Neural dynamics underlying coherent motion perception in children and adults
Manning C., Kaneshiro B., Kohler PJ., Duta M., Scerif G., Norcia A.
<p>Motion sensitivity increases during childhood, but little is known about the underlying neural correlates. Most studies investigating children’s evoked responses have not dissociated direction-specific and non-direction-specific responses. To isolate direction-specific responses, we presented coherently moving dot stimuli preceded by a period of incoherent motion, to 6- to 7-year-olds (n = 34), 8- to 10-year-olds (n = 34), 10- to 12-year-olds (n = 34) and adults (n = 20). Participants reported the direction of coherent motion while high-density EEG was recorded. Using a data-driven approach, we identified two stimulus-locked EEG components with distinct topographies: an early component with an occipital topography and a later, sustained positive component over centro-parietal electrodes. The component waveforms showed clear age-related differences, and scaled with motion coherence. In the early, occipital component, all groups showed a negativity peaking at ~300ms, like the previously reported coherent-motion N2. However, the children, unlike adults, showed an additional positive peak at ~200ms. The later positive response in the centro-parietal component rose more steeply for adults than for the youngest children, likely reflecting age-related changes in decision-making. These results suggest that children’s protracted development of coherent motion sensitivity is associated with gradual maturation of both early sensory and later decision-related processes.</p>