Hemodynamic response to visual stimulation in newborn infants using functional near‐infrared spectroscopy

Abstract

Brain activity is associated with physiological changes, which alter the optical properties of tissue. These changes can be detected by near‐infrared spectroscopy (NIRS). Aim of the study was to determine changes in cerebral oxygenation in response to stimulation in the visual cortex in newborn infants during spontaneous sleep in the first days of life. We used an in‐house developed multichannel NIRS imaging instrument, the MCP‐II, to measure changes in concentration of oxyhemoglobin (O₂Hb) and deoxyhemoglobin (HHb) in specific brain areas. In 10 out of 15 subjects, a significant increase in O₂Hb and/or a significant decrease in HHb were found in one or more channels over the occipital cortex. During stimulation, O₂Hb increased by a mean of 0.98 μmol/l, HHb decreased by a mean 0.17 μmol/l, and total‐Hb increased by a mean of 0.81 μmol/l. The hemodynamic response to visual stimulation in the occipital cortex in newborn infants is similar to adults. The increase in O₂Hb and the simultaneous decrease in HHb during stimulation suggest an increase in cerebral blood flow (CBF) that overcompensates for the increased oxygen consumption (CMRO₂) in the activated cortical area. Hum Brain Mapp, 2008.