A new continuous alternation task in T-maze detects hippocampal dysfunction in mice. A strain comparison and lesion study.

The mammalian hippocampus has been the focus of several neurobiology studies because of its important behavioral function and because long-term potentiation (LTP) is a prominent feature of this brain region. Converging evidence suggests that hippocampal function is associated with learning multiple relationships of environmental cues. In this paper a novel behavioral test procedure is introduced, a modified T-maze continuous alternation task (T-CAT), that may serve as a simple, automatable, and quick test of hippocampal function in addition to the frequently applied water maze and fear conditioning paradigms. A comparison is made between mice (strain C57BL/6) with ibotenic acid lesioned or vehicle injected hippocampus, two transgenic strains (on CD1 background) overexpressing a calcium binding protein, S100beta, and inbred (C57BL/6, DBA/2, 129/SV and 129/SVEV) and outbred (CD1) strains of mice. This study shows that hippocampal lesioning led to a significant impairment in T-CAT. Furthermore, overexpression of S100beta, which impairs hippocampal LTP, also led to an impairment demonstrating that T-CAT is sensitive to detect hippocampal dysfunction. Analysis of the mouse strains revealed that C57BL/6 and CD1 mice performed well in T-CAT, whereas 129/SV, 129/SVEV and DBA/2 were significantly impaired, a finding that underscores the importance of strain differences in pharmacological or single gene manipulation studies of hippocampal function in mice.