Simultanous EEG+NIRS Signal Processing from the Brain
Dec 2015 – June 2016
Abstract
Electroencephalography (EEG) and cerebral near-infrared spectroscopy (NIRS) are both well-known monitoring methods for analyzing cerebral neurophysiology and hemodynamics. Neuronal activity in the gray matter of the brain requires energy and thus a high metabolic rate, which is related to oxygen consumption. The blood regulatory system operates to ensure sufficient spatial and temporal distribution of oxygen and energy substrates to supply neuronal activity. In this research, we studied NIRS/EEG signals for electrophysiological activity and hemodynamic changes in the human forehead. A bandpass filter separates each source based on the carrier frequency. Three experiments were conducted using the aforementioned NIRS/EEG instrument. The experiments were performed on five healthy human subjects. The initial experiment was conducted to evaluate the functionality of the developed NIRS/EEG prototype. The association between alpha-band oscillations and total hemoglobin during subjective pain (Cold Presser Test, CPT) was demonstrated. The increase in alpha-band oscillations, as measured by EEG electrodes on the forehead, and the increase of total hemoglobin, as measured by NIRS optodes on the forehead, have been recorded and reported accordingly. Conventional EEG recording is conducted in the 0.16 to 70 Hz frequency range. However, ultra-low-frequency EEG, found in the range of 0.015 to 4 Hz, is highly informative and allows discovery of the general state of neurons. The genesis of non low-frequency EEG signals may be non-neuronal. In the last experiment, the changes of pCO2 and low-frequency EEG are measured concurrently and the results are presented accordingly. The slow shifts of EEG signals and changes in oxygenation due to the hypoxic breathing are demonstrated in the in the results of this experiment.
Collaborators:
Adjunct Professor of Electrical and Computer Engineering at The University of British Columbia
