Attention to change: A neurological investigation

Neglect, a dramatic manifestation of attention, is a primary source of stroke-related long-term disability (Katz, Hartman-Maeir, Ting, & Soroker, 1999). Subtle attention deficits (extinction) may recover more slowly than overt symptoms (neglect). (Heir, Mondlock, & Caplan, 1983) While often not captured by traditional bedside tests, subtle deficits have real-world implications. To guide rehabilitation efforts, it is clinically relevant to examine attention in a 6-month post-lesion population.; The visual attention tasks in this study were a simple detection task and a change detection task. A novel component of this study was vigilance, sustaining attention over extended periods of time. The frontal lobes are associated with vigilance (e.g. Manly & Robertson, 1997), and the frontal-parietal cortex mediates spatial attention (e.g. Beck, Rees, Frith, & Lavie, 2001). This study examined the role of the frontal-parietal network in detecting change at spatial locations over time.; Nine frontal-lesioned, seven parietal-lesioned, and twenty-nine non-lesioned individuals were administered the Detection and Monitoring Tasks. The Detection Task required participants to report whether the letter 'T' appeared, and if so, in which hemispace. The Monitoring Task involved bilateral stimuli presentation of two blinking red 'T's. The participants were asked to report whether either letter changed to green, and if so, in which hemispace. The temporal component of both tasks was for the stimuli to appear (Detect Task) or change (Monitor Task) over the time intervals of 200, 800, 1400, or 2000 msec.; Detection task. No participants showed an accuracy performance difference over time or hemispace. Contralesional accuracy performance was worse than Ipsilesional performance for Parietals, but not Frontals. Contralesional RT performance, relative to Ipsilesional, was worse for all patients. Parietals performed significantly worse (accuracy and RT) than Controls.; Monitoring task. No participants showed a performance difference over time. Surprisingly, all participants showed a hemispheric difference. Accuracy performance for right hemispace was significantly worse than left hemispace. This left-hemispace advantage may explain why patients did not demonstrate worse Contralesional accuracy performance, relative to Ipsilesional, despite slower Contralesional RT performance. Parietals performed worse (accuracy and RT) than Controls. A trend suggested better accuracy performance for Frontals relative to Parietals.