Abstract
Background
Repetitive transcranial magnetic stimulation (rTMS) affects the excitability of the
motor cortex and is thought to influence activity in other brain areas as well. We
combined the administration of varying intensities of 1-Hz rTMS of the motor cortex
with simultaneous positron emission tomography (PET) to delineate local and distant
effects on brain activity.
Methods
Ten healthy subjects received 1-Hz rTMS to the optimal position over motor cortex
(M1) for producing a twitch in the right hand at 80, 90, 100, 110, and 120% of the
twitch threshold, while regional cerebral blood flow (rCBF) was measured using H215O and PET. Repetitive transcranial magnetic stimulation (rTMS) was delivered in 75-pulse
trains at each intensity every 10 min through a figure-eight coil. The regional relationship
of stimulation intensity to normalized rCBF was assessed statistically.
Results
Intensity-dependent rCBF increases were produced under the M1 stimulation site in
ipsilateral primary auditory cortex, contralateral cerebellum, and bilateral putamen,
insula, and red nucleus. Intensity-dependent reductions in rCBF occurred in contralateral
frontal and parietal cortices and bilateral anterior cingulate gyrus and occipital
cortex.
Conclusions
This study demonstrates that 1-Hz rTMS delivered to the primary motor cortex (M1)
produces intensity-dependent increases in brain activity locally and has associated
effects in distant sites with known connections to M1.
Keywords
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Article info
Publication history
Accepted:
December 7,
2002
Received in revised form:
November 15,
2002
Received:
March 21,
2002
Identification
Copyright
© 2003 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.
