Abstract
The aim of the present study was (i) to investigate the effect of inner speech on cerebral hemodynamics and oxygenation, and (ii) to analyze if these changes could be the result of alternations of the arterial carbon dioxide pressure (PaCO2). To this end, in seven adult volunteers, we measured changes of cerebral absolute [O2Hb], [HHb], [tHb] concentrations and tissue oxygen saturation (StO2) (over the left and right anterior prefrontal cortex (PFC)), as well as changes in end-tidal CO2 (PETCO2), a reliable and accurate estimate of PaCO2. Each subject performed three different tasks (inner recitation of hexameter (IRH) or prose (IRP) verses) and a control task (mental arithmetic (MA)) on different days according to a randomized crossover design. Statistical analysis was applied to the differences between pre-baseline, two tasks, and four post-baseline periods. The two brain hemispheres and three tasks were tested separately. During the tasks, we found (i) PETCO2 decreased significantly (p < 0.05) during the IRH ( ~ 3 mmHg) and MA ( ~ 0.5 mmHg) task. (ii) [O2Hb] and StO2 decreased significantly during IRH ( ~ 1.5 μM; ~ 2 %), IRP ( ~ 1 μM; ~ 1.5 %), and MA ( ~ 1 μM; ~ 1.5 %) tasks. During the post-baseline period, [O2Hb] and [tHb] of the left PFC decreased significantly after the IRP and MA task ( ~ 1 μM and ~ 2 μM, respectively). In conclusion, the study showed that inner speech affects PaCO2, probably due to changes in respiration. Although a decrease in PaCO2 is causing cerebral vasoconstriction and could potentially explain the decreases of [O2Hb] and StO2 during inner speech, the changes in PaCO2 were significantly different between the three tasks (no change in PaCO2 for MA) but led to very similar changes in [O2Hb] and StO2. Thus, the cerebral changes cannot solely be explained by PaCO2.
This is a preview of subscription content, log in via an institution.
Buying options
Tax calculation will be finalised at checkout
Purchases are for personal use only
Learn about institutional subscriptionsReferences
Bettermann H, von Bonin D, Frühwirth M, Cysarz D, Moser M (2002) Effects of speech therapy with poetry on heart rate rhythmicity and cardiorespiratory coordination. Int J Cardiol 84(1):77–88
von Bonin D, Frühwirth M, Heuser P, Moser M (2001) Effects of speech therapy with poetry on heart rate variability and well-being. Forsch Komplementarmed Klass Naturheilkd 8(3):144–160
Cysarz D, von Bonin D, Lackner H, Heusser P, Moser M, Bettermann H (2004) Oscillations of heart rate and respiration synchronize during poetry recitation. Am J Physiol Heart Circ Physiol 287(2):H579–H587
Scholkmann F, Gerber U, Wolf M, Wolf U (2012) End-tidal CO2: an important parameter for a correct interpretation in functional brain studies using speech tasks. Neuroimage 66:71–79
Wolf M, von Bonin D, Wolf U (2011) Speech therapy changes blood circulation and oxygenation in the brain and muscle: a near-infrared spectrophotometry study. Adv Exp Med Biol 701:21–25
Wolf U, Scholkmann F, Rosenberger R, Wolf M, Nelle M (2011) Changes in hemodynamics and tissue oxygenation saturation in the brain and skeletal muscle induced by speech therapy – a near-infrared spectroscopy study. Sci World J 11:1206–1215
Weinger MB, Brimm JE (1987) End-tidal carbon dioxide as a measure of arterial carbon dioxide during intermittent mandatory ventilation. J Clin Monit 3(2):73–79
Scholkmann F, Spichtig S, Muehlemann T (2010) How to detect and reduce movement artifacts in near-infrared imaging using moving standard deviation and spline interpolation. Physiol Meas 31(5):649–662
Buxton RB (2012) Dynamic models of BOLD contrast. Neuroimage 62(2):953–961
Szabo K, Lako E, Juhasz T, Rosengarten B, Csiba L, Olah L (2011) Hypocapnia induced vasoconstriction significantly inhibits the neurovascular coupling in humans. J Neurol Sci 309(1–2):58–62
Grubb RL, Raichle ME, Eichling JO, Ter-Pogossian MM (1974) The effects of changes in PaCO2 on cerebral blood volume, blood flow, and vascular mean transit time. Stroke 5(5):630–639
Sullivan RM, Gratton A (2002) Prefrontal cortical regulation of hypothalamic-pituitary-adrenal function in the rat and implications for psychopathology: side matters. Psychoneuroendocrinology 27(1–2):99–114
Buijs RM, Van Eden CG (2000) The integration of stress by the hypothalamus, amygdala and prefrontal cortex: balance between the autonomic nervous system and the neuroendocrine system. Prog Brain Res 126:117–132
Koechlin E, Hyafil A (2007) Anterior prefrontal function and the limits of human decision-making. Science 318(5850):594–598
Simons CJP, Tracy DK, Sanghera KK et al (2010) Functional magnetic resonance imaging of inner speech in schizophrenia. Biol Psychiatry 67(3):232–237
Acknowledgments
We thank all subjects and the arts speech therapist Andrea Klapproth for their participation in this study, Rachel Folkes for proofreading of the manuscript, and the numerous participants of the ISOTT conferences 2010, 2011, and 2012 for their stimulating discussions about CO2 and cerebral hemodynamics/oxygenation.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2013 Springer Science+Business Media New York
About this paper
Cite this paper
Scholkmann, F., Wolf, M., Wolf, U. (2013). The Effect of Inner Speech on Arterial CO2 and Cerebral Hemodynamics and Oxygenation: A Functional NIRS Study. In: Van Huffel, S., Naulaers, G., Caicedo, A., Bruley, D.F., Harrison, D.K. (eds) Oxygen Transport to Tissue XXXV. Advances in Experimental Medicine and Biology, vol 789. Springer, New York, NY. https://doi.org/10.1007/978-1-4614-7411-1_12
Download citation
DOI: https://doi.org/10.1007/978-1-4614-7411-1_12
Published:
Publisher Name: Springer, New York, NY
Print ISBN: 978-1-4614-7256-8
Online ISBN: 978-1-4614-7411-1
eBook Packages: Biomedical and Life SciencesBiomedical and Life Sciences (R0)