Brain entrainment by audio-visual gamma frequency stimulations

Neurodegeneration, network alteration and cognitive deficits are commonly observed in patients with Alzheimer's disease. To improve the altered brain networks, external stimulations at gamma frequency have been applied in animal models and human patients. However, whether these external stimuli can entrain brain activity remains elusive. In the present study, to investigate the neural mechanisms underlying gamma stimulation, we presented auditory and visual stimuli of gamma frequency and examined the changes in neural activity after gamma stimulation of different sensory modalities. We found that audio-visual gamma stimulations cause the strongest supra-linear gamma entrainment in the brain, followed by auditory gamma stimulations and visual gamma stimulations. Together, these data deepen our understanding of the neural mechanism of sensory gamma stimulation and will shed light on future research of other non-invasive brain stimulation to treat Alzheimer's disease.