Perceiving what is reachable depends on motor representations: evidence from a transcranial magnetic stimulation study.
BACKGROUND
Visually determining what is reachable in peripersonal space requires information about the egocentric location of objects but also information about the possibilities of action with the body, which are context dependent. The aim of the present study was to test the role of motor representations in the visual perception of peripersonal space.


METHODS
Seven healthy participants underwent a TMS study while performing a right-left decision (control) task or perceptually judging whether a visual target was reachable or not with their right hand. An actual grasping movement task was also included. Single pulse TMS was delivered 80% of the trials on the left motor and premotor cortex and on a control site (the temporo-occipital area), at 90% of the resting motor threshold and at different SOA conditions (50ms, 100ms, 200ms or 300ms).


RESULTS
Results showed a facilitation effect of the TMS on reaction times in all tasks, whatever the site stimulated and until 200ms after stimulus presentation. However, the facilitation effect was on average 34ms lower when stimulating the motor cortex in the perceptual judgement task, especially for stimuli located at the boundary of peripersonal space.


CONCLUSIONS
This study provides the first evidence that brain motor area participate in the visual determination of what is reachable. We discuss how motor representations may feed the perceptual system with information about possible interactions with nearby objects and thus may contribute to the perception of the boundary of peripersonal space.
Coello
Yann
Y
Lab URECA, EA 1059, Université de Lille-Nord de France, Lille, France. yann.coello@univ-lille3.fr
Bartolo
Angela
A
Amiri
Bastien
B
Devanne
Hervé
H
Houdayer
Elise
E
Derambure
Philippe
P
D000328:Adult; D002540:Cerebral Cortex / Q000502:physiology*; D003657:Decision Making; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D010465:Perception / Q000502:physiology*; D010775:Photic Stimulation; D011930:Reaction Time; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D014796:Visual Perception / Q000502:physiology