Dorsal root ganglion magnetic resonance imaging biomarker correlations with pain in Fabry disease.

Fabry disease is a rare monogenetic, X-linked lysosomal storage disorder with neuropathic pain as one characteristic symptom. Impairment of the enzyme alpha-galactosidase A leads to an accumulation of globotriaosylceramide in the dorsal root ganglia. Here, we investigate novel dorsal root ganglia MR imaging biomarkers and their association with Fabry genotype and pain phenotype. In this prospective study, 89 Fabry patients were examined using a standardized 3 T MRI protocol of the dorsal root ganglia. Fabry pain was assessed through a validated Fabry pain questionnaire. The genotype was determined by diagnostic sequencing of the alpha-galactosidase A gene. MR imaging end-points were dorsal root ganglia volume by voxel-wise morphometric analysis and dorsal root ganglia T2 signal. Reference groups included 55 healthy subjects and Fabry patients of different genotype categories without Fabry pain. In patients with Fabry pain, T2 signal of the dorsal root ganglia was increased by +39.2% compared to healthy controls (P = 0.001) and by +29.4% compared to painless Fabry disease (P = 0.017). This effect was pronounced in hemizygous males (+40.7% compared to healthy; P = 0.008 and +29.1% compared to painless; P = 0.032) and was consistently observed across the genotype spectrum of nonsense (+38.1% compared to healthy, P < 0.001) and missense mutations (+39.2% compared to healthy; P = 0.009). T2 signal of dorsal root ganglia and globotriaosylsphingosine levels were the only independent predictors of Fabry pain (P = 0.047; P = 0.002). Volume of dorsal root ganglia was enlarged by +46.0% in Fabry males in the nonsense compared to missense genotype category (P = 0.005) and by +34.5% compared to healthy controls (P = 0.034). In painful Fabry disease, MRI T2 signal of dorsal root ganglia is increased across different genotypes. Dorsal root ganglion MRI T2 signal as a novel in vivo imaging biomarker may help to better understand whether Fabry pain is modulated or even caused by dorsal root ganglion pathology.

Heart rate variability, interoceptive accuracy and functional connectivity in middle-aged and older patients with depression.

BACKGROUND AND OBJECTIVE: Major depressive disorder (MDD) is associated with increased cardiac morbidity. Reduced heart rate variability (HRV) as well as lower interoceptive accuracy (IAc) have been observed in MDD as possible sympathomimetic mechanisms related to insula activity. The salience network (SN) anchored by the insula has been posited as a crucial functional network for cardiac sensations and the default mode network (DMN) for MDD. This study aimed to investigate the relation between insula-centered and depression-related brain networks, IAc and HRV in patients with depression as a possible mechanism by which MDD increases cardiac morbidity. METHODS: 30 depressed inpatients and 30 healthy subjects (derived from the population-based "Characteristics and Course of Heart Failure Stages A-B and Determinants of Progression" cohort study, STAAB) all over 50 years were examined. HRV and IAc were assessed via electrocardiogram and a heartbeat perception task prior to a 3 T resting-state functional magnetic resonance imaging. Seed-to-voxel resting-state functional connectivity (FC) analysis was conducted with six seeds in the insula and two seeds in the DMN. RESULTS: Depressed patients on the one hand showed decreased FC between insula cortex and frontal as well occipital cortical brain regions compared to controls. Depressed patients on the other hand exhibited higher FC between the medial prefrontal cortex and the insula cortex compared to controls. However, depressed patients did not differ in HRV nor in IAc compared to controls. CONCLUSION: Thus, differences in insula-related brain networks in depression in our study were not mirrored by differences in HRV and IAc. Future research is needed to define the mechanism by which depression increases cardiac morbidity.

Profiles of cognitive impairment in chronic heart failure-A cluster analytic approach.

