The role of the coil click in TMS assessed with simultaneous EEG.
OBJECTIVE
We have used EEG to measure effects of air- and bone-conducted sound from the coil in transcranial magnetic stimulation (TMS).


METHODS
Auditory-evoked potentials to TMS were recorded in three different experimental conditions: (1) the coil 2 cm above the head, (2) the coil 2 cm above the head but rigidly connected by a plastic piece to the scalp, (3) the coil pressed against the scalp over the motor cortex.


RESULTS
The acoustical click from the TMS coil evoked large auditory potentials, whose amplitude depended critically on the mechanical contact of the coil with the head.


CONCLUSIONS
Both air- and bone-conducted sounds have to be taken into account in the design and interpretation of TMS experiments.
Nikouline
V
V
BioMag Laboratory, Medical Engineering Centre, Helsinki University Central Hospital, Finland. vadim@biomag.helsinki.fi
Ruohonen
J
J
Ilmoniemi
R J
RJ
D000161:Acoustic Stimulation; D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008280:Magnetics; D008297:Male