Multisensory integration development during prenatal and postnatal life

In the present talk, I will focus on multisensory integration (MSI) from a developmental perspective. In the first study I will present you, we aimed at investigating whether MSI is already present and spatially organized at birth. By recording EEG responses to unimodal (audio and tactile) and bimodal (audio-tactile) stimulation in 25 human newborns, we described a genuine electrophysiological pattern of MSI at birth, with super-additive responses to bimodal stimuli. Furthermore, MSI was spatially modulated by the proximity to the baby’s body, with larger MSI effect when auditory stimuli occurred close to the body district receiving tactile stimuli. This suggests that the prenatal experience of multisensory cues during the long and sensory-enriched gestation characterizing human pregnancy likely allows MSI to emerge even before birth. Thus, in the second study I will present you, we moved our research question backward to the prenatal life and we asked when MSI and its spatial organization emerge along the third trimester of gestation. We capitalized on foetal eye-lens movements recording through 2D ultrasound, as a reliable measure of foetal attention orienting we successfully described in response to visual, acoustic and vibro-tactile stimuli delivered in isolation. In the MSI protocol, we deliver unimodal (audio and visual) and bimodal (audio-visual) stimulation at different timepoints (i.e. 27, 33, 37 weeks). Visual stimuli are delivered at a fixed location according to the foetal head position, while acoustic stimuli are delivered either colocalized or not colocalized with the visual ones. Once MSI is present and spatially organized, we should expect to observe an increased number of foetal eye-lens movements in response to bimodal than unimodal stimuli and to colocalized than not colocalized bimodal stimuli.