Visual attention task performance in Wistar and Lister hooded rats: Response inhibition deficits after medial prefrontal cortex lesions

The prefrontal cortex has traditionally been implicated in a variety of cognitive processes, including memory, attention and decision making. The detection of effects of prefrontal cortex lesions on attention has been shown to depend on the procedure used to assess the attentional process. We therefore investigated the effects of lesions of the prefrontal cortex in two different visual attention tasks, i.e. a three-choice serial reaction time task involving sustained and divided attention processes and a visual timing task involving sustained attention and response inhibition processes. In two rat strains that are frequently used in behavioural analysis, i.e. albino Wistar rats and pigmented Lister Hooded rats, lesions of the medial prefrontal cortex caused a deterioration of performance in both tasks, although the effect lasted much longer in the visual timing task. This latter task proved to be especially sensitive to detect the consequences of medial prefrontal cortex lesions, consisting of a loss of both attention control and response inhibition. In both attention tasks, Wistar rats performed less accurate and made more anticipatory responses than Listers. Strain differences could not entirely be attributed to possible visual deficits in albinos, which was also evident when locomotor activity in an open field and food-motivated behaviour in a hoarding paradigm were assessed. Due to slower habituation rates, Lister rats were more active and displayed little food hoarding behaviour. In Wistar rats, hoarding was disrupted by medial prefrontal cortex lesions, showing the effectiveness of the lesion. The results indicate that, although different rat strains provide different baseline levels of behaviour for testing lesion- or drug-induced behavioural changes, lesions of the medial prefrontal cortex do not only disrupt sustained attention processes, but also induce a strong impairment in response inhibition in both Wistar and Lister rats. (C) 1999 IBRO. Published by Elsevier Science Ltd.