Effects of visual deprivation on synaptic plasticity of visual cortex

  TBS (Theta Burst Stimulation) and PBs (Primed Bursts) are among effective tetanic stimulations for induction of LTP in hippocampus. Recent studies have indicated that TBS is effective in LTP induction in layer III synapses of neocortex, only if applied to layer IV. However, the possibility of neocortical LTP induction using PBs, has not yet been investigated. Sensory deprivation greatly influences the development of neocortex. Based on the effect of sensory deprivation on synaptic plasticity of developing neocortex, the induction of LTP by PBs in visual cortical slices of control and dark-reared rats, was studied. Results obtained show that application of PBs to layer IV, could effectively induce LTP. Field potential recordings consisted of two components pEPSPl and pEPSP2. In most cases PBs lead to selective potentiation of pEPSP2. Visual deprivation increased the incidence of LTP of pEPSP2 and also increased the incidence of LTD of pEPSP2. These findings show that PBs could be used as an effective tetanic stimulation to study the synaptic plasticity in neocortex. The effects of visual deprivation on LTP/LTD are consistent with its role on the development of NMDA system in neocortex.