Movement-Related Desynchronization of the Cerebral Cortex Studied with Spatially Filtered Magnetoencephalography

• Published in: NeuroImage (Orlando, Fla.) Vol. 12; no. 3; pp. 298 - 306
• Main Authors: Taniguchi, Masaaki, Kato, Amami, Fujita, Norihiko, Hirata, Masayuki, Tanaka, Hisashi, Kihara, Taizo, Ninomiya, Hirotomo, Hirabuki, Norio, Nakamura, Hironobu, Robinson, Stephen E., Cheyne, Douglas, Yoshimine, Toshiki
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.2000; Elsevier Limited
• Subjects: Adult; Brain mapping; Cerebral cortex; Cerebral Cortex - anatomy & histology; Cerebral Cortex - physiology; Cortical Synchronization; Electroencephalography; Female; Fingers - innervation; Fingers - physiology; Fourier Analysis; Functional magnetic resonance imaging; Grasping; Hand - innervation; Hand - physiology; Hand Strength - physiology; Humans; Magnetic Resonance Imaging; Magnetoencephalography; Male; Middle Aged; Movement - physiology; Neuroimaging; Sensorimotor system; Space life sciences; Statistics; Synchronization
• ISSN: 1053-8119; 1095-9572
• DOI: 10.1006/nimg.2000.0611

Event-related desynchronization (ERD) within the α and β bands on unilateral index finger extension and hand grasping was investigated on six normal volunteers with magnetoencephalography (MEG). A novel spatial filtering technique for imaging cortical source power, synthetic aperture magnetometry (SAM), was employed for the tomographic demonstration of ERD. SAM source image results were transformed into statistical parametric images. On the same hand grasping task, a functional MRI (fMRI) study was conducted on two subjects and compared with the ERD result. When the MEG data were analyzed with the fast Fourier transformation, power attenuation within the α and β bands was evident on the contralateral sensorimotor area just prior to movement onset. The tomographic distribution of ERD was clearly obtained with SAM statistical imaging analysis. The equivalent current dipole (ECD) for the signal-averaged motor field was localized to the hemisphere contralateral to the hand movement, roughly at the center of the region displaying β-band ERD. The signal increase on fMRI roughly colocalized with the ERD on the contralateral sensorimotor area. In conclusion, with the novel spatial filtering technique for the brain magnetic field, SAM, cortical regions contributing to ERD on finger movement were successfully demonstrated in a tomographic manner. The relative colocalization of the contralateral SAM ERD with ECD as well as the fMRI activation suggests that SAM is a practically useful technique to extract event-related signals from brain noise.