Cerebral blood oxygenation changes induced by auditory stimulation in newborn infants measured by near infrared spectroscopy

Recent neuronal activation studies on newborns using functional MRI or near infrared spectroscopy (NIRS) have suggested that the increase in O-2 consu mption accompanying neuronal activation exceeds the increase in O-2 deliver y in the visual cortex during photic stimulation. In the present study, we evaluated the cerebral blood oxygenation (CBO) changes induced by auditory stimulation in the frontal lobe of newborns using NIRS. We studied 28 newbo rns; the postnatal age at CBO measurements was 3.1+/-0.3 days (mean+/-S.E.M .). We measured concentration changes of deoxyhemoglobin (Deoxy-Hb), oxyhem oglobin (Oxy-Hb), and total hemoglobin (Total-Hb) induced by auditory (musi c) stimulation in the bilateral frontal lobes of the newborns. Twenty-six ( 92.9%) out of 28 subjects showed increases of Oxy-Hb and Total-Hb during th e stimulation. In these subjects, 17 (60.7%) subjects showed an increase of Deoxy-Hb associated with increases of Oxy-Hb and Total-Hb, while nine (32. 1%) subjects showed a decrease of Deoxy-Hb. Although the direction of the D eoxy-Hb differed, these two groups did not differ for Oxy-Hb and Total-Hb ( P > 0.05). Two (7.1%) subjects showed other changes. The frontal lobe of ne wborns shows CBO responses similar to those observed in the visual cortex, specifically neuronal activation causes an increase of Deoxy-Hb associated with increases of Oxy-Hb and Total-Hb. These results support the hypothesis that increments in O-2 consumption exceed increments in O-2 delivery durin g neuronal activity in newborns. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.