Music Synchronizes Brain Circuits to Alleviate Depression

Introduction

Depression is a major global health challenge, affecting around 4.4% of the world's population and being a leading cause of disability. Researchers have been exploring non-pharmacological approaches to address this issue, and one promising avenue is the use of music listening.

Music has the ability to modulate neural activity in brain regions involved in emotion and reward processing, such as the

and the

nucleus accumbens (NAc)

A region in the brain that is part of the reward system. It is involved in processing feelings of pleasure and motivation.

 

. These brain structures are part of the reward circuitry and play crucial roles in how we experience and respond to emotions, including those related to depression.

The researchers behind this study hypothesized that targeting the BNST-NAc circuit through music-based interventions could be a promising strategy for alleviating depressive disorders, particularly in patients with

who do not respond well to conventional treatments.

Results

Musical Enjoyment Differentiates the Depression Alleviation Effect of Music in TRD

The researchers enrolled 23 TRD patients and implanted electrodes in their BNST-NAc circuit to study the neural mechanisms underlying the effects of music on depression. They found that the therapeutic effects of music listening on TRD patients were not dependent on the emotional context of the music, but rather on the individual's enjoyment of the music.

Bridging Temporal EEG Signal to Musical Appreciation via Deep Learning

Using a deep learning approach, the researchers discovered that

signals from the temporal lobe, which primarily reflect activity in the auditory cortex, could effectively predict an individual's level of music enjoyment.

Modulatory Effects of Music on Temporal EEG Based on Synchronization

Further analysis revealed that in individuals who enjoyed the music more, there was enhanced synchronization between the temporal EEG and the music, as well as increased activation of the BNST and NAc within the reward circuit.

Temporal Theta Oscillations Regulate BNST-NAc Activation in Responses to Music Enjoyment

The researchers found that the music-driven temporal

(brain waves in the theta frequency range) modulated the

gamma oscillations

Rhythmic patterns of electrical activity in the brain that occur at a higher frequency range, which are associated with attention, perception, and information processing.

 

in the BNST, leading to a higher prevalence of "nested" gamma oscillations in the high-enjoyment group.

Triple Time-Locked Oscillatory Activity in the Cortico-BNST-NAc Circuit Mediates the Depression Alleviation Effect of Music

The study identified a key neural mechanism underlying the depression-alleviating effects of music - a triple time-locked oscillatory activity involving the auditory cortex, BNST, and NAc. This triple time-locking was significantly more prevalent in the high-enjoyment group, suggesting that the positive effects of music on depression are closely tied to its ability to synchronize and activate the reward circuit through the auditory cortex.

Auditory Entrainment Promoted Triple Time Locking Synchrony in Unresponsive Patients

The researchers also found that incorporating modulatory sounds at specific frequencies into music that patients had previously shown poor responsiveness to could enhance temporal area synchronicity and promote triple time locking of cortical-BNST-NAc activity. This led to significantly higher levels of enjoyment for the modulated music and a reduction in depressive symptoms compared to the sham condition.

Discussion

The findings of this study provide important insights into the neural basis of music's therapeutic potential for depression. The researchers propose that the antidepressant effect of music is driven by

and

gamma coupling

The synchronization of the higher-frequency gamma rhythms between different brain regions, such as the BNST and NAc, which is thought to be important for coordinating information processing and neural communication.

 

within the BNST-NAc reward network.

, the process of synchronizing neural activity to external rhythmic stimuli, appears to be a key mechanism by which music can coordinate a triple time-locked synchronization network involving the auditory cortex, BNST, and NAc. This synchronized activity and information exchange between these brain regions is critical for the antidepressant effects of music.

Importantly, the improvement in depressive symptoms was correlated with the patient's level of music enjoyment, rather than the emotional context of the music itself. This suggests that the positive effects of music on depression are closely tied to its ability to activate and synchronize the reward circuit through the auditory cortex.

Overall, these findings demonstrate the potential of music-based interventions, particularly those that incorporate auditory entrainment, as a promising approach for alleviating depressive disorders, especially in patients with treatment-resistant depression.