Abstract

Multiple unit activity(MUA) was recorded from the cerebellar dentato-interpositus nucleus during classical conditioning of the nictitating membrane response(NMR) in the rabbit with a tone conditioned stimulus(CS) and an airpuff unconditioned stimulus(US). The MUA was processed to 16msec bin histogram and the NMR was averaged in each session respectively. The result showed that The averaged NMR was highly correlated with the histogram and that the histogram of MUA preceded the averaged NMR by several tens millisecond. This supports the previous reports that dentato-interpositus nucleus may be the neural substrate of the NMR conditioning. In some studies, it was reported that the stimulation of accessory abducens nucleus as US can support the NMR conditioning. So, one purpose of this study was the examination of the role of accessory abducens nucleus in the NMR conditioning. Following days of aquisition, the nucleus was lesioned electrolytically. The result showed that the lesion abolished both conditioned and unconditioned responses, but MUA recorded from deutatointerpositus nucleus maintains the same level as it prior to lesion. Results suggest that accessory abducens nucleus is merely motor output nucleus and isn't involved in the retention of the NMR conditioning.