P 226. Robot guided positioning of a magnetic coil for rTMS over the cortex in patients with cerebral lesions—A. Hartmann a ,R.

Results: The peak values of E and J in the cerebellum are higher than the ones in the cortex of 56% and of 73% respectively. The percentage of volume of the cortex where the amplitude of E is greater than 70% of the peak found in the cerebellum it is much less than 1%. Varying the position of the active electrode of ±0.5 cm longitudinally and laterally, the maximum variation of the peak values of E and J in the cortex and in the cerebellum is of 4%. Conclusion: The higher amplitudes of the electric field (and/or the current density) occur mainly in the cerebellum with a spread toward the occipital region of the cortex. Data, moreover, show that small changes in the positioning of the active electrode result in a small effect on the induced field amplitudes in all the brain structures here analyzed. The model shows that the cerebellum is the main structure involved by cerebellar transcranial DC stimulation in humans and the current spread to other structures is negligible, probably without any physiological relevance. References