Effects of task and coordinate frame of attention in area 7a of the primate posterior parietal cortex.

The activity of neurons in the primate posterior parietal cortex reflects the location of visual stimuli relative to the eye, body, and world, and is modulated by selective attention and task rules. It is not known however how these effects interact with each other. To address this question, we recorded neuronal activity from area 7a of monkeys trained to perform two variants of a delayed match-to-sample task. The monkeys attended a spatial location defined in either spatiotopic (world-centered) or retinotopic (eye-centered) coordinates. We found neuronal responses to be remarkably plastic depending on the task. In contrast to previous studies using the simple version of the delayed match-to-sample task, we discovered that after training in a task where the locus of attention shifted during the trial, neural responses were typically enhanced for a match stimulus. Our results further revealed that responses were mostly enhanced for stimuli matching in spatiotopic coordinates, although the proportion of neurons modulated by either coordinate frame was influenced by the behavioral task executed.