EFFECTS OF LESIONS IN THE HORIZONTAL DIAGONAL BAND NUCLEUS ON OLFACTORY HABITUATION IN THE RAT

The nucleus of the horizontal limb of the diagonal band, a component o f the basal forebrain magnocellular complex affected in Alzheimer type dementia, supplies centrifugal innervation to the olfactory bulb. We have tested the hypothesis that horizontal limb of the diagonal band l esions will interfere with olfactory memory in a simple olfactory test paradigm. Lesions occupied a restricted volume, approximately 20%, of medial horizontal limb of the diagonal band. There was interference w ith habituation of investigation latency and duration, six and 16 days after lesioning. It is concluded that bilateral partial lesions of th e medial nucleus of the horizontal limb of the diagonal band interfere with habituation memory for odours.