Effects of Gamma-tACS on EEG Periodic Activity (GAMMAtACS)

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.

Study Overview

• Status: Completed
• Conditions: Transcranial Alternating Current Stimulation
• Intervention / Treatment: Device: real tACS; Device: sham tACS

• Study Type: Interventional
• Enrollment (Actual): 34
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Italy
  • Venice, Italy
    • IRCCS San Camillo Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: real tACS	Device: real tACS; tACS is a non-invasive method to induce brain modulation. It will be applied at a frequency of 40 Hz (gamma-tACS) with a peak-to-peak intensity of 2 mA. During the real tACS condition, the alternating current will be administered for 20 minutes.
Sham Comparator: sham tACS	Device: sham tACS; In the sham tACS condition, the current will be delivered only for the first 30 seconds and then stopped, in order to simulate the same somatosensory sensations as real tACS, but without inducing modulation.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
resting-state electroencephalography (EEG) signal	The periodic and aperiodic activity of the EEG signal will be estimated through Brainstorm (i.e., EEG analysis software) and quantified in terms of numerical values representing the periodic/aperiodic component of the EEG signal. The periodic and aperiodic activity of the EEG signal will be assessed during three time frames: baseline, during the intervention, and immediately after the intervention (real or sham tACS)	baseline
resting-state electroencephalography (EEG) signal	The periodic and aperiodic activity of the EEG signal will be estimated through Brainstorm (i.e., EEG analysis software) and quantified in terms of numerical values representing the periodic/aperiodic component of the EEG signal. The periodic and aperiodic activity of the EEG signal will be assessed during three time frames: baseline, during the intervention, and immediately after the intervention (real or sham tACS)	during the intervension
resting-state electroencephalography (EEG) signal	The periodic and aperiodic activity of the EEG signal will be estimated through Brainstorm (i.e., EEG analysis software) and quantified in terms of numerical values representing the periodic/aperiodic component of the EEG signal. The periodic and aperiodic activity of the EEG signal will be assessed during three time frames: baseline, during the intervention, and immediately after the intervention (real or sham tACS)	immediately after the intervention

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
behavioral performance (response times)	Participants' motor performance at a computerized task will be measured in terms of response times (how fast the participants press a computer button, according to the task's instructions). The participants' motor performance will be assessed during two time frames: baseline and immediately after the intervention (real or sham tACS)	baseline
behavioral performance (response times)	Participants' motor performance at a computerized task will be measured in terms of response times (how fast the participants press a computer button, according to the task's instructions). The participants' motor performance will be assessed during two time frames: baseline and immediately after the intervention (real or sham tACS)	immediately after the intervention
behavioral performance (accuracy)	Participants' motor performance at a computerized task will be measured in terms of accuracy (% of correct responses at the computerized task, according to the task's instructions). The participants' motor performance will be assessed during two time frames: baseline and immediately after the intervention (real or sham tACS)	baseline
behavioral performance (accuracy)	Participants' motor performance at a computerized task will be measured in terms of accuracy (% of correct responses at the computerized task, according to the task's instructions). The participants' motor performance will be assessed during two time frames: baseline and immediately after the intervention (real or sham tACS)	immediately after the intervention
auditory steady state response (ASSR)	The auditory steady state response will be measured via EEG during entrainment through exposure to amplitude-modulated 40Hz sounds (5 min, sequence of amplitude-modulated tones at 40 Hz, delivered via earplug binaurally). The auditory steady state response will be measured as power of the EEG gamma band. The auditory steady state response will be assessed during two time frames: baseline and immediately after the intervention (real or sham tACS)	baseline
auditory steady state response (ASSR)	The auditory steady state response will be measured via EEG during entrainment through exposure to amplitude-modulated 40Hz sounds (5 min, sequence of amplitude-modulated tones at 40 Hz, delivered via earplug binaurally). The auditory steady state response will be measured as power of the EEG gamma band. The auditory steady state response will be assessed during two time frames: baseline and immediately after the intervention (real or sham tACS)	immediately after the intervention

Collaborators and Investigators

• Sponsor: IRCCS San Camillo, Venezia, Italy
• Investigators: Principal Investigator: Arcara, IRCCS San Camillo Hospital

Study record dates

Study Major Dates

• Study Start (Actual): July 20, 2021
• Primary Completion (Actual): January 18, 2023
• Study Completion (Actual): January 18, 2023

Study Registration Dates

• First Submitted: March 16, 2023
• First Submitted That Met QC Criteria: March 29, 2023
• First Posted (Actual): April 12, 2023

Study Record Updates

• Last Update Posted (Actual): April 12, 2023
• Last Update Submitted That Met QC Criteria: March 29, 2023
• Last Verified: March 1, 2023

More Information

Terms related to this study

• Other Study ID Numbers: 2021.18

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No