Cortical Activation During Spatiotemporal Processing in the Infant Brain

Abstract

Neuroscientists have uncovered much about the dorsal and ventral visual object processing pathways. However, little is understood about the functional development of these pathways in human infants. Behavioral data has shown that as early as 2.5 months, infants are sensitive to spatiotemporal information for object individuation in occlusion events. This study used Near Infrared Spectroscopy to assess neural activation (as evidenced by an increase in HbO2) in four areas of the pathways: primary visual cortex (O1), posterior parietal cortex (P3), lateral occipital (T5), and inferior temporal (T3) in awake human infants aged 5.5 months while they view either a spatiotemporaldiscontinuity event or a control event. Three major predictions were made: 1) since the events contain visually distinct objects, there should be significant neural activation in O1 to both events, 2) if the dorsal route mediates the processing of spatiotemporal discontinuities, then there should also be a significant increase in P3 in response to the spatiotemporal-discontinuity event but not to the control event, and 3) activation present in T3 and T5 should not vary by condition if the ventral pathway is not responsible for the processing of spatiotemporal discontinuities. Results supported all three predictions.