When the voice power rises, beta rhythm leaves.
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1
Laboratoire de Cartographie Fonctionnelle du Cerveau, ULB-Hôpital Erasme, Belgium
Introduction
The neural basis of human speech processing is typically addressed using highly controlled word or single sentence stimuli, though everyday verbal communication implies more continuous speech listening. Here, we investigate using canonical correlation analysis (CCA) the spectral brain dynamic during continuous speech and non-speech listening.
Methods
Twelve healthy right-handed subjects were measured with 306-channel MEG (Elekta Oy, Finland) while listening to two sound recordings lasting 5 minutes each. The first recording corresponded to a French-speaking female reading a text in French (Zola E. La Terre, Chapter 1, http://www.litteratureaudio.com/livre-audio-gratuit-mp3/zola-emile-la-terre.html). The second recording was derived from the first recording and consisted of non-speech sound matched for envelope and power spectrum. The power of MEG and sound signals was evaluated in adjacent 200–ms epochs. CCA was performed between MEG power–time-series in 8 frequency bands (θ: 4–8 Hz; α: 8–13 Hz; low-β: 13–20 Hz; high-β: 20–30 Hz; γ1: 30–48 Hz; γ2: 52–70 Hz; high-γ1: 70–98; high-γ2: 102–148) and sound power–time-series with 7 time-delays relative to MEG signals (–800 ms, –600 ms, –400 ms, –200 ms, 0 ms, 200 ms, and 400 ms). Statistical significance of canonical correlation was assessed using subjects’ MEG signals and 1000 different sound recordings of 5 minutes from the same reader (http://www.litteratureaudio.com). Differences in canonical correlation between speech and non-speech recordings, and hemispheric laterality effects, were assessed using non-parametric permutation test.
Results
CCA disclosed significant negative correlation between β-band and voice powers; the β-band power decreased following the voice, with a 200–400 ms delay. Beamformer analysis localized the neural substrate of this β-band power correlation at superior temporal gyrus (STG) bilaterally, with no significant difference between hemispheres (speech: p = 0.28, non-speech: p = 0.47). Correlation was significantly higher in speech compared to non-speech condition in both auditory cortices (p < 0.01).
Discussion
During continuous speech listening, the voice modulates β-band activity in left and right auditory cortices, β-band power being reduced when the voice power increases and vice-versa. The higher correlation observed in speech compared to non-speech highlights the role of the STG for speech processing. Modulation of β rhythm we observe at the STG probably reflects cortical activity tuning to the perceived speech.
Keywords:
Magnetoencephalography,
canonical correlation analysis,
speech listening,
superior temporal gyrus,
brain rhythms
Conference:
Belgian Brain Council, Liège, Belgium, 27 Oct - 27 Oct, 2012.
Presentation Type:
Poster Presentation
Topic:
Other basic/clinical neurosciences topic
Citation:
Bourguignon
M,
Wens
V,
Marty
B,
Op De Beeck
M,
Van Bogaert
P,
Goldman
S and
De Tiège
X
(2012). When the voice power rises, beta rhythm leaves..
Conference Abstract:
Belgian Brain Council.
doi: 10.3389/conf.fnhum.2012.210.00030
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Received:
10 Sep 2012;
Published Online:
12 Sep 2012.
*
Correspondence:
Mr. Mathieu Bourguignon, Laboratoire de Cartographie Fonctionnelle du Cerveau, ULB-Hôpital Erasme, Brussel, Belgium, mabourgu@ulb.ac.be