Explainable Exploration of the Interplay Between HRV Features and EEG Local Connectivity Patterns in Dyslexia

Heart Rate Variability (HRV) is a measure of the variation in time between successive heartbeats, reflecting the influence of the autonomic nervous system on the heart. It can provide insights into the balance between sympathetic and parasympathetic activity. The relationship between autonomic nervous system function, specifically parasympathetic activity, and certain learning disorders, including dyslexia, is currently under study. In this paper, we propose the use of explainable techniques to explore the relationships between HRV markers and local functional brain activity, estimated by cross-frequency coupling (CFC) from electroencephalography (EEG) signals recorded while auditory stimuli were applied to 7-year-old children. We analyze EEG data to examine the phase-to-phase brainwave coupling and use machine learning tools such as XGBoost and Shapley values to reveal brain regions that most contribute to different HRV features, with a focus on parasympathetic activity. Our findings suggest that HRV features related to stress can explain differential activations in the auditory cortex (Brodmann areas 39 and 40) during auditory stimulation in dyslexic children.