Potentiation of Gamma Oscillatory Activity through Repetitive Transcranial Magnetic Stimulation of the Dorsolateral Prefrontal Cortex

• Published in: Neuropsychopharmacology (New York, N.Y.) Vol. 34; no. 11; pp. 2359 - 2367
• Main Authors: Barr, Mera S, Farzan, Faranak, Rusjan, Pablo M, Chen, Robert, Fitzgerald, Paul B, Daskalakis, Zafiris J
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.10.2009; Nature Publishing Group
• Subjects: Addictions; Adult; Behavioral Sciences; Biological and medical sciences; Biological Psychology; Cognition & reasoning; Cognition - physiology; Cognition. Intelligence; Electroencephalography; Female; Fundamental and applied biological sciences. Psychology; Human; Humans; Learning. Memory; Male; Medical sciences; Medicine; Medicine & Public Health; Memory; Memory, Short-Term - physiology; Mental health; Methodology. Experimentation; Middle Aged; Miscellaneous; Neuropsychological Tests; Neurosciences; original-article; Periodicity; Pharmacotherapy; Prefrontal Cortex - physiology; Psychiatry; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Psychopathology. Psychiatry; Reaction Time; Techniques and methods; Transcranial magnetic stimulation; Transcranial Magnetic Stimulation - methods; Young Adult; Toronto Ontario Canada; Canada; cognition; DLPFC; working memory; rTMS; EEG; gamma oscillations; Human; Potentiation; Transcranial magnetic stimulation; Healthy subject; Volunteer; Electrophysiology; Exploration; Cognition; Electroencephalography; Neurophysiology; Dorsolateral prefrontal cortex; Oscillation; Adult; Working memory
• ISSN: 0893-133X; 1740-634X; 1740-634X
• DOI: 10.1038/npp.2009.79

Neuronal oscillations in the gamma ( γ ) frequency range (30–50 Hz) have been associated with cognition. Working memory (WM), a cognitive task involving the on-line maintenance and manipulation of information, elicits increases in γ oscillations with greater cognitive demand, particularly in the dorsolateral prefrontal cortex (DLPFC). The generation and modulation of γ oscillations have been attributed to inhibitory interneuron networks that use γ -aminobutyric acid (GABA) as their principal neurotransmitter. Repetitive transcranial magnetic stimulation (rTMS) represents a non-invasive method to stimulate the cortex that has been shown to modify cognition and GABA inhibitory mechanisms, particularly with higher frequencies (ie, 10–20 Hz). We measured the effect of high-frequency rTMS applied to the DLPFC on γ -oscillations elicited during the N -back WM task in healthy individuals. Active rTMS significantly increased γ -oscillations generated during the N -back conditions with the greatest cognitive demand. Further, no significant changes were found in other frequency ranges, suggesting that rTMS selectively modulates γ -oscillations in the frontal brain regions. These findings provide important insights into the neurophysiological mechanisms that underlie higher-order cognitive processes, and suggest that rTMS may be used as a cognitive enhancing strategy in neuropsychiatric disorders that suffer from cognitive deficits.