Seahorse wins all races: hippocampus participates in both linear and non-linear visual discrimination learning.
Consistent with configural/conjunctive theories of the hippocampus, we report that rats trained on the non-linear transverse patterning discrimination problem (A+ versus B-, B+ versus C-, and C+ versus A) displayed retrograde amnesia when the hippocampus was later damaged. They also failed to relearn the solution to this problem. Damage to the hippocampus following training also produced retrograde amnesia in rats trained on a set of elemental discrimination problems (A+ versus B-, C+ versus D-, and E+ versus F-) that could be solved based on the associative strengths of the individual choice cues. However, in contrast to transverse patterning, rats easily relearned and retained these elemental problems and learned a new set of elemental problems after the damage. These results support two theoretical conclusions: (a) elemental discriminations can be learned by both a system that depends on the hippocampus and a system that does not require the hippocampus, and (b) in the intact animal these two systems competitively interact with the hippocampal-dependent system inhibiting memory formation by the extra-hippocampal system.
Driscoll
Ira
I
Canadian Centre for Behavioural Neuroscience, Department of Psychology and Neuroscience, University of Lethbridge, Alta.. robert.sutherland@uleth.ca
Howard
Sarah R
SR
Prusky
Glen T
GT
Rudy
Jerry W
JW
Sutherland
Robert J
RJ
D000818:Animals; D002755:Choice Behavior / Q000502:physiology; D004193:Discrimination Learning / Q000502:physiology*; D005260:Female; D006624:Hippocampus / Q000502:physiology*; D008568:Memory / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011340:Problem Solving / Q000502:physiology*; D051381:Rats