The motor cortex approximately 20 Hz rhythm reacts differently to thumb and middle finger stimulation: an MEG study.
The human thumb is functionally and morphologically different from the other digits, enabling capability for a wide range of movements and for precision grasping. We investigated the reactivity of the magnetic approximately 20 Hz motor cortex rhythm by stimulating thumb and middle finger electrically and by quantifying the poststimulus rebounds. The level of the approximately 20 Hz rhythm level was significantly higher after thumb than middle finger stimulation. In contrast, the somatosensory 20-ms responses were stronger after middle finger than the thumb stimulation. We found an inverse thumb/middle finger ratio between the 20 ms responses and the reactivity of the approximately 20 Hz motor cortex rhythm. Thus the sensorimotor processing differs for thumb and middle finger in the human primary motor and somatosensory cortices.
Järveläinen
Juha
J
Brain Research Unit, Low Temperature Laboratory, Helsinki University of Technology, FIN-02015 HUT, Finland.
Schürmann
Martin
M
D000328:Adult; D004558:Electric Stimulation; D005260:Female; D005385:Fingers / Q000294:innervation*; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D013003:Somatosensory Cortex / Q000502:physiology; D013933:Thumb / Q000294:innervation*