Present address: Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge CB2 3EB, UK.
A double dissociation between serial reaction time and radial maze performance in rats subjected to 192 IgG-saporin lesions of the nucleus basalis and/or the septal region
Article first published online: 11 AUG 2003
European Journal of Neuroscience
Volume 18, Issue 3, pages 651–666, August 2003
How to Cite
Lehmann, O., Grottick, A. J., Cassel, J. .-C. and Higgins, G. A. (2003), A double dissociation between serial reaction time and radial maze performance in rats subjected to 192 IgG-saporin lesions of the nucleus basalis and/or the septal region. European Journal of Neuroscience, 18: 651–666. doi: 10.1046/j.1460-9568.2003.02745.x
- Issue published online: 11 AUG 2003
- Article first published online: 11 AUG 2003
- Received 15 February 2003, revised 16 April 2003, accepted 1 May 2003
- five-choice serial reaction time task;
- immunotoxic lesions;
- spatial memory;
- visual attention
The cholinergic basal forebrain has been implicated in aspects of cognitive function including memory and attention, but the precise contribution of its major components, the basalocortical and the septohippocampal systems, remains unclear. Rats were subjected to lesions of either the nucleus basalis magnocellularis (Basalis), the medial septum/vertical limb of the diagonal band of Broca (Septum), or both nuclei (Basalis + Septum), using the selective cholinotoxin 192 IgG-saporin. Cognitive performance was evaluated in tasks taxing attention (the five-choice serial reaction time task, 5-CSRTT) and spatial working memory (radial arm maze, RAM). Nucleus basalis lesions disrupted performance of the 5-CSRTT, as demonstrated by decreased choice accuracy, increased incidence of missed trials, increased latencies to respond correctly, and a disrupted pattern of response control. Combined lesions of the Basalis and Septum resulted in qualitatively similar deficits to Basalis lesions alone, although interestingly, these rats were unimpaired on measures of response speed, and showed weaker deficits on accuracy and omissions. Decreasing the attentional load by lengthening stimulus duration reversed some of the deficits in Basalis and Basalis + Septum rats, suggesting an attentional deficit rather than motivation or motor perturbations. Performance in rats with septal lesions was only affected when task difficulty was increased. In the RAM an opposing pattern of effects was observed, with Septum and Basalis + Septum rats showing dramatic impairments, and Basalis rats performing normally. Taken together, these data provide clear evidence for a functional dissociation between septohippocampal and basalocortical cholinergic systems in aspects of cognitive function.