Figure 2.

A series of studies from Li-Huei Tsai indicating that gamma stimulations ameliorate pathology and cognitive impairment in Alzheimer's disease (AD). (A) Gamma induced by optogenetic stimuli reduced amyloid beta (Aβ) production in CA1, increased number and cell body diameter of microglia, and reduced the process length of microglia compared with the control group, indicating an engulfing state of microglia. The percentage of microglia co-localized with Aβ in the cell body increased, suggesting that gamma stimulation triggers microglia to increase Aβ uptake. (B) Gamma induced by light flicker reduces Aβ levels and plaque load in the visual cortex (VC). Microglia changes similar to (A), except that the number does not change. (C) In 5xFAD mice, 40-Hz auditory stimulation improves memory performance and reduces amyloid load and tau phosphorylation and seeding in the auditory cortex (AC) and hippocampus. The changes of microglia similar to (A) and the number of astrocytes increased. Furthermore, blood vessel diameter increased. (D) Combined auditory and visual stimulation induces a clustering phenotype response by microglia and reduces amyloid load across broad cortical regions.