RODENT POSTERIOR PARIETAL CORTEX AS A COMPONENT OF A CORTICAL NETWORKMEDIATING DIRECTED SPATIAL ATTENTION

The rat posterior parietal cortex has been found to be a multimodal co nvergence area identifiable by its pattern of neuroanatomical connecti ons with the cortex and thalamus. The rat posterior parietal cortex is part of a cortical network that also includes the medial agranular an d ventrolateral orbital areas. Each of these three cortical areas is a region of multimodal convergence. Bilateral destruction of any of the se areas produces deficits in spatial learning, whereas unilateral les ions induce deficits in directed attention. These findings suggest tha t together these cortical regions form an integrated network for spati al processing and orientation. In a recent test of this hypothesis, th e posterior parietal area was selectively disconnected from the medial agranular cortex without direct damage to either area. This resulted in severe neglect which was qualitatively and quantitatively similar t o that produced by unilateral destruction of wither cortical area, the reby supporting the network hypothesis. Some earlier conflicting repor ts bearing on the functional role of rat posterior parietal cortex may be explained in light of these disconnection data. The anatomical and behavioral findings suggest that in rats, as in primates, a parieto-f rontal network mediates the integrated, dynamic spatial representation s essential for normal directed attention and spatial orientation.