Temporal activation pattern of parietal and premotor areas related to praxis movements.
OBJECTIVE
We sought to determine the cortical physiology underlying praxis movements in normal subjects using electroencephalography (EEG).


METHODS
Eight normal subjects were instructed to perform six types of self-paced tool-use pantomime and communicative gesture movements with the right hand. We recorded 64-channel EEG using a linked ear reference and electromyogram (EMG) from right thumb and forearm flexors.


RESULTS
Data revealed early slow wave components of the movement-related cortical potential (MRCP) beginning over the left parietal area about 3s before movement onset, similarly for both movement types. At movement onset, maximal amplitude was present over central and bilateral sensorimotor areas. Event-related desynchronization (ERD) in the beta band was seen over the left parietal and sensorimotor cortices during preparation, later spreading to the homologous area of the right hemisphere. Alpha ERD was mainly in the left sensorimotor cortex about 1.5s before movement onset. Beta ERD in mesial frontal areas was greater during preparation for tool use compared to communicative gesture movements. Mesial frontal beta event-related synchronization (ERS) developed more rapidly after communicative gestures than tool-use.


CONCLUSIONS
The dynamics of parietal and frontal activities indicates the timing of these areas in the production of praxis. The posterior parietal cortex contributes to the early slow wave negativity of the MRCP.


CONCLUSIONS
Planning self-paced praxis movements begins as early as 3s before movement in the left parietal area and subsequently engages frontal cortical regions.
Wheaton
Lewis A
LA
Human Motor Control Section, Medical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, MD 20892-1428 Maryland, USA.
Shibasaki
Hiroshi
H
Hallett
Mark
M
D000328:Adult; D000368:Aged; D003344:Cortical Synchronization; D004569:Electroencephalography; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D010296:Parietal Lobe / Q000502:physiology*