Deficits for representational memory induced by septal and cortical lesions (singly and combined) in rats

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A differentiation was made between dispositional memory and representational memory. A delayed nonmatching-to-sample task in a T-maze operationalized this distinction. Experimental brain lesions in posterior septum and in prelimbic cortex resulted in amnesia for representational memories among male Long-Evans rats (N = 24). Amnesia ameliorated as a function of continued reinforced postoperative testing. When lesions were placed in both structures in the same Ss, amnesia for representational memories also occurred, and with further testing, the amnesia ameliorated as indicated by group data. However, examination of the behavioral performance and the lesions in individuals revealed that when both lesions were adequate, choices remained at chance levels, suggesting permanent amnesia for representational memories. That the lesion-induced amnesia was restricted to representational memory was indicated by the fact that the Ss displayed no amnesia for dispositional memories regarding what they do in the maze. They did not act like naive Ss as they should if they had forgotten the dispositional memories necessary for successful T-maze performance. (13 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved)

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