Case Report: Lateral Habenula Deep Brain Stimulation for Treatment-Resistant Depression

Input-output specific orchestration of aversive valence in lateral habenula during stress dynamics

Stress has been considered as a major risk factor for depressive disorders, triggering depression onset via inducing persistent dysfunctions in specialized brain regions and neural circuits. Among various regions across the brain, the lateral habenula (LHb) serves as a critical hub for processing aversive information during the dynamic process of stress accumulation, thus having been implicated in the pathogenesis of depression. LHb neurons integrate aversive valence conveyed by distinct upstream inputs, many of which selectively innervate the medial part (LHbM) or lateral part (LHbL) of LHb. LHb subregions also separately assign aversive valence via dissociable projections to the downstream targets in the midbrain which provides feedback loops. Despite these strides, the spatiotemporal dynamics of LHb-centric neural circuits remain elusive during the progression of depression-like state under stress. In this review, we attempt to describe a framework in which LHb orchestrates aversive valence via the input-output specific neuronal architecture. Notably, a physiological form of Hebbian plasticity in LHb under multiple stressors has been unveiled to incubate neuronal hyperactivity in an input-specific manner, which causally encodes chronic stress experience and drives depression onset. Collectively, the recent progress and future efforts in elucidating LHb circuits shed light on early interventions and circuit-specific antidepressant therapies.

Opportunities and challenges for the use of deep brain stimulation in the treatment of refractory major depression

Major Depressive Disorder continues to remain one of the most prevalent psychiatric diseases globally. Despite multiple trials of conventional therapies, a subset of patients fail to have adequate benefit to treatment. Deep brain stimulation (DBS) is a promising treatment in this difficult to treat population and has shown strong antidepressant effects across multiple cohorts. Nearly two decades of work have provided insights into the potential for chronic focal stimulation in precise brain targets to modulate pathological brain circuits that are implicated in the pathogenesis of depression. In this paper we review the rationale that prompted the selection of various brain targets for DBS, their subsequent clinical outcomes and common adverse events reported. We additionally discuss some of the pitfalls and challenges that have prevented more widespread adoption of this technology as well as future directions that have shown promise in improving therapeutic efficacy of DBS in the treatment of depression.

Recent Advances in Habenula Imaging Technology: A Comprehensive Review

The habenula (Hb) is involved in many natural human behaviors, and the relevance of its alterations in size and neural activity to several psychiatric disorders and addictive behaviors has been presumed and investigated in recent years using magnetic resonance imaging (MRI). Although the Hb is small, an increasing number of studies have overcome the difficulties in MRI. Conventional structural-based imaging also has great defects in observing the Hb contrast with adjacent structures. In addition, more and more attention should be paid to the Hb's functional, structural, and quantitative imaging studies. Several advanced MRI methods have recently been employed in clinical studies to explore the Hb and its involvement in psychiatric diseases. This review summarizes the anatomy and function of the human Hb; moreover, it focuses on exploring the human Hb with noninvasive MRI approaches, highlighting strategies to overcome the poor contrast with adjacent structures and the need for multiparametric MRI to develop imaging markers for diagnosis and treatment follow-up. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY STAGE: 2.

Current perspectives on tractography-guided deep brain stimulation for the treatment of mood disorders

INTRODUCTION

Deep brain stimulation (DBS) is an emerging therapy for mood disorders, particularly treatment-resistant depression (TRD). Different brain areas implicated in depression-related brain networks have been investigated as DBS targets and variable clinical outcomes highlight the importance of target identification. Tractography has provided insight into how DBS modulates disorder-related brain networks and is being increasingly used to guide DBS for psychiatric disorders.

AREAS COVERED

In this perspective, an overview of the current state of DBS for TRD and the principles of tractography is provided. Next, a comprehensive review of DBS targets is presented with a focus on tractography. Finally, the challenges and future directions of tractography-guided DBS are discussed.

EXPERT OPINION

Tractography-guided DBS is a promising tool for improving DBS outcomes for mood disorders. Tractography is particularly useful for targeting patient-specific white matter tracts that are not visible using conventional structural MRI. Developments in tractography methods will help refine DBS targeting for TRD and may facilitate symptom-specific precision neuromodulation. Ultimately, the standardization of tractography methods will be essential to transforming DBS into an established therapy for mood disorders.

