Statistical and temporal brain cortical mapping by simultaneous recording of functional near infrared spectroscopy (NIRS) and EEGs from the whole brain

Abstract

Relationships between neuronal activities and hemodynamic responses remain unknown. We recorded simultaneously hemodynamics (Oxy-, deoxy-, and total-Hb tissue concentration) by NIRS and EEGs from the whole brain, while human subjects received the right median nerve electrical stimulation. Stimulus frequencies varied form 2 to 10 Hz. The 3-D coordinates of the NIRS probes and EEG electrodes were stereotaxically measured. Statistical significance of hemodynamic responses was evaluated by general linear model (GLM). The resultant NIRS and EEGs data were stereotaxically superimposed on the reconstructed brain of each subject. EEG data indicated that typical somatosensory evoked potentials (N21) were recorded from the contralateral somatomotor cortex. The NIRS data indicated that Oxy-Hb concentration increased at the contralateral SI area and then the responses spread to more posterior and ipsilateral areas. Comparison of these 2 data indicated that; (1) 3-D distance between dipoles of N21 and position of the channels with maximum Oxy-Hb responses was less than 10 mm, (2) the 2 topographical maps of NIRS and EEGs were significantly correlated. These results suggest usefulness of simultaneous recording of NIRS and EEGs. [J Physiol Sci. 2007;57 Suppl:S111]