Allocentric versus Egocentric Representation of Remembered Reach Targets in Human Cortex

摘要: The location of a remembered reach target can be encoded in egocentric and/or allocentric reference frames. Cortical mechanisms for are relatively well described, but the corresponding representations essentially unknown. Here, we used an event-related fMRI design to distinguish human brain areas involved these two types representation. Our paradigm consisted three tasks with identical stimulus display different instructions: (remember absolute location), relative visual landmark), and nonspatial control, color report (report target). During delay phase (when only was specified), elicited widely overlapping regions cortical activity (relative control), higher activation parietofrontal cortex task early tasks. In addition, directional selectivity (target gaze) observed superior occipital gyrus inferior gyrus, whereas landmark) temporal gyrus. response (after movement direction had been specified either by reappearance landmark or pro-/anti-reach instruction), network resumed selectivity, showing contralateral than ipsilateral reaches. These results show that use partially substrates specification is memory versus response.