Effects of Gamma-tACS on EEG Periodic Activity

Evaluation of the Effects of Gamma-tACS on the Periodic Activity of Neural Signals as a Function of State-dependency

In this study on healthy subjects, the effect of transcranial alternating current stimulation (tACS) will be investigated. In particular, the distinction between periodic and aperiodic electroencephalogram (EEG) activity will be considered, as well as the state-dependency phenomenon. Participants will take part in two experimental sessions that will include tACS stimulation (one real, one control). Before, during, and after stimulation, subjects will have their EEG recorded during rest or during tasks.

The aim of this study is to investigate how the modulatory effects of gamma-tACS interact with intrinsic neural activity, measured in terms of periodic and aperiodic activity, as well as neurophysiological and behavioral modulation, taking into consideration the state-dependency phenomenon, which refers to the brain's activation state prior to stimulation.

Inclusion Criteria:

- Healthy adults

Exclusion Criteria:

• Common exclusion criteria
• Left-handedness (assessed through the Oldfield test)
• Diagnosis of neurological or psychiatric disorders
• Vision problems that prevent reading, not correctable with lenses
• Diagnosis of substance dependence on drugs or alcohol
• Presence of hearing aids/prostheses
• Diagnosis of epilepsy or family history up to the second degree with it
• Episodes of febrile convulsions or recurrent fainting
• Head trauma
• Presence of surgical clips or metal implants in the head
• Diagnosis of heart disease
• Presence of a cardiac pacemaker or artificial heart valve
• Presence of hearing aids/prostheses
• Hearing problems or tinnitus
• Vision problems not corrected with lenses (such as color blindness)
• Taking tricyclic antidepressant medications
• Taking neuroleptic medications
• Diagnosis of headache or migraine
• Taking more than 3 alcoholic units in the last 24 hours
• Taking 2 or more cups of coffee or caffeine from other sources in the last 2 hours