Movement interference attenuates somatosensory high-frequency oscillations: contribution of local axon collaterals of 3b pyramidal neurons.
OBJECTIVE
We examined the effects of movement interference on high-frequency oscillations (HFOs) and N20m in 10 healthy subjects.


METHODS
For the movement interference condition, somatosensory evoked magnetic fields (SEFs) following electric median nerve stimulation were recorded during voluntary movement of the digits. For the control condition, the SEFs were recorded without interference. The N20m and HFOs were separated by 3-300Hz and 300-900Hz bandpass filtering. Then, the peak-to-peak amplitudes were measured.


RESULTS
Both interference/control amplitude ratios for the N20m and HFOs were smaller than 100%. In contrast, the HFO/N20m amplitude index, which was calculated by dividing the interference/control amplitude ratio for the HFOs with that for the N20m, was significantly greater in the movement interference condition than in the control condition.


CONCLUSIONS
Although the overall amplitude of the HFOs was decreased by movement, enhancement of the HFOs by the movement was revealed by the HFO/N20m amplitude index. Thus, we suggest that the HFOs represent activity of the inhibitory interneurons excited by both thalamocortical afferent impulses and excitatory synaptic inputs from pyramidal neurons in area 3b through their local axon collaterals, thereby reflecting both feed-forward and feedback inhibitory effects onto the post-synaptic pyramidal neurons.
Tanosaki
Masato
M
Department of Integrated Neuroscience, Tokyo Institute of Psychiatry, 2-1-8 Kamikitazawa, Setagaya-Ku, Japan. tanosaki@prit.go.jp
Kimura
Tomoaki
T
Takino
Ryosuke
R
Iguchi
Yoshinobu
Y
Suzuki
Atsushi
A
Kurobe
Yuji
Y
Haruta
Yasuhiro
Y
Hoshi
Yoko
Y
Hashimoto
Isao
I
D000328:Adult; D001369:Axons / Q000502:physiology*; D004558:Electric Stimulation; D004594:Electrophysiology; D005260:Female; D005385:Fingers / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D008297:Male; D008475:Median Nerve / Q000502:physiology; D008959:Models, Neurological; D009068:Movement / Q000502:physiology*; D017966:Pyramidal Cells / Q000502:physiology*; D013003:Somatosensory Cortex / Q000033:anatomy & histology / Q000166:cytology / Q000502:physiology*; D014110:Touch / Q000502:physiology