More recently, to take advantage of superior spatial and temporal resolution characteristics, there has been interest in simultaneous measurement methods that combine noninvasive brain measurement methods.

Simultaneous measurement with fNIRS and EEG was used to investigate the relationship between neural activity and the hemodynamic response of the somatosensory cortex to electric stimulation of the median nerve*.

* The median nerve extends from the brachial plexus and runs roughly down the center of the abdominal side of the upper extremities.

Fig. 1 Relative Positions of NIRS and EEG Probes

Fig. 1 Relative Positions of NIRS and EEG Probes

The whole-head holder (Fig. 1) includes EEG sockets ( ) located midway between the NIRS transmitter and receiver probes ( ) to align the NIRS channels (measurement points) with the position of EEG probes (Fig. 2a and 3a).

Fig. 4  Brain Activity at Indicated Time (sec) Intervals After Electric Stimulation

Of all the locations where Oxy-Hb (Fig. 2b) and somatosensory evoked electric potential (Fig. 3b) were measured, the somatosensory evoked potential at P22 (positive wave at 22 ms of latency) increased in the primary somatosensory cortex of the ear (left) on the opposite side from the side that was electrically stimulated (Fig. 3a and 3b). In addition, Oxy-Hb increased in the primary somatosensory cortex of the opposite ear from the electrical stimulation 5 seconds after the electrical stimulation (Fig. 4). Simultaneous measurement using NIRS and EEG is especially effective for investigating the correlation between hemodynamic response and neural activity.

(Data provided by: Mr. Hisao Nishijo, Graduate School of Medicine and Pharmaceutical Sciences for Research, University of Toyama)

Reference: Takeuchi., M, Hori, E., Takamoto, K., Tran, A.H., Kohno, S., Ishikawa, A., Ono, T., Endo, S. and Nishijo, H. (2009)
"Brain cortical mapping by simultaneous recording of functional near infrared spectroscopy and electroencephalograms from the whole brain during right median nerve stimulation." Brain Topogr, 22, 197-214.

Note: The data shown was acquired using a FOIRE/OMM series model.

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