Saccadic trajectory in Huntington's disease.
Trajectories of saccadic eye movements can be modulated by the presence of a competing visual distractor. It is proposed that the superior colliculus (SC) controls the initial deviation through competitive lateral interactions. Given the ramifications of connections between basal ganglia (BG) thalamo-cortical circuitry and the SC, it was anticipated that this modulation would be differentially effected in those with Huntington's disease, which in its early stages is primarily a disorder of the BG. Horizontal deviation was determined for exogenously driven and endogenously driven vertical saccades in the presence of peripheral distractors. For neurologically healthy participants, the initial trajectories of both saccade types curved away from distractor locations, as predicted. However, for HD participants exogenous saccades consistently deviated leftwards, irrespective of distractor location. Endogenous saccades also revealed anomalous horizontal deviation, with significant leftward deviation evident for saccades directed upward and significant rightward deviation for saccades directed downward. Further, both groups generated a comparable proportion of erroneous responses to distractor stimuli, but only neurologically healthy participants demonstrated a response time advantage for compatible target/distractor presentation. These results suggest anomalous regulation of distractor-related activity in HD.
Fielding
Joanne
J
Experimental Neuropsychology Research Unit, Department of Psychology, School of Psychology, Psychiatry and Psychological Medicine, Monash University, Clayton Campus, Victoria 3800, Australia. joanne.fielding@med.monash.edu.au
Georgiou-Karistianis
Nellie
N
Millist
Lynette
L
Fahey
Michael
M
White
Owen
O
D000328:Adult; D001288:Attention / Q000502:physiology; D001479:Basal Ganglia / Q000473:pathology; D005260:Female; D006801:Humans; D006816:Huntington Disease / Q000473:pathology* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000473:pathology; D012438:Saccades / Q000502:physiology*; D013477:Superior Colliculi / Q000473:pathology; D013788:Thalamus / Q000473:pathology