title: Neural dynamics in motor preparation: From phase-mediated global computation to amplitude-mediated local computation.
abstract: Oscillatory activity plays a critical role in the brain. Here, we illustrate the dynamics of neural oscillations in the motor system of the brain. We used a non-directional cue to instruct participants to prepare a motor response with either the left or the right hand and recorded electroencephalography during the preparation of the response. Consistent with previous findings, the amplitude of alpha-band (8-14Hz) oscillations significantly decreased over the motor region contralateral to the hand prepared for the response. Prior to this decrease, there were a number of inter-regional phase synchronies at lower frequencies (2-4Hz; delta band). Cross-frequency coupling was quantified to further explore the direct link between alpha amplitudes and delta synchrony. The cross-frequency coupling of showed response-specific modulation, whereby the motor region contralateral to the preparation hand exhibited an increase in coupling relative to the baseline. The amplitude of alpha oscillations had an unpreferred and a preferred delta phase, in which the amplitude was modulated negatively and positively, respectively. Given the amplitude of alpha-band oscillations decreased over the analyzed period, the alpha amplitude might be down-regulated by the phase-amplitude coupling, although we do not have direct evidence for that. Taken together, these results show global-to-local computation in the motor system, which started from inter-regional delta phase synchrony and ended at an effector-specific decrease in the amplitude of alpha-band oscillations, with phase-amplitude coupling connecting both computations.
authors.affiliation: Rhythm-Based Brain Information Processing Unit, RIKEN BSI-TOYOTA Collaboration Center, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan; Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Kajihara
authors.affiliation: Rhythm-Based Brain Information Processing Unit, RIKEN BSI-TOYOTA Collaboration Center, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan; School of Mechanical and Manufacturing Engineering, National University of Sciences and Technology (NUST), H-12 Islamabad, 44000, Pakistan.
authors.forename: Muhammad Nabeel
authors.initials: MN
authors.lastname: Anwar
authors.affiliation: Rhythm-Based Brain Information Processing Unit, RIKEN BSI-TOYOTA Collaboration Center, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan; Graduate School of Systems and Information Engineering, University of Tsukuba, Tsukuba, Ibaraki 305-0006, Japan; Laboratory for Advanced Brain Signal Processing, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kawasaki
authors.affiliation: Rhythm-Based Brain Information Processing Unit, RIKEN BSI-TOYOTA Collaboration Center, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan; Graduate School of Engineering, Tokyo University of Agriculture and Technology, Tokyo 183-0057, Japan; Japan Society for the Promotion of Science, Tokyo 102-0083, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Mizuno
authors.affiliation: Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan.
authors.forename: Kimitaka
authors.initials: K
authors.lastname: Nakazawa
authors.affiliation: Rhythm-Based Brain Information Processing Unit, RIKEN BSI-TOYOTA Collaboration Center, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan; Laboratory for Advanced Brain Signal Processing, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan; Graduate School of Engineering, Tokyo University of Agriculture and Technology, Tokyo 183-0057, Japan. Electronic address: kkitajo@brain.riken.jp.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Kitajo
mesh_terms: D000328:Adult; D059031:Anticipation, Psychological / Q000502:physiology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D010775:Photic Stimulation; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult