Modulation of Resting Connectivity Between the Mesial Frontal Cortex and Basal Ganglia

Attraction is altered via modulation of the medial prefrontal cortex without explicit knowledge

Previous studies have demonstrated that brain stimulation can alter an individual's physical appearance via dysregulation of the medial prefrontal cortex (MPFC). In this study, we attempted to determine if individuals who receive repetitive transcranial magnetic stimulation (rTMS) delivered to the MPFC were rated as more attractive by others. It has been previously reported that 1 hertz (Hz) (inhibitory) TMS can alter one's facial expressions such that frontal cortex inhibition can increase expressiveness. These alterations, detected by external observation, remain below the level of awareness of the subject itself. In Phase I, subjects (N = 10) received MPFC rTMS and had their photographs taken after each of the five stimulation conditions, in addition to making self-ratings across a number of variables, including attractiveness. In Phase II, participants (N = 430) rated five pictures of each of the Phase 1 individuals on attractiveness. It was found that there were no significant differences in self-assessment following rTMS (Phase I). However, attractiveness ratings differed significantly in Phase II. There was a significant difference found between 10 Hz TMS delivered to the MPFC (p < 0.001), such that individuals were rated as less attractive. Furthermore, 1 Hz TMS to the MPFC increased the number of 'Most Attractive' ratings, while 10Hz TMS decreased the number of 'Most Attractive' ratings (p < 0.001). These results suggest that the MPFC plays a role in attractiveness ratings to others. These data also support research showing that one's appearance can be altered below the level of awareness via rTMS. To our knowledge, this is the first investigation to examine how brain stimulation influences one's attractiveness.

Dopamine in the prefrontal cortex plays multiple roles in the executive function of patients with Parkinson's disease

Parkinson's disease can affect not only motor functions but also cognitive abilities, leading to cognitive impairment. One common issue in Parkinson's disease with cognitive dysfunction is the difficulty in executive functioning. Executive functions help us plan, organize, and control our actions based on our goals. The brain area responsible for executive functions is called the prefrontal cortex. It acts as the command center for the brain, especially when it comes to regulating executive functions. The role of the prefrontal cortex in cognitive processes is influenced by a chemical messenger called dopamine. However, little is known about how dopamine affects the cognitive functions of patients with Parkinson's disease. In this article, the authors review the latest research on this topic. They start by looking at how the dopaminergic system, is altered in Parkinson's disease with executive dysfunction. Then, they explore how these changes in dopamine impact the synaptic structure, electrical activity, and connection components of the prefrontal cortex. The authors also summarize the relationship between Parkinson's disease and dopamine-related cognitive issues. This information may offer valuable insights and directions for further research and improvement in the clinical treatment of cognitive impairment in Parkinson's disease.

Association between P300 parameters and cognitive function in people with diabetic neuropathy

Purpose

The purpose of this study was to investigate the association between event-related potential (ERP) P300 with cognitive function in people with diabetic peripheral neuropathy (DPN).

Methods

We performed a cross-sectional analysis of 19 type 2 diabetes mellitus (T2DM) patients, aged 18 and older with DPN. The participants were assessed for neuropathy, cognitive function, & dual-task performance. DPN was examined via the administration of diabetic neuropathy symptom score (DNSS) and vibration perception threshold (VPT). Cognitive dysfunction was evaluated using Mini-mental state examination (MMSE), trail making test-B (TMT-B), and ERP P300 wave latency & amplitude. For assessing dual-task performance, the dual-task cost (DTC) was calculated using the timed-up and go (TUG) test and TUG with dual task (TUG-DT).

Results

P300 latency was linearly related to TMT-B (R = 0.31, p = 0.01) and DTC (R = 0.22, p = 0.04). A similar trend was observed in TMT-B (R = 0.13, p = 0.04) & DTC (R =0 .67, p = 0.001) with respect to P300 amplitude. MMSE did not relate with P300 latency (R = 0.14, p = 0.58) & amplitude (R = 0.63, p = .44).

Conclusion

P300 latency and amplitude are associated with cognitive function and DTC of individuals with DPN.

Cerebellum Dysfunction in Patients With PRRT2-Related Paroxysmal Dyskinesia

Background and Objectives:

The main culprit gene for paroxysmal kinesigenic dyskinesia, characterized by brief and recurrent attacks of involuntary movements, is PRRT2. The location of the primary dysfunction associated with paroxysmal dyskinesia remains a matter of debate and may vary depending on the etiology. While striatal dysfunction has often been implicated in these patients, evidence from preclinical models indicate that the cerebellum could also play a role. We aimed to investigate the role of the cerebellum in the pathogenesis of PRRT2-related dyskinesia in humans.

