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Updated: Jun 2, 2026

Intracortical Inhibition Within the Primary Motor Cortex Can Be Modulated by Changing the Focus of Attention
Published on: September 11, 2017
Oscillatory interaction between the hand area of human primary motor cortex and finger muscles during steady-state
Manyoel Lim1, June Sic Kim, Chun Kee Chung
1Interdisciplinary Program in Neuroscience, Seoul National University, Seoul, South Korea.
Objective:
To compare the magnitudes of β-band coherence between the primary motor cortex (M1) and electromyogram (EMG) for finger muscles, and to determine whether M1-EMG coherence is related to the stability of muscle contraction.
Methods:
Cortical signals and EMG during steady-state isometric contraction of right thumb muscle (flexor pollicis brevis (FPB)) or right little finger muscle (flexor digiti minimi brevis (FDMB)) were recorded simultaneously with magnetoencephalography system from 13 right-handed healthy subjects.
Results:
The magnitudes of β-band M1-EMG coherence and spectral power in the M1 for the FPB muscle were greater than that for the FDMB muscle (P < 0.001 and P < 0.005, respectively). The stability of EMG for the FPB was higher than that for FDMB (P < 0.001). Greater levels of β-band M1-EMG coherence were associated with higher levels of EMG stability (P < 0.05). The mean dipole sources of the FPB muscle were located more laterally, inferiorly and anteriorly than that of FDMB in the M1 hand area (P < 0.005).
Conclusions:
The strength of β-band M1-EMG coherence would play an important role in the stability level of finger-muscle contraction.
Significance:
The β-band M1-EMG coherence may reflect effective oscillatory interaction between the M1 and finger muscle during steady-state motor output.
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