Head hemodynamics and systemic responses during auditory stimulation

Abstract

The present study aims to analyze the systemic response to auditory stimulation by means of hemodynamic (cephalic and peripheral) and autonomic responses in a broad range of auditory intensities (70.9, 77.9, 84.5, 89.5, 94.5 dBA). This approach could help to understand the possible influence of the autonomic nervous system on the cephalic blood flow. Twenty‐five subjects were exposed to auditory stimulation while electrodermal activity (EDA), photoplethysmography (PPG), electrocardiogram, and functional near‐infrared spectroscopy signals were recorded. Seven trials with 20 individual tones, each for the five intensities, were presented. The results showed a differentiated response to the higher intensity (94.5 dBA) with a decrease in some peripheral signals such as the heart rate (HR), the pulse signal, the pulse transit time (PTT), an increase of the LFnu power in PPG, and at the head level a decrease in oxygenated and total hemoglobin concentration. After the regression of the visual channel activity from the auditory channels, a decrease in deoxyhemoglobin in the auditory cortex was obtained, indicating a likely active response at the highest intensity. Nevertheless, other measures, such as EDA (Phasic and Tonic), and heart rate variability (Frequency and time domain) showed no significant differences between intensities. Altogether, these results suggest a systemic and complex response to high‐intensity auditory stimuli. The results obtained in the decrease of the PTT and the increase in LFnu power of PPG suggest a possible vasoconstriction reflex by a sympathetic control of vascular tone, which could be related to the decrease in blood oxygenation at the head level.

Neurovascular Coupling During Auditory Stimulation: Event-related Potentials and Fnirs Hemodynamic

“…The indirect nature of fNIRS and its limited depth coverage compared to fMRI, in addition to physiological factors in uencing cerebral hemodynamics, could explain the contradictory results found in the literature (Chen et al, 2015;Muñoz-Caracuel et al, 2021;Muñoz et al, 2022). Mulert (2010), suggests that, concerning the study of the hemodynamic response, it is possible that the synchronous activity of a small number of neurons may result in changes detectable by EEG, but that the hemodynamic changes generated are not enough to be detected by statistical tests, due to an insu cient change in baseline.…”

“…Thus, some conditions that stress the cerebral vasculature, could further decrease vascular distensibility, making it more di cult to nd the neurovascular coupling response between the electrical and hemodynamic signal. In humans, vascular responses to stress conditions have been most studied in autonomic and peripheral measurements, in which high intensities sounds seem to lead to a process of vasoconstriction analyzed by Pulse transit time (PTT) and/or Power spectral density (PSD) of the pulse signal, both vasoconstriction indicators (Franco et al, 2002;Galland et al, 2007, Muñoz et al, 2022. This issue could be especially relevant in studies in which the defense re ex could be masking the hemodynamic signals, as in the present report when high intensities are employed.…”

“…As a way to obtain just the cortical activity a regression of the short channels with the hmrSSR function, was also applied. In this point, we want to focus on the importance of peripheral masking of the hemodynamic signal, as reported in previous auditory research (Muñoz-Caracuel et al, 2021;Muñoz et al, 2022). In this report, to improve the signal processing, we have added the use of principal component analysis (PCA) and have prioritized the cleaning of physiological signals, which is a major issue of fNIRS, as proposed by the cited studies.…”

“…Similarly, Weder et al (2018) found that higher intensity levels led to higher concentration changes, especially in the superior temporal gyrus, they also found differences in waveform patterns, being phasic near the supramarginal and caudal superior temporal gyrus, and tonic in channels over Broca's area, The same results were found by Weder et al (2020), moreover this study pointed out that the dependence of the intensity changes may be better explained by the perception of the subjects (loudness) rather than intensity, being this response more pronounced in the superior temporal gyrus of the right hemisphere. Conversely, Muñoz-Caracuel et al (2020) and Muñoz et al (2022), found that the highest intensities (94.5dB), could lead to a decrease in HbO concentrations, which would be possible due to the in uence of systemic vasoconstriction. Furthermore, Chen et al (2015) did not nd an auditory intensity effect in the auditory cortex, but found a modulation for perceived intensity, suggesting similarly to Weder et al (2020) that auditory cortical responses studied with fNIRS would be more sensitive to perceived intensity than to the physical property of sound intensity.…”

Systemic neurophysiological signals of auditory predictive coding

“…On the other hand, although embodied cognition is a relevant conceptual issue within the predictive coding framework (Allen & Friston, 2018;Seth & Friston, 2016), little empirical research has addressed this question in an integrative manner. Recent work from our group (Muñoz et al, 2022;Muñoz-Caracuel et al, 2021) has shown the complex relationship between the peripheral and central nervous system (CNS) during sensory information encoding and, to our knowledge, only a few studies have investigated these systemic responses using oddball paradigms. Lyytinen et al (1992) found that neither heart rate (HR) nor skin conductance response (SCR) seemed to correlate with the MMN elicitation, whereas elicitation of the P300 component would be associated with a higher SCR.…”