High-Resolution ERD Using Realistic Head Geometry
Event-related desynchronization (ERD) of Rolandic mu and beta rhythms is characteristic for a voluntary movement [ 1]. The ERD Starts about 2 s before the actual movement over the contralateral hemisphere and gets bilaterally symmetrical with movement execution [2]. Movement-related magnetic fields measurements showed that the mu-rhythm is mostly of somatosensory origin whereas the beta activity seems to be generated in the primary motor cortex [3). Imagination of movement results in an ERD over the sensorimotor area [4], The aim of this paper is to compare two different highresolution methods, that is the surface Laplacian (SL) and the Linear Estimation (LE) method. The realistic geometry of the subject's head was taken into account. We investigated data recorded during motor imagery of right and left hand movements, respectively.