Dynamics of sensorimotor cortex activation to spatial sounds precueing ipsi- versus contralateral manual responses.
Spatially informative visual precues give rise to event-related potential asymmetries with higher negativities over the contralateral hemisphere. However the attribution of these potentials to sensorimotor areas is still unclear. The present magnetoencephalography study assessed movement preparation processes to auditory spatial precues. Event-related desynchronization (ERD) was measured to test the hypothesis that lateralized sounds would give rise to a fast, stimulus-driven activation of motor networks independent of the precued response side. The lateralized vowels /a/ and /e/ served as precues for either ipsi- or contralateral responses, respectively, which had to be executed when an imperative stimulus was presented 1 s after precue onset. Two separate experiments were conducted with either blocked or mixed presentation of ipsi- and contralateral precues. Beta ERD over sensorimotor regions representing the stimulus side was elicited by both types of precues approximately 200 ms after their onset. For contralateral precues, a switch of beta ERD to the response hemisphere took place approximately 400 ms after trial-onset, peaking prior to the imperative stimulus (approximately 800 ms post trial-onset). Signal subspace projection demonstrated a high topographical correspondence between the early precue-related ERD and the pattern immediately preceding the response, suggesting that both were generated in similar motor networks. Apparently lateralized sounds give rise to an early activation of contralateral motor networks independent of the precued response. This suggests strong associations between space processing and action preparation networks, with fast activations preceding a detailed cortical analysis of stimulus meaning.
Kaiser
Jochen
J
MEG-Center, Institute of Medical Psychology and Behavioral Neurobiology, Eberhard-Karls-University of Tübingen, Gartenstrasse 29, 72074 Tübingen, Germany. jochen.kaiser@uni-tuebingen.de
Ulrich
Rolf
R
Lutzenberger
Werner
W
D000328:Adult; D000465:Algorithms; D001307:Auditory Perception / Q000502:physiology*; D001931:Brain Mapping; D003463:Cues; D005072:Evoked Potentials, Auditory / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D013003:Somatosensory Cortex / Q000502:physiology*; D013017:Sound Localization / Q000502:physiology*