What does it take for increasing cortical excitability?

A paper published by Campana and colleagues shows that, when using transcranial random noise stimulation (a form of non -invasive brain stimulation where a very mild alternating current is injected in the brain at random frequencies) for increasing cortical excitability (neural responsiveness), such an increase is obtained only if a wide range of frequencies is used; instead, when the frequency band is halved, stimulation does not produce any sizeable change in excitability. This is likely due to the different amount of "neural noise" generated by the different amount of frequencies used.
This result has direct impacts on the understanding of the mechanisms involved in the modulation of the neuronal response through transcranial electrical stimulation, and on indications of adequate parameters when using this stimulation technique.

www.nature.com/articles/s41598-019-51553-7