Functional imaging of the brain in infant using near infrared topography under sedated sleep

Abstract We demonstrated spatiotemporal changes in hemoglobin concentrations in the sensorimotor cortex of a neonate during passive motor stimulation using multichannel near-infrared spectroscopy. This study was carried out on a healthy term neonate without neurological problems under the condition of sedative sleep. We employed a 24-channel near-infrared topography device with two wavelengths (780 and 830 nm), each with an interoptode distance of 2 cm, in this study. The probes were placed in the parietotemporal region over the sensorimotor cortex. An examiner flexed and extended the infant's leg and arm at the knee and elbow joints at a frequency of approximately 0.7 Hz. This passive motor stimulation consisted of 8–10 repetitions of the movement, each lasting for 15 s, followed by a 30-s rest period. Contralateral knee movement caused marked increases in oxyhemoglobin concentration ([HbO 2 ]) and totalhemoglobin concentration ([T-Hb]) from the baseline values at almost all locations in the primary sensorimotor area and a decrease in local deoxyhemoglobin concentration ([Hb]). On the other hand, contralateral elbow movement caused marked increases in [HbO 2 ] and [T-Hb] in more restricted regions than did knee movement. The results show that sensorimotor area function in response to passive motor stimulation can be imaged and evaluated even in newborn infants during sedative sleep.