parietal cortex update visual information in conjunction with eye movements.This remapping of stimulus representations is thought to contribute to spatial constancy.We hypothesized that a similar process occurs in parietal cortex and that we could visualize it with functional MRI.
We observed an initial response in the hemisphere contralateral to the visual stimulus, followed by a remapped response in the hemisphere ipsilateral to the stimulus.
We ruled out the possibility that this remapped response resulted from either eye movements or visual stimuli alone.
Single-unit recordings have identified a region in the posterior parietal cortex (PPC) of the monkey that represents and updates visual space in a gaze-centered frame.
Here, using event-related functional magnetic resonance imaging, we identified an analogous bilateral region in the human PPC that shows contralateral topography for memory-guided eye movements and arm movements.
Furthermore, when eye movements reversed the remembered horizontal target location relative to the gaze fixation point, this PPC region exchanged activity across the two cortical lobules.
This shows that the human PPC dynamically updates the spatial goals for action in a gaze-centered frame.
The posterior parietal cortex (PPC) is important for spatial processing and visually guided action (Goodale and Milner, 1992; Jeannerod et al., 1995; Andersen et al., 1997; Colby and Goldberg, 1999).
In the monkey, different regions within the PPC process information for different actions.
For example, the lateral intraparietal sulcus (LIP) codes target location for eye movements called saccades (Gnadt and Andersen, 1988; Barash et al., 1991; Duhamel et al.