Background: Cognitive impairment is a major comorbidity in patients with chronic heart failure (HF) with a wide range of phenotypes. In this study, we aimed to identify and compare different clusters of cognitive deficits. Methods: The prospective cohort study "Cognition.Matters-HF" recruited 147 chronic HF patients (aged 64.5 ± 10.8 years; 16.2% female) of any etiology. All patients underwent extensive neuropsychological testing. We performed a hierarchical cluster analysis of the cognitive domains, such as intensity of attention, visual/verbal memory, and executive function. Generated clusters were compared exploratively with respect to the results of cardiological, neurological, and neuroradiological examinations without correction for multiple testing. Results: Dendrogram and the scree plot suggested three distinct cognitive profiles: In the first cluster, 42 patients (28.6%) performed without any deficits in all domains. Exclusively, the intensity of attention deficits was seen in the second cluster, including 55 patients (37.4%). A third cluster with 50 patients (34.0%) was characterized by deficits in all cognitive domains. Age (p = 0.163) and typical clinical markers of chronic HF, such as ejection fraction (p = 0.222), 6-min walking test distance (p = 0.138), NT-proBNP (p = 0.364), and New York Heart Association class (p = 0.868) did not differ between clusters. However, we observed that women (p = 0.012) and patients with previous cardiac valve surgery (p = 0.005) prevailed in the "global deficits" cluster and the "no deficits" group had a lower prevalence of underlying arterial hypertension (p = 0.029). Total brain volume (p = 0.017) was smaller in the global deficit cluster, and serum levels of glial fibrillary acidic protein were increased (p = 0.048). Conclusion: Apart from cognitively healthy and globally impaired HF patients, we identified a group with deficits only in the intensity of attention. Women and patients with previous cardiac valve surgery are at risk for global cognitive impairment when suffering HF and could benefit from special multimodal treatment addressing the psychosocial condition.

Deep phenotyping as a contribution to personalized depression therapy: the GEParD and DaCFail protocols.

Depressive patients suffer from a complex of symptoms of varying intensity compromising their mood, emotions, self-concept, neurocognition, and somatic function. Due to a mosaic of aetiologies involved in developing depression, such as somatic, neurobiological, (epi-)genetic factors, or adverse life events, patients often experience recurrent depressive episodes. About 20-30% of these patients develop difficult-to-treat depression. Here, we describe the design of the GEParD (Genetics and Epigenetics of Pharmaco- and Psychotherapy in acute and recurrent Depression) cohort and the DaCFail (Depression-associated Cardiac Failure) case-control protocol. Both protocols intended to investigate the incremental utility of multimodal biomarkers including cardiovascular and (epi-)genetic markers, functional brain and heart imaging when evaluating the response to antidepressive therapy using comprehensive psychometry. From 2012 to 2020, 346 depressed patients (mean age 45 years) were recruited to the prospective, observational GEParD cohort protocol. Between 2016 and 2020, the DaCFail case-control protocol was initiated integrating four study subgroups to focus on heart-brain interactions and stress systems in patients > 50 years with depression and heart failure, respectively. For DaCFail, 120 depressed patients (mean age 60 years, group 1 + 2), of which 115 also completed GEParD, and 95 non-depressed controls (mean age 66 years) were recruited. The latter comprised 47 patients with heart failure (group 3) and 48 healthy subjects (group 4) of a population-based control group derived from the Characteristics and Course of Heart Failure Stages A-B and Determinants of Progression (STAAB) cohort study. Our hypothesis-driven, exploratory study design may serve as an exemplary roadmap for a standardized, reproducible investigation of personalized antidepressant therapy in an inpatient setting with focus on heart comorbidities in future multicentre studies.

Serum glial fibrillary acidic protein indicates memory impairment in patients with chronic heart failure.

AIMS: Cognitive dysfunction occurs frequently in patients with heart failure (HF), but early detection remains challenging. Serum glial fibrillary acidic protein (GFAP) is an emerging biomarker of cognitive decline in disorders of primary neurodegeneration such as Alzheimer's disease. We evaluated the utility of serum GFAP as a biomarker for cognitive dysfunction and structural brain damage in patients with stable chronic HF. METHODS AND RESULTS: Using bead-based single molecule immunoassays, we quantified serum levels of GFAP in patients with HF participating in the prospective Cognition.Matters-HF study. Participants were extensively phenotyped, including cognitive testing of five separate domains and magnetic resonance imaging (MRI) of the brain. Univariable and multivariable models, also accounting for multiple testing, were run. One hundred and forty-six chronic HF patients with a mean age of 63.8 ± 10.8 years were included (15.1% women). Serum GFAP levels (median 246 pg/mL, quartiles 165, 384 pg/mL; range 66 to 1512 pg/mL) did not differ between sexes. In the multivariable adjusted model, independent predictors of GFAP levels were age (T = 5.5; P < 0.001), smoking (T = 3.2; P = 0.002), estimated glomerular filtration rate (T = -4.7; P < 0.001), alanine aminotransferase (T = -2.1; P = 0.036), and the left atrial end-systolic volume index (T = 3.4; P = 0.004). NT-proBNP but not serum GFAP explained global cerebral atrophy beyond ageing. However, serum GFAP levels were associated with the cognitive domain visual/verbal memory (T = -3.0; P = 0.003) along with focal hippocampal atrophy (T = 2.3; P = 0.025). CONCLUSIONS: Serum GFAP levels are affected by age, smoking, and surrogates of the severity of HF. The association of GFAP with memory dysfunction suggests that astroglial pathologies, which evade detection by conventional MRI, may contribute to memory loss beyond ageing in patients with chronic HF.

