EFFECT OF DIRECTED ATTENTION IN HUNTINGTONS-DISEASE

This experiment sought to ascertain whether overt gaze (i.e., directed attention) would influence attentional performance in Huntington's di sease (HD), via the use of a vibrotactile choice reaction time procedu re involving biased probabilities of event occurrence. Subjects looked (i.e., direct gaze) either at the hand receiving the most (expected) vibrations, or the hand less often stimulated (the unexpected), for bo th crossed and uncrossed arm postures. Patients with HD showed perform ance advantages when directing attention (i.e., gaze) at the respondin g hand, especially for expected events. Patients with HD, however, wer e not sensitive to distributions of event probability in the uncrossed arm posture, nor when looking away from the responding hand. With the crossed arm posture, and when directing attention at the expected sid e, patients with HD became more sensitive to distributions of event pr obability. In HD, there may be a disruption of fronto-striatal circuit ry on both cortical and subcortical levels which may account for impai rments both in holding and shifting attention.