Primed-bursts induced long-term potentiation in rat visual cortex: effectsof dark-rearing

Theta burst stimulation (TBS) and primed bursts (PBs) stimulation ari:among the effective tetanic stimulations for induction of long-term potentiation (LTP) in the hippocampus. Recent studies have indicated that TBS is effect ive in LTP induction of layer III synapses of neocortex, only if applied to layer IV. However, the possibility of neocortical LTP induction using PBs has not been investigated yet. Sensory deprivation greatly influences the d evelopment of neocortex. According to the effect of sensory deprivation on synaptic plasticity of developing neocortex, we studied the induction of LT P by PBs in visual cortical slices of control and dark-reared rats. The res ults showed that application of PBs to layer IV could effectively induce LT P of layer II/III field potentials. These potentials are consisted of two c omponents: pEPSP(1) (population excitatory postsynaptic potential 1) and pE PSP(2), In control slices PBs led to selective potentiation of pEPSP(2). Vi sual deprivation increased the incidence of LTP of pEPSP(1) and decreased t he amount of LTP of pEPSP(2). These findings showed that PBs could be used as an effective tetanic stimulation to study the synaptic plasticity in neo cortex. The effects of visual deprivation on PBs-induced LTP are consistent with its role in the development of excitatory system in neocortex. (C) 19 99 Published by Elsevier Science B.V. All rights reserved.