Neurophysiological Synchrony Between Children With Severe Physical Disabilities and Their Parents During Music Therapy

Abstract

Although physiological synchronization has been associated with the level of empathy in emotionally meaningful relationships, little is known about the interbrain synchrony between non-speaking children with severe disabilities and their familial caregivers. In a repeated measures observational study, we ascertained the degree of interbrain synchrony during music therapy in 10 child-parent dyads, where the children were non-speaking and living with severe motor impairments. Interbrain synchrony was quantified via measurements of spectral coherence and Granger causality between child and parent electroencephalographic (EEG) signals collected during ten 15-min music therapy sessions per dyad, where parents were present as non-participating, covert observers. Using cluster-based permutation tests, we found significant child-parent interbrain synchrony, manifesting most prominently across dyads in frontal brain regions within β and low γ frequencies. Specifically, significant dyadic coherence was observed contra-laterally, between child frontal right and parental frontal left regions at β and lower γ bands in empathy-related brain areas. Furthermore, significant Granger influences were detected bidirectionally (from child to parent and vice versa) in the same frequency bands. In all dyads, significant increases in session-specific coherence and Granger influences were observed over the time course of a music therapy session. The observed interbrain synchrony suggests a cognitive-emotional coupling during music therapy between child and parent that is responsive to change. These findings encourage further study of the socio-empathic capacity and interpersonal relationships formed between caregivers and non-speaking children with severe physical impairments.

Keywords: EEG; child-parent dyad; children with severe physical disabilities; granger influence; interbrain synchrony; music therapy; neural synchrony; spectral coherence.

Figure 1

Experimental setup for simultaneous EEG recording from children and their parents. For clarity, wired connections between data acquisition computer and sensors are not shown.

Figure 2

Sessional protocol. All data streams were synchronized with an external sync pulse. Saliva was collected post-session. Only EEG data are reported here. Each of the 10 sessions per participant followed the same protocol. EEG, electroencephalography; EDA, electrodermal activity; HR, heart rate.

Figure 3

Schematic of the connectivity analysis. BL, baseline; MT1, first 5 min of music therapy; MT2, second 5 min of music therapy; MT3, last 5 min of music therapy.

Figure 4

Four regions formed based on the location of EEG channels. FR, frontal right; FL, frontal left; PR, posterior right; PL, posterior left.

Figure 5

Proportion of child-parent dyads exhibiting significant music therapy coherences with respect to their corresponding baseline segments. Red shading thus denotes 100% of dyads with significant coherence. The proportions are tabulated by frequency band (rows) and pairings of child-parent brain regions i.e., frontal left (FL), frontal right (FR), posterior left (PL), and posterior right (PR).

Figure 6

Proportion of child-parent dyads exhibiting significant increases in coherence over the course of a music therapy session. Red shading thus denotes 100% of dyads with significant increases in coherence. The proportions are tabulated by frequency band (rows) and pairing of child-parent brain regions i.e., frontal left (FL), frontal right (FR), posterior left (PL), and posterior right (PR).

Figure 7

Proportion of child → parent and parent → child directional analyses exhibiting significant Granger influences during music therapy compared to preceding baseline values. Red shading thus denotes 100% of dyads with significant Granger influence. The proportions are tabulated by frequency band (rows) and directional pairing of brain regions, i.e., frontal left (FL), frontal right (FR), posterior left (PL) and posterior right (PR) from (A) child to parent, and (B) parent to child.

Figure 8

Proportion of child → parent and parent → child directional analyses exhibiting significant increases in Granger influences over the course of a music therapy session. The proportions are tabulated by frequency band (rows) and brain region, i.e., frontal left (FL), frontal right (FR), posterior left (PL), and posterior right (PR) from (A) child to parent, and (B) parent to child.