Maternal touch and infant’s brain responses to affective and discriminative touch: an fNIRS Study

Recently, we found evidence that activation to affective touch in right Superior Temporal Sulcus (rSTS) can be detected at 12 months. Here we report, using a preexisting longitudinal dataset, that the neural response to affective touch, using fNIRS and in the rSTS, is associated with maternal touch frequency.Mother-infant dyads (n = 35) participated in two tasks at 7 and 12 months: a free-play and an experimental touch task. In the touch task, an experimenter alternately applied two stimuli to the infant’s forearm: gentle brushing (affective stimulus); and tapping with a wooden block (discriminative stimulus). Our fNIRS array covered the left primary somatosensory cortex (lS1) and rSTS. Using age, task, and the covariate proportion of interaction time with maternal touch, as predictors of the activation to touch, we found that maternal touch is a predictor of the activation.Moreover, infants of mothers who touch more often, had an activation profile indicative of earlier specialization. We measured the association using the slope of the covariate. At 7 months, infants of mother who touched more frequently had a lower activation in the lS1 for the affective stimulus. At 12 months, infants of mother who touched more frequently had higher activation in the rSTS, also only in the affective stimulus condition.