Cerebellar Purkinje cell activity during changes in the intensity of the conditioned stimulus.
Field:	Other
Authors:	Svensson, Pär Bengtsson, Fredrik Hesslow, Germund
Address of presenting author:	Inst fysiologiska vetenskaper Sölvegatan 19 223 62 Lund
E-mail:	Par.Svensson@mphy.lu.se
Phone:	046-2220327
Fax:	046-2224546
Text of abstract:	In classical blink conditioning the timing of the conditioned response (CR) is an important feature. The CR is elicited just prior to the unconditioned stimulus (US) so that the eye will be closed at the delivery of the US and thus protect against the aversive US. It is not known what brain structure contains this temporal memory. Recent data show that it is possible to maipulate the latency of the CR. A sudden increase in the intenisty of the conditioned stimulus (CS) will elicit the CR about 100 ms earlier. If the cerebellar cortex is inovlved in the CR timing, changes in CR latency should be reflected in the activity of the cortical Purkinje cells. To test this hypothesis, decerebrate ferrets were conditioned to electrical forelimb stimulation as CS and electrical periorbital stimulation as the US. When the CR was elicited reliably the animals were curarized and single unit activity were recorded from the eyeblink controlling area in the c3 zone in lobule HVI while increasing the CS intensity from 1mA to 2mA. Cerebellar Purkinje cells were identified as blink related when short latency climbing fiber responses were evoked by the US. A CR related inhibition of the simple spike activity appeared earlier to the increased CS intensity in blink related Purkinje cells. In Purkinje cells not related to the blink, no changes in simple spike activity were observed. The presence of the CR latency related simple spike activity is consistent with a temporal memory in the cerebellar cortex.
Keywords:	Cerebellum, Blink, Timing, Purkinje cell, Memory

Created 2000-03-15