Relative Contribution of Feedforward Excitatory Connections to Expression of Ocular Dominance Plasticity in Layer 4 of Visual Cortex

SummaryBrief monocular deprivation (MD) shifts ocular dominance (OD) in primary visual cortex by causing depression of responses to the deprived eye. Here we address the extent to which the shift is expressed by a modification of excitatory synaptic transmission. An OD shift was first induced with 3 days of MD, and then the influences of intracortical polysynaptic inhibitory and excitatory synapses were pharmacologically removed, leaving only “feedforward” thalamocortical synaptic currents. The results show that the rapid OD shift following MD is strongly expressed at the level of thalamocortical synaptic transmission.

► Changes in thalamocortical transmission support deprived-eye depression after MD
► This change can fully account for the magnitude of the observed OD shift
► Thalamocortical synaptic plasticity is more rapid than previously believed