Coding of visual space during motor preparation: Approaching objects rapidly modulate corticospinal excitability in hand-centered coordinates.

Journal article

Defensive behaviors, such as withdrawing your hand to avoid potentially harmful approaching objects, rely on rapid sensorimotor transformations between visual and motor coordinates. We examined the reference frame for coding visual information about objects approaching the hand during motor preparation. Subjects performed a simple visuomanual task while a task-irrelevant distractor ball rapidly approached a location either near to or far from their hand. After the distractor ball appearance, single pulses of transcranial magnetic stimulation were delivered over the subject's primary motor cortex, eliciting motor evoked potentials (MEPs) in their responding hand. MEP amplitude was reduced when the ball approached near the responding hand, both when the hand was on the left and the right of the midline. Strikingly, this suppression occurred very early, at 70-80 ms after ball appearance, and was not modified by visual fixation location. Furthermore, it was selective for approaching balls, since static visual distractors did not modulate MEP amplitude. Together with additional behavioral measurements, we provide converging evidence for automatic hand-centered coding of visual space in the human brain.

Authors: Makin, T; Holmes, N; Brozzoli, C; Rossetti, Y; Farnè, A

• Publication status: Published
• Journal: Journal of neuroscience : the official journal of the Society for Neuroscience
• Volume: 29
• Issue: 38
• Pages: 11841-11851
• Publication date: 2009-09-01
• DOI: 10.1523/JNEUROSCI.2955-09.2009
• EISSN: 1529-2401
• ISSN: 0270-6474
• Language: English
• Keywords: Evoked Potentials, Motor; Visual Perception; Adult; Photic Stimulation; Motor Cortex; Male; Uncertainty; Young Adult; Electromyography; Motor Activity; Humans; Female; Fixation, Ocular; Middle Aged; Pyramidal Tracts; Time Factors; Transcranial Magnetic Stimulation; Psychomotor Performance; Video Recording; Hand