Blood flow and oxygenation changes due to low-frequency repetitive transcranial magnetic stimulation of the cerebral cortex

• Published in: Journal of biomedical optics Vol. 18; no. 6; p. 067006
• Main Authors: Mesquita, Rickson C, Faseyitan, Olufunsho K, Turkeltaub, Peter E, Buckley, Erin M, Thomas, Amy, Kim, Meeri N, Durduran, Turgut, Greenberg, Joel H, Detre, John A, Yodh, Arjun G, Hamilton, Roy H
• Format: Journal Article
• Language: English
• Published: United States Society of Photo-Optical Instrumentation Engineers 01.06.2013
• Subjects: Adult; Aged; Blood flow; Blood Flow Velocity; Cerebral cortex; Cerebral Cortex - blood supply; Cerebral Cortex - metabolism; Cerebral Cortex - pathology; Cerebrovascular Circulation; Diffusion; Electric Stimulation; Female; Hemodynamics; Hemoglobins - metabolism; Humans; Male; Middle Aged; Optics and Photonics; Oxygen - metabolism; Oxygenation; Research Papers: Sensing; Resin transfer molding; Spectrophotometry; Stimulation; Transcranial magnetic stimulation; Transcranial Magnetic Stimulation - methods; brain function; transcranial magnetic stimulation; diffuse correlation spectroscopy; diffuse optical spectroscopy
• ISSN: 1083-3668; 1560-2281; 1560-2281
• DOI: 10.1117/1.JBO.18.6.067006

Transcranial magnetic stimulation (TMS) modulates processing in the human brain and is therefore of interest as a treatment modality for neurologic conditions. During TMS administration, an electric current passing through a coil on the scalp creates a rapidly varying magnetic field that induces currents in the cerebral cortex. The effects of low-frequency (1 Hz), repetitive TMS (rTMS) on motor cortex cerebral blood flow (CBF) and tissue oxygenation in seven healthy adults, during/after 20 min stimulation, is reported. Noninvasive optical methods are employed: diffuse correlation spectroscopy (DCS) for blood flow and diffuse optical spectroscopy (DOS) for hemoglobin concentrations. A significant increase in median CBF (33%) on the side ipsilateral to stimulation was observed during rTMS and persisted after discontinuation. The measured hemodynamic parameter variations enabled computation of relative changes in cerebral metabolic rate of oxygen consumption during rTMS, which increased significantly (28%) in the stimulated hemisphere. By contrast, hemodynamic changes from baseline were not observed contralateral to rTMS administration (all parameters, p>0.29). In total, these findings provide new information about hemodynamic/metabolic responses to low-frequency rTMS and, importantly, demonstrate the feasibility of DCS/DOS for noninvasive monitoring of TMS-induced physiologic effects.