Neural adolescent pragmatic development mirrors pragmatic differences in adulthood: an fMRI-study

Pragmatic development is still ongoing during adolescence. However, the developmental trajectory during this period is understudied and the underlying neural correlates of pragmatic development are unknown. In this study, we used an established fMRI paradigm contrasting indirect and direct speech acts in a newly acquired adolescent sample (n = 51) and a previously collected adult sample (n = 57). The adolescent sample was subdivided into Young (ages 13-15) and Mid (ages 16-18) groups and the adult sample (Old, ages 20-36) was split based on pragmatic skill level (established in separate behavioral tests). We observed age-related increases in activity in the posterior medial superior frontal gyrus, and a combination of age-related differences and adult individual differences in the dorsal aspects of the posterior cingulate cortex (dPCC). Both clusters were located outside the classic perisylvian language network. We interpret the dPCC findings in terms of its overlap with the Default Mode Network. Similar activity in the dPCC between adolescents and adults with lower pragmatic skill is consistent with a view that a delayed adolescent development may lead to persistent pragmatic difficulties in adulthood. The findings also indicate development towards context-specific processing. By studying adolescence, a presumably uniquely human extended developmental period, we provide a rare empirical angle on the question of which aspects of brain and cultural evolution contributed to the human communicative faculty.