The effect of gamma-enhancing binaural beats on the control of feature bindings

The Effect of Brainwave Synchronization Using Binaural Beats on Improving Working Memory and Reducing the Severity of Symptoms in Women With Obsessive-compulsive Disorder

Introduction

Binaural beats are one of the new methods of brainwave synchronization. However, there is little knowledge about its clinical applications. The positive effect of this method on executive functions, such as attention and working memory, in the γ band has been mainly confirmed in healthy individuals. Still, its effectiveness on disorders such as obsessive-compulsive disorder (OCD), with a prominent cognitive profile, has not been established. Therefore, the present study was conducted to examine the effect of binaural beats on working memory and the severity of OCD symptoms in the γ band in the affected women.

Methods

Twenty-nine OCD women aged 25-40 years referring to psychological clinics in Tehran City, Iran, were selected by convenience sampling. After completing the symptom checklist 90 (SCL90) and the Yale-Brown severity scale (SS), the participants were given the Wechsler memory scale (WMS) digit repetition subtests. Then, they were randomly assigned to the experimental (n=15) and control (n=14) groups. The audio file of the binaural beats in the γ band was provided to the experimental group. The participants in the control group listened to the normal (no-wave) audio file. Both groups listened to the audio files for two weeks, three times a week, for 30 minutes each time. The Yale-Brown SS and digit repetition in post-test and one-month follow-up periods were obtained from both groups.

Results

According to the results, the severity of OCD symptoms was significantly reduced in the post-test and follow-up stages by the γ binaural beats (P<0.05). Also, the working memory function was improved, although it was not statistically significant (P>0.05).

Conclusion

The results of this study show that binaural beats can be used as a complementary treatment to reduce the severity of OCD symptoms. Also, it seems that the patients' working memory is strengthened with this method.

Influence of Binaural Beats Stimulation of Gamma Frequency over Memory Performance and EEG Spectral Density

Similar to short-term memory, working memory cannot hold information for a long period of time. Studies have shown that binaural beats (BB) can stimulate the brain through sound, affecting working memory function. Although the literature is not conclusive regarding the effects of BB stimulation (stim) on memory, some studies have shown that gamma-BB stim (40 Hz) can increase attentional focusing and improve visual working memory. To better understand the relationship between BB stim and memory, we collected electroencephalographic data (EEG) from 30 subjects in 3 phases—a baseline, with gamma-BB stim, and control stim—in a rest state, with eyes closed, and while performing memory tasks. Both EEG data and memory task performance were analyzed. The results showed no significant changes in the memory task performance or the EEG data when comparing experimental and control conditions. We concluded that brain entrainment was not achieved with our parameters of gamma-BB stimulation when analyzing EEG power spectral density (PSD) and memory task performance. Hence, we suggest that other aspects of EEG data, such as connectivity and correlations with task performance, should also be analyzed for future studies.

Personalized Theta and Beta Binaural Beats for Brain Entrainment: An Electroencephalographic Analysis

Binaural beats (BB) consist of two slightly distinct auditory frequencies (one in each ear), which are differentiated with clinical electroencephalographic (EEG) bandwidths, namely, delta, theta, alpha, beta, or gamma. This auditory stimulation has been widely used to module brain rhythms and thus inducing the mental condition associated with the EEG bandwidth in use. The aim of this research was to investigate whether personalized BB (specifically those within theta and beta EEG bands) improve brain entrainment. Personalized BB consisted of pure tones with a carrier tone of 500 Hz in the left ear together with an adjustable frequency in the right ear that was defined for theta BB (since f_c for theta EEG band was 4.60 Hz ± 0.70 SD) and beta BB (since f_c for beta EEG band was 18.42 Hz ± 2.82 SD). The adjustable frequencies were estimated for each participant in accordance with their heart rate by applying the Brain-Body Coupling Theorem postulated by Klimesch. To achieve this aim, 20 healthy volunteers were stimulated with their personalized theta and beta BB for 20 min and their EEG signals were collected with 22 channels. EEG analysis was based on the comparison of power spectral density among three mental conditions: (1) theta BB stimulation, (2) beta BB stimulation, and (3) resting state. Results showed larger absolute power differences for both BB stimulation sessions than resting state on bilateral temporal and parietal regions. This power change seems to be related to auditory perception and sound location. However, no significant differences were found between theta and beta BB sessions when it was expected to achieve different brain entrainments, since theta and beta BB induce relaxation and readiness, respectively. In addition, relative power analysis (theta BB/resting state) revealed alpha band desynchronization in the parieto-occipital region when volunteers listened to theta BB, suggesting that participants felt uncomfortable. In conclusion, neural resynchronization was met with both personalized theta and beta BB, but no different mental conditions seemed to be achieved.

40-Hz Binaural beats enhance training to mitigate the attentional blink

This study investigated whether binaural beat stimulation could accelerate the training outcome in an attentional blink (AB) task. The AB refers to the lapse in detecting a target T2 in rapid serial visual presentation (RSVP) after the identification of a preceding target T1. Binaural beats (BB) are assumed to entrain neural oscillations and support cognitive function. Participants were assigned into two groups and presented with BB sounds while performing the AB task on three subsequent days in a cross-over design. Group A was presented with 40-Hz BB during the first day and 16 Hz during the second day, while the order of beat frequencies was reversed in Group B. No sound was presented on the third day. MEG recordings confirmed a strong entrainment of gamma oscillations during 40-Hz BB stimulation and smaller gamma entrainment with 16-Hz BB. The rhythm of the visual stimulation elicited 10-Hz oscillations in occipital MEG sensors which were of similar magnitude for both BB frequencies. The AB performance did not increase within a session. However, participants improved between sessions, with overall improvement equal in both groups. Group A improved more after the first day than the second day. In contrast, group B gained more from the 40 Hz stimulation on the second day than from 16-Hz stimulation on the first day. Taken together, 40-Hz BB stimulation during training accelerates the training outcome. The improvement becomes evident not immediately, but after consolidation during sleep. Therefore, auditory beats stimulation is a promising method of non-invasive brain stimulation for enhancing training and learning which is well-suited to rehabilitation training.

Efficacy of binaural auditory beats in cognition, anxiety, and pain perception: a meta-analysis

Binaural auditory beats are a perceptual phenomenon that occurs when presenting separately to each ear two tones that slightly differ in their frequency. It has been suggested that binaural beats can influence cognition and mental states among others. The objective of this meta-analysis was to study the effect of binaural beats on memory, attention, anxiety, and analgesia. Twenty-two studies met our inclusion criteria for this meta-analysis. The results, based on 35 effect sizes, showed an overall medium, significant, consistent effect size (g = 0.45). Meta-regression results indicated that it does not seem to be necessary to mask binaural beats with white noise or pink noise in terms of effectiveness, obtaining similar effects with unmasked binaural beats. Moreover, the findings suggest that binaural-beat exposure before, and before and during the task produces superior results than exposure during the task. Time under exposure contributed significantly to the model indicating that longer periods are advisable to ensure maximum effectiveness. Our meta-analysis adds to the growing evidence that binaural-beat exposure is an effective way to affect cognition over and above reducing anxiety levels and the perception of pain without prior training, and that the direction and the magnitude of the effect depends upon the frequency used, time under exposure, and the moment in which the exposure takes place.