出生後2日以内の新生児におけるトップダウン感覚予測の証拠

Recent studies have demonstrated top-down modulation in perceptual cortices in infants as young as 6 months. However, it is unclear when and how this ability emerges given conflicting evidence available. This study investigates top-down perceptual modulation by focusing on a neural signature referred to as top-down sensory prediction, where the prediction of upcoming sensory information is exhibited in the modulation of activity in perceptual cortices. We extended a paradigm previously used to identify top-down sensory prediction in 6-month-old infants to neonates. Using functional near-infrared spectroscopy (fNIRS), we monitored occipital lobe activity in sleeping neonates held by their caregivers. The study consisted of a Learning session, where neonates were exposed to a novel auditory-visual stimulus combination (A+V+), followed by sessions presenting occasional visual stimulus omissions (A+V-). Results showed that fNIRS channels over the occipital lobe, which were active during the Learning session, also responded to the unexpected visual omissions, indicating neonatal brains' capability for top-down sensory prediction. Experiment 2 confirmed that this response depended on learning the audiovisual association, ruling out non-specific mechanisms such as heightened arousal or an increase in the visual response when a non-specific auditory stimulus is presented. These findings offer the first evidence of top-down modulation of visual responses in neonates, suggesting this capacity exists at birth, significantly earlier than previously thought. This study suggests that top-down predictive processing is crucial for early perceptual and cognitive development.