Cerebral Blood Oxygenation Changes over the Occipital and Frontal Cortexes During Sucking in Infants: An Optical Topographic Study

Objectives: Human infants learn about their surrounding world by acquiring information and integrating different sensory modalities in the brain. We have two prevailing theoretical views on mechanisms of information acquisition, known as the integration approach and differentiation approach. To understand the feasibility of these concepts, we studied changes in regional cerebral blood oxygenation in infants during nutritive sucking using near-infrared optical topography (NIR-OT). Methods: Thirty-two infants, aged 1 month, were randomly divided into two groups. In group A, blood oxygenation was measured in the occipital and parieto-temporal areas (24 measurements in 18 infants). In group B, measurements were collected in the frontal and parieto-temporal areas (21 measurements in 14 infants). Measurements were performed while infants were spontaneously sucking with their eyes closed. Results: In group A, sucking behavior corresponded with significant increases in [oxy-Hb] in all measurements, four measurements in the occipital area, six measurements in the left parieto-temporal area, and six measurements in both areas. In group B, sucking behavior corresponded with significant increases in [oxy-Hb] in 10 of 13 measurements, one measurement in the right parieto-temporal area and nine measurements in both frontal and right parieto-temporal areas. Discussion: Sucking behavior activated not only the parieto-temporal area corresponding to the primary sensory area of lips but also the inferior frontal and occipital areas. These findings suggest that the brain in early infancy has more redundant connections with other regions than the adult brain, and connections between regions used daily will become predominant. These results favor the differentiation view.