Modulation of cortical oscillatory activity during transcranial
magnetic stimulation
Debora Brignani 1 2, Paolo Manganotti 2, Paolo M. Rossini 1 3, Carlo
Miniussi 1 4 *
1Unit=E0 di Neuroscienze Cognitive, IRCCS Centro S. Giovanni di Dio
Fatebenefratelli, Brescia, Italy
2Dipartimento di Scienze Neurologiche e della Visione, Universit=E0 di
Verona, Verona, Italy
3Dipartimento di Neuroscienze, AFaR S. Giovanni Calibita
Fatebenefratelli & Clinica Neurologica, Universit=E0 Campus Bio-medico,
Roma, Italy
4Dipartimento di Scienze Biomediche e Biotecnologie, Universit=E0 di
Brescia, Brescia, Italy
email: Carlo Miniussi (miniussi@[EMAIL PROTECTED]
)
*Correspondence to Carlo Miniussi, Dipartimento di Scienze Biomediche
e Biotecnologie, Sezione di Fisiologia, Universit=E0 di Brescia, Viale
Europa 11, 25123 Brescia
Transcranial magnetic stimulation (TMS) can transiently modulate
cortical excitability, with a net effect depending on the stimulation
frequency (1 Hz inhibition vs. 5 Hz facilitation, at least for the
motor cortex). This possibility has generated interest in experiments
aiming to improve deficits in clinical settings, as well as deficits
in the cognitive domain. The aim of the present study was to
investigate the on-line effects of low frequency (1 Hz) TMS on the EEG
oscillatory activity in the healthy human brain, focusing particularly
on the outcome of these modulatory effects in relation to the duration
of the TMS stimulation. To this end, we used the event-related
desynchronization/synchronization (ERD/ERS) approach to determine the
patterns of oscillatory activity during two consecutive trains of sham
and real TMS. Each train of stimulation was delivered to the left
primary motor cortex (MI) of healthy subjects over a period of 10 min,
while EEG rhythms were simultaneously recorded. Results indicated that
TMS induced an increase in the power of brain rhythms that was related
to the period of the stimulation, i.e. the synchronization of the
band increased with the duration of the stimulation, and this increase
was inversely correlated with motor-evoked potentials (MEPs)
amplitude. In conclusion, low frequency TMS over primary motor cortex
induces a synchronization of the background oscillatory activity on
the stimulated region. This induced modulation in brain oscillations
seems to increase coherently with the duration of stimulation,
suggesting that TMS effects may involve short-term modification of the
neural circuitry sustaining MEPs characteristics. Hum Brain Mapp 2008.
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