(2013), sources for areas 4 and 3b, separated by the central sulcus, are located side by side in the lateral–medial direction (see also Fig. ​Fig.55 in Kawamura et al. 1996). The

same scheme can be found in our data (Fig. ​(Fig.6B-a),6B-a), and thus strengthen our proposal of a precentral origin of s1/4. The third source s5 in the postcentral gyrus was in its caudal-most part around the intraparietal sulcus at a latency of 50 msec, probably corresponding to area Inhibitors,research,lifescience,medical 5 in agreement with previous MEG studies (Forss et al. 1994; Hoshiyama et al. 1997; Inui et al. 2004). A few previous MEG studies on decomposing MRCFs have proposed that the source of MEFI is of postcentral origin, perhaps in area 3b, and reflects Brefeldin A chemical structure feedback from the periphery (Oishi et al. 2004; Cheyne et al. 2006), leading to our speculation of the commonality Inhibitors,research,lifescience,medical of source locations for MEFI during movement experiments and area 3b

in SEF experiments. However, the source locations we specified differed substantially, mainly in the medial–lateral direction (Fig. ​(Fig.6;6; Table ​Table1).1). By Inhibitors,research,lifescience,medical contrast, the location of all sources for MRCFs and s1/4 in SEFs nearly overlapped in the same precentral region (Fig. ​(Fig.6;6; Table ​Table1),1), whereas there was an apparent disagreement of source orientations between them (Table ​(Table2).2). This may refect the differentiation of neuronal assemblies in response to different kinds of afferent inputs, for example, the sm1 for MEFI was elicited by the natural finger Inhibitors,research,lifescience,medical movements, whereas s1/4 in SEFs was elicited by median nerve stimulation. Although both are the first cortical responses triggered in the periphery, different afferent inputs may contribute to the generation of these two types of source response. Relation of MRCFs to EMGs To control rapid, self-terminated movements about a single joint,

the activities of antagonist muscles toward Inhibitors,research,lifescience,medical the movement end are needed not only for braking ongoing movement (Marsden et al. 1983; Mustard and Lee 1987), but for end-point precision (Suzuki et al. 2001). However, neither of these was needed in our task. Instead, the complete relaxation of antagonist muscles was needed immediately after a pulsatile command had been issued. Therefore, even if the MEFI might be attributable to the reafferent signal from the periphery as suggested above, this MEFI component is not linked to the generation of reflexive muscle second responses. MacKinnon et al. (1994) have examined an experimental situation in which a load compensatory reaction is or is not needed in the stretched wrist muscles. They found that the magnitude of EMG responses was modulated with task instruction, being largest with active and smallest with passive resistance. By contrast, the magnitude of the early evoked potentials, the dipole generator for which was confirmed to be in the deep layers of area 4, did not change across tasks.