Hippocampectomy disrupts trace eye-blink conditioning in rabbits

Behav Neurosci. 1990 Apr;104(2):243-52. doi: 10.1037//0735-7044.104.2.243.


The role of the hippocampus (HPC) in trace eye-blink conditioning was evaluated using a 100-ms tone conditioned stimulus (CS), a 300- or 500-ms trace interval, and a 150-ms air puff unconditioned stimulus (UCS). Rabbits received complete hippocampectomy (dorsal & ventral), sham lesions, or neocortical lesions. Hippocampectomy produced differential effects in relation to the trace interval used. With a 300-ms trace interval, HPC-lesioned Ss showed profound resistance to extinction after acquisition. With a 500-ms trace interval, HPC-lesioned Ss did not learn the task (only 22% conditioned responses (CRs) after 25 sessions, whereas controls showed greater than 80% after 10 sessions), and on the few trials in which a CR occurred, most were "nonadaptive" short-latency CRs (i.e., they started during or just after the CS and always terminated prior to UCS onset). The authors conclude that the HPC encodes a temporal relationship between CS and UCS, and when the trace interval is long enough (e.g., 500 ms), that the HPC is necessary for associative learning of the conditioned eye-blink response.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Association Learning / physiology*
  • Brain Mapping
  • Cerebral Cortex / physiology
  • Conditioning, Eyelid / physiology*
  • Dominance, Cerebral / physiology
  • Extinction, Psychological / physiology
  • Hippocampus / physiology*
  • Learning / physiology*
  • Male
  • Mental Recall / physiology
  • Neurons / physiology
  • Rabbits
  • Reaction Time / physiology