CNS imaging characteristics in fibromyalgia patients with and without peripheral nerve involvement.

We tested the hypothesis that reduced skin innervation in fibromyalgia syndrome is associated with specific CNS changes. This prospective case-control study included 43 women diagnosed with fibromyalgia syndrome and 40 healthy controls. We further compared the fibromyalgia subgroups with reduced (n = 21) and normal (n = 22) skin innervation. Brains were analysed for cortical volume, for white matter integrity, and for functional connectivity. Compared to controls, cortical thickness was decreased in regions of the frontal, temporal and parietal cortex in the fibromyalgia group as a whole, and decreased in the bilateral pericalcarine cortices in the fibromyalgia subgroup with reduced skin innervation. Diffusion tensor imaging revealed a significant increase in fractional anisotropy in the corona radiata, the corpus callosum, cingulum and fornix in patients with fibromyalgia compared to healthy controls and decreased FA in parts of the internal capsule and thalamic radiation in the subgroup with reduced skin innervation. Using resting-state fMRI, the fibromyalgia group as a whole showed functional hypoconnectivity between the right midfrontal gyrus and the posterior cerebellum and the right crus cerebellum, respectively. The subgroup with reduced skin innervation showed hyperconnectivity between the inferior frontal gyrus, the angular gyrus and the posterior parietal gyrus. Our results suggest that the subgroup of fibromyalgia patients with pronounced pathology in the peripheral nervous system shows alterations in morphology, structural and functional connectivity also at the level of the encephalon. We propose considering these subgroups when conducting clinical trials.

Temporal changes in total and hippocampal brain volume and cognitive function in patients with chronic heart failure-the COGNITION.MATTERS-HF cohort study.

AIMS: We quantified the concurring dynamics affecting total and hippocampal brain volume and cognitive function in patients with chronic heart failure (HF) over a period of three years. METHODS AND RESULTS: A total of 148 patients with mild stable HF entered this monocentric prospective cohort study: mean age 64.5 (10.8) years; 16.2% female; 77% in New York Heart Association functional classes I-II; 128 and 105 patients attended follow-up visits after 1 and 3 years, respectively. The assessment included cardiological, neurological, psychological work-up, and brain magnetic resonance imaging. Total and regional brain volumes were quantified using an operator-independent fully automated approach and reported normalized to the mean estimated intracranial volume. At baseline, the mean hippocampal volume was ∼13% lower than expected. However, the 3-year progressive hippocampal volume loss was small: -62 mm3 [95% confidence interval (CI) -81 to -42, P < 0.0001). This corresponded to a relative change of -1.8% (95% CI -2.3 to -1.2), which was similar in magnitude as observed with physiological aging. Moreover, the load of white matter hypointensities increased within the limits of normal aging. Cognitive function during the 3-year observation period remained stable, with 'intensity of attention' as the only domain declining (LSmean -1.82 points, 95% CI -3.05 to -0.58, P = 0.004). After 3 years, performance in all domains of cognition remained associated with hippocampal volume (r ≥ 0.29). CONCLUSION: In patients with predominantly mild HF, the markedly reduced hippocampal volume observed at baseline was associated with impaired cognitive function, but no accelerated deterioration in cognition and brain atrophy became evident over a mid-term period of three years.

Split-Belt Training but Not Cerebellar Anodal tDCS Improves Stability Control and Reduces Risk of Fall in Patients with Multiple Sclerosis.

