The Contribution of Human Superior Intraparietal Sulcus to Visual Short-Term Memory and Perception

The human superior intraparietal sulcus (IPS) has been shown to track the number of items stored in visual short-term memory. Although prior studies have implied that this brain region can represent a variety of visual information dynamically based on task demands, existing neuropsychological and neuroimaging studies have associated human parietal cortex primarily with attention-related processing. As such, superior IPS activation may simply track the deployment of attentional resources without actually carrying any detailed visual representations. Using functional magnetic resonance imaging and multivoxel pattern analysis, we found that, with identical visual input under different task conditions, neural response patterns in the superior IPS contained object shape information only when it was required by the task. This finding puts forward an alternative, perhaps equally important, mechanism by which parietal attention control mechanism can exert its influence on visual information processing in the brain. By directly encoding task-relevant visual information, superior IPS functions similarly to the random access memory in a computer in which information important for the current task and goal is gathered and possibly integrated. This finding adds to the growing body of evidence suggesting that the human parietal cortex is part of a brain network involved in the flexible and dynamic representation and processing of incoming information. We argue that superior IPS may be a key node in this network and mediates the moment-to-moment goal-directed visual information representation in the human brain.