Out of Sight, Out of Mind? Neuronal Gamma Oscillations During Occlusion Events in Infants

Object permanence allows infants to interact successfully with objects in the environment. What happens in the human infant brain when objects move in and out of sight? This study used high-density electroencephalography (hdEEG) to record induced oscillatory brain activities in 29 locomotor infants before, during, and after occlusion of a moving object traveling at different speeds. Temporal spectral evolution (TSE) showed that before and after the occlusion event, event-related synchronized (ERS) brain activity was observed, whereas event-related desynchronized (ERD) activity was detected when the car was hidden behind the occluder. Both synchronized and desynchronized brain activities were found in the gamma frequency band (>30 Hz) in visual areas. Coherence connectivity analysis showed significant cluster differences before and during occlusion, during and after occlusion, and before and after occlusion in the gamma (30-150 Hz) and theta range (4-7 Hz) in several brain sources of interest. It was concluded that locomotor infants between 8.5 and 12 months of age show high-frequency brain oscillations while perceiving a moving object going temporarily out of sight. The significant cluster differences indicate the beginning of specialized connectivity networks, where object permanence is processed within dedicated visual, parietal, and central areas along the dorsal processing stream.