Regulation mechanism of synaptic input to Purkinje cell and LTD

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In order to test the hypothesis Concerning the elementary mechanisms of long term depression of cerebellar Purkinje cells, the patch clamp experiment was conducted together with a non-stationary noise analysis and a computer simulation of excitatory postsynaptic currents recorder from somata of Purkinje cells. The obtained results were (1) The contribution of change in kinetics of AMPA receptor channels to the reduction of the amplitudes of EPSCs was small. (2) No change in single channel conductance of AMPA receptor channels was observed during LTD.(3) By using computer simulation, it was concluded that a reduction in affinity of glutamate to receptors causes LTD and that open probability of receptor channels decreased during LTD.(4) Taken together above results, it was suggested that LTD could be induced as the result of the possible decrease in the number of the active receptor channels in the postsynaptic membrane at the peak of excitatory postsynaptic currents.The present result was obtained for the first time in LTD of Purkinje cell and was unique and important suggestions for the research field of cerebellar cortex. During the course of this experiment, it was necessary to record stable signals from a cell in the deep layer of a slice preparation, so that a newly developed Infrared DIG video microscope was designed for this purpose.