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Humans utilize egocentric and allocentric spatial information to guide goal-directed movements. Egocentric encoding is a well-known property of brain areas along the dorsal pathway. We ask if dorsal stream reach planning areas like parietal reach region (PRR) and dorsal premotor cortex (PMd) also encode object-centered (allocentric) information. During two consecutive instructed delay periods, rhesus monkeys first memorized an object-relative target position and then planned a reach to this position after the object re-occurred at variable positions with potentially different size. In both areas, we find predominant object-centered encoding during visual memory, which is invariant to object position and object size, and predominant egocentric encoding during reach planning. Such dynamic transition from allo- to egocentric encoding within individual dorsal stream areas contrasts the idea of task-independent functional segregation between processing pathways. Instead, demand-specific local computations might facilitate spatial cognition in dynamic environments to facilitate motor planning towards objects changing their location.Significance statementHuman and non-human primates interact with their environment by manipulating objects. This requires planning and executing reaches to transport the hand to object-relative positions close to or on the object. Previous studies showed that frontal and parietal lobe areas encode reach goals in coordinate systems anchored to different parts of the subjects’ body, such as hand position or gaze direction, and modulated by pose. We show that neurons in the same areas can encode object-centered allocentric spatial information, independent of object location and object size, or egocentric information, depending on dynamically changing task demands. Such dynamic adaptation seems inconsistent with a functional segregation for ego- and allocentric encoding between processing streams. |
