Gamma-band Changes in Psychiatric Disorders: Understanding the Underlying Pathophysiology

Subachhanda Behuriya^*
*Correspondence: Subachhanda Behuriya, Department of Neurosurgery, University Hospital of Lausanne, 1011 Lausanne, Switzerland, Email:

Keywords

Gamma-band oscillations • Psychiatric disorders• Electroencephalography • Neuroimaging

Introduction

Gamma-band oscillations, typically defined as neural oscillations in the frequency range of 30-100 Hz, represent a fundamental aspect of brain activity and play a critical role in various cognitive processes, including sensory perception, attention, working memory and conscious awareness. These high-frequency oscillations are generated by synchronous firing of neuronal ensembles and are thought to reflect the coordinated activity of local cortical circuits and long-range neuronal communication. In recent years, there has been growing interest in the role of gamma-band oscillations in psychiatric disorders, with accumulating evidence suggesting that dysregulation of gamma-band activity may contribute to the pathophysiology of conditions such as schizophrenia, bipolar disorder, major depressive disorder and anxiety disorders. Abnormalities in gamma-band oscillations have been observed in both resting-state and task-related neural activity, implicating dysfunction in cortical and subcortical circuits underlying cognitive and emotional processing [1].

Electroencephalography (EEG) and Magnetoencephalography (MEG) studies have provided valuable insights into gamma-band changes in psychiatric disorders, revealing alterations in spectral power, phase synchronization and cross-frequency coupling in patients compared to healthy controls. Neuroimaging techniques such as functional Magnetic Resonance Imaging (fMRI) and Positron Emission Tomography (PET) have further elucidated the neural correlates of gamma-band dysregulation, highlighting aberrant activity in cortical regions implicated in emotion regulation, executive function and salience processing. Despite advances in our understanding of gamma-band changes in psychiatric disorders, the underlying mechanisms driving these alterations remain incompletely understood. Proposed mechanisms include alterations in neurotransmitter systems, such as Gamma-Aminobutyric Acid (GABA) and glutamate, which play a critical role in the generation and modulation of gamma-band oscillations. Additionally, synaptic dysfunction, disrupted neural circuitry and aberrant connectivity patterns have been implicated in gamma-band dysregulation in psychiatric conditions [2].

Literature Review

Gamma-band oscillations, typically defined as neural oscillations in the frequency range of 30-100 Hz, have garnered increasing attention in the context of psychiatric disorders due to their critical role in various cognitive processes and their potential relevance to the pathophysiology of these conditions. A growing body of literature has provided evidence for alterations in gamma-band activity across different psychiatric disorders, including schizophrenia, bipolar disorder, major depressive disorder and anxiety disorders. In schizophrenia, numerous studies using Electroencephalography (EEG) and Magnetoencephalography (MEG) have reported abnormalities in gamma-band oscillations, including reduced power, phase synchronization and coherence in cortical and subcortical regions implicated in sensory processing, attention and working memory. These gamma-band deficits have been associated with cognitive impairments and positive symptoms such as hallucinations and delusions, suggesting a link between gamma-band dysregulation and the pathophysiology of schizophrenia [3].

Similarly, alterations in gamma-band activity have been observed in bipolar disorder, with studies demonstrating changes in gamma-band power and coherence during mood episodes and interepisode periods. Abnormalities in gamma-band oscillations have been implicated in mood dysregulation, cognitive dysfunction and emotion processing deficits in bipolar disorder, highlighting the potential role of gamma-band activity as a biomarker for illness severity and treatment response. In major depressive disorder, aberrant gamma-band oscillations have also been reported, particularly in prefrontal and limbic regions associated with emotion regulation and reward processing. Decreased gamma-band power and synchronization have been linked to depressive symptomatology, anhedonia and executive dysfunction in patients with major depression, suggesting that gamma-band dysregulation may contribute to the pathophysiology of depression. Furthermore, alterations in gamma-band activity have been observed in anxiety disorders, including generalized anxiety disorder, panic disorder and Post-Traumatic Stress Disorder (PTSD). Studies have demonstrated changes in gamma-band power and coherence in regions involved in fear processing and threat detection, suggesting a role for gamma-band oscillations in the maintenance of anxiety symptoms and the processing of emotional stimuli [4].

Discussion

The findings presented in the literature review provide compelling evidence for alterations in gamma-band oscillations across various psychiatric disorders, implicating dysregulation of neural circuits underlying cognitive, emotional and sensory processing. The observed gamma-band deficits may reflect abnormalities in neurotransmitter systems, synaptic function and neural connectivity, contributing to the pathophysiology of these conditions. The precise mechanisms underlying gamma-band dysregulation in psychiatric disorders remain incompletely understood, highlighting the need for further research to elucidate the neurobiological basis of these alterations. Proposed mechanisms include alterations in Gamma-Aminobutyric Acid (GABA) and glutamate neurotransmission, which play critical roles in the generation and modulation of gamma-band oscillations. Additionally, synaptic dysfunction, disrupted neural circuitry and aberrant connectivity patterns may contribute to gamma-band deficits in psychiatric conditions. Despite advances in our understanding of gamma-band changes in psychiatric disorders, several challenges and limitations remain. Variability in study methodologies, sample characteristics and analytical techniques may contribute to inconsistencies in findings across studies. Moreover, the causal relationship between gamma-band dysregulation and symptomatology remains unclear, necessitating longitudinal and mechanistic studies to establish causal links and identifies potential therapeutic targets [5,6].

Conclusion

In conclusion, alterations in gamma-band oscillations represent a common feature of psychiatric disorders, including schizophrenia, bipolar disorder, major depressive disorder and anxiety disorders. Dysregulation of gamma-band activity may reflect abnormalities in neurotransmitter systems, synaptic function and neural connectivity, contributing to the pathophysiology of these conditions. The findings presented in the literature review underscore the importance of further research to elucidate the mechanisms underlying gamma-band dysregulation in psychiatric disorders and identify potential targets for therapeutic intervention. By gaining a better understanding of the role of gamma-band oscillations in the pathophysiology of psychiatric disorders, we may uncover novel treatment approaches aimed at modulating gamma-band activity and improving outcomes for patients affected by these debilitating conditions.

Acknowledgement

None.

Conflict of Interest

None.

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