Differences in behavioural test battery performance between mice with hippocampal and cerebellar lesions

Effects of hippocampal or cerebellar lesions have been described extensively, but the ability of behavioural tests for laboratory mice to distinguish between such lesions has not been studied in detail. We compared the behavioural consequences of large bilateral hippocampal and hemispheric cerebellar lesions with eight commonly used tests that included elements of neuromotor performance, exploratory behaviour, and learning and memory ability. Dissociation between the effects of the different lesions was most obviously demonstrated by neuromotor impairment in cerebellum-lesioned mice (typically in the rotarod task) and hyperactivity in hippocampus-lesioned mice (typically in cage activity recordings). Several of the behavioural variables derived from the test battery correlated differently with the size of the hippocampal and cerebellar lesions. In contrast, no absolute dissociation between the effects of these lesions was found in the Morris maze, a reportedly hippocampus-dependent learning and memory task. The contextual fear conditioning task, on the other hand, did reveal a selective decrease of context-dependent freezing in hippocampus-lesioned mice, whereas cerebellum-lesioned animals displayed an increase in freezing responses. By and large, the present battery of tests does allow differentiation between the effects of cerebellar and hippocampal lesions in laboratory mice.