title: Blood flow and oxygenation changes due to low-frequency repetitive transcranial magnetic stimulation of the cerebral cortex.
abstract: 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.
authors.affiliation: University of Pennsylvania, Department of Physics and Astronomy, Philadelphia, Pennsylvania 19104, USA. rickson@ifi.unicamp.br
authors.forename: Rickson C
authors.initials: RC
authors.lastname: Mesquita
authors.forename: Olufunsho K
authors.initials: OK
authors.lastname: Faseyitan
authors.forename: Peter E
authors.initials: PE
authors.lastname: Turkeltaub
authors.forename: Erin M
authors.initials: EM
authors.lastname: Buckley
authors.forename: Amy
authors.initials: A
authors.lastname: Thomas
authors.forename: Meeri N
authors.initials: MN
authors.lastname: Kim
authors.forename: Turgut
authors.initials: T
authors.lastname: Durduran
authors.forename: Joel H
authors.initials: JH
authors.lastname: Greenberg
authors.forename: John A
authors.initials: JA
authors.lastname: Detre
authors.forename: Arjun G
authors.initials: AG
authors.lastname: Yodh
authors.forename: Roy H
authors.initials: RH
authors.lastname: Hamilton
mesh_terms: D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity; D002540:Cerebral Cortex / Q000098:blood supply / Q000378:metabolism / Q000473:pathology*; D002560:Cerebrovascular Circulation; D004558:Electric Stimulation; D005260:Female; D006439:Hemodynamics; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D055095:Optics and Photonics; D010100:Oxygen / Q000378:metabolism*; D013053:Spectrophotometry; D050781:Transcranial Magnetic Stimulation / Q000379:methods*
chemical_list: D006454:Hemoglobins; D010100:Oxygen