Basic functions and clinical applications

Abstract

Investigation for motor system by magnetoencephalographic (MEG) recordings has focused on detecting the primary motor area. In order to collect data with high S/N ratio, selection of a motor paradigm and an analysis method to assure events time-locked to movement onset is important. Self-paced movement paradigm has been widely employed, because the same paradigm in electroencephalographic (EEG) and subdural recordings has provided bunch of physiological data. The motor field (MF) component in movement-related cortical magnetic fields (MRCFs) is believed to reflect the final stage of motor execution in MI. Frequency analysis on the background rhythm related to movement can be also utilized to estimate motor-related areas. Considering the difficulties in performing the self-paced movement, easier motor paradigms such as isometric contraction or cyclic repetitive movements have been recently introduced. Although estimated sources from these paradigms have provided sources of reasonable locations, physiological significance should await for further study.