Neurophysiological correlates of maternal touch and its implications for infant-mother interbrain synchrony

• Grant number: 23/12250-3
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: November 01, 2023
• End date: April 30, 2027
• Field of knowledge: Humanities - Psychology - Human Development Psychology
• Principal Investigator: Ana Alexandra Caldas Osório
• Grantee: Camila Fragoso Ribeiro
• Host Institution: Centro de Ciências Biológicas e da Saúde (CCBS). Universidade Presbiteriana Mackenzie (UPM). Instituto Presbiteriano Mackenzie. São Paulo , SP, Brazil
• Associated research grant: 21/06693-4 - The importance of social touch for infant social-emotional development: integrating neuroimaging, psychophysiological, endocrine, and behavioral evidence, AP.JP2
• Associated scholarship(s): 25/04991-9 - The Role of Touch in Mother-Infant Neural Synchrony, BE.EP.DD

Abstract

Evidence in adults suggests that neural and behavioral responses to touch vary as a function of the perceived identity of the toucher (Gazzola et al., 2012; Suvilehto et al., 2015). Research on infants is significantly scarcer, with only one study published to date. In their seminal work, Aguirre et al. assessed the heart rate of 9-month-old infants in two conditions: a) soft brush strokes administered in the presence of the mother, b) the same type of touch administered in the presence of an unfamiliar female. Interestingly, the authors found a reduction in heart rate only in response to touch perceived as coming from the mother (Aguirre et al. 2019). However, the influence of the toucher's identity on cardiac reactivity to touch by hand (instead of by an object) and the neuronal responses to touch perceived as coming from the mother (vs. an unfamiliar female) in the first year of life - a critical stage in the formation of the attachment relationship - remain unknown. Furthermore, touch in dyadic interactions between mothers and their children appears to serve as a mediating pathway for the development of an important social skill: interpersonal synchrony. Evidence shows that behavioral cues in the environment induce physiological and neural entrainment (Wass et al., 2020; Zhao et al., 2024; Feldman, 2007). More specifically, studies with adults have demonstrated that touch enhances neural synchronization, optimizing mutual receptivity, communication and empathy between individuals (Goldstein et al., 2018; Long et al., 2021). Although the same would be hypothesized to occur among caregiver-infant dyads, to date, the only study on this matter (Nguyen et al., 2021) found increased neural synchronization during mother-caregiver interaction with touching conditions. However, Nguyen and colleaguses did not assess brain regions known to be activated in response to affective touch. Thus, the main goal of this work plan is to advance our understanding of the factors influencing neural and physiological responses to affective touch during the first year of life. To address this, the first aim is to investigate differences in neural and cardiac responses to affective touch when infants believed they were being caressed by their mothers versus an unfamiliar woman. The second aim is to explore whether the observed differences in neural activation to maternal affective touch can be partly attributed to the mechanism of interpersonal synchrony. More specifically, whether there is greater neural synchrony between mothers and infants during moments of interaction with touch.