||A lateralized alerting deficit in left brain-damaged patients.
Any warning stimulus preceding a visual target generally leads to progressive reduction in response times with increases in the warning-to-target temporal interval. This effect, called alerting, seems to be correlated with cortical activation. Three visuospatial cueing experiments were conducted with 10 nonneglecting left brain-damaged patients in order to examine the possibility of an alerting impairment following lesions of the left hemisphere. On each trial, a spatial cue/warning signal preceded target onset by a stimulus asynchrony of 50, 150, 600, or 1,000 msec. Results indicate that large left-hemisphere lesions lead to a delay in the alerting effect of a warning signal for the processing of contralesional targets. They also suggest that a lowered alerting state of the damaged hemisphere leads to a refractory difficulty in disengaging the focus of spatial attention from an invalidly cued ipsilesional location. (PsycINFO Database Record (c) 2007 APA, all rights reserved)