Cortical processing of flexible and context-dependent sensorimotor sequences.

The brain generates complex sequences of movements that can be flexibly configured based on behavioural context or real-time sensory feedback1, but how this occurs is not fully understood. Here we developed a 'sequence licking' task in which mice directed their tongue to a target that moved through a series of locations. Mice could rapidly branch the sequence online based on tactile feedback. Closed-loop optogenetics and electrophysiology revealed that the tongue and jaw regions of the primary somatosensory (S1TJ) and motor (M1TJ) cortices2 encoded and controlled tongue kinematics at the level of individual licks. By contrast, the tongue 'premotor' (anterolateral motor) cortex3-10 encoded latent variables including intended lick angle, sequence identity and progress towards the reward that marked successful sequence execution. Movement-nonspecific sequence branching signals occurred in the anterolateral motor cortex and M1TJ. Our results reveal a set of key cortical areas for flexible and context-informed sequence generation.

Disparities in Access to Deep Brain Stimulation for Parkinson's Disease and Proposed Interventions: A Literature Review.

BACKGROUND: Deep brain stimulation (DBS) is an effective therapy for Parkinson's disease (PD), but disparities exist in access to DBS along gender, racial, and socioeconomic lines. SUMMARY: Women are underrepresented in clinical trials and less likely to undergo DBS compared to their male counterparts. Racial and ethnic minorities are also less likely to undergo DBS procedures, even when controlling for disease severity and other demographic factors. These disparities can have significant impacts on patients' access to care, quality of life, and ability to manage their debilitating movement disorders. KEY MESSAGES: Addressing these disparities requires increasing patient awareness and education, minimizing barriers to equitable access, and implementing diversity and inclusion initiatives within the healthcare system. In this systematic review, we first review literature discussing gender, racial, and socioeconomic disparities in DBS access and then propose several patient, provider, community, and national-level interventions to improve DBS access for all populations.

Copper deficiency myelopathy mimicking cervical spondylitic myelopathy: a systematic review of the literature with case report.

BACKGROUND AND CONTEXT: Copper deficiency myelopathy (CDM) is a rare disease that can present with spastic quadriparesis and sensory ataxia. As a result, it can precisely mimic cervical spondylitic myelopathy (CSM). Copper deficiency may be seen following gastric bypass surgery, malabsorption syndromes such as celiac disease, and with excessive exogenous zinc intake. We present a systematic review of the literature for CDM and an illustrative case. PURPOSE: Provide a systematic review of CDM to highlight the importance of recognizing the consideration of CDM in patients presenting to a spine surgeon with myelopathy that progress despite adequate surgical decompression, or myelopathy concomitant with cytopenia, thus requiring further workup. STUDY DESIGN/SETTING: Retrospective medical record review and systematic review of the literature PATIENT SAMPLE: PubMed and Ovid-Embase database search was conducted in July 2022 OUTCOME MEASURES: Self-reported measures include PRISMA flow diagram for retrospective review; Physiological measures include retrospective review of MRI imaging of cervical spine; alternate demographic and laboratory value data extracted via literature review METHODS: A PubMed and Ovid-Embase database search was conducted in July 2022 searching for "copper deficiency myelopathy (MeSH)" from 2000 to 2022 via PRISMA guidelines. Following title and abstract review, the following data was extracted from full text: age, sex, etiology, hematological values upon presentation (mean corpuscular volume, white blood count, platelet count, and hemoglobin level), metal serum studies (serum copper, ceruloplasmin, and zinc), 24-hour collection of copper and zinc, and distinct radiographic findings on MRI. RESULTS: A total of 116 studies were included in this review which contained 198 cases of copper deficiency myelopathy. The mean age was 53.57 ± 14.14 years, with the majority being females (63.8%). The most common etiology was prior gastric surgery (n=55, 36.2 %) followed by excessive zinc consumption from the use of zinc denture cream (n=39, 19.9%). The mean serum copper was 15.67 ± 17.84 (normal=80.0-155.0) mcg/dL and mean ceruloplasmin was 6.43 ± 5.25 (normal=16-45) mg/dL. In spite of appropriate treatment with copper supplementation, only 47 cases (24%) reported improvement in neurological status, and only 10 (5.1%) recovered to baseline. A hyperintense T2 signal abnormality resembling an inverted "v" in the dorsal columns was the most common radiographic abnormality. CONCLUSION: Pertinent risk factors for copper deficiency myelopathy include prior upper gastrointestinal surgery, zinc excess, and malabsorption. Characteristic laboratory and imaging findings include cytopenia, low serum copper and ceruloplasmin, and distinct inverted "v" T2 signal hyperintensity in the dorsal columns. The neurologic deterioration with copper deficiency will progress in spite of decompressive surgery, and can be devastating and irreversible even with copper supplementation, reinforcing the importance of early detection. We thus recommend patients with myelopathy presenting with a history of gastric bypass, malabsorption syndromes, excessive zinc exposure, cytopenia, or imaging resembling an inverted "v" shaped hyperintense T2 MRI signal in the dorsal columns, should first undergo blood tests for copper, ceruloplasmin, and B12 levels prior to surgical consideration.

