Increased Finger-Tapping Related Cerebellar Activation in Cervical Dystonia, Enhanced by Transcranial Stimulation: An Indicator of Compensation?

Background: Cervical dystonia is a movement disorder causing abnormal postures and movements of the head. While the exact pathophysiology of cervical dystonia has not yet been fully elucidated, a growing body of evidence points to the cerebellum as an important node.Methods: Here, we examined the impact of cerebellar interference by transcranial magnetic stimulation on finger-tapping related brain activation and neurophysiological measures of cortical excitability and inhibition in cervical dystonia and controls. Bilateral continuous theta-burst stimulation was used to modulate cerebellar cortical excitability in 16 patients and matched healthy controls. In a functional magnetic resonance imaging arm, data were acquired during simple finger tapping before and after cerebellar stimulation. In a neurophysiological arm, assessment comprised motor-evoked potentials amplitude and cortical silent period duration. Theta-burst stimulation over the dorsal premotor cortex and sham stimulation (neurophysiological arm only) served as control conditions.Results: At baseline, finger tapping was associated with increased activation in the ipsilateral cerebellum in patients compared to controls. Following cerebellar theta-burst stimulation, this pattern was even more pronounced, along with an additional movement-related activation in the contralateral somatosensory region and angular gyrus. Baseline motor-evoked potential amplitudes were higher and cortical silent period duration shorter in patients compared to controls. After cerebellar theta-burst stimulation, cortical silent period duration increased significantly in dystonia patients.Conclusion: We conclude that in cervical dystonia, finger movements—though clinically non-dystonic—are associated with increased activation of the lateral cerebellum, possibly pointing to general motor disorganization, which remains subclinical in most body regions. Enhancement of this activation together with an increase of silent period duration by cerebellar continuous theta-burst stimulation may indicate predominant disinhibitory effects on Purkinje cells, eventually resulting in an inhibition of cerebello-thalamocortical circuits

Genetic variance of dopamine D2 receptor gene and its influence on working memory and action monitoring

