Longitudinal study of looming in infants with high-density EEG

Abstract

A rapidly approaching object provides information about the object’s approach and how imminent a collision is. Prospective control when responding to a looming object approaching on a direct collision course was studied longitudinally in infants aged 5/6 and 12/13 months. Different characteristics of peak VEP activity from infants’ brain electrical recordings (EEG) were explored and compared between the infants at these different ages. The aim of this study was to find evidence for infant brain electrical responses coherent with a looming stimulus approaching the infant under three different accelerations. It was also investigated whether the use of different timing-strategies to estimate the looming object’s time-to-collision would produce differences in the EEG recordings. The results showed that there were differences in peak VEP activation with age. At the age of 5/6 months, infants showed peak VEP activation earlier in the looming sequence and VEP peaks with longer duration than when they were 12/13 months old. Further, it was found that peak VEP activation in the investigated O, PO, and P areas propagated from the O area to the P area, indicating that the highest observed activation was shown in the O area at the age of 5/6 months, whereas the P area showed the highest activation when the infants were 12/13 months. Results from the timing-strategy analysis based on the index of dispersion showed that with age, four infants shifted from a less efficient strategy involving the loom’s velocity to the more efficient timing-strategy involving the loom’s time-to-collision. The decrease in processing time together with a peak VEP activation closer to the loom’s time-to-collision indicate a developmental trend in infants’ prediction of an object’s time-to-collision. This developmental trend is further substantiated by the results showing propagated peak VEP activation towards higher information processing areas in the visual pathway and the shift from a less efficient to a more efficient timing-strategy. As the infants grow older and become more mobile one of the underlying causes of the developmental trend found in our study could be due to an increase in locomotor experience. More follow-up research is needed to investigate the relation between behavioural development and changes in brain activity associated with infants’ perception of looming motion.