Involvement of voltage-dependent calcium channels in synaptic plasticity of the rat visual cortex

In this study, involvement ofvoltage-dependent calcium channels in LTP of responses of rat visual cortex slices was analyzed. Field potentials including EPSP1 and EPSP2 from layers II/III were recorded through stimulation of layer IV. Whereas nifedipine, a L-type calcium channel blocker (L-VDCC), did not considerably affect the LTP of responses, but Ni2+, a relatively selective blocker of T-type calcium channels (T-VDCC) decreased potentiation of EPSP1 and partly blocked that of EPSP2. The effect of visual experience on the function of channels was also evaluated. The results showed that T-VDCCs mediate a transient augmentation of EPSP1, while contribute to a stable LTP of EPSP2. Whereas sensory experience influences the occurrence of LTP in field potentials, it seems to be ineffective on the role of calcium channels in synaptic plasticity. It is concluded that the T-VDCCs alone by allowing calcium influx into neurons or by sharing NMDA receptors are involved in the synaptic plasticity.