In dieser Studie sollte die Bedeutung von genetischer Varianz im Gen des Dopaminrezeptors D2 (DRD2) insbesondere für Fehlermonitoring- und Arbeitsgedächtnisprozesse untersucht werden. Vorstudien implizieren die Relevanz der dopaminergen Neurotransmission für diese Systeme und geben Hinweise, dass Defizite in entsprechenden kognitiven Prozessen für psychiatrische Erkrankungen prädisponieren. Daher wurden die Verhaltensdaten in zwei verschiedenen kognitiven Leistungstests, als auch parallel dazu erhobene Messergebnisse von zwei unterschiedlichen bildgebenden Verfahren für drei ausgewählte, vermutlich funktionale Polymorphismen im DRD2-Gen bei 210 gesunden Kontrollprobanden und 39 schizophrenen Patienten untersucht. Auf der Basis der vorhandenen Literatur hypothetisierten wir Risikoallele für die jeweiligen Polymorphismen: Das A-Allel von DRD2 TAQ1A scheint mit einer verminderten striatalen Rezeptordichte verknüpft zu sein. Das Insertionsallel des DRD2 -141C Ins/Del wird mit Schizophrenie in Verbindung gebracht, wogegen allerdings das Deletionsallel wiederholt mit niedrigerer striataler Rezeptordichte assoziiert wurde. Bei DRD2 rs1076560 scheint das T-Allel für defizitäre Performance bei Arbeitsgedächtnis-Tests verantwortlich zu sein. Zudem wurde hier eine geringere Expression der kurzen Splicevariante D2S des Rezeptors nachgewiesen und dies mit verminderter präfrontaler Aktivität assoziiert. Gemeinsam ist allen Risikoallelen eine Prädisposition für Suchterkrankungen. Unser Ziel war es, diese Risikokonstellationen in unseren Untersuchungen zu replizieren. Das Fehlermonitoring und seine Korrelate Error-related negativity (ERN) und Error-related positivity (PE) wurden in einer EEG-Studie untersucht, in der sich 170 Probanden einem sog. Eriksen-Flanker-Task unterzogen. Eine Stichprobe von 39 Patienten mit schizophrenen Psychosen und eine gesunde Kontrollgruppe (n=40) unterzogen sich dem N-Back-Task zur Testung des Arbeitsgedächtnisses. Zusätzlich wurden dabei in einer funktionellen NIRS-Untersuchung Messwerte für oxygeniertes und deoxygeniertes Hämoglobin zur Erfassung der cerebralen Aktivität ermittelt. Wir gingen von der Hypothese aus, dass die Träger der Risikoallele Defizite bei den kognitiven Aufgaben zeigen und sich zusätzlich Veränderungen der Gehirnaktivität nachweisen lassen, die auf Basis der Theorie der neurovaskulären Kopplung als reduzierte Aktivierung interpretiert werden können. Leider konnten die meisten der Hypothesen nicht bestätigt werden. Für DRD2 TAQ1A konnte in der NIRS-Messung lediglich für die Deoxygenierung eine geringere cerebrale Aktivität bei Vorliegen des Risikoallels festgestellt werden, dies allerdings nur rechtsseitig und in der Patientengruppe. Für das Fehlermonitoring konnten keine signifikanten Ergebnisse ermittelt werden. Beim Insertionsallel des DRD2 -141C Ins/Del (rs1799732) fanden wir eine Verringerung der ERN spezifisch bei fehlerhaften Antworten, sowie zusätzlich stärkere Ausprägungen der Persönlichkeitseigenschaft Neurotizismus bei den Risikoallelträgern. Wir werteten vor allem Erstes als möglicherweise prädisponierend für schizophrene Psychosen bzw. Alkoholabhängigkeit und konnten hier also teilweise unsere Hypothesen bestätigen. Die Auswertung der Daten der NIRS-Messung für den rs1799732 erbrachte keine signifikanten Ergebnisse. Bei DRD2 rs1076560 erreichte die Risikogruppe im N-Back-Test entgegen unserer Erwartung sogar ein besseres Leistungsniveau. Mittels bildgebenden Verfahren zeigten sich keine Gruppenunterschiede. Auch die EEG-Studie erbrachte keine signifikanten Ergebnisse. Die Ergebnisse werden auch unter dem Aspekt der Prädisposition zu Abhängigkeitserkrankungen diskutiert, die für alle drei Polymorphismen zu bestehen scheint. Die von uns gewählte Zuordnung der Risikoallele wurde kritisch bewertet. Für die Inkonsistenz der Befunde wurde eine direkte regulatorische Verknüpfung von TAQ1A mit der striatalen Rezeptordichte diskutiert. Zusätzlich wurde mit dem Hinweis auf eine Assoziation mit ANKK1 und ihrem regulatorischem Einfluss auf den NF-κB-Signalweg ein mögliches zukünftiges Erklärungsmodell aufgezeigt. Auch ein durch rs1076560 vermittelter Zusammenhang einer gesteigerten Expression der kurzen Splicevariante D2S mit höherer striataler Aktivität wurde in Frage gestellt. Zusammenfassend lässt sich sagen, dass die Bedeutung des dopaminergen Systems und insbesondere des Dopaminrezeptors D2 für die kognitive Leistungsfähigkeit des menschlichen Gehirns und damit auch die Pathophysiologie psychiatrischer Erkrankungen unzweifelhaft bleibt. Jedoch implizieren einige der Ergebnisse komplexere Zusammenhänge zwischen Genotyp und Phänotyp. Anscheinend sind die untersuchten Polymorphismen im DRD2-Gen nicht ausreichend, um Defizite im Fehlermonitoring und Arbeitsgedächtnis zu erklären. Die kombinierte Untersuchung mit anderen Risikogenvarianten im dopaminergen System scheint daher vielversprechender zu sein als eine isolierte Betrachtung von DRD2.Introduction: The influence of genetic variance in dopamine D2 receptor Gene (DRD2) on error monitoring and working memory was examined in this study. Former research emphasizes the relevance of dopaminergic neurotransmission to these systems and implicates that deficiency in these cognitive processes may lead to psychiatric disorders. We analyzed performance data of two cognitive performance tasks and results from two different imaging methods of 210 healthy persons and 39 schizophrenic patients. We chose 3 functional polymorphisms of DRD2 receptor gene and defined risk alleles based on existing literature: DRD2 TAQ1A and DRD2 - 141C Del alleles seem to be associated with reduced striatal receptor density. DRD2 - 141C Ins allele is linked to schizophrenia. Expression of DRD2 rs1076560 T allele may lead to poorer working memory performance, less expression of the short splicing variant D2S and lower prefrontal activity. All alleles are associated with addictive disorders. Material and Methods: In an EEG study with 170 healthy participants we investigated error monitoring by Eriksen-Flanker-Task and its correlates error-related negativity (ERN) and error-related positivity (PE). By N-Back Task we tested working memory performance of 39 schizophrenic patients and 40 healthy persons and measured cerebral activity by fNIRS. We aimed at associate risk alleles with poorer performance data and lower cerebral activity. Results: DRD2 TAQ1A allele could only be linked to lower cerebral activity for DEOXY-Hb on right hemisphere in patients. DRD 2 - 141C Ins allele carriers showed decreased ERN levels specifically for errors and scored lower in neuroticism scales. Especially the first result may predispose schizophrenia and addictive disorders. DRD2 rs1076560 T allele was even associated with better performance data. Only significant results were reported, most hypotheses could not be proven. Discussion: The attribution of risk alleles must be considered critically. The inconsistence of the results might be due to the still unclear regulation process of striatal receptor density by TAQ1A. Perhaps there is a regulating influence of ANKK1 on NF-κB-pathway. The association of higher expression of short splicing variant D2S and striatal activity must be questioned as well. We may state finally that the relevance of dopamine and especially DRD2 on cognitive performance and pathophysiology of psychiatric disorders remains important. However the context of phenotype and genotype seems to be more complex. Obviously the examined polymorphisms are insufficient to explain deficits in action monitoring and working memory. A combined investigation of different genes in dopaminergic systems seems to be more promising then an isolated consideration of DRD2

