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Abstract:
Abstract: Objective: Transcranial magnetic stimulation (TMS)
is a useful tool for the study of centralnervous information
processing. Functional magnetic resonance imaging (fMRI) identifies
cortical areas of cognitive functions. We tested on a single
subject basis the anatomical correspondance between fMRI activion
and TMS influence of the same cortical function. Methods: Five
subjects performed a rhythmic 1,5 Hz movement of the right thumb
during fMRI scanning. Using a real-time neuronavigational system
the magnetic coil was then guided to the activated area in the left
motor cortex. 50 to 100 stimuli with 120% motor threshold intensity
were applied, varying the coil position, while the motor response
of the M. abductor pollicis brevis was recorded. The regions of
maximum motor responses were compared with the regions of fMRI
activation. Results: In all subjects both regions overlapped. The
centers of the areas with maximal motor responses were located in
the range of 3-11 mm to the centers of fMRI activation, and,
dependent on coil position, mostly anteromedial. Conclusion: The
optimal coil position to stimulate a cortical area may be, at least
for the motor cortex, about 0,5-1 cm anteromedial of the fMRI
activated area. The navigated TMS is useful for stimulating
individually determined functional cortical areas and may become an
important role in studying higher cognitive functions as localized
by fMRI.
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