Multisensory integration in children: a preliminary ERP study

Abstract

The spatio-temporal scalp distribution of multisensory auditory-somatosensory integration was investigated in typically developing children ages 6-13. Event-related potentials were recorded from 32 scalp electrodes while participants watched a silent cartoon. Three types of sensory stimulation were presented pseudo-randomly: auditory clicks, somatosensory median nerve electrical pulses, or simultaneous auditory and somatosensory stimuli. No behavioral responses were required of the participant. To examine integration, responses to simultaneous auditory and somatosensory stimulation were compared to the sum of unisensory auditory plus unisensory somatosensory responses for four time-windows: (60-80 ms, 80-110 ms, 110-150 ms and 180-220 ms). Results indicated significant multisensory integration occurred in central/post-central scalp regions between 60-80 ms in the hemisphere contralateral to the side of somatosensory stimulation and between 110-150 ms in the hemisphere ipsilateral to the side of somatosensory stimulation. Between 180-220 ms, significant multisensory integration was evident in central/post-central regions in both hemispheres as well as midline scalp regions. This study suggests that children exhibit differential processing of multisensory compared to unisensory stimuli, as has previously been reported in adults.

Fig. 1

Event Related Potentials (ERPs). The grand averages of event related potentials (ERPs) for auditory (black traces), somatosensory (red traces) and simultaneous auditory and somatosensory stimuli (green traces) are shown for a sample of 21 children. The ERPs are shown at midline electrode sites (Fz, Cz and Pz) and central/post-central electrode sites (C3, CP5, C4 and CP6). The P100, N100 and P200 ERP amplitude peaks are labeled at electrode site Cz. The placement of the electrode sites are indicated in a top view schematic in the upper left corner.

Fig. 2

ERP voltage maps. The spatio-temporal distribution of grand average auditory and somatosensory ERPs are displayed in 20 ms intervals. The key to the right shows the range of voltages (in µV) for both types of ERPs.

Fig. 3

Auditory–somatosensory multisensory integration (MSI). The grand averages of ERPs for 21 children are shown for the seven electrode sites (Fz, Cz Pz, C3, CP5, C4 and CP6) designated in the schematic in the upper left-hand corner. Simultaneous auditory and somatosensory ERPs (green traces) are compared to the sum of unisensory auditory added to unisensory somatosensory ERPs (orange traces). Difference waves (black traces = simultaneous – summed) identify possible scalp locations for MSI.

Fig. 4

P-values for MSI. Significant p values are displayed over time for 32 electrodes from running t-tests comparing the simultaneous (AS) and summed (A+S) ERPs. Statistically significant p values ranging from 0.01 to 0.05 are represented by the color code (key is to the right of graph). Time is plotted on the x-axis from 0 to 400 ms. Electrode sites are plotted on the y-axis.