Effects of fimbria-fornix, hippocampus, and amygdala lesions on discrimination between proximal locations

Behav Neurosci. 2004 Aug;118(4):770-84. doi: 10.1037/0735-7044.118.4.770.

Abstract

The conditioned cue preference (CCP) task was used to study the information required to discriminate between spatial locations defined by adjacent arms of an 8-arm radial maze. Normal rats learned the discrimination after 3 unreinforced preexposure (PE) sessions and 4 food paired-unpaired training trials. Fimbria-fornix lesions made before, but not after, PE, and hippocampus lesions made at either time, blocked the discrimination, suggesting that the 2 structures processed different information. Lateral amygdala lesions made before PE facilitated the discrimination. This amygdala-mediated interference with the discrimination was the result of a conditioned approach response that did not discriminate between the 2 arm locations. A hippocampus/fimbria-fornix system and an amygdala system process different information about the same learning situation simultaneously and in parallel.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amygdala / injuries
  • Amygdala / physiology
  • Animals
  • Brain Diseases / physiopathology
  • Choice Behavior
  • Conditioning, Psychological / physiology*
  • Cues
  • Discrimination Learning / physiology*
  • Fornix, Brain / injuries
  • Fornix, Brain / physiology
  • Hippocampus / injuries
  • Hippocampus / physiology
  • Limbic System / injuries
  • Limbic System / physiopathology*
  • Maze Learning
  • N-Methylaspartate / toxicity
  • Neurotoxins / toxicity
  • Rats
  • Rats, Long-Evans
  • Reaction Time / physiology
  • Reinforcement, Psychology
  • Space Perception / physiology*

Substances

  • Neurotoxins
  • N-Methylaspartate