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The Barnes maze offers advantages for cognitive aging studies, because of its relatively unstressful design and its modest physical demands. The authors therefore undertook a detailed chronological investigation of performance against age, for female Sprague-Dawley and male and female Dark Agouti rats. The trial duration was 10 days. Rats were tested at 6, 11, 14, 17, 20, and 26 months of age, but individual rats were tested at one age only. At 6 months of age, all rats reached the criterion. Sprague-Dawley rats performed best at this age. Impairment began at 14 months in Dark Agouti rats and continued to increase up to 26 months of age. Impairment was greater in Dark Agouti than Sprague- Dawley rats and was greater in females than males. At 26 months, 70% of Sprague-Dawley females reached criterion; of the Dark Agoutis, only 33% of females and 57% of males reached criterion. This study confirms the utility of the Barnes maze as a robust vehicle in aged rats. It also highlights major performance differences between strains and genders in aging rats. [ABSTRACT FROM AUTHOR]

An influential view in the field of spatial cognition is that an obligatory geometric module constrains spatial learning and memory. In this issue, P. M. Jones, J. M. Pearce, V. J. Davies, M. A. Good, and A. McGregor (2007) showed that learning based on the geometry, or shape, of the environment requires the hippocampus. To place this work in context, the author of the present article considers the evidence for and against a geometric module for rat spatial learning, outlines the influence of geometry on neurons that encode spatial information, and attempts to relate spatial behavior to neuronal representations of direction and location. [ABSTRACT FROM AUTHOR]