Figure 1.

Stimulus configuration and behavioral protocol. The animal fixated on the central spot and had previously been cued to direct his attention to one of the two stimulus grids. The blue dashed circle represents the receptive field of the recorded neuron and was not present on the screen. Trials in which the animal's attention was directed to the grid overlying the receptive field were defined as attended, whereas those trials in which his attention was directed to the other grid were defined as unattended. A small colored patch (in this example, follow the dashed blue arrow to a red square in the top left stimulus grid) was visible for 250-350 ms, during which time all of the other pixels in the stimulus continued to change luminance randomly. If the animal's attention had been cued to the grid on the top left, the correct response would be a saccade to the red target, illustrated by the solid blue arrow. If the animal's attention had been directed to the stimulus grid on the bottom right (no colored patch shown in this example), the correct response would have been to maintain fixation. Such catch trials ended after a random interval ranging from 260 to 3300 ms.