The association between motor and non-motor symptoms in essential tremor patients being evaluated for deep brain stimulation surgery.

BACKGROUND: Non-motor symptoms, including depression and cognitive impairment, are common in essential tremor (ET), but associations between these symptoms and tremor are poorly understood. METHODS: A retrospective, single-institution, cohort study evaluated 140 patients with ET undergoing evaluation for deep brain stimulation (DBS) surgery. The Fahn-Tolosa-Marin (FTM) or Washington Heights-Inwood Genetic Study of ET (WHIGET) scale was used to grade tremor. Tremor scores were divided into quartiles. Patients underwent clinical neuropsychological evaluations that included a comprehensive cognitive test battery and Beck Depression Inventory-II (BDI-II). Subgroup analysis was performed with groups who met criteria for depression (BDI-II > 14) or overall cognitive impairment (<9th percentile on at least two dissimilar cognitive tests). Independent samples t-tests were used for continuous variables and chi square tests for categorical variables. Univariable and multivariable regressions were used to determine relationships between tremor and non-motor scores. RESULTS: Tremor quartile was correlated with language domain performance (p = 0.044) but not depression scores. FTM score was associated with BDI-II (ß = 0.940, p = 0.010), language (ß = -0.936, p = 0.012), and visuospatial domain (ß = -0.836, p = 0.025) scores, such that worse tremor was associated with more depression and worse language and visuospatial function. WHIGET score was not associated with any neuropsychological scores on multivariable regression. CONCLUSION: FTM score was associated with language, visuospatial, and mood symptoms, suggesting a relationship between the severity of these symptom types. Different tremor scores capture different motor symptoms and relationships with nonmotor symptoms.

Benefits of stereotactic radiosurgical anterior capsulotomy for obsessive-compulsive disorder: a meta-analysis.

