Lesions in four parts of the basal forebrain change basic behaviour in rats.

Subdivisions of the basal forebrain (BF) are postulated to be differently involved in the regulation of behavioural functions. We compared 16 parameters of rat open field behaviour before, 10 days and 60 days after lesions in four BF subdivisions, the anterior and the posterior nucleus basalis magnocellularis (NBMa, NBMp), the vertical and the horizontal diagonal band nucleus (VDB, HDB) with sham-operated control rats. Every lesion type caused a significantly different pattern of significant behavioural changes. VDB and NBMp lesions both produced different patterns of ambulatory and exploratory hyperactivity, whereas NBMa lesions caused hypoactivity. Changes after HDB lesions were relatively small. The rate of habituation also shared changes that differed according to the lesion site. These changes in basic unlearned behaviour are likely to interact with more complex functions such as cognitive processes, learning and memory.