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Visual orienting response and the nucleus basalis of Meynert.

Isaac M, Pearce JM, Muir JL (2001) Visual orienting response and the nucleus basalis of Meynert. Neuroscience 2001 Abstracts 313.2. Society for Neuroscience, San Diego, CA.

Summary: The nucleus basalis of Meynert (nbM), within the basal forebrain, contains a mass of large cholinergic neurones that send axons throughout the cortex. Previous studies have shown the nbM may be involved in attentional processing. The current study attempted to look at the effects of a cholinergic specific nbM lesion (using 192 IgG-saporin) on an attentional task involving two different serial conditioning schedules. In the Consistent condition a light (10s) was followed by a tone (10s), that signaled food. In the Inconsistent condition the light was presented alone for some trials and for other trials the light was followed by the reinforced tone. The orienting response towards the light was measured at three points throughout its presentation: within the first two seconds (light onset) and then twice within the post-onset period (2s-10s). According to the Pearce-Hall theory (1980), animals pay more attention to the light when it is followed by unpredictable events (Inconsistent condition) rather than predictable events (Consistent condition). Accordingly, the orienting response directed towards the post-onset light (2-10s), was stronger for sham operated rats that were trained with the Inconsistent than the Consistent condition. By contrast by the lesioned group was weak and at a similar level for both groups. These results suggest that the nbM lesions prevented enhanced attention to the light in the Inconsistent condition. These findings support the claim that the nbM is important for enhancing attention to stimuli (Chiba et al, 1995).

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

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