The objective of this study was to examine the therapeutic potential of multiple sessions of training on a split-belt treadmill (SBT) combined with cerebellar anodal transcranial direct current stimulation (tDCS) on gait and balance in People with Multiple Sclerosis (PwMS). Twenty-two PwMS received six sessions of anodal (PwMSreal, n = 12) or sham (PwMSsham, n = 10) tDCS to the cerebellum prior to performing the locomotor adaptation task on the SBT. To evaluate the effect of the intervention, functional gait assessment (FGA) scores and distance walked in 2 min (2MWT) were measured at the baseline (T0), day 6 (T5), and at the 4-week follow up (T6). Locomotor performance and changes of motor outcomes were similar in PwMSreal and PwMSsham independently from tDCS mode applied to the cerebellum (anodal vs. sham, on FGA, p = 0.23; and 2MWT, p = 0.49). When the data were pooled across the groups to investigate the effects of multiple sessions of SBT training alone, significant improvement of gait and balance was found on T5 and T6, respectively, relative to baseline (FGA, p < 0.001 for both time points). The FGA change at T6 was significantly higher than at T5 (p = 0.01) underlining a long-lasting improvement. An improvement of the distance walked during the 2MWT was also observed on T5 and T6 relative to T0 (p = 0.002). Multiple sessions of SBT training resulted in a lasting improvement of gait stability and endurance, thus potentially reducing the risk of fall as measured by FGA and 2MWT. Application of cerebellar tDCS during SBT walking had no additional effect on locomotor outcomes.

A Single Session of Anodal Cerebellar Transcranial Direct Current Stimulation Does Not Induce Facilitation of Locomotor Consolidation in Patients With Multiple Sclerosis.

Background: Multiple sclerosis (MS) may cause variable functional impairment. The discrepancy between functional impairment and brain imaging findings in patients with MS (PwMS) might be attributed to differential adaptive and consolidation capacities. Modulating those abilities could contribute to a favorable clinical course of the disease. Objectives: We examined the effect of cerebellar transcranial direct current stimulation (c-tDCS) on locomotor adaptation and consolidation in PwMS using a split-belt treadmill (SBT) paradigm. Methods: 40 PwMS and 30 matched healthy controls performed a locomotor adaptation task on a SBT. First, we assessed locomotor adaptation in PwMS. In a second investigation, this training was followed by cerebellar anodal tDCS applied immediately after the task ipsilateral to the fast leg (T0). The SBT paradigm was repeated 24 h (T1) and 78 h (T2) post-stimulation to evaluate consolidation. Results: The gait dynamics and adaptation on the SBT were comparable between PwMS and controls. We found no effects of offline cerebellar anodal tDCS on locomotor adaptation and consolidation. Participants who received the active stimulation showed the same retention index than sham-stimulated subjects at T1 (p = 0.33) and T2 (p = 0.46). Conclusion: Locomotor adaptation is preserved in people with mild-to-moderate MS. However, cerebellar anodal tDCS applied immediately post-training does not further enhance this ability. Future studies should define the neurobiological substrates of maintained plasticity in PwMS and how these substrates can be manipulated to improve compensation. Systematic assessments of methodological variables for cerebellar tDCS are urgently needed to increase the consistency and replicability of the results across experiments in various settings.

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.

Orexin in the anxiety spectrum: association of a HCRTR1 polymorphism with panic disorder/agoraphobia, CBT treatment response and fear-related intermediate phenotypes.

Preclinical studies point to a pivotal role of the orexin 1 (OX1) receptor in arousal and fear learning and therefore suggest the HCRTR1 gene as a prime candidate in panic disorder (PD) with/without agoraphobia (AG), PD/AG treatment response, and PD/AG-related intermediate phenotypes. Here, a multilevel approach was applied to test the non-synonymous HCRTR1 C/T Ile408Val gene variant (rs2271933) for association with PD/AG in two independent case-control samples (total n = 613 cases, 1839 healthy subjects), as an outcome predictor of a six-weeks exposure-based cognitive behavioral therapy (CBT) in PD/AG patients (n = 189), as well as with respect to agoraphobic cognitions (ACQ) (n = 483 patients, n = 2382 healthy subjects), fMRI alerting network activation in healthy subjects (n = 94), and a behavioral avoidance task in PD/AG pre- and post-CBT (n = 271). The HCRTR1 rs2271933 T allele was associated with PD/AG in both samples independently, and in their meta-analysis (p = 4.2 × 10-7), particularly in the female subsample (p = 9.8 × 10-9). T allele carriers displayed a significantly poorer CBT outcome (e.g., Hamilton anxiety rating scale: p = 7.5 × 10-4). The T allele count was linked to higher ACQ sores in PD/AG and healthy subjects, decreased inferior frontal gyrus and increased locus coeruleus activation in the alerting network. Finally, the T allele count was associated with increased pre-CBT exposure avoidance and autonomic arousal as well as decreased post-CBT improvement. In sum, the present results provide converging evidence for an involvement of HCRTR1 gene variation in the etiology of PD/AG and PD/AG-related traits as well as treatment response to CBT, supporting future therapeutic approaches targeting the orexin-related arousal system.