Diencephalic organoids - A key to unraveling development, connectivity, and pathology of the human diencephalon

The diencephalon, an integral component of the forebrain, governs a spectrum of crucial functions, ranging from sensory processing to emotional regulation. Yet, unraveling its unique development, intricate connectivity, and its role in neurodevelopmental disorders has long been hampered by the scarcity of human brain tissue and ethical constraints. Recent advancements in stem cell technology, particularly the emergence of brain organoids, have heralded a new era in neuroscience research. Although most brain organoid methodologies have hitherto concentrated on directing stem cells toward telencephalic fates, novel techniques now permit the generation of region-specific brain organoids that faithfully replicate precise diencephalic identities. These models mirror the complexity of the human diencephalon, providing unprecedented opportunities for investigating diencephalic development, functionality, connectivity, and pathophysiology in vitro. This review summarizes the development, function, and connectivity of diencephalic structures and touches upon developmental brain disorders linked to diencephalic abnormalities. Furthermore, it presents current diencephalic organoid models and their applications in unraveling the intricacies of diencephalic development, function, and pathology in humans. Lastly, it highlights thalamocortical assembloid models, adept at capturing human-specific aspects of thalamocortical connections, along with their relevance in neurodevelopmental disorders.

Lateral habenula deep brain stimulation alleviates depression-like behaviors and reverses the oscillatory pattern in the nucleus accumbens in an animal model of depression

Depression is a series of symptoms that influence mood, thinking, and behavior and create unpleasant emotions like hopelessness and apathy. Treatment-resistant depression (TRD) affects 30 % of depression patients despite the availability of several non-invasive therapies. Deep brain stimulation (DBS) is a novel therapy for TRD. The aim of the current study was to evaluate the effect of LHb-DBS by recording local field potentials (LFP) and conducting behavioral experiments. Thirty-two mature male Wistar rats were randomly divided into four groups: control, chronic mild stress (CMS), CMS+DBS, and DBS. After surgery and electrode placement in the lateral habenula (LHb), nucleus accumbens (NAc), and prelimbic cortex (PrL), the CMS protocol was applied for 3 weeks to create depression-like models. The open field test (OFT), sucrose preference test (SPT), and forced swim test (FST) were also performed. In the DBS groups, the LHb area was stimulated for four consecutive days. Finally, on the 22nd day, LFP was recorded from the NAc and PrL and analyzed using MATLAB software. Analyzing the findings using ANOVA and P-values ≤ 0.05 was considered. LHb-DBS alleviated depression-like behaviors in chronic moderate stress model rats (P ≤ 0.05). Three weeks of CMS enhanced almost all band powers in the NAc, while LHb-DBS decreased the power of the theta, alpha, beta, and gamma bands in the NAc (P ≤ 0.05), and the low-gamma band in the PrL. CMS also boosted the NAc-PrL coherence in low-frequency bands, while LHb-DBS increased beta and low gamma band coherence (P ≤ 0.05). In sum, the results of the present study showed that depression enhances low-frequency coherence between NAc and PrL cortex. Depression also potentiates many brain oscillations in the NAc, which can be mainly reversed by LHb-DBS.

Instantaneous antidepressant effect of lateral habenula deep brain stimulation in rats studied with functional MRI

The available treatments for depression have substantial limitations, including low response rates and substantial lag time before a response is achieved. We applied deep brain stimulation (DBS) to the lateral habenula (LHb) of two rat models of depression (Wistar Kyoto rats and lipopolysaccharide-treated rats) and observed an immediate (within seconds to minutes) alleviation of depressive-like symptoms with a high-response rate. Simultaneous functional MRI (fMRI) conducted on the same sets of depressive rats used in behavioral tests revealed DBS-induced activation of multiple regions in afferent and efferent circuitry of the LHb. The activation levels of brain regions connected to the medial LHb (M-LHb) were correlated with the extent of behavioral improvements. Rats with more medial stimulation sites in the LHb exhibited greater antidepressant effects than those with more lateral stimulation sites. These results indicated that the antidromic activation of the limbic system and orthodromic activation of the monoaminergic systems connected to the M-LHb played a critical role in the rapid antidepressant effects of LHb-DBS. This study indicates that M-LHb-DBS might act as a valuable, rapid-acting antidepressant therapeutic strategy for treatment-resistant depression and demonstrates the potential of using fMRI activation of specific brain regions as biomarkers to predict and evaluate antidepressant efficacy.

