Cerebral Cortex Advance Access published online on March 12, 2009
Cerebral Cortex, doi:10.1093/cercor/bhp016
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No Neglect-Specific Deficits in Reaching Tasks
1 Department of Psychology, University of Glasgow, Glasgow, G12 8QB, UK, 2 Division of Neurosciences and Mental Health, Imperial College London, London, SW7 2AZ, UK, 3 Institute of Neurological Sciences, Southern General Hospital, Glasgow, G51 4TF, UK, 4 Department of Medicine for the Elderly, Southern General Hospital, Glasgow, G51 4TF, UK, 5 Stroke Discharge and Rehabilitation Team, Southern General Hospital, Glasgow, G51 4TF, UK, 6 Stroke Unit, Southern General Hospital, Glasgow, G51 4TF, UK, 7 Mansion House Unit, Glasgow, G41 3DX, UK, 8 Victoria Infirmary, Glasgow, G42 9TY, UK
Address correspondence to M. Harvey, PhD, Department of Psychology, University of Glasgow, Glasgow G12 8QB, UK. Email: M.Harvey{at}psy.gla.ac.uk.
It is well established that patients with hemispatial neglect present with severe visuospatial impairments, but studies that have directly investigated visuomotor control have revealed diverging results, with some studies showing that neglect patients perform relatively better on such tasks. The present study compared the visuomotor performance of patients with and without neglect after right-hemisphere stroke with those of age-matched controls. Participants were asked to point either directly towards targets or halfway between two stimuli, both with and without visual feedback during movement. Although we did not find any neglect-specific impairment, both patient groups showed increased reaction times to leftward stimuli as well as decreased accuracies for open loop leftward reaches. We argue that these findings agree with the view that neglect patients code spatial parameters for action veridically. Moreover, we suggest that lesions in the right hemisphere may cause motor deficits irrespective of the presence of neglect and we performed an initial voxel-lesion symptom analysis to assess this. Lesion-symptom analysis revealed that the reported deficits did not result from damage to neglect-associated areas alone, but were further associated with lesions to crucial nodes in the visuomotor control network (the basal ganglia as well as occipito-parietal and frontal areas).
Key Words: brain lesions • motor control • neuropsychology • parietal cortex • temporal cortex