Methods:

We enrolled 22 consecutive right-handed patients with paroxysmal kinesigenic dyskinesia with a pathogenic variant of PRRT2, and their matched controls. Participants underwent a multi-modal neuroimaging protocol. We recorded anatomic and diffusion-weighted MRI, as well as resting-state functional MRI during which we tested the after-effects of sham and repetitive transcranial magnetic stimulation applied to the cerebellum on endogenous brain activity. We quantified: (i) the structural integrity of gray matter using voxel-based morphometry; (ii) the structural integrity of white matter using fixel-based analysis; (iii) the strength and direction of functional cerebellar connections using spectral dynamic causal modeling.

Results:

PRRT2 patients had: (i) decreased gray matter volume in the cerebellar lobule VI and in the medial prefrontal cortex; (ii) microstructural alterations of white matter in the cerebellum and along the tracts connecting the cerebellum to the striatum and the cortical motor areas; (iii) dysfunction of cerebellar motor pathways to the striatum and the cortical motor areas, as well as abnormal communication between the associative cerebellum (Crus I) and the medial prefrontal cortex. Cerebellar stimulation modulated communication within the motor and associative cerebellar networks, and tended to restore this communication to the level observed in healthy controls.

Discussion:

Patients with PRRT2-related dyskinesia have converging structural alterations of the motor cerebellum and related pathways with a dysfunction of cerebellar output towards the cerebello-thalamo-striato-cortical network. We hypothesize that abnormal cerebellar output is the primary dysfunction in patients with a PRRT2 pathogenic variant, resulting in striatal dysregulation and paroxysmal dyskinesia. More broadly, striatal dysfunction in paroxysmal dyskinesia might be secondary to aberrant cerebellar output transmitted by thalamic relays in certain disorders.

Clinical trial number:

NCT03481491 (https://ichgcp.net/clinical-trials-registry/NCT03481491)

Noninvasive neuromodulation of the prefrontal cortex in mental health disorders

More than any other brain region, the prefrontal cortex (PFC) gives rise to the singularity of human experience. It is therefore frequently implicated in the most distinctly human of all disorders, those of mental health. Noninvasive neuromodulation, including electroconvulsive therapy (ECT), repetitive transcranial magnetic stimulation (rTMS), and transcranial direct current stimulation (tDCS) among others, can-unlike pharmacotherapy-directly target the PFC and its neural circuits. Direct targeting enables significantly greater on-target therapeutic effects compared with off-target adverse effects. In contrast to invasive neuromodulation approaches, such as deep-brain stimulation (DBS), noninvasive neuromodulation can reversibly modulate neural activity from outside the scalp. This combination of direct targeting and reversibility enables noninvasive neuromodulation to iteratively change activity in the PFC and its neural circuits to reveal causal mechanisms of both disease processes and healthy function. When coupled with neuronavigation and neurophysiological readouts, noninvasive neuromodulation holds promise for personalizing PFC neuromodulation to relieve symptoms of mental health disorders by optimizing the function of the PFC and its neural circuits. ClinicalTrials.gov Identifier: NCT03191058.

Deep TMS H7 Coil: Features, Applications & Future

INTRODUCTION

Transcranial magnetic stimulation (TMS) uses magnetic pulses to induce electrical current in the underlying neuronal tissue. A variety of TMS coils exist on the market, differing primarily in configuration, orientation, and flexibility of the wire windings of the coil. Deep TMS^TM utilizes H-Coils, flexible coils with different configurations for stimulating different brain regions implicated in different neuropsychiatric disorders. The H7 Coil, designed to target primarily the medial prefrontal cortex and the anterior cingulate cortex, is FDA-cleared for obsessive-compulsive disorder (OCD). It was chosen as the focus of this review since it recently showed promise in various neuropsychiatric populations in addition to growing understanding of its mechanism of action (MOA).

AREAS COVERED

Here we assembled all peer-reviewed publications on the H7 Coil to showcase its efficacy in: (a) various OCD patient populations (e.g., different degrees of symptom severity, treatment resistance, comorbidities) (b) other neuropsychiatric populations (e.g., addiction, major depressive disorder and autism spectrum disorder).

EXPERT OPINION

While substantial evidence pertaining to the H7 Coil's efficacy as well as its MOA has accumulated, much work remains. In the final section of this review, we highlight areas of ongoing and future research that will further elucidate the coil's MOA as well as its full efficacy potential.

