title: Neurochemical effects of theta burst stimulation as assessed by magnetic resonance spectroscopy.
abstract: Continuous theta burst stimulation (cTBS) is a novel transcranial stimulation technique that causes significant inhibition of synaptic transmission for <or=1 h when applied over the primary motor cortex (M1) in humans. Here we use magnetic resonance spectroscopy to define mechanisms mediating this inhibition by noninvasively measuring local changes in the cortical concentrations of gamma-aminobutyric acid (GABA) and glutamate/glutamine (Glx). cTBS to the left M1 led to an increase in GABA compared with stimulation at a control site without significant change in Glx. This direct evidence for increased GABAergic interneuronal activity is framed in terms of a new hypothesis regarding mechanisms underlying cTBS.
authors.affiliation: Centre for Functional Resonance Imaging of the Brain, University of Oxford, Oxford, United Kingdom. cstagg@fmrib.ox.ac.uk
authors.forename: C J
authors.initials: CJ
authors.lastname: Stagg
authors.forename: M
authors.initials: M
authors.lastname: Wylezinska
authors.forename: P M
authors.initials: PM
authors.lastname: Matthews
authors.forename: H
authors.initials: H
authors.lastname: Johansen-Berg
authors.forename: P
authors.initials: P
authors.lastname: Jezzard
authors.forename: J C
authors.initials: JC
authors.lastname: Rothwell
authors.forename: S
authors.initials: S
authors.lastname: Bestmann