2024年8⽉21⽇
慶應SFC学会 研究助成⾦
成果報告書
採択者：⼭崎稜⼀郎（政策・メディア研究科後期博⼠課程）
助成カテゴリ：（Ａ）研究成果発表（学会発表）
学会名称：XXIVth Congress of International Society for Electrophysiology andKinesiology (ISEK)
開催場所：名古屋国際会議場
開催期間：2024年6⽉26⽇から2024年6⽉29⽇
発表題⽬：Rhythmic galvanic vestibular stimulation modulates sensorimotor
synchronization to auditory syncopation
著者名：Ryoichiro Yamazaki, Junichi Ushiyama
発表形式：会場でのポスター発表
報告内容：
ISEK
（第24回国際電気⽣理運動学会）は、三⼗を超える国と地域から約五百⼈の研究者が参加した、⼈間の運動・筋⾁・神経系について扱う⼤規模な国際学会であった（中京⼤学．「ISEKが愛知で開催。スポーツ科学部渡邊教授が⼤会⻑」．https://www.chukyo-u.ac.jp/news// /.html，
年8⽉20⽇参照．）。ポスター
発表の演題数は⼆百を超え、ポスターセッションは三⽇間にわたりおこなわれた（予稿集および⼤会プログラムを参照）。
採択者は、最新の研究成果についてポスター発表をおこなった。内容は、前庭感覚系に電気刺激を与えることでリズム運動の安定性を向上させる効果を⾒出した、という電気⽣理学・神経科学・実験⼼理学を組み合わせた実験の結果を報告するものであった。学会全体としては筋電図を扱う研究が多いなか、筋電図を使⽤していない研究でありながら国内外の多くの参加者と議論を交わした。これまで採択者は⾃⾝の研究と分野やスコープが合致する学会を主として参加してきたが、今回のようにスコープを少し異にする学会への参加したことで、共通の背景知識の少ない相⼿との議論によって得られる新たな気づきや視点の重要性を再確認した。また、川上泰雄先⽣（早稲⽥⼤学スポーツ科学学術院）や野坂和則先⽣（School of Medical and Health Sciences, Edith Cowan University）といった⽇本の研究者が国際学会である本学会でkeynote lectureで講演をおこなっており、世界⽔準の研究としてのロールモデルを⽬にした。今回の学会でのディスカッションで得ら420268042070420242024202

れた視点や、講演を視聴して得た新たな知⾒については、発表した研究の原著論⽂執筆における考察や構成に取り⼊れることを予定している。

‣ Auditory stimuli: 10 syncopated auditory rhythms (the duplicates of a previous study (Chapin et al., Front Psychol. 2010))

20+(2) Proprioceptive feedback
from neck muscles(1) Vestibular feedback

synchronization during head movements.

Figure. 1 | Two possible mechanisms causing the stabilization of sensorimotor

Sensorimotor synchronization

WN ND

perception

Pulse

rhythmngerexion with the same beats in

There is no competing interest to be declared for this study.

5. Tichko P, Kim JC, Large EW. Bouncing the network: A dynamicalsystems model of auditory-vestibular interactions underlying infants’
perception of musical rhythm. Dev Sci. 2021 Sep 1;24(5):e13103.
6. Tichko P, Large EW. Modeling infants’ perceptual narrowing to musicalrhythms: neural oscillation and Hebbian plasticity. Ann N Y Acad Sci. 2019Oct 25;1453(1):125–39.
7. Trainor LJ, Gao X, Lei J, Lehtovaara K, Harris LR. The primal role ofthe vestibular system in determining musical rhythm. Cortex. 2009 Jan
1;45(1):35–43.
8. Yamazaki R, Ushiyama J. Head Movements Induced by Voluntary
Neck Flexion Stabilize Sensorimotor Synchronization of the Finger toSyncopated Auditory Rhythms. Front Psychol. 2024;15.

References

1. Aoyama K, Iizuka H, Ando H, Maeda T. Four-pole galvanic vestibular
stimulation causes body sway about three axes. Sci Rep. 2015 May
11;5(1):10168.
2. Bravi R, Cohen EJ, Martinelli A, Gottard A, Minciacchi D. When NonDominant Is Better than Dominant: Kinesiotape Modulates Asymmetries
in Timed Performance during a Synchronization-Continuation Task. Front
Integr Neurosci. 2017 Sep 8;11:21.
3. Chapin HL, Zanto T, Jantzen KJ, Kelso SJA, Steinberg F, Large EW.
Neural Responses to Complex Auditory Rhythms: The Role of Attending.
Front Psychol. 2010 Dec 24;1:224.
4. Piccolo C, Bakkum A, Marigold DS. Subthreshold stochastic vestibular
stimulation affects balance-challenged standing and walking. PLoS One.
2020 Apr 1;15(4).

two experiments.

experiment 2. We compared the modulation of synchronization performance between

performance was speci c to GVS, we applied the same stimuli to the left shoulder inexperiment 1. In addition, to con rm that the e ect of electrical stimulation on theauditory beats while participants synchronized

applying electrical stimulation to the vestibular system (i.e., GVS) concurrently with theTo address this issue, we replicated the vestibular feedback from head movements by

20406080100

p = 0.54120Syncopated

30WN ND

p < 0.001

405060Yamazaki and Ushiyama.
Front Psychol. 2024 (edited)

