Neural Mechanisms of Parental Communicative Adjustments in Spoken Language

Abstract

During cultural transmission, caregivers typically adjust their form of speech according to the presumed characteristics of an infant/child, a phenomenon known as infant/child directed speech (IDS/CDS) or "parentese." Although ventromedial prefrontal cortex (vmPFC) damage was previously found to be associated with failure in adjusting non-verbal communicative behaviors, little is known about the neural mechanisms of verbal communicative adjustments, such as IDS/CDS. In the current study, 30 healthy mothers with preschool-age children underwent functional magnetic resonance imaging (fMRI) while performing a picture naming task which required them to name an object for either a child or an adult. In the picture naming task, mothers exhibited a longer naming duration in the toward-child condition than the toward-adult control condition. Naming an object for a child, compared with naming it for an adult, resulted in greater involvement in the vmPFC and other regions (e.g., cerebellum) in the global caregiving network. In particular, the vmPFC exhibited task-related deactivation and decreased functional connectivity with the supplementary motor, precentral, postcentral, and supramarginal regions. These findings suggest that the vmPFC, which is included in the default mode network, is involved in optimizing communicative behaviors for the inter-generational transmission of knowledge. This function of the vmPFC may be considered as a prosocial drive to lead to prosocial communicative behaviors depending on the context. This study provides a better understanding of the neural mechanisms involved in communicative adjustments for children and insight into related applied research fields such as parenting, pedagogy, and education.

Keywords: communicative adjustments; functional neuroimaging; global caregiving network; infant/child directed speech; ventromedial prefrontal cortex.