Eyeblink conditioning during an interstimulus interval switch in rabbits (Oryctolagus cuniculus) using picrotoxin to disrupt cerebellar cortical input to the interpositus nucleus.
The role of the cerebellar cortex in eyeblink classical conditioning remains unclear. Experimental manipulations that disrupt the normal function impair learning to various degrees, and task parameters may be important factors in determining the severity of impairment. This study examined the role of cerebellar cortex in eyeblink conditioning under conditioned stimulus?unconditioned stimulus intervals known to be optimal or nonoptimal for learning. Using infusions of picrotoxin to the interpositus nucleus of the rabbit cerebellum, the authors pharmacologically disrupted input from the cerebellar cortex while training with an interstimulus interval (ISI)-switch procedure. One group of rabbits (Oryctolagus cuniculus) was 1st trained with a 250-ms ISI (optimal) and then switched to a 750-ms ISI (nonoptimal). A 2nd group was trained in the opposite order. The most striking effect was that picrotoxin-treated rabbits initially trained with a 250-ms ISI learned comparably to controls, but those initially trained with a 750-ms ISI were severely impaired. These results suggest that functional input from cerebellar cortex becomes increasingly important for the interpositus nucleus to learn delay eyeblink conditioning as the ISI departs from an optimal interval.
Vogel
Richard W
RW
Department of Psychological and Brain Sciences, Indiana University, Indiana, USA.
Amundson
Jeffrey C
JC
Lindquist
Derick H
DH
Steinmetz
Joseph E
JE
D000161:Acoustic Stimulation; D000704:Analysis of Variance; D000818:Animals; D001931:Brain Mapping; D002525:Cerebellar Cortex / Q000187:drug effects* / Q000502:physiology; D002529:Cerebellar Nuclei / Q000187:drug effects* / Q000502:physiology; D003214:Conditioning, Classical / Q000187:drug effects / Q000502:physiology; D003215:Conditioning, Eyelid / Q000187:drug effects* / Q000502:physiology; D018756:GABA Antagonists / Q000494:pharmacology*; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D010852:Picrotoxin / Q000494:pharmacology*; D011817:Rabbits; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D013997:Time Factors
D018756:GABA Antagonists; D010852:Picrotoxin