Cognitive functions and corticostriatal circuits: insights from Huntington's disease

The basic Bade basic mechanisms of information processing by corticostriatal circuits are currently a matter of intense debate amongst cognitive scientists. Huntington's disease, an autosomal-dominant neurogenetic disorder characterized clinically by a triad of motor, cognitive, and affective disturbance, is associated with neuronal loss within corticostriatal circuits, and as such provides a valuable model for understanding the role of these circuits in normal behaviour, and their disruption in disease. We review findings from our studies of the breakdown of cognition in Huntington's disease, with particular emphasis on executive functions and visual recognition memory. We show that Huntington's disease patients exhibit a neuropsychological profile that shows a discernible pattern of progression with advancing disease, and appears to result from a in the mechanisms of response selection. These findings are consistent with computational models that suggest that corticostriatal circuits compute the patterns of sensory input and response output which are of behavioural significance a particular environmental context.