The purpose of the present study was to examine the contributions
made by cat posterior parietal cortex to the analyses of
the relative position of objects in visual space. Two cats
were trained on a landmark task in which they learned to
report the position of a landmark object relative to a
right or left food-reward chamber. Subsequently, three
pairs of cooling loops were implanted bilaterally in contact
with visuoparietal cortices forming the crown of the middle
suprasylvian gyrus (MSg; architectonic area 7) and the
banks of the posterior-middle suprasylvian sulcus (pMS
sulcal cortex) and in contact with the ventral-posterior
suprasylvian (vPS) region of visuotemporal cortex. Bilateral
deactivation of pMS sulcal cortex resulted in a profound
impairment for all six tested positions of the landmark,
yet bilateral deactivation of neither area 7 nor vPS cortex
yielded any deficits. In control tasks (visual orienting
and object discrimination), there was no evidence for any
degree of attentional blindness or impairment of form discrimination
during bilateral deactivation of pMS cortex. Therefore,
we conclude that bilateral cooling of pMS cortex, but neither
area 7 nor vPS cortex, induces a specific deficit in spatial
localization as examined with the landmark task. These
observations have significant bearing on our understanding
of visuospatial processing in cat, monkey, and human cortices.
Craniotopic updating of visual space across saccades in the human posterior parietal cortex