Speech Fluency Improvement in Developmental Stuttering Using Non-invasive Brain Stimulation: Insights From Available Evidence

Developmental stuttering (DS) is a disturbance of the normal rhythm of speech that may be interpreted as very debilitating in the most affected cases. Interventions for DS are historically based on the behavioral modifications of speech patterns (e.g., through speech therapy), which are useful to regain a better speech fluency. However, a great variability in intervention outcomes is normally observed, and no definitive evidence is currently available to resolve stuttering, especially in the case of its persistence in adulthood. In the last few decades, DS has been increasingly considered as a functional disturbance, affecting the correct programming of complex motor sequences such as speech. Compatibly, understanding of the neurophysiological bases of DS has dramatically improved, thanks to neuroimaging, and techniques able to interact with neural tissue functioning [e.g., non-invasive brain stimulation (NIBS)]. In this context, the dysfunctional activity of the cortico-basal-thalamo-cortical networks, as well as the defective patterns of connectivity, seems to play a key role, especially in sensorimotor networks. As a consequence, a direct action on the functionality of "defective" or "impaired" brain circuits may help people who stutter to manage dysfluencies in a better way. This may also "potentiate" available interventions, thus favoring more stable outcomes of speech fluency. Attempts aiming at modulating (and improving) brain functioning of people who stutter, realized by using NIBS, are quickly increasing. Here, we will review these recent advancements being applied to the treatment of DS. Insights will be useful not only to assess whether the speech fluency of people who stutter may be ameliorated by acting directly on brain functioning but also will provide further suggestions about the complex and dynamic pathophysiology of DS, where causal effects and "adaptive''/''maladaptive" compensation mechanisms may be strongly overlapped. In conclusion, this review focuses future research toward more specific, targeted, and effective interventions for DS, based on neuromodulation of brain functioning.

Effect of Cognitive Function on Balance and Posture Control after Stroke

Hemiplegic gait is the most common sequela of stroke. Patients with hemiplegic gait are at a risk of falling because of poor balance. The theory of cognitive-motor networks paved the way for a new field of research. However, the mechanism of the relationship of cognition with gait or posture control networks is unclear because of the dynamic characteristics of walking and changing postures. To explore differences in the balance function and fall risk between patients with and without cognitive impairment after stroke, we utilized the Berg balance scale, Timed “Up and Go” test, and 10 m walking test. Patients were divided into two groups: the observation group (16 patients, female 6 and male 10), comprising patients with cognitive impairment after stroke, and the control group (16 patients, female 7 and male 9), comprising patients without cognitive impairment after stroke. We found that patients with cognitive impairment had worse balance function and a higher risk of falls. They needed a longer time to turn around or sit down. Our findings indicated that posture control in turning around and sitting down required more cognitive resources in daily life.

The Impact of Pediatric Basal Ganglia Stroke on Mental Health in Children: Report of 2 Cases

Background:

The impact of basal ganglia stroke on mental health is better described in adults than in children. We report 2 children with significant mental health issues after basal ganglia stroke.

Case Reports:

Patient 1, an 8-year-old boy, had mild anxiety before his left basal ganglia stroke. Post-stroke, he developed severe anxiety, obsessions, depression, and attention deficit hyperactivity disorder, in addition to a right hemiplegia and some mild chorea. He gradually improved over 3 years with psychiatric care and medication but continued to have residual symptoms. Patient 2, a 10-year-old boy, had no history of mental health issues before his right basal ganglia stroke. Post-stroke, he developed significant anxiety and mild depression, along with a left hemiplegia. He improved over 9 months and returned to his mental health baseline.

Conclusions:

Mental health issues after basal ganglia stroke in children can be significant, and recovery can take months to years.

Group-level analysis of induced electric field in deep brain regions by different TMS coils

Deep transcranial magnetic stimulation (dTMS) is a non-invasive technique used for the treatment of depression and obsessive compulsive disorder. In this study, we computationally evaluated group-level dosage for dTMS to characterize the targeted deep brain regions to overcome the limitations of using individualized head models to characterize coil performance in a population. We used an inter-subject registration method adapted to the deep brain regions that enable projection of computed electric fields (EFs) from individual realistic head models (n  =  18) to the average space of deep brain regions. The computational results showed consistent group-level hotspots of the EF in the deep brain regions. The halo circular assembly coils induced the highest EFs in deep brain regions (up to 50% of the maximum EF in the cortex) for optimized positioning. In terms of the trade-off between field spread and penetration, the performance of the H7 coil was the best. The computational model allowed the optimization of generalized dTMS-induced EF on deep region targets despite inter-individual differences while informing and possibly minimizing unintended stimulation of superficial regions and possible mixed stimulation effects from deep and cortical areas. These results will facilitate the decision process during dTMS interventions in clinical practice.