Brain Gamma-Stimulation: Mechanisms and Optimization of Impact

The γ-rhythm plays a key role in coordinating the activity of the major brain systems and facilitating higher-level neurological processes. Several pathological conditions are associated with impaired generation or regulation of γ-oscillations. Modulating the γ-rhythm using periodic signals is considered a potential way to halt and/or treat such neurodegenerative processes. Despite the extensive knowledge gained in this field over the last 70 years, a unified theory linking the effectiveness of γ-stimulation to the characteristics of the stimulus and the stimulated remains elusive. In this review, we conducted a quantitative analysis of these relationships. The γ-stimulation effectiveness depends on species, age, frequency, and stimulus type. Here, we found with our analysis that experiments using white light were more effective than red and infrared. The range of effective central frequencies depends on age. We also showed that AD patients and mouse models respond differently to γ-stimulation, so the careful selection of study subjects is essential when assessing therapeutic potential. This review also provides an overview of the mechanisms of γ-stimulation and makes recommendations for optimizing the method based on these mechanisms. Our findings may be useful to understanding -stimulation mechanisms, planning future experiments for research groups and identifying potential therapeutic γ-stimulation regimens.