Ramirez J J, Labbe R, Stein D G
Department of Psychology, Davidson College, NC 28036.
Brain Res. 1988 Aug 30;459(1):153-6. doi: 10.1016/0006-8993(88)90296-x.
In a previous investigation we observed that entorhinal cortex lesions produce an impairment in spatial alternation characterized by repeated responses in one direction (i.e. 'perseveration'). Since this impairment disappears at the same time when the dentate gyrus is reinnervated by several of its remaining afferents, recovery from perseveration and sprouting may be related. To test this possibility, we examined the performance of two groups of rats with bilateral entorhinal lesions: one group began testing for retention of an alternation task on day 2 after the lesions; the other group began on day 12 (i.e. the time at which hippocampal sprouting occurs). Both groups exhibited significantly greater perseveration than their respective sham-operated groups over the first 6-12 days of testing. Thus, postoperative testing was required to facilitate the shift from perseverative to non-perseverative responding independent of the time at which sprouting in the dentate gyrus became established.
