Affiliations: Department of Neurophysiology, Medical Faculty,
Ruhr-University Bochum, Germany | Center for Integrative Neuroscience, University of
Tübingen, Germany
Note: [] Corresponding author: Prof. Dr. Klaus Funke Department of
Neurophysiology MA 4/149, Universitätsstrasse 150, 44801 Bochum. Tel.: +49
234 3223944; Fax: +49 234 3214192; E-mail: funke@neurop.rub.de
Abstract: Transcranial magnetic stimulation (TMS) can be used in two different
ways to manipulate cortical information processing, either by applying a single
pulse around the time point of expected task processing or by persistently
shifting cortical excitability by repetitive stimulation (rTMS). Single pulses
applied when specific cortical processing takes place always impair cortical
function due to increased noise or enhanced inhibition, both resulting in
decreased signal-to-noise ratio, while repetitive stimulation may allow to
weaken or improve cortical processing depending on the type of stimulation. The
opposite effects of low- (∼1 Hz) and high-frequency rTMS
(5–20 Hz), as well as the opposing effects of continuous versus intermittent
theta-burst trains, lowering or raising cortical excitability respectively,
have mainly been attributed to synaptic plasticity. As reviewed in this
article, in a series of electrophysiological, immunohistochemical and
molecular-biological animal experiments we obtained evidence for modulation of
inhibitory cortical activity as a further reason of changing cortical
excitability following rTMS.