Temporal discrimination thresholds and proprioceptive performance: impact of age and nerve conduction

Background Increasing attention is payed to the contribution of somatosensory processing in motor control. In particular, temporal somatosensory discrimination has been found to be altered differentially in common movement disorders. To date, there have only been speculations as to how impaired temporal discrimination and clinical motor signs may relate to each other. Prior to disentangling this relationship, potential confounders of temporal discrimination, in particular age and peripheral nerve conduction, should be assessed, and a quantifiable measure of proprioceptive performance should be established. ObjectiveTo assess the influence of age and polyneuropathy (PNP) on somatosensory temporal discrimination threshold (STDT), temporal discrimination movement threshold (TDMT), and behavioral measures of proprioception of upper and lower limbs. Methods STDT and TDMT were assessed in 79 subjects (54 healthy, 25 with PNP; age 30–79 years). STDT was tested with surface electrodes over the thenar or dorsal foot region. TDMT was probed with needle electrodes in flexor carpi radialis (FCR) and tibialis anterior (TA) muscle. Goniometer-based devices were used to assess limb proprioception during (i) active pointing to LED markers, (ii) active movements in response to variable visual cues, and (iii) estimation of limb position following passive movements. Pointing (or estimation) error was taken as a measure of proprioceptive performance. Results In healthy subjects, higher age was associated with higher STDT and TDMT at upper and lower extremities, while age did not correlate with proprioceptive performance. Patients with PNP showed higher STDT and TDMT values and decreased proprioceptive performance in active pointing tasks compared to matched healthy subjects. As an additional finding, there was a significant correlation between performance in active pointing tasks and temporal discrimination thresholds. Conclusion Given their notable impact on measures of temporal discrimination, age and peripheral nerve conduction need to be accounted for if STDT and TDMT are applied in patients with movement disorders. As a side observation, the correlation between measures of proprioception and temporal discrimination may prompt further studies on the presumptive link between these two domains

LSVT-BIG therapy in Parkinson's disease: physiological evidence for proprioceptive recalibration

Background There is growing evidence for proprioceptive dysfunction in patients with Parkinson's disease (PD). The Lee Silvermann Voice Treatment-BIG therapy (LSVT-BIG), a special training program aiming at an increase of movement amplitudes in persons with PD (PwPD), has shown to be effective on motor symptoms. LSVT-BIG is conceptionally based on improving bradykinesia, in particular the decrement of repetitive movements, by proprioceptive recalibration. Objective To assess proprioceptive impairment in PwPD as compared to matched controls and to probe potential recalibration effects of the LSVT-BIG therapy on proprioception. Methods Proprioceptive performance and fine motor skills were assessed in 30 PwPD and 15 matched controls. Measurements with significant impairment in PwPD were chosen as outcome parameters for a standardized 4 weeks amplitude-based training intervention (LSVT-BIG) in 11 PwPD. Proprioceptive performance served as primary outcome measure. Secondary outcome measures included the motor part of the MDS-UPDRS, the nine-hole-peg test, and a questionnaire on quality of life. Post-interventional assessments were conducted at weeks 4 and 8. Results Compared to the control group, PwPD showed significantly larger pointing errors. After 4 weeks of LSVT-BIG therapy and even more so after an additional 4 weeks of continued training, proprioceptive performance improved significantly. In addition, quality of life improved as indicated by a questionnaire. Conclusion LSVT-BIG training may achieve a recalibration of proprioceptive processing in PwPD. Our data indicates a probable physiological mechanism of a symptom-specific, amplitude-based behavioral intervention in PwPD

Feasibility of local field potential-guided programming for deep brain stimulation in Parkinson's disease: A comparison with clinical and neuro-imaging guided approaches in a randomized, controlled pilot trial

