Hippocampal lesioned rats are able to learn a spatial position using non-spatial strategies

• Published in: Behavioural brain research Vol. 133; no. 2; pp. 279 - 291
• Main Authors: Pouzet, Bruno, Zhang, Wei-Ning, Feldon, Joram, Rawlins, J.Nicholas P
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier B.V 18.07.2002; Elsevier Science
• Subjects: Anatomical correlates of behavior; Animals; Behavioral psychophysiology; Biological and medical sciences; Coloring Agents; Cues; Fundamental and applied biological sciences. Psychology; Hippocampus; Hippocampus - injuries; Hippocampus - pathology; Hippocampus - physiology; Lesion; Male; Maze Learning - physiology; Memory - physiology; Memory, Short-Term - physiology; Morris water maze; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Psychomotor Performance - physiology; Rats; Rats, Wistar; Reversal Learning - physiology; Space Perception - physiology; Spatial learning; Morris water maze; Lesion; Hippocampus; Spatial learning; Reference memory; Rat; Rodentia; Central nervous system; Spatial ability; Learning; Vertebrata; Mammalia; Acquisition process; Investigation method; Animal; Strategy; Working memory; Brain (vertebrata)
• ISSN: 0166-4328; 1872-7549
• DOI: 10.1016/S0166-4328(02)00007-4

In the last two decades, many experiments have demonstrated that the hippocampus plays a role in the learning and processing of spatial and contextual information. Despite these demonstrations, some recent publications have indicated that the hippocampus is not the only structure involved in spatial learning and that even after hippocampal lesions, rats can perform spatial tasks. However, it is not well established whether animals with hippocampal dysfunction still have some spatial learning capacities or develop non-spatial solutions; these may require lengthier acquisition training. We now report the effects of conventional, dorsal hippocampal ablation on rats’ performance on the water maze. We tested rats using a short (4 days) versus a long (16 days) acquisition period. We demonstrated that animals with dorsal hippocampal lesions have some residual capacity for learning the localization of a hidden escape platform in a pool during both a reference memory task and a working memory task. The animals with dorsal hippocampal lesions learned to escape at a fixed location, but only with extended training. It is suggested that these animals used non-spatial strategies to compensate for a spatial memory impairment. The results are discussed with respect to the experimental procedure and the strategy applied by the lesioned rats.