Gamma brain waves are associated with peak concentration, high levels of cognitive functioning, and enhanced problem-solving abilities. Many individuals seek to achieve this state through various methods, including meditation, mindfulness practices, and audio entrainment.
We performed the Principal Component Analysis (PCA) to reduce dimensionality using the algorithm of Singular Value Decomposition (SVD), the default mode of the Matlab function pca(). We have several matrices, 30 × 64 (one matrix for each condition and each frequency band), composed by the PSD values, where 30 was the number of volunteers, and 64 was the number of channels. We reduced to matrices 30 × 1 (the first component representing all channels).
Has anyone achieved gamma state using audio entrainment?
The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results. The groups did not present differences considering the first component and channel F2, nor after outlier detection and exclusion for any condition. Figure 7 exemplifies how we identified the outliers using a boxplot in Jasp software. During the evaluation, subjects were asked to relax with eyes open and listen to trains of clicks presented through insert earphones (Etymotic Research, Elk Grove Village, Ill). The stimuli were 1-millisecond duration clicks, presented as trains of clicks that varied in rate of presentation (20, 30, and 40 Hz) in each of 3 blocks.
Jirakittayakorn and Wongsawat [20] showed that the FFT absolute power of gamma oscillation increased with time, especially in the frontal and central regions of the brain after the participants were exposed to the 40 Hz BB. Similarly, Mujib et al. [19] found significant differences in the group with BB stimulus at 30 Hz. The authors observed an increase in the frontal gamma band power during the stim stage and both theta and gamma power increase in the bilateral frontal and left parietal cortex post-stim state. Recently, Iaccarino et al.6 showed that gamma waves entrained by 40 Hz flickering room light for 1 h a day for a week reduced Aβ burden by increasing amyloid endocytosis of microglia in the primary visual cortex of a transgenic AD mouse model (5XFAD). Their following study also showed that entrained gamma oscillations by a combination of 40 Hz flickering room light and 40 Hz auditory stimuli for 1 h a day for a week reduced Aβ burden in the medial prefrontal cortex and improved the recognition and spatial memory in 5XFAD mice7.
There have been reports of individuals successfully reaching gamma state using audio entrainment techniques. By listening to specially designed audio tracks that stimulate the brain to produce gamma waves, some people have experienced improved focus, creativity, and overall mental clarity.
How does audio entrainment work?
Studies applied auditory stimuli in the gamma frequency in humans and produced gamma entrainment in the frontal area [33,34]. Also, topographical distributions in Scholz et al. [35] suggest the generation of memory-related low beta oscillations in medial and frontal neural structures. Apart from stimulation parameters, another possible reason for variability between studies could be participant/patient specificity and response. The accuracy and functionality of 40 Hz sensory stimulation may differ during various stages of AD pathogenesis, as Aβ load varies during the process.
- Audio entrainment involves listening to sound frequencies that are intended to synchronize brainwave activity.
- By exposing the brain to specific beats and tones, it is believed that the brain can be guided into different states of consciousness.
- For achieving gamma state, audio tracks with frequencies ranging from 40 to 100 Hz are often used to stimulate the brain to produce gamma waves.
Among the sparse and controversial studies found in the literature, only Mujib et al. [19] investigated gamma-BB stimulation with EEG and working memory performance analysis, similar to our approach. However, our study presents some improvements, such as the presence of a control condition with a potential placebo effect, besides a detailed cross-over experiment with new approaches for signal processing. Figure 4, Figure 5 and Figure 6 show the violin graph of the relative PSD of channel F2 in experimental and control conditions across the delta, theta, alpha, beta, and gamma frequencies and their respective p-value. The positive values of the y-axis mean higher energy for the stim phase compared to the without stim, while the negative values indicate the opposite. FLS with high luminance intensity and/or contrast was also found to induce stronger SSVEP than FLS with low luminance intensity and/or contrast in humans20,21,22. The amplitudes of SSVEP entrained by 100 cd/m2, 400 cd/m2, and 700 cd/m2 FLS were 94.1%, 180.4%, and 201.9% higher than those entrained by 10 cd/m2 FLS in our study, respectively.
A hotly debated aspect of gamma stimulation is how it affects the electrical activity of neurons, and how pervasively. Studies indicate that inhibitory “interneurons” are especially affected, though, offering a clue about how increased gamma activity, and its physiological effects, might propagate. The “Auditory Gamma Entrainment” dataset contains EEG signals recorded in one session of an auditory entrainment task (see Methods) from 13 participants who had referred to the memory clinic of Ziaeian Hospital in Tehran, Iran, with memory complaints. The participants were diagnosed through neurologic examination either as normal aging (non-AD) or suffering from mild AD (two participants were subsequently excluded from the study as the diagnosis of their status required further examination). Pearson’s product moment correlation coefficient (PMCC) test was leveraged during correlation analysis of MFQ scores for each individual participant. Additionally, the frequency group means were calculated based on the constituent participant scores for that group.
Are there any risks associated with audio entrainment?
- While audio entrainment is generally considered safe for most individuals, it may not be suitable for those with certain medical conditions or neurologic disorders.
- It is always recommended to consult with a healthcare professional before incorporating audio entrainment into your routine, especially if you have a history of epilepsy or seizures.
- Some people may experience headaches, dizziness, or other side effects when first starting with audio entrainment, but these symptoms usually subside with regular practice.
Overall, the effectiveness of audio entrainment in achieving gamma state may vary from person to person. It is essential to experiment with different techniques and find what works best for you. With dedication and practice, some individuals have reported significant improvements in their cognitive abilities and overall well-being through audio entrainment.
