Date of Award

Spring 1996

Document Type

Thesis

Degree Name

Master of Science in Biomedical Engineering - (M.S.)

Department

Biomedical Engineering Committee

First Advisor

Stanley S. Reisman

Second Advisor

Edip Niver

Third Advisor

David S. Kristol

Abstract

Electrical activity in the human body was investigated using EEG and ECG measurements while subjects remained with eyes open, eyes closed and in a meditation state. During these measurements, additional antennas were attached to the equipment to record atmospheric noise and signal activity simultaneously. The obtained data was analyzed and various observations were made. Processed data based on antenna signals clearly showed the presence of man-made signals, having narrow spectral widths that could be treated as atmospheric noise in the frequency range up to 50 Hz. In addition, signals clustered around 7.8, 14.1, 20.3, 26.4, and 32.5 Hz were observed as Schumann resonances of the earth-ionosphere waveguide. Careful analysis of the noise in the EEG and ECG signals showed the noise activity to be identical to the signals detected by the antennas. Hence, it was possible to differentiate the physiological brain and heart activity from the noise, which is now clearly identified as man-made signals and Schumann resonances up to 50 Hz. The presence of coherence in dual EEG channels is a good measure to quantify the meditation state. The performed measurements showed high coherence around 10 Hz in single subjects while meditating. When these measurements extended to two subjects, with the goal to study group meditation, it was observed that coherence spectra spread significantly to other frequencies.

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