Effects of attention on the processing of motion in macaque middle temporal and medial superior temporal visual cortical areas

The visual system is continually inundated with information received by the eyes. Only a fraction of this information appears to reach visual awareness. This process of selection is one of the functions ascribed to visual attention. Although many stud-ies have investigated the role of attention in shaping neuronal representations in cortical areas, few have focused on atten-tional modulation of neuronal signals related to visual motion. We recorded from 89 direction-selective neurons in middle temporal (MT) and medial superior temporal (MST) visual cor-tical areas of two macaque monkeys using identical sensory stimulation under various attentional conditions. Neural re-sponses in both areas were greatly influenced by attention. When attention was directed to a stimulus inside the receptive field of a neuron, responses in MT and MST were enhanced an average of 20 and 40 % compared with a condition in whic