LONG-TERM DEPRESSION OF IPSPS IN RAT DEEP CEREBELLAR NUCLEI

STIMULATION of the white matter between the cerebellar cortex and the deep cerebellar nuclei in rat cerebellar slices, evoked inhibitory pos tsynaptic potentials (IPSPs) in deep nuclear neurones. These IPSPs had reversal potentials close to - 75 mV and were blocked by picrotoxinin . Stable IPSPs were evoked when the white matter was stimulated at 0.0 33 Hz; however, at frequencies > 0.2 Hz, the synaptic transient was su ppressed. Paired-pulse depression of the IPSP occurred at inter-pulse intervals of 100-400 ms. Subsequent to stimulation at 0.2-5 Hz, a shor t-term depression of the IPSP occurred while a tetanic stimulation at 1 00 Hz caused a long-term depression. These results indicate that IPS Ps in the deep cerebellar nuclei undergo activity-mediated plasticity.