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

Intensity Dependent Amplitude Changes (IDAP) have been extensively studied using Event-Related Potentials (ERPs) and have been linked to several psychiatric disorders. This study aimed to explore the application of functional near-infrared spectroscopy (fNIRS) in IDAP paradigms and to relate it to ERPs. Thirty-three and thirty-one subjects participated in two experiments, respectively. The first experiment consisted of the presentation of three-tone intensities (77.9dB, 84.5dB, and 89.5dB) lasting 500 ms, each type randomly presented 54 times, while the second experiment consisted of the presentation of five-tone intensities (70.9dB, 77.9dB, 84.5dB, 89.5dB, and 95.5dB) in blocks composed of eight tones of the same intensity lasting 70 ms each one, in total 20 blocks were presented. EEG was used to measure ERP components: N1, P2, and N1-P2 peak-to-peak amplitude. fNIRS allowed the analysis of the hemodynamic activity in the auditory and prefrontal cortices. The results showed an increase in N1, P2, and N1-P2 peak-to-peak amplitude with auditory intensity. Similarly, oxyhemoglobin and deoxyhemoglobin concentrations showed amplitude increases and decreases, respectively, with auditory intensity in the auditory and prefrontal cortices. Spearman correlation analysis showed a relationship between the left auditory cortex and N1 and the right dorsolateral cortex and P2 amplitude. These results suggest that there is a brain response to auditory intensity changes that can be obtained by EEG and fNIRS, supporting the neurovascular coupling process. Overall, this study contributes to the understanding and application of fNIRS in auditory paradigms and highlights its potential to be used in a complementary manner to ERPs.