HIPPOCAMPAL LESIONS AND ORIENTING RESPONSE

Investigated the orienting response to novel stimuli in 8 normal albino rats and 16 rats with either bilateral hippocampal lesions or bilateral lesions of the neocortex overlying the hippocampus. Several different experimental situations were used. The results show that, while there is no impairment in the orienting response itself as a function of either brain lesion, the level of orienting in the hippocampally lesioned rats was severely reduced only when the novel stimulus followed another stimulus and a shift of attention was necessary for normal orienting to the novel stimulus. These results, together with earlier reports, mean that the hippocampus is importantly involved in those selective attentional processes in the rat indexed by the orienting response, depending on reciprocal neural connections between the brain stem reticular formation and the hippocampus. (21 ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1969 American Psychological Association.