Lesions of the entorhinal cortex impair acquisition of hippocampal-dependent trace conditioning

Neurobiol Learn Mem. 2001 Mar;75(2):121-7. doi: 10.1006/nlme.2000.3966.


Rabbits with the electrolytic lesions of bilateral entorhinal cortex (EC) were trained with the hippocampal-dependent trace conditioning of the nictitating membrane response. The multiple-unit activity of the hippocampal CA1 region was recorded during conditioning. The conditioned stimulus was a tone (1 kHz, 85 dB, 200-ms duration), the unconditioned stimulus was a corneal air puff (3 psi, 150-ms duration), and the interstimulus interval was 750 ms. The EC-lesioned animals showed only 30% conditioned response (CR) by the ninth session while the sham-operated animals showed above 80% CR. The lesioned animals did not show learning-related changes in the hippocampal activity. When the training was switched to the 300-ms interstimulus interval trace conditioning, both groups learned above 80% CR. The EC-lesioned animals, however, showed less learning-related activity in the hippocampus than the sham-operated animals. These results suggest that the development of the learning-related activity in the hippocampus depends on the intact EC, and that the EC may provide a possible pathway conveying learning information from the cerebellum or cerebral cortex to the hippocampus during the trace conditioning.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain Mapping
  • Conditioning, Classical / physiology*
  • Conditioning, Eyelid / physiology
  • Entorhinal Cortex / physiology*
  • Hippocampus / physiology*
  • Mental Recall / physiology*
  • Perforant Pathway / physiology
  • Rabbits