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Abstract:
Our subjective experience links covert visual and egocentric spatial attention seamlessly. However, the latter can extend beyond the visual field, covering all directions relative to our body. Even with closed eyes we can rotate from the computer screen to face the window with little loss of accuracy, and once rotated we are aware of the computer’s updated egocentric position. It appears thus that our egocentric model includes seen and unseen locations. In contrast to visual representations, little is known about unseen egocentric representations in the healthy brain. Parietal cortex appears to be involved in both, because its lesions can lead to deficits in visual
attention, but also to a disorder of egocentric spatial awareness, known as hemispatial neglect. In this study, our participants performed a novel egocentric orientation task inside an octagonal room. Once they were familiar with this setup, we exposed our participants to a virtual version of
the same paradigm during fMRI recordings. We found egocentric unseen space represented by patterns of voxel activity in parietal cortex, independent of visual information. Intriguingly, the best decoding performances corresponded to brain areas associated with visual covert attention and reaching, as well as to lesion sites associated with spatial neglect.