Safety and precision of frontal trajectory of lateral habenula deep brain stimulation surgery in treatment-resistant depression

Introduction

The lateral habenula (LHb) is a promising deep brain stimulation (DBS) target for treatment-resistant depression (TRD). However, the optimal surgical trajectory and its safety of LHb DBS are lacking.

Methods

We reported surgical trajectories for the LHb in six TRD patients treated with DBS at the General Hospital of the Chinese People's Liberation Army between April 2021 and May 2022. Pre-operative fusions of magnetic resonance imaging (MRI) and computed tomography (CT) were conducted to design the implantation trajectory of DBS electrodes. Fusions of MRI and CT were conducted to assess the safety or precision of LHb DBS surgery or implantable electrodes locations.

Results

Results showed that the optimal entry point was the posterior middle frontal gyrus. The target coordinates (electrode tips) were 3.25 ± 0.82 mm and 3.25 ± 0.82 mm laterally, 12.75 ± 0.42 mm and 13.00 ± 0.71 mm posterior to the midpoint of the anterior commissure–posterior commissure (AC-PC) line, and 1.83 ± 0.68 mm and 1.17 ± 0.75 mm inferior to the AC-PC line in the left and right LHb, respectively. The “Ring” angles (relative to the AC-PC level on the sagittal section plane) of the trajectories to the left and right LHb were 51.87° ± 6.67° and 52.00° ± 7.18°, respectively. The “Arc” angles (relative to the midline of the sagittal plane) were 33.82° ± 3.39° and 33.55° ± 3.72°, respectively. Moreover, there was small deviation of actual from planned target coordinates. No patient had surgery-, disease- or device-related adverse events during the perioperative period.

Conclusion

Our results suggested that LHb-DBS surgery via frontal trajectory is safe, accurate, and feasible. This is an applicable work to report in detail the target coordinates and surgical path of human LHb-DBS. It has of great clinical reference value to treat more cases of LHb-DBS for TRD.

Circuits regulating pleasure and happiness - focus on potential biomarkers for circuitry including the habenuloid complex

INTRODUCTION

The multiplicity and complexity of the neuronal connections in the central nervous system make it difficult to disentangle circuits that play an essential role in the development or treatment of (neuro)psychiatric disorders. By choosing the evolutionary development of the forebrain as a starting point, a certain order in the connections can be created. The dorsal diencephalic connection (DDC) system can be applied for the development of biomarkers that can predict treatment response.

MATERIALS AND METHODS

After providing a brief introduction to the theory, we examined neuroanatomical publications on the connectivity of the DDC system. We then searched for neurochemical components that are specific for the habenula.

RESULTS AND DISCUSSION

The best strategy to find biomarkers that reflect the function of the habenular connection is to use genetic variants of receptors, transporters or enzymes specific to this complex. By activating these with probes and measuring the response in people with different functional genotypes, the usefulness of biomarkers can be assessed.

CONCLUSIONS

The most promising biomarkers in this respect are those linked to activation or inhibition of the nicotine receptor, dopamine D4 receptor, μ-opioid receptor and also those of the functioning of habenular glia cells (astrocytes and microglia).

White Matter Tracts Associated With Deep Brain Stimulation Targets in Major Depressive Disorder: A Systematic Review

Background

Deep brain stimulation (DBS) has been proposed as a last-resort treatment for major depressive disorder (MDD) and has shown potential antidepressant effects in multiple clinical trials. However, the clinical effects of DBS for MDD are inconsistent and suboptimal, with 30-70% responder rates. The currently used DBS targets for MDD are not individualized, which may account for suboptimal effect.

Objective

We aim to review and summarize currently used DBS targets for MDD and relevant diffusion tensor imaging (DTI) studies.

Methods

A literature search of the currently used DBS targets for MDD, including clinical trials, case reports and anatomy, was performed. We also performed a literature search on DTI studies in MDD.

Results

A total of 95 studies are eligible for our review, including 51 DBS studies, and 44 DTI studies. There are 7 brain structures targeted for MDD DBS, and 9 white matter tracts with microstructural abnormalities reported in MDD. These DBS targets modulate different brain regions implicated in distinguished dysfunctional brain circuits, consistent with DTI findings in MDD.

Conclusions

In this review, we propose a taxonomy of DBS targets for MDD. These results imply that clinical characteristics and white matter tracts abnormalities may serve as valuable supplements in future personalized DBS for MDD.

