Spatial neglect and the neural coding of attentional priority.

The concept of attentional priority plays an increasingly important role in theoretical interpretations of the neurophysiological mechanisms underlying attentional selection. A priority map is a feature-independent, spatiotopic representation of the environment that combines stimulus-driven information with goal-related signals. It emerges from the functional properties of parietal brain regions involved in spatial attention and saccade programming on the one hand, and reaching or grasping movements on the other hand. Here, we explore the value of this concept for the understanding of neuropsychological deficits of attention such as spatial extinction and neglect. We argue that these conditions reflect spatially graded, multisensory deficits affecting a processing level at which stimulus-driven and goal-driven signals interact. These attributes of neglect and extinction agree with the functional characteristics of attentional priority and suggest that components of both disorders can be understood as manifestations of damage or dysfunction affecting the parietal priority map.