Cognitive Brain Research 17 (2003) 573–583 www.elsevier.com / locate / cogbrainres Research report Dynamics of sensorimotor cortex activation to spatial sounds precueing ipsi- versus contralateral manual responses a, b a * Jochen Kaiser , Rolf Ulrich , Werner Lutzenberger a 1 ¨ MEG-Center, Institute of Medical Psychology and Behavioral Neurobiology , Eberhard-Karls-University of Tubingen, Gartenstrasse 29, 72074 ¨ Tubingen, Germany b ¨ ¨ Institute of Psychology, Eberhard-Karls-University of Tubingen, Tubingen, Germany Accepted 30 May 2003 Abstract 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 |200 ms after their onset. For contralateral precues, a switch of beta ERD to the response hemisphere took place |400 ms after trial-onset, peaking prior to the imperative stimulus ( |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.  2003 Elsevier B.V. All rights reserved. Theme: Motor systems and sensorimotor integration Topic: Cortex Keywords: Event-related desynchronization (ERD); Magnetoencephalography (MEG); Auditory precues; Motor responses; Sensorimotor cortex 1. Introduction negative variation paradigms where a warning signal informed about the time point of a required response Movements are preceded by event-related desynchroni- [7,18,20]. ERD has been interpreted as an electrophysio- zation (ERD) in the electro- and magnetoencephalogram logical correlate of activated cortical areas involved in (EEG and MEG, respectively), i.e., by relative decreases in motor preparation [21]. Recently, we have found faster spectral amplitude in the alpha and beta frequency bands contralateral beta ERD in MEG when a lateralized motor ( |8–30 Hz). ERD over sensorimotor areas in the hemi- response was precued by sounds lateralized on the re- sphere representing the response hand has been demon- sponse side than by midline precues, suggesting a close strated both for self-paced movements in readiness po- relationship between beta ERD and response preparation tential paradigms [15,22,26,27,30] and for contingent processes [10]. Surprisingly, sensorimotor beta ERD was also observed during passive listening to lateralized sounds with a *Corresponding author. Tel.: 149-7071-297-4224; fax: 149-7071- potential relevance for orienting. Both language stimuli 295-956. like the German syllable ‘da’ (English: ‘there’) and animal E-mail address: jochen.kaiser@uni-tuebingen.de (J. Kaiser). 1 URL: http: / / www.uni-tuebingen.de / medizinischepsychologie. vocalizations presented as lateralized deviants in spatial 0926-6410 / 03 / $ – see front matter  2003 Elsevier B.V. All rights reserved. doi:10.1016 / S0926-6410(03)00171-X