Cognitive-behavioral therapy effects on alerting network activity and effective connectivity in panic disorder.

Given the particular relevance of arousal and alerting in panic disorder (PD), here the alerting network was investigated (1) contrasting patients with PD and healthy controls, (2) as a function of anxiety sensitivity constituting a dimensional measure of panic-related anxiety, and (3) as a possible correlate of treatment response. Using functional magnetic resonance imaging (fMRI), 45 out-patients with PD (f = 34) and 51 matched healthy controls were investigated for brain activation patterns and effective connectivity (Dynamic Causal Modeling, DCM) while performing the Attention Network Task (ANT). Anxiety sensitivity was ascertained by the Anxiety Sensitivity Index (ASI). Forty patients and 48 controls were re-scanned after a 6 weeks cognitive-behavioral treatment (CBT) or an equivalent waiting time, respectively. In the alerting condition, patients showed decreased activation in fronto-parietal pathways including the middle frontal gyrus and the superior parietal lobule (MFG, SPL). In addition, ASI scores were negatively correlated with connectivity emerging from the SPL, the SFB and the LC and going to the MFG in patients but not in healthy controls. CBT resulted in an increase in middle frontal and parietal activation along with increased connectivity going from the MFG to the SPL. This change in connectivity was positively correlated with reduction in ASI scores. There were no changes in controls. The present findings point to a pathological disintegration of the MFG in a fronto-parietal pathway in the alerting network in PD which was observed to be reversible by a successful CBT intervention.

Anti-CD52 antibody treatment depletes B cell aggregates in the central nervous system in a mouse model of multiple sclerosis.

BACKGROUND: Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS) for which several new treatment options were recently introduced. Among them is the monoclonal anti-CD52 antibody alemtuzumab that depletes mainly B cells and T cells in the immune periphery. Considering the ongoing controversy about the involvement of B cells and in particular the formation of B cell aggregates in the brains of progressive MS patients, an in-depth understanding of the effects of anti-CD52 antibody treatment on the B cell compartment in the CNS itself is desirable. METHODS: We used myelin basic protein (MBP)-proteolipid protein (PLP)-induced experimental autoimmune encephalomyelitis (EAE) in C57BL/6 (B6) mice as B cell-dependent model of MS. Mice were treated intraperitoneally either at the peak of EAE or at 60 days after onset with 200 µg murine anti-CD52 vs. IgG2a isotype control antibody for five consecutive days. Disease was subsequently monitored for 10 days. The antigen-specific B cell/antibody response was measured by ELISPOT and ELISA. Effects on CNS infiltration and B cell aggregation were determined by immunohistochemistry. Neurodegeneration was evaluated by Luxol Fast Blue, SMI-32, and Olig2/APC staining as well as by electron microscopy and phosphorylated heavy neurofilament serum ELISA. RESULTS: Treatment with anti-CD52 antibody attenuated EAE only when administered at the peak of disease. While there was no effect on the production of MP4-specific IgG, the treatment almost completely depleted CNS infiltrates and B cell aggregates even when given as late as 60 days after onset. On the ultrastructural level, we observed significantly less axonal damage in the spinal cord and cerebellum in chronic EAE after anti-CD52 treatment. CONCLUSION: Anti-CD52 treatment abrogated B cell infiltration and disrupted existing B cell aggregates in the CNS.

Cognitive Deficits and Related Brain Lesions in Patients With Chronic Heart Failure.

