発表

1B-047

遅延聴覚フィードバックへの順応に伴う知覚促進の神経相関

[責任発表者] 菅野 禎盛:1
[連名発表者] Jeroen Stekelenburg#:2, [連名発表者] Frouke De Schipper#:2, [連名発表者] Jean Vroomen#:2
1:九州産業大学, 2:ティルブルフ大学

Introduction
Perception of synchrony between a voluntary action and the sensory feedback thereof is changed after a short exposure phase to delayed auditory feedback (DAF) (Heron et al., 2009; Sugano et al., 2010). Auditory reaction times (RTs) are also shorter after exposure to DAF, suggesting that auditory processing is enhanced (Sugano et al., 2016). Here, we examined the neural correlates of this speed-up.

Method
Twenty-two students from Tilburg University participated in the experiment (12 females, 22.0±2.7 years, all were right-handed). All had normal hearing and normal or corrected-to-normal vision.
Participants were exposed to either delayed (150 ms) or subjectively synchronous (50 ms) auditory feedback (30 ms, 2 kHz tone at 78 dB(A) via speakers) while they pressed a mouse 7 times at a constant pace (~750 ms). Immediately thereafter, they performed a simple auditory RT task, in which 3 tone pips were delivered at pseudo-random inter-stimulus intervals between 1500 to 3450 ms. Participants received 20 of these 7-exposure/3-RT trials per condition (sync or delayed) in one block, and did two blocks in total, with order counter-balanced across participants.
The electroencephalogram (EEG) was sampled at 512 Hz from 64 locations using active Ag-AgCl electrodes (BioSemi, Amsterdam, the Netherlands) mounted in an elastic cap and two mastoid electrodes. Electrodes were placed in accordance with the extended International 10-20 system. Two additional electrodes served as reference (Common Mode Sense [CMS] active electrode) and ground (Driven Right Leg [DRL] passive electrode). Eye movements were monitored by bipolar horizontal and vertical EOG derivations. EEG was referenced offline to an average of the left and right mastoids and band-pass filtered (0.1–30 Hz, 24 dB/octave).

Results
RTs shorter than 100 ms or longer than 500 ms were excluded from analyses. Individual RT-distributions, fitted by an ex-Gaussian function (Luce, 1986; Harrar et al., 2016), showed that the tau parameter (covering the tail) was significantly smaller after exposure to DAF than synced feedback (54.9 ms vs. 60.5 ms, respectively), F(1,21)=4.97, p=.037, meaning that slower RTs were sped-up after DAF. The EEG, time-locked to tone onset, showed that the P1 (25-50 ms) and LPP (350-750 ms) were more positive after exposure to DAF than sync, F(1,21)=5.31, p=.032 and F(1,21)=6.67, p=.017, respectively (Fig 1).
Discussion
Our results demonstrate that exposure to DAF causes auditory facilitation that can be attributed to both early sensory and late attentional processing stages.


Figure 1: (A) Group-averaged RT distribution fitted with an ex-Gaussian function, (B) Tone-locked ERPs, (C) Scalp potential maps of the difference wave for P1 (left) and LPP (right), (D) Point-wise t-tests on the difference wave between sync (50 ms) and DAF (150 ms).

Acknowledgements
This work was supported by Tilburg University and JSPS KAKENHI Grant Number 26380998.


References
Harrar, V., Harris, L. R., & Spence, C. (2016). Multisensory integration is independent of perceived simultaneity. Experimental Brain Research, 235(3), 763–775.
Heron, J., Hanson, J. V. M., & Whitaker, D. (2009). Effect before cause: Supramodal recalibration of sensorimotor timing. PloS One, 4(11), e7681.
Luce, R. D. (1986). Response times: Their role in inferring elementary mental organization. Oxford University Press.
Sugano, Y., Keetels, M., & Vroomen, J. (2010). Adaptation to motor-visual and motor-auditory temporal lags transfer across modalities. Experimental Brain Research, 201(3), 393–399.
Sugano, Y., Keetels, M., & Vroomen, J. (2016). Temporal recalibration after motor-auditory delay is accompanied with reduction of auditory latency, Poster presented at the 31st International Congress of Psychology, (Yokohama, Japan).

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