IMPULSIVITY AS A CONFOUNDING FACTOR IN CERTAIN ANIMAL TESTS OF COGNITIVE FUNCTION

Performance in cognitive tasks which require the subject to wait and/o r to process a large amount of information can be disrupted by an incr ease in impulsive-like behaviour. Accordingly, a decrease in impulsive -like behaviour can improve performance in such tasks. Conversely, imp ulsive-like behaviour may improve performance in cognitive tasks where simple and fast responses and/or only little information processing i s required. Thus, impulsivity constitutes a confounding factor in stud ies of cognitive function. Impulsive-like behaviour may be modified by serotonergic (5-HT) activity, with underactivity in 5-HT neurotransmi ssion increasing impulsivity and vice versa. Drug- or lesion-induced a lteration in 5-HT neurotransmission may, therefore, constitute suitabl e tools to investigate the role of impulsivity in animal tests of cogn itive function. Benzodiazepines also increase impulsive-like behaviour , possibly by decreasing 5-HT neurotransmission. Hence, the effects of modulation of 5-HT systems and of the benzodiazepine-binding site on performance in animals tests of cognitive function will be discussed. It is predicted that the effects of manipulations of serotonergic acti vity or of benzodiazepine administration depend upon the nature of the response required, and that these effects may be mediated through cha nges in impulse control.