Role of Habenula in Social and Reproductive Behaviors in Fish: Comparison With Mammals

Social behaviors such as mating, parenting, fighting, and avoiding are essential functions as a communication tool in social animals, and are critical for the survival of individuals and species. Social behaviors are controlled by a complex circuitry that comprises several key social brain regions, which is called the social behavior network (SBN). The SBN further integrates social information with external and internal factors to select appropriate behavioral responses to social circumstances, called social decision-making. The social decision-making network (SDMN) and SBN are structurally, neurochemically and functionally conserved in vertebrates. The social decision-making process is also closely influenced by emotional assessment. The habenula has recently been recognized as a crucial center for emotion-associated adaptation behaviors. Here we review the potential role of the habenula in social function with a special emphasis on fish studies. Further, based on evolutional, molecular, morphological, and behavioral perspectives, we discuss the crucial role of the habenula in the vertebrate SDMN.

Protease-activated receptor 2 activation induces behavioural changes associated with depression-like behaviour through microglial-independent modulation of inflammatory cytokines

RATIONALE

Major depressive disorder (MDD) is a leading cause of disability worldwide but currently prescribed treatments do not adequately ameliorate the disorder in a significant portion of patients. Hence, a better appreciation of its aetiology may lead to the development of novel therapies.

OBJECTIVES

In the present study, we have built on our previous findings indicating a role for protease-activated receptor-2 (PAR2) in sickness behaviour to determine whether the PAR2 activator, AC264613, induces behavioural changes similar to those observed in depression-like behaviour.

METHODS

AC264613-induced behavioural changes were examined using the open field test (OFT), sucrose preference test (SPT), elevated plus maze (EPM), and novel object recognition test (NOR). Whole-cell patch clamping was used to investigate the effects of PAR2 activation in the lateral habenula with peripheral and central cytokine levels determined using ELISA and quantitative PCR.

RESULTS

Using a blood-brain barrier (BBB) permeable PAR2 activator, we reveal that AC-264613 (AC) injection leads to reduced locomotor activity and sucrose preference in mice but is without effect in anxiety and memory-related tasks. In addition, we show that AC injection leads to elevated blood sera IL-6 levels and altered cytokine mRNA expression within the brain. However, neither microglia nor peripheral lymphocytes are the source of these altered cytokine profiles.

CONCLUSIONS

These data reveal that PAR2 activation results in behavioural changes often associated with depression-like behaviour and an inflammatory profile that resembles that seen in patients with MDD and therefore PAR2 may be a target for novel antidepressant therapies.

Habenular Involvement in Response to Subcallosal Cingulate Deep Brain Stimulation for Depression

The habenula (Hb) is a small, evolutionarily conserved epithalamic structure implicated in functions such as reward and mood regulation. Prior imaging work suggests that Hb's structural and functional properties may relate to treatment response in depression and other mood disorders. We used multimodal MRI techniques to investigate the potential involvement of Hb in response to subcallosal cingulate area deep brain stimulation (SCC-DBS) for treatment-resistant mood disorders. Using an automated segmentation technique, we compared Hb volume at baseline and at a subsequent post-operative timepoint (4.4 ± 3.0 years after surgery) in a cohort of 32 patients who received SCC-DBS. Clinical response to treatment (≥50% decrease in HAMD-17 from baseline to 12 months post-operation) was significantly associated with longitudinal Hb volume change: responders tended to have increased Hb volume over time, while non-responders showed decreased Hb volume (t = 2.4, p = 0.021). We additionally used functional MRI (fMRI) in a subcohort of SCC-DBS patients (n = 12) to investigate immediate within-patient changes in Hb functional connectivity associated with SCC-DBS stimulation. Active DBS was significantly associated with increased Hb connectivity to several prefrontal and corticolimbic regions (TFCE-adjusted p _Bonferroni < 0.0001), many of which have been previously implicated in the neurocircuitry of depression. Taken together, our results suggest that Hb may play an important role in the antidepressant effect of SCC-DBS.

Habenula as a Neural Substrate for Aggressive Behavior

Over the past decades, an ever growing body of literature has explored the anatomy, connections, and functions of the habenula (Hb). It has been postulated that the Hb plays a central role in the control of the monoaminergic system, thus influencing a wide range of behavioral responses, and participating in the pathophysiology of a number of psychiatric disorders and neuropsychiatric symptoms, such as aggressive behaviors. Aggressive behaviors are frequently accompanied by restlessness and agitation, and are commonly observed in patients with psychiatric disorders, intellectual disabilities, and neurodegenerative diseases of aging. Recently, the Hb has been explored as a new target for neuromodulation therapies, such as deep brain stimulation, with promising results. Here we review the anatomical organization of the habenula and discuss several distinct mechanisms by which the Hb is involved in the modulation of aggressive behaviors, and propose new investigations for the development of novel treatments targeting the habenula to reduce aggressive behaviors.

