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Cholinergic modulation of both visual and olfactory attention with the five-choice serial reaction time test

Ljubojevic V, Luu P, De Rosa E (2010) Cholinergic modulation of both visual and olfactory attention with the five-choice serial reaction time test. Neuroscience 2010 Abstracts 535.8. Society for Neuroscience, San Diego, CA.

Summary: The nucleus basalis magnocellularis (NBM) sends acetylcholine (ACh) to neocortical regions that are involved in attentional cognitive processes. Using the five choice serial reaction time task (5CSRTT), the rodent analog of sustained attention in the human cognitive literature, it has been shown that a loss of cholinergic cells in the NBM causes impaired visual attentional performance in rats (Lehmann et al., 2003; McGaughy et al., 2002). The present research examined the neurochemical modulation of attentional processes using both a visual and an olfactory version of the 5CSRTT. To that purpose, we trained 14 male adult Long-Evans rats to attend and react to the briefly presented visual or odor stimuli until they achieved a stable performance under the baseline task conditions, i.e., low attentional demand with stimulus duration (SD) of 1s. Following the successful acquisition of both versions of the 5CSRTT, the rats were subjected to selective cholinergic lesions of the NBM with the cholinergic immunotoxin 192 IgG-saporin to remove the cholinergic innervation from the neocortical mantle. This allowed an examination of the role of ACh in modulation of visual and olfactory attention. After the two week post-surgical recovery period, we compared the attentional performance of the saporin-lesioned (SAP) group (N=8) to that of the sham-lesioned (SHAM) group (N=6) on the two versions of the 5CSRTT task. We observed the impaired attentional performance of the SAP rats on the visual 5CSRTT under the baseline conditions (SD=1s); shortening the SD = 0.5s increased the extent of their deficits. With the olfactory 5CSRTT, the SAP impairment was only observed under the attentional challenge of SD=0.5s. However, in both modalities the difference between two groups trended toward statistical significance due to the low number of the experimental subjects in each group. We are currently performing further parametric manipulations to further challenge the rats in both modalities. We will then collect data from an additional 14 rats to increase the statistical power of our experiment. After the completion of the behavioral data collection, we will conduct acetylcholinesterase histochemistry and choline acetyltransferase immunohistochemistry in order to determine the extent of the loss of cholinergic afferents in fronto-parietal target cortical areas and the loss of cholinergic cell bodies in the NBM, respectively. In addition, parvalbumin immunohistochemistry will be carried out to quantify GABA-releasing neurons colocalized in NBM to confirm the selectivity of our lesion.

Related Products: 192-IgG-SAP (Cat. #IT-01)