Combined visual attention and finger movement effects on human brain representations

Sensory and motor systems interact in complex ways; visual attention modifi es behavior, neural encoding, and brain activation; and dividing attention with simultaneous tasks may impede performance while producing specific bra in activation patterns. We hypothesized that combining voluntary movement w ith visual attention would yield unique brain representations differing fro m those occurring for movement or visual attention alone. Hemodynamic signa ls in humans were obtained with functional magnetic resonance imaging (MRI) while participants performed one of four tasks that required only a repeti tive finger movement, only attending to the color of a visual stimulus, sim ultaneous finger movement and visual attention, or no movement and no visua l attention. The movement-alone task yielded brain activation in structures commonly engaged during voluntary movement, including the primary motor co rtex, supplementary motor area, and cerebellum. Visual attention alone resu lted in sparse cerebral cortical and substantial bilateral cerebellar activ ation. Simultaneous performance of visual attention and finger movements yi elded widespread cerebral cortical, cerebellar, and other subcortical activ ation, in many of the same sites activated for the movement or attention ta sks. However, the movement-related plus attention-related activation extend ed beyond the movement-alone or attention-alone activation sites, indicatin g a novel activation pattern related to the combined performance of attenti on and movement. Additionally, the conjoint effects of visual attention and movement upon brain activation were probably not simple gain effects, sinc e we found activation-related interactions in the left superior parietal lo bule, the right fusiform gyrus, and left insula, indicating a potent combin atory role for visual attention and movement for activation patterns in the human brain. In conclusion, performing, visual attention and movement task s simultaneously, even thou gh the tasks had no specific interrelationship, resulted in novel activation patterns not predicted by performing movement s or visual attention alone.