Bilateral entorhinal cortex lesions impair acquisition of delayed spatial alternation in rats.
Entorhinal cortex lesions induce significant reorganization of several homotypic and heterotypic inputs to the hippocampus. This investigation determined whether surviving heterotypic inputs after bilateral entorhinal lesions would support the acquisition of a learned alternation task. Rats with entorhinal lesions or sham operations were trained to acquire a spatial alternation task. Although the sham-operated rats acquired the task within about 3 weeks postsurgery, rats with bilateral entorhinal lesions failed to learn the task after 12 consecutive weeks of training despite heterotypic sprouting of the cholinergic septodentate pathway and the expansion of the commissural/associational fiber plexus within the dentate gyrus. Thus, heterotypic sprouting failed to ameliorate significantly the effects of bilateral entorhinal lesions. Rather, entorhinal lesions produced a persistent impairment of spatial memory, characterized by a mixture of random error production and perseverative responding.
Ramirez
Julio J
JJ
Department of Psychology and Neuroscience Program, Davidson College, Davidson, NC 28035, USA. juramirez@davidson.edu
Campbell
David
D
Poulton
Winona
W
Barton
Cole
C
Swails
Jennifer
J
Geghman
Kindiya
K
Courchesne
Stephanie L
SL
Wentworth
Sean
S
D000818:Animals; D001522:Behavior, Animal; D001930:Brain Injuries / Q000473:pathology* / Q000503:physiopathology; D018728:Entorhinal Cortex / Q000503:physiopathology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000502:physiology*; D013037:Spatial Behavior / Q000502:physiology*