Abstract
Usually, visual processing precedes decision making. Here, we show that activity of the visual cortex is strongly modulated by feedback in sequential decision making tasks. Observers were presented with a clip art image, such as a boat, and 2, 3, or 4 disks below the image. Clicking on a disk led to the presentation of the next image, which could be the same image (No reward), a new image (Intermediate reward), or the goal image (Full reward). Observers clicked on the disks until the goal was found. In addition, we recorded 128 channel EEG. For the three feedback conditions, we found strong differences in the amplitudes of occipital electrodes at the P2 (150-275ms) and P3 (250-500ms). Inverse solutions in the frequency domain during these periods, computed by sLoreta, showed that the visual cortex is less activated in the theta band (4-7Hz) and more strongly activated in the beta band (15-30Hz) when comparing the Full with the No reward condition. There were no differences between these conditions in the alpha (7-10Hz) and the gamma band (above 30Hz). In the anterior cingulate cortex (ACC), the Full reward condition leads to higher activation than the No reward conditions in all frequency bands. Since the modulation occurs well beyond early visual processing, we suggest that top-down activation from the frontal areas, including the ACC, changes visual processing of the images depending on the specific feedback obtained. Our findings are well in line with neurophysiological work showing that beta activity in the visual cortex of cat is bursting if there is a rewarding cue. As a speculation, we propose that the visual cortex and the ACC communicate in these types of tasks mainly in the beta frequency regime.
Meeting abstract presented at VSS 2017