The neural substrates of script knowledge deficits as revealed by a PET study in Huntington's disease.

Previous neuropsychological investigations have suggested that both the prefrontal cortex and the basal ganglia are involved in the management of script event knowledge required in planning behavior.This study was designated to map, the correlations between resting-state brain glucose utilization as measured by FDG-PET (positron emission tomography) and scores obtained by means of a series of script generation and script sorting tasks in 8 patients with early Huntington's disease.These patients exhibited a selectively greater impairment for the organizational aspects of scripts compared to the semantic aspects of scripts. We showed significant negative correlations between the number of sequencing, boundary, perseverative and intrusion errors and the metabolism of several cortical regions, not only including frontal, but also posterior regions.Our findings suggest that, within the fronto-striatal system, the cortical frontal regions are more crucial in script retrieval and script sequencing than the basal ganglia.