Music of brain hemispheres sheds light on schizophrenia

Researchers at the University of California in San Diego have suggested that careful analyses of the electrical signals of brain activity, measured using electroencephalography (EEG), may reveal important harmonic relationships in the electrical activity of brain circuits. The underlying premise is a simple one - that brain function is expressed by circuits that fire, and therefore generate oscillating EEG signals, at different frequencies. High frequency EEG activity called gamma, for example, might reflect the activity of fast-spiking cells which are often a subclass of inhibitory nerve cells containing parvalbumin. Represented musically, this would be a high pitch, i.e., toward the right side of the piano. Lower frequency EEG activity, called theta, might come from cells that fire with a lower frequency. As circuits interact with each other, one would see different "musical combinations", like the chords of music, emerging in the EEG signal. Abnormalities in the structure and function of brain circuits would be reflected in cacophonous music, chords where the musical "voices" are firing at the wrong rate (pitch), volume (amplitude), or timing. It is increasingly evident that schizophrenia is a disorder characterized by disturbances in the "music of the brain hemispheres." Their new report in the latest issue of Biological Psychiatry described relationships between low- and high-frequency EEG oscillations in the human brain produced when high frequency auditory stimuli are presented to a research subject. The researchers observed relatively slower oscillations and reduced cross-phase synchrony (for example, peak of theta coinciding with peak of gamma) in schizophrenia patients compared to healthy study participants. "The new findings highlight the importance of understanding the relationships between different circuits. It seems that cortical abnormalities in schizophrenia disturb brain function, in part, by disturbing the 'tuning' of brain circuits in relation to each other," commented Dr. John Krystal, Editor of Biological Psychiatry.