OBJECTIVE: Anterior capsulotomy (AC) is a therapeutic option for patients with severe, treatment-resistant obsessive-compulsive disorder (OCD). The procedure can be performed via multiple techniques, with stereotactic radiosurgery (SRS) gaining popularity because of its minimally invasive nature. The risk-benefit profile of AC performed specifically with SRS has not been well characterized. Therefore, the primary objective of this study was to characterize outcomes following stereotactic radiosurgical AC in OCD patients. METHODS: Studies assessing mean Yale-Brown Obsessive Compulsive Scale (Y-BOCS) scores before and after stereotactic radiosurgical AC for OCD were included in this analysis. Inverse-variance fixed-effect modeling was used for pooling, and random-effects estimate of the ratio of means and standard mean differences were calculated at 6 months, 12 months, and the last follow-up for Y-BOCS scores, as well as the last follow-up for the Beck Depression Inventory (BDI)/BDI-II scores. A generalized linear mixed model was used to generate fixed- and random-effects models for categorical outcomes. Univariate random-effects meta-regression was used to evaluate associations between postoperative Y-BOCS scores and study covariates. Adverse events were summed across studies. Publication bias was assessed with Begg's test. RESULTS: Eleven studies with 180 patients were eligible for inclusion. The mean Y-BOCS score decreased from 33.28 to 17.45 at the last-follow up (p < 0.001). Sixty percent of patients were classified as responders and 10% as partial responders, 18% experienced remission, and 4% had worsened Y-BOCS scores. The degree of improvement in the Y-BOCS score correlated with time since surgery (p = 0.046). In the random-effects model, the mean BDI at the last follow-up was not significantly different from that preoperatively. However, in an analysis performed with available paired pre- and postoperative BDI/BDI-II scores, there was significant improvement in the BDI/BDI-II scores postoperatively. Adverse events numbered 235, with headaches, weight change, mood changes, worsened depression/anxiety, and apathy occurring most commonly. CONCLUSIONS: Stereotactic radiosurgical AC is an effective technique for treating OCD. Its efficacy is similar to that of AC performed via other lesioning techniques.

Reward Circuit Local Field Potential Modulations Precede Risk Taking.

Risk taking behavior is a symptom of multiple neuropsychiatric disorders and often lacks effective treatments. Reward circuitry regions including the amygdala, orbitofrontal cortex, insula, and anterior cingulate have been implicated in risk-taking by neuroimaging studies. Electrophysiological activity associated with risk taking in these regions is not well understood in humans. Further characterizing the neural signalling that underlies risk-taking may provide therapeutic insight into disorders associated with risk-taking. Eleven patients with pharmacoresistant epilepsy who underwent stereotactic electroencephalography with electrodes in the amygdala, orbitofrontal cortex, insula, and/or anterior cingulate participated. Patients participated in a gambling task where they wagered on a visible playing card being higher than a hidden card, betting $5 or $20 on this outcome, while local field potentials were recorded from implanted electrodes. We used cluster-based permutation testing to identify reward prediction error signals by comparing oscillatory power following unexpected and expected rewards. We also used cluster-based permutation testing to compare power preceding high and low bets in high-risk (<50% chance of winning) trials and two-way ANOVA with bet and risk level to identify signals associated with risky, risk averse, and optimized decisions. We used linear mixed effects models to evaluate the relationship between reward prediction error and risky decision signals across trials, and a linear regression model for associations between risky decision signal power and Barratt Impulsiveness Scale scores for each patient. Reward prediction error signals were identified in the amygdala (p=0.0066), anterior cingulate (p=0.0092), and orbitofrontal cortex (p=6.0E-4, p=4.0E-4). Risky decisions were predicted by increased oscillatory power in high-gamma frequency range during card presentation in the orbitofrontal cortex (p=0.0022), and by increased power following bet cue presentation across the theta-to-beta range in the orbitofrontal cortex ( p =0.0022), high-gamma in the anterior cingulate ( p =0.0004), and high-gamma in the insula ( p =0.0014). Risk averse decisions were predicted by decreased orbitofrontal cortex gamma power ( p =2.0E-4). Optimized decisions that maximized earnings were preceded by decreases within the theta to beta range in orbitofrontal cortex ( p =2.0E-4), broad frequencies in amygdala ( p =2.0E-4), and theta to low-gamma in insula ( p =4.0E-4). Insula risky decision power was associated with orbitofrontal cortex high-gamma reward prediction error signal ( p =0.0048) and with patient impulsivity ( p =0.00478). Our findings identify and help characterize reward circuitry activity predictive of risk-taking in humans. These findings may serve as potential biomarkers to inform the development of novel treatment strategies such as closed loop neuromodulation for disorders of risk taking.