On the role of posterior parietal and prefrontal cortex in visuo-spatial perception and attention.

Monkeys with bilateral removal of caudal prefrontal cortex (area 8) or dorso-lateral parietal cortex (areas 5 and 7) or the inferior temporal cortex (area TE) were presented with two versions of a go-left/go-right visuo-spatial discrimination. In the first task they had to displace either the left or right of two identical plaques according to whether both plaques were black or white respectively. There were no performance differences among groups. In the second task, the two plaques were always red and the appropriate response was indicated by whether a spatially remote third plaque was black or white. Both the prefrontal and parietal groups were impaired relative to the inferotemporal group on this task. The results indicate that whether an impairment occurs on a task that is thought to test the perception of egocentric space may depend on whether the animal has to notice and attend to a remote cue, and that an attentional disorder may also explain impairments reported on tests of allocentric perception where the critical cue is spatially remote from the response site.