Brain stimulation in Huntington's disease

Transcranial magnetic stimulation in animal models of neurodegeneration

Brain stimulation techniques offer powerful means of modulating the physiology of specific neural structures. In recent years, non-invasive brain stimulation techniques, such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation, have emerged as therapeutic tools for neurology and neuroscience. However, the possible repercussions of these techniques remain unclear, and there are few reports on the incisive recovery mechanisms through brain stimulation. Although several studies have recommended the use of non-invasive brain stimulation in clinical neuroscience, with a special emphasis on TMS, the suggested mechanisms of action have not been confirmed directly at the neural level. Insights into the neural mechanisms of non-invasive brain stimulation would unveil the strategies necessary to enhance the safety and efficacy of this progressive approach. Therefore, animal studies investigating the mechanisms of TMS-induced recovery at the neural level are crucial for the elaboration of non-invasive brain stimulation. Translational research done using animal models has several advantages and is able to investigate knowledge gaps by directly targeting neuronal levels. In this review, we have discussed the role of TMS in different animal models, the impact of animal studies on various disease states, and the findings regarding brain function of animal models after TMS in pharmacology research.

Medical, Surgical, and Genetic Treatment of Huntington Disease

Huntington disease, a neurodegenerative disease characterized by progressive motor, behavioral, and cognitive decline, is caused by a CAG trinucleotide repeat expansion in the huntingtin gene on chromosome 4. Current treatments target symptom management because there are no disease-modifying therapies at this time. Investigation of RNA-based and DNA-based treatment strategies are emerging and hold promise of possible future disease-modifying therapy.

Treatment options for chorea

INTRODUCTION

Chorea is defined as jerk-like movements that move randomly from one body part to another. It is due to a variety of disorders and although current symptomatic therapy is quite effective there are few etiology- or pathogenesis-targeted therapies. The aim of this review is to summarize our own experience and published evidence in the treatment of chorea. Areas covered: After evaluating current guidelines and clinical practices for chorea of all etiologies, PubMed was searched for the most recent clinical trials and reviews using the term 'chorea' cross referenced with specific drug names. Expert commentary: Inhibitors of presynaptic vesicular monoamine transporter type 2 (VMAT2) that cause striatal dopamine depletion, such as tetrabenazine, deutetrabenazine, and valbenazine, are considered the treatment of choice in patients with chorea. Some clinicians also use dopamine receptor blockers (e.g. antipsychotics) and other drugs, including anti-epileptics and anti-glutamatargics. 'Dopamine stabilizers' such as pridopidine and other experimental drugs are currently being investigated in the treatment of chorea. Deep brain stimulation is usually reserved for patients with disabling chorea despite optimal medical therapy.

Deep Brain Stimulation in Huntington's Disease-Preliminary Evidence on Pathophysiology, Efficacy and Safety

Huntington's disease (HD) is one of the most disabling degenerative movement disorders, as it not only affects the motor system but also leads to cognitive disabilities and psychiatric symptoms. Deep brain stimulation (DBS) of the pallidum is a promising symptomatic treatment targeting the core motor symptom: chorea. This article gives an overview of preliminary evidence on pathophysiology, safety and efficacy of DBS in HD.

Combined Invasive Subcortical and Non-invasive Surface Neurophysiological Recordings for the Assessment of Cognitive and Emotional Functions in Humans

In spite of the success in applying non-invasive electroencephalography (EEG), magneto-encephalography (MEG) and functional magnetic resonance imaging (fMRI) for extracting crucial information about the mechanism of the human brain, such methods remain insufficient to provide information about physiological processes reflecting cognitive and emotional functions at the subcortical level. In this respect, modern invasive clinical approaches in humans, such as deep brain stimulation (DBS), offer a tremendous possibility to record subcortical brain activity, namely local field potentials (LFPs) representing coherent activity of neural assemblies from localized basal ganglia or thalamic regions. Notwithstanding the fact that invasive approaches in humans are applied only after medical indication and thus recorded data correspond to altered brain circuits, valuable insight can be gained regarding the presence of intact brain functions in relation to brain oscillatory activity and the pathophysiology of disorders in response to experimental cognitive paradigms. In this direction, a growing number of DBS studies in patients with Parkinson's disease (PD) target not only motor functions but also higher level processes such as emotions, decision-making, attention, memory and sensory perception. Recent clinical trials also emphasize the role of DBS as an alternative treatment in neuropsychiatric disorders ranging from obsessive compulsive disorder (OCD) to chronic disorders of consciousness (DOC). Consequently, we focus on the use of combined invasive (LFP) and non-invasive (EEG) human brain recordings in assessing the role of cortical-subcortical structures in cognitive and emotional processing trough experimental paradigms (e.g. speech stimuli with emotional connotation or paradigms of cognitive control such as the Flanker task), for patients undergoing DBS treatment.