Foveal attention modulates responses to peripheral stimuli

Foveal attention modulates responses to peripheral stimuli. J. Neurophysiol . 83: 2443-2452, 2000. When attending to a visual object, peripheral stimul i must be monitored fur appropriate redirection of attention and gaze. Earl ier work has revealed precentral and posterior parietal activation when att ention has been directed to peripheral vision. We wanted to find out whethe r similar cortical areas are active when stimuli are presented in nonattend ed regions of the visual field. The timing and distribution of neuromagneti c responses to a peripheral luminance stimulus were studied in human subjec ts with and without attention to fixation. Cortical current distribution wa s analyzed with a minimum L1-norm estimate. Attention enhanced responses 10 0-160 ms after the stimulus onset in the right precentral cortex, close to the known location of the right frontal eye field. In subjects whose right precentral region was not distinctly active before 160 ins, focused attenti on commonly enhanced right inferior parietal responses between 180 and 230 ms, whereas in the subjects with clear earlier precentral response no parie tal enhancement was detected, hi control studies both attended and nonatten ded stimuli in the peripheral visual field evoked the right precentral resp onse, whereas during auditory attention the visual stimuli failed to evoke such response. These results show that during focused visual attention the right precentral cortex is sensitive to stimuli in all parts of the visual field. A rapid response suggests bypassing of elaborate analysis of stimulu s features, possibly to encode target location for a saccade or redirection of attention. In addition, load for frontal and parietal nodi of the atten tional network seem to vary between individuals.