Changes in intracortical circuits of the human motor cortex following theta burst stimulation of the lateral cerebellum.
OBJECTIVE
The cerebellum takes part in several motor functions through its influence on the motor cortex (M1). Here, we applied the theta burst stimulation (TBS) protocol, a novel form of repetitive Transcranial Magnetic Stimulation (rTMS) over the lateral cerebellum. The aim of this study was to test whether TBS of the lateral cerebellum could be able to modulate the excitability of the contralateral M1 in healthy subjects.


METHODS
Motor-evoked potentials (MEPs) amplitude, short intracortical inhibition (SICI), long intracortical inhibition (LICI) and short intracortical facilitation (SICF) were tested in the M1 before and after cerebellar continuous TBS (cTBS) or intermittent TBS (iTBS).


RESULTS
We found that cTBS induced a reduction of SICI and an increase of LICI. On the other hand, cerebellar iTBS reduced LICI. MEPs amplitude also differently vary following cerebellar stimulation with cTBS or iTBS, resulting in a decrease by the former and an increase by the latter.


CONCLUSIONS
Although the interpretation of these data remains highly speculative, these findings reveal that the cerebellar cortex undergoes bidirectional plastic changes that modulate different intracortical circuits within the contralateral primary motor cortex.


CONCLUSIONS
Long-lasting modifications of these pathways could be useful to treat various pathological conditions characterized by an altered cortical excitability.
Koch
Giacomo
G
Laboratorio di Neurologia Clinica e Comportamentale, Fondazione Santa Lucia IRCCS, Via Ardeatina, 306, 00179 Rome, Italy. g.koch@hsantalucia.it
Mori
Francesco
F
Marconi
Barbara
B
Codecà
Claudia
C
Pecchioli
Cristiano
C
Salerno
Silvia
S
Torriero
Sara
S
Lo Gerfo
Emanuele
E
Mir
Pablo
P
Oliveri
Massimiliano
M
Caltagirone
Carlo
C
D000328:Adult; D000704:Analysis of Variance; D002531:Cerebellum / Q000502:physiology / Q000528:radiation effects*; D004056:Differential Threshold / Q000502:physiology; D004558:Electric Stimulation / Q000379:methods*; D004576:Electromyography / Q000379:methods; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006225:Hand / Q000294:innervation; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009334:Neck Muscles / Q000294:innervation; D009433:Neural Inhibition / Q000502:physiology / Q000528:radiation effects; D011597:Psychomotor Performance; D013826:Theta Rhythm; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult