نهمین کنگره نقشه برداری مغز

نمایش مقاله

Title:

EEG Characterization of Gamma-Band Entrainment During 40-Hz Audiovisual Sensory Stimulation: A Pilot Study

Subject:

Advanced Techniques in Signal Acquisition and Image Processing

Presenter Author:
Name:	Fateme Maghsoodlu

Author:
Name 1:	Fateme Maghsoodlu - Corresponding - Presenter
Affiliation 1:	Department of Biomedical Engineering, Shahid Beheshti University of Medical Sciences, Tehran, IRN

Name 2:	Ali Esteki
Affiliation 2:	Department of Biomedical Engineering, Shahid Beheshti University of Medical Sciences, Tehran, IRN

Name 3:
Affiliation 3:

Name 4:
Affiliation 4:

Name 5:
Affiliation 5:

Name 6:
Affiliation 6:

Name 7:
Affiliation 7:

Name 8:
Affiliation 8:

Name 9:
Affiliation 9:

Name 10:
Affiliation 10:

Abstract

Original Research

introduction :

In recent years, sensory stimulation in the gamma-frequency band, particularly at 40 Hz, has gained attention as a non-invasive approach for inducing neural entrainment and modulating brain activity. Gamma Entrainment Using Sensory Stimulation (GENUS), which combines auditory and visual stimulation at 40 Hz, has been shown to induce gamma-band responses in human participants and has been investigated in the context of neurodegenerative disorders, including Alzheimer’s disease. However, further characterization of the neural responses elicited by 40-Hz stimulation in healthy individuals is important before investigating its potential clinical applications. In this study, we investigated the EEG response pattern elicited by a synchronized 40-Hz audiovisual stimulation device in healthy individuals.

Methods:

EEG signals were recorded during a single session of simultaneous 40-Hz auditory and visual stimulation in three healthy individuals. Auditory and visual stimuli were delivered through headphones and stimulation glasses, respectively. The protocol consisted of 5 minutes of resting-state EEG recording, followed by three 5-min periods of 40-Hz stimulation, with 30-s rest intervals between stimulation periods. After EEG preprocessing, Z-scores were calculated to quantify gamma-band responses under stimulation and resting conditions. Subsequently, EEG channels and independent components (ICs) showing consistent stimulation-related responses were identified, and the anatomical distribution of responsive ICs was investigated using source localization.

Results:

EEG analysis demonstrated increased 40-Hz gamma-band responses during synchronized audiovisual stimulation compared with the resting condition, with responses observed across multiple cortical regions and source-localized responses involving selected subcortical areas. The Z-score analysis identified stimulation-related responses across multiple EEG channels and independent components (ICs). Responses were observed in the frontal, temporal, parietal, and occipital regions at the channel level. ICA and source localization identified responsive components in several cortical regions, including the occipital, lingual, temporal, supramarginal, frontal, parietal, precuneus, and cingulate regions, as well as selected subcortical regions, including the thalamus and caudate. Scalp topographic maps further demonstrated a distinct spatial distribution of 40-Hz activity during stimulation compared with the resting state.

Conclusion:

Taken together, the convergence of scalp-level and source-localization findings revealed a distributed 40-Hz response involving sensory regions and regions associated with higher-order processing. The presence of responses in the occipital and temporal regions is consistent with the visual and auditory components of the stimulation, while responses in the frontal, parietal, precuneus, and cingulate regions indicate that the observed gamma-band response was not restricted to primary sensory areas. The observed responses in the precuneus and cingulate regions, which are associated with the default mode network (DMN), further suggest potential engagement of broader cortical systems. These preliminary findings support the feasibility of the developed 40-Hz audiovisual stimulation methods and provide a basis for further investigation of its effects on brain regions and neural responses relevant to neurodegenerative disorders, particularly Alzheimer’s disease. Larger studies with appropriate control conditions are required to confirm the reproducibility and determine the functional significance of these responses.

Keywords:

40-Hz Gamma Stimulation; Audiovisual Stimulation; EEG; Gamma-Band Entrainment; Neuromodulation