plasticity of rat barrel cortex: Redistribution of activity across barrel-columns

The redistribution of neuronal activity across rat barrel cortex following an alteration in whisker usage has been investigated. In adult rats, two my stacial vibrissae - D-2 and one neighbor, D-1 or D-3 - were left intact whi le all other vibrissae on that side of the snout were clipped. Neurons in c ontralateral barrel cortex were sampled with a microelectrode array 3.5 day s later. Stimulation of clipped vibrissae produced a narrow spatial distrib ution of cortical activity, whereas stimulation of intact vibrissae produce d a widened spatial distribution. Simultaneous recordings from multiple cor tical barrel-columns suggest that changes in the effective connectivity bet ween barrel-columns may partially account for this redistribution of sensor y responses. Evidence is also presented for a second mechanism, a release f rom inhibition in sensory-deprived cortical areas, A model is therefore pro posed where these two mechanisms operate together to regulate the cortical distribution of evoked activity.