Research reportDon't watch where you're going: The neural correlates of decoupling eye and arm movements

- We use fMRI to examine the neural correlates of spatially dissociating the targets of eye and arm movements (non-standard visuomotor mapping) compared with the standard visuomotor mapping where the targets of eye and arm movements are spatially congruent.
- Multivoxel pattern analysis approaches reveal that the cuneus and medial premotor regions distinguish between preparatory brain activity associated with standard and non-standard visuomotor mappings.
- General linear model contrasts of BOLD signal amplitude reveal greater activity in the inferior parietal lobule and cerebellum for the non-standard task.
- The results provide an understanding of the functional brain activity underlying our ability to overcome the default tendency to couple eye and arm movements during non-standard visuomotor tasks.

“Standard” visually-guided reaching movements consist of a saccade and an arm movement to the same target location. In the current study, functional magnetic resonance imaging was used to contrast brain activity during standard visually-guided reaches with activity during a “non-standard” visuomotor mapping where the targets of the saccade and arm movement were spatially decoupled. Multi-voxel pattern analysis approaches showed discrimination of standard versus non-standard visuomotor mapping in the cuneus and medial premotor regions without accompanying task-related differences in MRI signal amplitude in these areas. Contrasts of signal amplitude did reveal greater activity associated with the non-standard task relative to the standard task in the right inferior parietal lobule and a portion of the left superior posterior cerebellum. The findings of this study shed light on brain regions involved in overcoming our default tendency to spatially couple eye and arm movements during visually-guided reaching. Further, the results suggest that the regions reported here may be important in neurological disorders such as optic ataxia, Alzheimer's disease, and mild cognitive impairment, which are associated with deficits in producing non-standard visuomotor mappings while leaving standard visuomotor mapping relatively intact.