OBJECTIVES: This study sought to determine the spectrum of brain lesions seen in heart failure (HF) patients and the extent to which lesion type contributes to cognitive impairment. BACKGROUND: Cognitive deficits have been reported in patients with HF. METHODS: A total of 148 systolic and diastolic HF patients (mean age 64 ± 11 years; 16% female; mean left ventricular ejection fraction 43 ± 8%) were extensively evaluated within 2 days by cardiological, neurological, and neuropsychological testing and brain magnetic resonance imaging (MRI). A total of 288 healthy, sex- and age-matched subjects sampled from the Austrian Stroke Prevention Study served as MRI controls. RESULTS: Deficits in reaction times were apparent in 41% of patients and deficits in verbal memory in 46%. On brain MRI, patients showed more advanced medial temporal lobe atrophy (MTA) (Scheltens score) compared to controls (2.1 ± 0.9 vs. 1.0 ± 0.6; p < 0.001). The degree of MTA was strongly associated with the severity of cognitive impairment, whereas the extent of white matter hyperintensities was similar in patients and controls. Moreover, patients had a 2.7-fold increased risk for presence of clinically silent lacunes. CONCLUSIONS: HF patients exhibit cognitive deficits in the domains of attention and memory. MTA but not white matter lesion load seems to be related to cognitive impairment.

Influence of Thrombolysis on the Safety and Efficacy of Blocking Platelet Adhesion or Secretory Activity in Acute Ischemic Stroke in Mice.

In acute ischemic stroke (AIS), there is an alarming discrepancy between recanalization rates of up to 70% by combined recombinant tissue-type plasminogen activator (rt-PA) therapy and mechanical thrombectomy, and no clinical benefit in at least every second stroke patient. This is partly due to ischemia/reperfusion (I/R) injury. In a translational approach, we used mice lacking dense- (Unc13d-/-) or α-granules (Nbeal2-/-) and mice after blocking of platelet glycoprotein receptor (GP) Ib conferring protection from I/R injury. These mice underwent transient middle cerebral artery occlusion (tMCAO) and, as in the clinic, were treated with rt-PA. Our data show that rt-PA treatment is still safe in conjunction with selected anti-platelet therapies and pave the way for eagerly awaited additive treatment options in acute human stroke.

Stimulation of the mesencephalic locomotor region for gait recovery after stroke.

OBJECTIVE: One-third of all stroke survivors are unable to walk, even after intensive physiotherapy. Thus, other concepts to restore walking are needed. Because electrical stimulation of the mesencephalic locomotor region (MLR) is known to elicit gait movements, this area might be a promising target for restorative neurostimulation in stroke patients with gait disability. The present study aims to delineate the effect of high-frequency stimulation of the MLR (MLR-HFS) on gait impairment in a rodent stroke model. METHODS: Male Wistar rats underwent photothrombotic stroke of the right sensorimotor cortex and chronic implantation of a stimulating electrode into the right MLR. Gait was assessed using clinical scoring of the beam-walking test and video-kinematic analysis (CatWalk) at baseline and on days 3 and 4 after experimental stroke with and without MLR-HFS. RESULTS: Kinematic analysis revealed significant changes in several dynamic and static gait parameters resulting in overall reduced gait velocity. All rats exhibited major coordination deficits during the beam-walking challenge and were unable to cross the beam. Simultaneous to the onset of MLR-HFS, a significantly higher walking speed and improvements in several dynamic gait parameters were detected by the CatWalk system. Rats regained the ability to cross the beam unassisted, showing a reduced number of paw slips and misses. INTERPRETATION: MLR-HFS can improve disordered locomotor function in a rodent stroke model. It may act by shielding brainstem and spinal locomotor centers from abnormal cortical input after stroke, thus allowing for compensatory and independent action of these circuits. Ann Neurol 2017;82:828-840.

Cholinergic activity and levodopa-induced dyskinesia: a multitracer molecular imaging study.

OBJECTIVE: To investigate the association between levodopa-induced dyskinesias and striatal cholinergic activity in patients with Parkinson's disease. METHODS: This study included 13 Parkinson's disease patients with peak-of-dose levodopa-induced dyskinesias, 12 nondyskinetic patients, and 12 healthy controls. Participants underwent 5-[123I]iodo-3-[2(S)-2-azetidinylmethoxy]pyridine single-photon emission computed tomography, a marker of nicotinic acetylcholine receptors, [123I]N-ω-fluoropropyl-2ß-carbomethoxy-3ß-(4-iodophenyl)nortropane single-photon emission computed tomography, to measure dopamine reuptake transporter density and 2-[18F]fluoro-2-deoxyglucose positron emission tomography to assess regional cerebral metabolic activity. Striatal binding potentials, uptake values at basal ganglia structures, and correlations with clinical variables were analyzed. RESULTS: Density of nicotinic acetylcholine receptors in the caudate nucleus of dyskinetic subjects was similar to that of healthy controls and significantly higher to that of nondyskinetic patients, in particular, contralaterally to the clinically most affected side. INTERPRETATION: Our findings support the hypothesis that the expression of dyskinesia may be related to cholinergic neuronal excitability in a dopaminergic-depleted striatum. Cholinergic signaling would play a role in maintaining striatal dopaminergic responsiveness, possibly defining disease phenotype and progression.