Background: Subthalamic nucleus deep brain stimulation (STN-DBS) is an effective treatment for advanced Parkinson's disease (PD). Clinical outcomes after DBS can be limited by poor programming, which remains a clinically driven, lengthy and iterative process. Electrophysiological recordings in PD patients undergoing STN-DBS have shown an association between STN spectral power in the beta frequency band (beta power) and the severity of clinical symptoms. New commercially-available DBS devices now enable the recording of STN beta oscillations in chronically-implanted PD patients, thereby allowing investigation into the use of beta power as a biomarker for DBS programming. Objective: To determine the potential advantages of beta-guided DBS programming over clinically and image-guided programming in terms of clinical efficacy and programming time. Methods: We conducted a randomized, blinded, three-arm, crossover clinical trial in eight Parkinson's patients with STN-DBS who were evaluated three months after DBS surgery. We compared clinical efficacy and time required for each DBS programming paradigm, as well as DBS parameters and total energy delivered between the three strategies (beta-, clinically- and image-guided). Results: All three programming methods showed similar clinical efficacy, but the time needed for programming was significantly shorter for beta- and image-guided programming compared to clinically-guided programming (p < 0.001). Conclusion: Beta-guided programming may be a useful and more efficient approach to DBS programming in Parkinson's patients with STN-DBS. It takes significantly less time to program than traditional clinically-based programming, while providing similar symptom control. In addition, it is readily available within the clinical DBS programmer, making it a valuable tool for improving current clinical practice

Reduced Programming Time and Strong Symptom Control Even in Chronic Course Through Imaging-Based DBS Programming

Objectives: Deep brain stimulation (DBS) programming is based on clinical response testing. Our clinical pilot trial assessed the feasibility of image-guided programing using software depicting the lead location in a patient-specific anatomical model. Methods: Parkinson's disease patients with subthalamic nucleus-DBS were randomly assigned to standard clinical-based programming (CBP) or anatomical-based (imaging-guided) programming (ABP) in an 8-week crossover trial. Programming characteristics and clinical outcomes were evaluated. Results: In 10 patients, both programs led to similar motor symptom control (MDS-UPDRS III) after 4 weeks (medicationOFF/stimulationON; CPB: 18.27 ± 9.23; ABP: 18.37 ± 6.66). Stimulation settings were not significantly different, apart from higher frequency in the baseline program than CBP (p = 0.01) or ABP (p = 0.003). Time spent in a program was not significantly different (CBP: 86.1 ± 29.82%, ABP: 88.6 ± 29.0%). Programing time was significantly shorter (p = 0.039) with ABP (19.78 ± 5.86 min) than CBP (45.22 ± 18.32). Conclusion: Image-guided DBS programming in PD patients drastically reduces programming time without compromising symptom control and patient satisfaction in this small feasibility trial

Fatty acid ethanolamide levels are altered in borderline personality and complex posttraumatic stress disorders

Borderline personality (BPD) and complex posttraumatic stress disorders (PTSD) are both powerfully associated with the experience of interpersonal violence during childhood and adolescence. The disorders frequently co-occur and often result in pervasive problems in, e.g., emotion regulation and altered pain perception, where the endocannabinoid system is deeply involved. We hypothesize an endocannabinoid role in both disorders. We investigated serum levels of the endocannabinoids anandamide and 2-arachidonoylglycerol and related fatty acid ethanolamides (FAEs) in BPD, PTSD, and controls. Significant alterations were found for both endocannabinoids in BPD and for the FAE oleoylethanolamide in PTSD suggesting a respective link to both disorders

A Multi-center Genome-wide Association Study of Cervical Dystonia

BACKGROUND: Several monogenic causes for isolated dystonia have been identified, but they collectively account for only a small proportion of cases. Two genome-wide association studies have reported a few potential dystonia risk loci; but conclusions have been limited by small sample sizes, partial coverage of genetic variants, or poor reproducibility. OBJECTIVE: To identify robust genetic variants and loci in a large multicenter cervical dystonia cohort using a genome-wide approach. METHODS: We performed a genome-wide association study using cervical dystonia samples from the Dystonia Coalition. Logistic and linear regressions, including age, sex, and population structure as covariates, were employed to assess variant- and gene-based genetic associations with disease status and age at onset. We also performed a replication study for an identified genome-wide significant signal. RESULTS: After quality control, 919 cervical dystonia patients compared with 1491 controls of European ancestry were included in the analyses. We identified one genome-wide significant variant (rs2219975, chromosome 3, upstream of COL8A1, P-value 3.04 × 10(-8) ). The association was not replicated in a newly genotyped sample of 473 cervical dystonia cases and 481 controls. Gene-based analysis identified DENND1A to be significantly associated with cervical dystonia (P-value 1.23 × 10(-6) ). One low-frequency variant was associated with lower age-at-onset (16.4 ± 2.9 years, P-value = 3.07 × 10(-8) , minor allele frequency = 0.01), located within the GABBR2 gene on chromosome 9 (rs147331823). CONCLUSION: The genetic underpinnings of cervical dystonia are complex and likely consist of multiple distinct variants of small effect sizes. Larger sample sizes may be needed to provide sufficient statistical power to address the presumably multi-genic etiology of cervical dystonia