Document Type

Article

Publication Date

10-1-2007

Journal

Cerebral cortex (New York, N.Y. : 1991)

Volume

17

Issue

10

First Page

2283

Last Page

2292

URL with Digital Object Identifier

https://doi.org/10.1093/cercor/bhl137

Abstract

Posterior parietal cortex (PPC) participates in the planning of visuospatial behaviors, including reach movements, in gaze-centered coordinates. It is not known if these representations encode the visual goal in retinal coordinates, or the movement direction relative to gaze. Here, by dissociating the intrinsic retinal stimulus from the extrinsic direction of movement, we show that PPC employs a visual code. Using delayed pointing and event-related functional magnetic resonance imaging, we identified a cluster of PPC regions whose activity was topographically (contralaterally) related to the direction of the planned movement. We then switched the normal visual-motor spatial relationship by adapting subjects to optical left/right reversing prisms. With prisms, movement-related PPC topography reversed, remaining tied to the retinal image. Thus, remarkably, the PPC region in each hemisphere now responded more for planned ipsilateral pointing movements. Other non-PPC regions showed the opposite world- or motor-fixed pattern. These findings suggest that PPC primarily encodes not motor commands but movement goals in visual coordinates.

Notes

Fernandez-Ruiz, J., Goltz, H.C., Desouza, J.F., Vilis, T., & Crawford, J.D. (2007). Human Parietal "Reach Region" Primarily Encodes Intrinsic Visual Direction, Not Extrinsic Movement Direction, in a Visual-Motor Dissociation Task. Cerebral Cortex, 17(10), 2283-92.

The version of record is available online at:

https://academic.oup.com/cercor/article/17/10/2283/309765

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