Deep Brain Stimulation of the Habenula: Systematic Review of the Literature and Clinical Trial Registries

The habenula is a small bilateral epithalamic structure that plays a key role in the regulation of the main monoaminergic systems. It is implicated in many aspects of behavior such as reward processing, motivational behavior, behavioral adaptation, and sensory integration. A role of the habenula has been indicated in the pathophysiology of a number of neuropsychiatric disorders such as depression, addiction, obsessive-compulsive disorder, and bipolar disorder. Neuromodulation of the habenula using deep brain stimulation (DBS) as potential treatment has been proposed and a first successful case of habenula DBS was reported a decade ago. To provide an overview of the current state of habenula DBS in human subjects for the treatment of neuropsychiatric disorders we conducted a systematic review of both the published literature using PUBMED and current and past registered clinical trials using ClinicalTrials.gov as well as the International Clinical Trials Registry Platform. Using PRISMA guidelines five articles and five registered clinical trials were identified. The published articles detailed the results of habenula DBS for the treatment of schizophrenia, depression, obsessive-compulsive disorder, and bipolar disorder. Four are single case studies; one reports findings in two patients and positive clinical outcome is described in five of the six patients. Of the five registered clinical trials identified, four investigate habenula DBS for the treatment of depression and one for obsessive-compulsive disorder. One trial is listed as terminated, one is recruiting, two are not yet recruiting and the status of the fifth is unknown. The planned enrollment varies between 2 to 13 subjects and four of the five are open label trials. While the published studies suggest a potential role of habenula DBS for a number of indications, future trials and studies are necessary. The outcomes of the ongoing clinical trials will provide further valuable insights. Establishing habenula DBS, however, will depend on successful randomized clinical trials to confirm application and clinical benefit of this promising intervention.

The Habenula in the Link Between ADHD and Mood Disorder

Attention-deficit/hyperactivity disorder (ADHD) is a childhood-onset, neurodevelopmental disorder, whereas major depressive disorder (MDD) is a mood disorder that typically emerges in adulthood. Accumulating evidence suggests that these seemingly unrelated psychiatric disorders, whose symptoms even appear antithetical [e.g., psychomotor retardation in depression vs. hyperactivity (psychomotor acceleration) in ADHD], are in fact associated with each other. Thus, individuals with ADHD exhibit high comorbidity with MDD later in life. Moreover, genetic studies have shown substantial overlaps of susceptibility genes between ADHD and MDD. Here, we propose a novel and testable hypothesis that the habenula, the epithalamic brain region important for the regulation of monoamine transmission, may be involved in both ADHD and MDD. The hypothesis suggests that an initially hypoactive habenula during childhood in individuals with ADHD may undergo compensatory changes during development, priming the habenula to be hyperactive in response to stress exposure and thereby increasing vulnerability to MDD in adulthood. Moreover, we propose a new perspective on habenular deficits in psychiatric disorders that consider the habenula a neural substrate that could explain multiple psychiatric disorders.

Neuronal adaptations in the lateral habenula during drug withdrawal: Preclinical evidence for addiction therapy

The epithalamic lateral habenula (LHb) regulates monoaminergic systems and contributes to the expression of both appetitive and aversive behaviours. Over the past years, the LHb has emerged as a vulnerable brain structure in mental illnesses including addiction. Behavioural and functional evidence in humans and rodents provide substantial support for a role of LHb in the negative affective symptoms emerging during withdrawal from addictive substances. Multiple forms of cellular and synaptic adaptations that take hold during drug withdrawal within the LHb are causally linked with the emergence of negative affective symptoms. These results indicate that targeting drug withdrawal-driven adaptations in the LHb may represent a potential strategy to normalize drug-related behavioural adaptations. In the current review we describe the mechanisms leading to functional alterations in the LHb, as well as the existing interventions used to counteract addictive behaviours. Finally, closing this loop we discuss and propose new avenues to potentially target the LHb in humans in light of the mechanistic understanding stemming from pre-clinical studies. Altogether, we provide an overview on how to leverage cellular-level understanding to envision clinically-relevant approaches for the treatment of specific aspects in drug addiction.