Attentional modulation ok visual response in neurons in the macaque anthrior inferotemporal cortex (AIT)

Purpose. Extrastriate cortex can he divided into functionally distinct temporal and parietal stream'-, that ha\e been implicated in featural (what) and spatial (where) vision. Our goal was to examine the role of the temporal stream in both t'eatural and spatial forms of attention. Methods. Single-unit activity was recorded in AIT of two monkeys performing a spatial attention task and a featural (shape) attention tusk After the monkex fixated a central spot, a sample shape was presented in 1 of * eccentric positions. The sample was immediate!) followed by a brief pattern mask. Alter a I -3 second delay. 3 test shapes appeared simultaneously. In the sp.iital attention task, the animal had to make a saccade to the test position in which the preceding sample appeared regaidless of shape. In the featural attention task, the animal had to make a saccade to the test shape that matched the sample shape legaidless of where it now appeared. The onl\ difference m the two tasks was whethei the animal u as attending to shape or location. Results. The majority of 144 umts recorded |7SCY ) showed significant differences in their responses to different sample shapes. About a quarter of the units (247e) showed significant differences in sample period activil) depending on whether the animal was to attend to the shape 01 location of the sample. Of those units, ty\'-7< showed increased responses m the shape task. Furthermore, about a quarter of the units (24Q] showed significant dilferences in delà) period activits depending on the shape of the remembeied sample Conclusions.. This study has confirmed shape-selective delà) period acti\it\ in IT. The majority of data was collected with a pattern mask following ihe sample stimulus, suggesting that delay activity is not necessarily eliminated h\ an intervening stimulus. Further, we found that the sensory response ol many AIT units was modulated by whether the animal was to attend to the sample shape or location.