The Samahita Blog

Multi Sensory Gamma Stimulation Reduces Alzheimers Symptoms

By Sarah Pierroz

Brain wave modulation through sound and light (AVE) has been shown to positively effect our mood, levels of concentration and relaxation and help us sleep better. Now ongoing research shows AVE, specifically with gamma waves, reduces symptoms of Alzheimer’s Disease not just on a psychological level but also repairs neurological damage. Read on and learn more about AVE and gamma wave therapy.

Ordered Mess: Brainwave Elegance

Over half a century ago, neurologists started placing electrodes on the scalp and found that they could measure the electrical signals of neurons firing.  At first, these signals appeared to be a random mess of activity.  But upon closer inspection, large networks of brain cells were found to fire together, rhythmically and in synchrony, to create patterns of elegant waves, forming a more complex electrical signature of the brain.

There are five main groupings of these waves: the lower hertz “delta” waves (0.5 – 4 Hz), then “theta” (4-8 Hz), “alpha” (8-13 Hz), “beta” (13-30 Hz), to faster “gamma” (30-100 Hz) rhythms.  The function of each brainwave is still unknown, but they seem to relate to how alert and awake we feel. For example, when we sleep, it appears that our brainwaves are the slowest, in the “delta” range, and the frequencies are faster when we are alert. [1]

The fastest brainwaves are “gamma” waves, which oscillate close to 40 times a second, or 40 hertz, ten times faster than the “theta” rhythm. This faster wave frequency is thought to help the brain package more information into coherent images, thoughts and memories. They tend to present when we are concentrating on something very specific, making decisions or recollecting the past. [2]

Last decade, Eugenio Rodriguez and his colleagues at the CNRS, the French national agency for scientific research, published evidence which linked gamma waves in humans to perceptual binding. They showed the participants ambiguous, high-contrast images, known as Mooney faces, which look like random shapes at first, and then become more recognizable as upside-down faces upon closer inspection. When the viewers first looked at the abstracted images, there was a lot of gamma brainwave activity along the visual cortex, but it was not synchronized. However, as soon as the participants perceived a face from the shapes, the gamma waves in the visual areas fell precisely into synch, perhaps as a means of organizing this new sensory information. [3]

Following this, more studies have been designed to explore the effects of external stimulation of sensory inputs on brainwave patterns.

Brainwave Modulation: What is Audio Visual Entrainment?

By gently using pulses of light or sound, also known as Audio-Visual Entrainment, to stimulate specific patterns, in particular, in the alpha wave range, it has been shown that you can help to heal and fine tune a brain, which may be dull, hurt, disturbed, affected by trauma, injury, or years of distraction.  Light and sound pulses at specific frequencies have helped to elevate mood, improve sleep patterns, heighten a sense of relaxation, sharpen mental functioning and cultivate the meditator’s mind, perhaps even leading to develop a broader sense of compassion.  [1]

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. [4]

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. [5] [6]

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.

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6130417/

2. https://www.newscientist.com/article/mg23731593-300-can-listening-to-a-low-hum-destroy-alzheimers-brain-plaques/

3. https://www.nature.com/articles/17120?foxtrotcallback=true

4. https://www.newscientist.com/article/mg16422104-600-mind-rhythms/

5. http://news.mit.edu/2019/brain-wave-stimulation-improve-alzheimers-0314
6. https://www.newscientist.com/article/mg16422104-600-mind-rhythms/

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