PRIMARY OBJECTIVE: To evaluate the behavioural and neural effects of TBI on the hemispheric integrity of three components of visuospatial attention: alerting, orienting and executive control.
METHOD: Behavioural performance and high density event-related potentials (ERPs) were acquired while a sample of 12 patients with chronic moderate-to-severe TBI and 12 controls performed the Lateralized Attention Network Test (LANT). Neural indices of attention (posterior N1 amplitude to alerting and orienting cues, midline P3 amplitude during conflict resolution) were examined.
RESULTS: Patients with TBI exhibited smaller N1 amplitude to alerting cues, but comparable behavioural performance to controls. Participants with TBI also demonstrated poorer orienting performance to the left hemispace relative to the right. A corresponding reduction in right hemisphere N1 was found during left orienting to spatial cues in the TBI group. No group differences were observed on behavioural measures of executive control; however, patients with TBI exhibited reduced P3 amplitude overall.
CONCLUSIONS: TBI may have an enduring effect on the orienting system at both neural and behavioural levels. Assessment of attention in chronic TBI can be improved by the integration of hemispheric findings that suggest disproportionate vulnerability in leftward orienting.
RESULTS may enhance clinical sensitivity to detection of subtle signs of neglect.