ASY[ms]SDof timing
SD [ms]neck muscles (Bravi et al. Front Integr Neurosci. 2017).

inputs synchronized with the rhythms or (2) increased proprioceptive feedback fromndings, the stabilization of SMS by head movements would be due to (1) vestibular

this stabilization was not the same phenomenon as a bimanual advantage. Given theseto the same rhythms (Yamazaki and Ushiyama. Front Psychol. 2024). As well, our data implied that

We recently found that SMS in the head to auditory rhythms stabilized SMS in the ngersynchronized to auditory rhythms (sensorimotor synchronization, SMS).

it has been unclear whether the vestibular system is involved with motor execution(Trainor et al. Cortex. 2009; Tichko and Large. Ann N Y Acad Sci. 2019; Tichko et al. Dev Sci. 2021). However,

The vestibular system is known to be implicated in the perception of auditory rhythms

Background

[ms]

abs

stabilizedASY

Control

110

120130more stable in real conditionp = 0.050

Anglardisplacement

GVS

Auditory tones(Syncopation)

Perceived beats

Ratio of CV IFI, % (real / sham)

100ShamRealandandSham

Real(B)

indicates individual data (averaged across trials).

stability modulation by stimulus application, theratio of CVIFI in real condition to sham. Each dot(bottom). The x axis represents the timing

Figure. 4 | The modulation of the timing stabilityof movements in experiment 1 (top) and 2

Inter-Flexion intervals (IFI)

vestibular system with rhythmic movements

The observed stabilization of rhythmic movements may re ect the direct interaction of theenhanced if supposing the reinforcement by Hebbian plasticity‣ Since each condition was provided alternately, the performance in both conditions would haveplasticity‣ The present experimental design was not likely to induce the connectivity reinforcement by Hebbianand Large. Ann N Y Acad Sci. 2019; Tichko et al. Dev Sci. 2021)

to the enhanced connectivity between auditory and vestibular network by Hebbian plasticity (Tichko‣ Previously, the contribution of the vestibular system to auditory perception is suggested to be due

90++Discussion

Experiment 2

Experiment 1
GVS

Experiment 2

Experiment 1

Results(A)‣ Evaluation: Coefficient variation of inter-flexion intervals (CVIFI)‣ Electrodes were placed over the bilateral mastoids process (experiment 1) or the left shoulder (experiment 2)‣ Stimuli: Direct current (square waveform of 10ms duration; 90% intensity of the cutaneous threshold) coinciding withthe onsets of the 4/4 meters of auditory stimuli‣ Conditions: Real stimulation condition and sham stimulation condition within individuals (single-blinded)‣ Motor Task: Flexing the right index finger in synchrony to 64 perceived beats (i.e., 4/4 meters) in 12 trials

Findings: GVS tended to improve the timing stability of movements.

sensorimotor synchronization to auditory syncopated rhythms‣ Participants: Healthy young right-handed adults (35 in experiment 1 and 14 in experiment 2)

Methods

Auditory stimuli

#1

#2

break

10

#3

#1

#4

#2

#5

#3

#6

#4

#5

#6

e ect or deteriorate the performance‣ Changing such parameters might boost or diminish the observed

Cortex. 2009; Aoyama et al. Sci Rep. 2015; Piccolo et al. PLoS One. 2020)or stochastic), higher intensity, and longer duration (Trainor et al.

‣ Previous studies adopted di erent waveforms (e.g., sinusoidal

movement execution

with auditory stimuli), which is expected to help rhythmic‣ We used a novel method of GVS (short-duration, repetitive, parallel

stimulation to the vestibular system

The modulation of performance might be speci c to thestability of movements‣ In experiment 2, stimuli on shoulder did not a ect the timing

stability of movements

patterns were presented for both conditions.

experiments, real and sham stimulating condition were provided alternately. Each of 6 syncopation

sensorimotor synchronization, while experiment 2 served as the control for experiment 1. (B) Interexion intervals (IFI) was de ned as the temporal distance between adjacent exions. (C) In bothGVS on

direction ipped was calculated as the threshold.

their perception vanished. The average of 6
intensities at which the increase/decrease

until participants perceived it and decreased until

Figure. 2 | The procedure of cutaneous thresholdassessment. The intensity gradually increased

Figure. 3 | The procedure of experiments. (A) Experiment 1 tested the e ect of(C)# of stimulation

5

Estimated threshold
Applied intensity (90%)

Cutaneous threshold assessment

Electrophysiology and Kinesiology
Nagoya Congress CenterThursday, June 27th, 2024

XXIVth Congress of International Society for‣ In experiment 1, GVS application tended to improve the timing

0.50

0.55

0.60

0.65

0.70

1Graduate School of Media and Governance, Keio University, Kanagawa, Japan; 2Faculty of Environment and Information Studies, Keio University, Kanagawa, Japan; 3Department of Rehabilitation Medicine, Keio University School of Medicine, Tokyo, Japan

Ryoichiro Yamazaki 1, Junichi Ushiyama 2,3

Rhythmic galvanic vestibular stimulation modulates
sensorimotor synchronization to auditory syncopation

Purpose: We investigated the e ects of galvanic vestibular stimulus (GVS) onSummary

P1.22-I

Amplitude [mA]