State-dependent effects of transcranial oscillatory currents on the motor system: What you think matters

Matteo Feurra, Patrizio Pasqualetti, Giovanni Bianco, Emiliano Santarnecchi, Alessandro Rossi, Simone Rossi

Research output: Contribution to journalArticlepeer-review


Imperceptible transcranial alternating current stimulation (tACS) changes the endogenous cortical oscillatory activity in a frequencyspecific manner. In the human motor system, tACS coincident with the idling beta rhythm of the quiescent motor cortex increased the corticospinal output. We reasoned that changing the initial state of the brain (i.e., from quiescence to a motor imagery task that desynchronizes the local beta rhythm) might also change the susceptibility of the corticospinal system to resonance effects induced by betatACS. We tested this hypothesis by delivering tACS at different frequencies (theta, alpha, beta, and gamma) on the primary motor cortex at rest and during motor imagery. Motor-evoked potentials (MEPs) were obtained by transcranial magnetic stimulation (TMS) on the primary motor cortex with an online-navigated TMS-tACS setting. During motor imagery, the increase of corticospinal excitability was maximal with theta-tACS, likely reflecting a reinforcement of working memory processes required to mentally process and "execute" the cognitive task. As expected, the maximal MEPs increase with subjects at rest was instead obtained with beta-tACS, substantiating previous evidence. This dissociation provides new evidence of state and frequency dependency of tACS effects on the motor system and helps discern the functional role of different oscillatory frequencies of this brain region. These findings may be relevant for rehabilitative neuromodulatory interventions.

Original languageEnglish
Pages (from-to)17483-17489
Number of pages7
JournalJournal of Neuroscience
Issue number44
Publication statusPublished - 2013

ASJC Scopus subject areas

  • Neuroscience(all)


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