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Journal of Biomedical Optics • Open Access

Cerebral hemodynamic and oxygenation changes induced by inner and heard speech: a study combining functional near-infrared spectroscopy and capnography
Author(s): Felix Scholkmann; Sabine D. Klein; Ursina Gerber; Martin Wolf; Ursula Wolf

Paper Abstract

The aim of this study was to investigate the effects of inner and heard speech on cerebral hemodynamics and oxygenation in the anterior prefrontal cortex (PFC) using functional near-infrared spectroscopy and to test whether potential effects were caused by alterations in the arterial carbon dioxide pressure (PaCO2). Twenty-nine healthy adult volunteers performed six different tasks of inner and heard speech according to a randomized crossover design. During the tasks, we generally found a decrease in PaCO2 (only for inner speech), tissue oxygen saturation (StO2), oxyhemoglobin ([O2 Hb]), total hemoglobin ([tHb]) concentration and an increase in deoxyhemoglobin concentration ([HHb]). Furthermore, we found significant relations between changes in [O2 Hb], [HHb], [tHb], or StO2 and the participants’ age, the baseline PETCO2, or certain speech tasks. We conclude that changes in breathing during the tasks led to lower PaCO2 (hypocapnia) for inner speech. During heard speech, no significant changes in PaCO 2 occurred, but the decreases in StO2, [O2 Hb], and [tHb] suggest that changes in PaCO2 were also involved here. Different verse types (hexameter and alliteration) led to different changes in [tHb], implying different brain activations. In conclusion, StO2, [O2 Hb], [HHb], and [tHb] are affected by interplay of both PaCO2 reactivity and functional brain activity.

Paper Details

Date Published: 13 January 2014
PDF: 10 pages
J. Biomed. Opt. 19(1) 017002 doi: 10.1117/1.JBO.19.1.017002
Published in: Journal of Biomedical Optics Volume 19, Issue 1
Show Author Affiliations
Felix Scholkmann, Univ. Hospital Zürich (Switzerland)
Sabine D. Klein, Univ. Bern (Switzerland)
Ursina Gerber, Univ. Bern (Switzerland)
Martin Wolf, Univ. Hospital Zürich (Switzerland)
Ursula Wolf, Univ. Bern (Switzerland)

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