Attention to both space and feature modulates neuronal responses in macaque area V4

Attention is the mechanism with which we select specific aspects of our env ironment for processing. Psychological experiments have shown that attentio n can be directed to a spatial location or to a particular object. Electrop hysiological studies in trained macaque monkeys have found that attention c an strengthen the responses of neurons in cortical area V4. Some of these s tudies have attributed these effects to spatial attention, whereas others h ave suggested that feature-directed attention may modulate the neuronal res ponse. Here we report that neuronal correlates for both spatial and feature -directed attention exist in individual neurons in area V4 of behaving rhes us monkeys.