New Findings: Brain Health and Gamma Wave Modulation
The research in this field is showing more promising and more therapeutic results. Especially as more recently, it has been shown that those with Alzheimer’s disease often have less gamma wave activity. 
MIT neuroscience researchers, led by Li-Huei Tsai, the founding member of MIT’s Aging Brain Initiative, are discovering effective ways to stimulate gamma wave activity, and in turn reduce Alzheimer’s disease markers and inflammation, as well as improve attention, perception and memory functioning.  
In 2016, Tsai and her colleagues first showed the benefit of exposing mice to light pulsing at the gamma wave frequency of 40 Hz. After delivering flickers of light for one hour each day, for seven days, they found a significant reduction in two known Alzheimer’s disease related markers, more specifically, in beta amyloid plaques and phosphorylated tauprotein. The gamma wave modulation also stimulated the activity of microglia, which act as macrophages, clearing debris and dead neurons from nervous tissue, in the stimulated visual cortex area of the brain.
Following this significant finding, this team of researchers tried to see if they could reach past visual cortex area by using sound stimulation. So, they exposed the brain to one hour of low-pitched sound pulses at 40-hertz gamma oscillations per day, for seven days. They found a dramatic reduction the amount of beta amyloid plaques in not only the auditory cortex (which processes sound), but also in the nearby hippocampus, a brain area that is important for navigation, learning, and memory.
The researchers also tested the effects of this intervention on the cognitive function. They found that after one week of treatment, the mice could better navigate through a maze, which required them to remember key landmarks and objects they had previously encountered. They also found that auditory stimulation induced changes not only in microglia, but also the blood vessels, which may increase more clearing of amyloid plaque build up in brain.
Then, after applying a combination of both visual AND auditory stimulation, the researchers discovered that both treatments had an even greater effect than either treatment alone. Amyloid plaque was reduced in an even greater area of the brain, which extended to the prefrontal cortex, the site of higher cognitive functioning. And the microglia response was even stronger.
In all of the gamma wave modulation, the positive effects on the mice faded within a week. So, the key to this treatment appears to be repeated, continuous use of the audio and visual entrainment in order to maintain the benefits.
Future Brain Health
Further studies will be needed to see how these findings can be applied to be the most effective for human subjects. This team of researchers will look into how gamma oscillations affect certain brain cell types and why the gamma oscillations have such a profound impact. The researchers are optimistic that these interventions could be beneficial to the human brain. It’s an exciting time for brain health science.