Differential modulation in human primary and secondary somatosensory cortices during the preparatory period of self-initiated finger movement.
To elucidate the mechanisms underlying sensorimotor integration, we investigated modulation in the primary (SI) and secondary (SII) somatosensory cortices during the preparatory period of a self-initiated finger extension. Electrical stimulation of the right median nerve was applied continuously, while the subjects performed a self-initiated finger extension and were instructed not to pay attention to the stimulation. The preparatory period was divided into five sub-periods from the onset of the electromyogram to 3000 ms before movement and the magnetoencephalogram signals following stimulation in each sub-period were averaged. Multiple source analysis indicated that the equivalent current dipoles (ECDs) were located in SI and bilateral SII. Although the ECD moment for N 20 m (the upward deflection peaking at around 20 ms) was not significantly changed, that for P 30 m (the downward deflection peaking at around 30 m) was significantly smaller in the 0- to -500-ms sub-period than the -2000- to -3000-ms sub-period. As for SII, the ECD moment for the SII ipsilateral to movement showed no significant change, while that for the contralateral SII was significantly larger in the 0- to -500-ms sub-period than the -1500- to -2000-ms or -2000- to -3000-ms sub-period. The opposite effects of movement on SI and SII cortices indicated that these cortical areas play a different role in the function of the sensorimotor integration and are affected differently by the centrifugal process.
Wasaka
Toshiaki
T
Department of Integrative Physiology, National Institute for Physiological Sciences, Okazaki, Japan. wasaka@nips.ac.jp
Nakata
Hiroki
H
Akatsuka
Kosuke
K
Kida
Tetsuo
T
Inui
Koji
K
Kakigi
Ryusuke
R
D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D004558:Electric Stimulation / Q000379:methods; D004569:Electroencephalography; D004576:Electromyography / Q000379:methods; D004585:Electrooculography / Q000379:methods; D005073:Evoked Potentials, Somatosensory / Q000502:physiology / Q000528:radiation effects; D005260:Female; D005385:Fingers / Q000502:physiology*; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D008475:Median Nerve; D009068:Movement / Q000502:physiology*; D010465:Perception / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology / Q000528:radiation effects; D013003:Somatosensory Cortex / Q000033:anatomy & histology / Q000502:physiology*