Proprioception-Related Evoked Potentials: Origin and Sensitivity to Movement Parameters E. Seiss,* C. W. Hesse,* S. Drane,* R. Oostenveld,† A. M. Wing,* and P. Praamstra* ,1 *Behavioural Brain Sciences Centre, University of Birmingham, Birmingham B15 2TT, United Kingdom; and †Departments of Neurology and Medical Physics, University Medical Centre Nijmegen, P.O. Box 9101, 6500HB Nijmegen, The Netherlands Received November 29, 2001 Reafferent electroencephalography (EEG) poten- tials evoked by active or passive movement are largely dependent on muscle spindle input, which projects to postrolandic sensory areas as well as the precentral motor cortex. The origin of these proprioception-re- lated evoked potentials has previously been studied by using N20-P20 source locations of the median nerve somatosensory evoked potential as an landmark for postcentral area 3b. As this approach has yielded con- tradictory findings, likely due to spatial undersam- pling, we applied dipole source analysis on two inde- pendently collected sets of high-density EEG data, containing the proprioception-related N90 elicited by passive finger movement, and the N20-P20 elicited by median nerve stimulation. In addition, the influence of movement parameters on the N90 was explored by varying amplitude/duration and direction of passive movements. The results showed that the propriocep- tive N90 component was not influenced by movement direction, but had a duration that covaried with the duration of the movement. Sources were localized in the precentral cortex, located on average 10 mm ante- rior to the N20-P20 sources. The latter result supports earlier claims that the motor cortex is involved in the generation of proprioception-related EEG potentials. © 2002 Elsevier Science (USA) INTRODUCTION Research interests in reafferent EEG potentials have developed along various different lines. Investi- gations of the readiness potential preceding voluntary movements have naturally generated questions re- garding the nature of movement-evoked potentials im- mediately following movement onset (e.g., Kornhuber and Deecke, 1965; Shibasaki et al., 1980; Kristeva- Feige et al., 1996; Bo ¨tzel et al., 1997). A separate body of work has developed in relation to EEG potentials that accompany long latency reflexes evoked by muscle stretch (e.g., Abbruzzese et al., 1985; Conrad et al., 1984; Goodin et al., 1990; MacKinnon et al., 2000). Finally, more recent work has investigated cerebral potentials evoked by passive movements with a view to application in rehabilitation studies or investigation of movement disorders (e.g., Mima et al., 1996, 1997a; Alary et al., 1998; Lange et al., 2001). In each of these lines of research local anesthetic procedures have shown that the investigated potentials are largely due to muscle spindle input, with little contribution from cutaneous and joint receptors (Kristeva-Feige et al., 1996; Abbruzzese et al., 1985; Mima et al., 1996). Fol- lowing Mima et al. (1996), they can be collectively designated as proprioception-related evoked poten- tials. Within the first line of work, the main emphasis has been on establishing the postmovement potentials’ re- lation to sensory feedback. In this context, an origin in the postcentral somatosensory cortex has often been taken for granted. Research on the long latency stretch reflex has attempted to provide arguments for or against a transcortical reflex loop. Hence, researchers have been open to a motor cortex contribution to cere- bral potentials evoked by muscle stretch, as a possible marker of activation of the efferent limb of the reflex loop (e.g., Abbruzzese et al., 1985). Indeed, MacKinnon et al. (2000) obtained support for motor cortex involve- ment by means of a dipole source analysis of these potentials, albeit independent of whether an imposed movement elicited a reflex or not. Such a result is compatible with evidence from single-cell neurophysi- ology for processing of muscle spindle afferent informa- tion in area 4 (e.g., Lemon and Van der Burg, 1979; Wiesendanger and Miles, 1982; for review see Porter and Lemon, 1993) and with epicortical recordings in a human subject (Mima et al., 1997a). However, muscle spindle input also projects to sensory areas in the post- central cortex (Phillips et al., 1971; Prud’homme and Kalaska, 1994). The approach of MacKinnon et al. (2000) was based on a comparison of source locations for EEG potentials 1 To whom correspondence should be addressed. Fax: 00-44-121- 414 4897. E-mail: p.praamstra@bham.ac.uk. NeuroImage 17, 461– 468 (2002) doi:10.1006/nimg.2002.1211 461 1053-8119/02 $35.00 © 2002 Elsevier Science (USA) All rights reserved.