Intra- and cross-modal refractory period effects in healthy children and adults: An ERP study

Aims: To assess multisensory interactions in the developing human brain, intra- and cross-modal refractory period effects of event-related potential (ERP) were investigated.

Methods: Forty-one children from 4 to 12 years and 15 young adults performed a bimodal oddball task with frequent and rare visual and auditory stimuli presented with two different inter-stimulus intervals (ISI). Amplitudes of the visual and auditory ERPs were analyzed as a function of the age of the participants, the modality of the preceding stimulus (same or different) and the preceding ISI (1,000 or 2,000 milliseconds).

Results: Significant unimodal auditory refractory effects were observed with a widespread scalp distribution in all age-groups. For visual stimuli, unimodal ISI effects were detected over the posterior scalp in participants older than 7 years. whereas in the youngest age-group (4 to 6 years.) these effects were most prominent at fronto-central, central and centro-temporal recordings sites. Interestingly, in children aged 4 to 6 years. Cross-modal refractory period effects were found in both modalities over frontal and fronto-central regions. In contrast, in older children and adults cross-modal ISI effects were most pronounced both for auditory and visual ERPs over the posterior scalp.

Conclusion: These data suggest that (i) sensory-specific brain regions can be influenced by the input of another modality and (ii) sensory cortical areas become more specialized with increasing age.

In conclusion, uni- and cross-modal refractory effects might be a promising tool to assess multisensory interactions at different processing steps in the developing and mature human brain.