Implanting Glioblastoma Spheroids into Rat Brains and Monitoring Tumor Growth by MRI Volumetry.

The outcome of patients suffering from glioblastoma multiforme (GBM) remains poor with a median survival of less than 15 months. To establish innovative therapeutical approaches or to analyze the effect of protein overexpression or protein knockdown by RNA interference in vivo, animal models are mandatory. Here, we describe the implantation of C6 glioma spheroids into the rats' brain and how to follow tumor growth by MRI scans. We show that C6 cells grown in Sprague-Dawley rats share several morphologic features of human glioblastoma like pleomorphic cells, areas of necrosis, vascular proliferation, and tumor cell invasion into the surrounding brain tissue. In addition, we describe a method for tumor volumetry utilizing the CISS 3D- or contrast-enhanced T1-weighted 3D sequence and freely available post-processing software.

Distinctive neuronal firing patterns in subterritories of the subthalamic nucleus.

OBJECTIVE: Deep brain stimulation of the subthalamic nucleus (STN-DBS) is an established treatment for Parkinson's disease (PD). Anatomical connectivity analyses and task-related physiological studies have divided the STN into different functional domains: sensorimotor, limbic, and associative - located in its dorsolateral (dSTN), anteroventral (vSTN) and medial territories, respectively. Targeting sensorimotor STN is essential for stimulation efficacy and is supported by intraoperative micro-electrode recordings. A different neuronal signature in microelectrode recordings across STN subterritories was explored in this study. METHODS: Stable recordings from 30 PD patients were assigned to dSTN or vSTN by means of an anatomical method (based on fused computed tomography/magnetic resonance images) and through a priori tri-segmented partition of the recording itself. We computed the inter-spike interval (ISI) and ISI-characteristics, mean firing rate (MFR), discharge patterns and mean burst rate (MBR) of each detected single unit activity. RESULTS: We showed a different MBR between dSTN and vSTN (1.51±0.18 vs. 1.76±0.22events/minute, Wilcoxon rank sum test, p<0.05) and a trend in the difference between their MFR (12.78 vs. 15.05Hz, Wilcoxon rank sum test, p=0.053) only with the anatomically based method. CONCLUSION: Burst firing differs across STN subterritories. SIGNIFICANCE: Different functions of subthalamic domains might be reflected by distinctive burst signalling of its subterritories.

ADORA2A genotype modulates interoceptive and exteroceptive processing in a fronto-insular network.

Facilitated processing of interoceptive and exteroceptive information in the salience network is suggested to promote the development of anxiety and anxiety disorders. Here, it was investigated whether the adenosine 2 A receptor gene (ADORA2A) 1976T/C (rs5751876) variant - previously associated with anxiety disorders and anxiety-related phenotypes as well as general attentional efficiency -was involved in the regulation of this network. In detail, fMRI recordings of 65 healthy participants (female=35) were analyzed regarding ADORA2A genotype effects on brain connectivity related to (1) interoceptive processing in terms of functional connectivity resting-state fMRI, and (2) exteroceptive processing using dynamic causal modeling in task-based fMRI. In a subsample, cardiac interoceptive accuracy was furthermore measured via the Mental Tracking Task. ADORA2A genotype was found to modulate a fronto-insular network at rest (interoceptive processing) and while performing an executive control task (exteroceptive processing). Across both modalities, the ADORA2A TT risk genotype was associated with increased connectivity between the insula and the prefrontal cortex. The strength in connectivity correlated with interoceptive accuracy. It is concluded that alterations in fronto-insular connectivity are modulated by both the adenosinergic system and interoceptive accuracy. Thus, fronto-insular connectivity in synopsis with ADORA2A genotypic information could serve as combined biomarkers for personalized treatment approaches in anxiety disorders targeting exteroceptive and interoceptive dysfunction.