Program no. 332.11. 2004 Abstract Viewer/Itinerary Planner. Washington, DC: Society for Neuroscience, 2004. Online.

Involvement of prelimbic cortex and hippocampus in visuospatial attention and working memory in rats: a comparison of delayed matching and nonmatching to sample performance
Lehmann O, Eagle DM, Ito R, Cardinal RN, Robbins TW
Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge, CB2 3EB, UK

The relationship of visuospatial attentional processes to those of spatial working memory are unclear and have seldom been examined with the same paradigm. In this study, we used a novel task (Combined Attention and Memory task, CAM) which allows for the simultaneous assessment of attention to a brief visual stimulus presented in one of 5 locations (attention phase) and memory for that stimulus over a variable delay (memory phase with two stimuli), to compare the effects of excitotoxic lesions of the prelimbic cortex and of the hippocampus. The former is known to contribute to working memory and attention and the latter to working memory function, but its participation in attentional processes has not been systematically assessed. In experiment 1, animals performed a delayed matching version of the CAM task and in experiment 2, another set of animals performed a delayed nonmatching version to determine whether the lesions differentially affected these processes.

In experiment 1, the prelimbic cortex lesion impaired the accuracy of detecting the to-be-attended sample stimulus whereas the accuracy of memory over the delay for that stimulus was not affected. In contrast, the hippocampal lesion induced a much greater deficit in attentional accuracy and produced a subsequent but transient delay-independent deficit in memory accuracy. In experiment 2, preliminary results confirmed that both lesions reduced attentional accuracy and also impaired memory.

These results suggest that the prelimbic cortex performs a dissociable role in attentional and working memory processes depending on the type of memory task, and that the hippocampus contributes in several distinct ways to performance in tests of working memory, including the regulation of attention to the sample cues.