Motor Mapping with EEG and fMRI

The synchronization and desynchronization of oscillatory electroencephalographic (EEG) activity is believed to reflect basic neurophysiological processes that are fundamental to information processing by the brain. Oscillatory events provide clues to how information is organized within particular brain regions, and how it is shared between multiple regions to form functional networks. The EGI Science Team examined the oscillations of the EEG in relation to the blood-oxygen-level dependent (BOLD) response as each subject performed a simple motor task (Figure 1). The high spatial resolution of source localization with 256 dEEG and accurate individual head models enabled us to localize movement-related source activity directly and non-invasively to compare with the BOLD data.

fMRI response to stimulus

Figure 1. fMRI hemodynamic response and cortical distributions of beta-band premotor event-related desynchronization (ERD) activities during right/left thumb movements using sLORETA inverse methods for individual head model. The thresholds for the beta-band cortical distributions were set 95% at scalp and 97% at source. The z score of BOLD activation was calculated by thresholds 2.5 and fraction 25%. M1 and S1 regions of interest (ROIs) are represented by green and yellow colors, respectively.

EEG and fMRI locations

Figure 2. EEG and fMRI locations relative to M1 (green) and S1 (yellow) ROIs. The peak and center of gravity (COG) of movement-related EEG activities for different frequency bands and fMRI are highlighted in blue cross (Theta), purple circle (Mu), brown crescent (Beta), white diamond (LG), red triangle (HG), and black star (fMRI) respectively. See updated published image.

Kuo, C.-C., Luu, P., Morgan, K., Dow, M., Davey, C., Song, J., . . . Tucker, D. M. (2014). Localizing movement-related primary sensorimotor cortices with multi-band EEEG frequency changes and functional MRI. PLoS One, 9(11), e112103.