Deep brain stimulation of the subthalamic nucleus restores spatial reversal learning in patients with Parkinson's disease

Spatial learning and navigation are supported by distinct memory systems in the human brain such as the hippocampus-based navigational system and the striatum-cortex-based system involved in motor sequence, habit and reversal learning. Here, we studied the role of subthalamic circuits in hippocampus-associated spatial memory and striatal-associated spatial reversal learning formation in patients with Parkinson's disease, who underwent a deep brain stimulation of the subthalamic nucleus. Deep brain stimulation patients (Parkinson's disease-subthalamic nucleus: n = 26) and healthy subjects (n = 15) were tested in a novel experimental spatial memory task based on the Morris water maze that assesses both hippocampal place memory as well as spatial reversal learning. All subjects were trained to navigate to a distinct spatial location hidden within the virtual environment during 16 learning trials in a subthalamic nucleus Stim-On condition. Patients were then randomized into two groups with either a deep brain stimulation On or Off condition. Four hours later, subjects were retested in a delayed recall and reversal learning condition. The reversal learning was realized with a new hidden location that should be memorized during six consecutive trials. The performance was measured by means of an index indicating the improvement during the reversal learning. In the delayed recall condition, neither patients, healthy subjects nor the deep brain stimulation On- versus Off groups showed a difference in place memory performance of the former trained location. In the reversal learning condition, healthy subjects (reversal index 2.0) and patients in the deep brain stimulation On condition (reversal index 1.6) showed a significant improvement. However, patients in the deep brain stimulation Off condition (reversal index 1.1) performed significantly worse and did not improve. There were no differences between all groups in a final visual guided navigation task with a visible target. These results suggest that deep brain stimulation of subthalamic nucleus restores spatial reversal learning in a virtual navigation task in patients with Parkinson's disease and gives insight into the neuromodulation effects on cognition of subthalamic circuits in Parkinson's disease.

Reduced overnight memory consolidation and associated alterations in sleep spindles and slow oscillations in early Alzheimer's disease

Spatial navigation critically underlies hippocampal-entorhinal circuit function that is early affected in Alzheimer's disease (AD). There is growing evidence that AD pathophysiology dynamically interacts with the sleep/wake cycle impairing hippocampal memory. To elucidate sleep-dependent consolidation in a cohort of symptomatic AD patients (n = 12, 71.25 ± 2.16 years), we tested hippocampal place learning by means of a virtual reality task and verbal memory by a word-pair association task before and after a night of sleep. Our results show an impaired overnight memory retention in AD compared with controls in the verbal task, together with a significant reduction of sleep spindle activity (i.e., lower amplitude of fast sleep spindles, p = 0.016) and increased duration of the slow oscillation (SO; p = 0.019). Higher spindle density, faster down-to-upstate transitions within SOs, and the time delay between SOs and nested spindles predicted better memory performance in healthy controls but not in AD patients. Our results show that mnemonic processing and memory consolidation in AD is slightly impaired as reflected by dysfunctional oscillatory dynamics and spindle-SO coupling during NonREM sleep. In this translational study based on experimental paradigms in animals and extending previous work in healthy aging and preclinical disease stages, our results in symptomatic AD further deepen the understanding of the memory decline within a bidirectional relationship of sleep and AD pathology.

Transcranial direct current stimulation of the right temporoparietal junction facilitates hippocampal spatial learning in Alzheimer's disease and mild cognitive impairment

OBJECTIVE

Spatial memory deficits are an early symptom in Alzheimer's disease (AD), reflecting the neurodegenerative processes in the neuronal navigation network such as in hippocampal and parietal cortical areas. As no effective treatment options are available, neuromodulatory interventions are increasingly evaluated. Against this backdrop, we investigated the neuromodulatory effect of anodal transcranial direct current stimulation (tDCS) on hippocampal place learning in patients with AD or mild cognitive impairment (MCI).

METHODS

In this randomized, double-blind, sham-controlled study with a cross-over design anodal tDCS of the right temporoparietal junction (2 mA for 20 min) was applied to 20 patients diagnosed with AD or MCI and in 22 healthy controls while they performed a virtual navigation paradigm testing hippocampal place learning.

RESULTS

We show an improved recall performance of hippocampal place learning after anodal tDCS in the patient group compared to sham stimulation but not in the control group.

CONCLUSIONS

These results suggest that tDCS can facilitate spatial memory consolidation via stimulating the parietal-hippocampal navigation network in AD and MCI patients.

SIGNIFICANCE

Our findings suggest that tDCS of the temporoparietal junction may restore spatial navigation and memory deficits in patients with AD and MCI.

Grey matter correlates of dystonic soft signs in essential tremor

BACKGROUND

Questionable signs of dystonia are a common finding in patients with essential tremor (ET). Brain structural alterations in ET patients plus dystonic soft signs (ET + ds) in comparison to ET patients without dystonic soft signs (ET-ds) or patients with tremor associated with manifest dystonia (TAWD) have not been examined yet. Therefore, our study aims to explore alterations of brain grey matter in patients with ET + ds.

METHODS

A total of 68 elderly patients with ET-ds (n = 32), ET + ds (n = 20) or idiopathic cervical dystonia with dystonia associated action tremor of the upper limbs (TAWD, n = 16) and 42 age-matched healthy controls underwent a clinical and electrophysiological assessment and 3T MRI. For grey matter alterations T1 MRI images were analysed by voxel-based morphometry. Additionally, regression analyses with clinical parameters (tremor frequency, severity and disease duration) were performed.

RESULTS

VBM showed a significant increase of grey matter in the right lentiform nucleus in ET + ds and TAWD compared to HC and ET-ds. Further, an increase of cortical grey matter in the middle frontal gyrus in ET + ds was shown. The hypertrophy of the lentiform nucleus in ET + ds was correlated with disease severity and duration.

CONCLUSION

Patients with ET + ds showed grey matter brain structural alterations similar to TAWD. Our findings suggest an involvement of the basal ganglia-cortical loop in ET + ds which may indicate a pathophysiological similarity with TAWD rather than ET.

Three-Dimensional Mesh Recovery from Common 2-Dimensional Pictures for Automated Assessment of Body Posture in Camptocormia

Background

Three-dimensional (3D) human body estimation from common photographs is an evolving method in the field of computer vision. It has not yet been evaluated on postural disorders. We generated 3D models from 2-dimensional pictures of camptocormia patients to measure the bending angle of the trunk according to recommendations in the literature.

Methods

We used the Part Attention Regressor algorithm to generate 3D models from photographs of camptocormia patients' posture and validated the resulting angles against the gold standard. A total of 2 virtual human models with camptocormia were generated to evaluate the performance depending on the camera angle.

Results

The bending angle assessment using the 3D mesh correlated highly with the gold standard (R = 0.97, P < 0.05) and is robust to deviations of the camera angle.

Conclusions

The generation of 3D models offers a new method for assessing postural disorders. It is automated and robust to nonperfect pictures, and the result offers a comprehensive analysis beyond the bending angle.

Neural Correlates of Executed Compared to Imagined Writing and Drawing Movements: A Functional Magnetic Resonance Imaging Study

Objective

In this study we used functional magnetic resonance imaging (fMRI) to investigate whether motor imagery (MI) of handwriting and circle drawing activates a similar handwriting network as writing and drawing itself.

Methods

Eighteen healthy right-handed participants wrote the German word “Wellen” and drew continuously circles in a sitting (vertical position) and lying position (horizontal position) to capture kinematic handwriting parameters such as velocity, pressure and regularity of hand movements. Afterward, they performed the same tasks during fMRI in a MI and an executed condition.

Results

The kinematic analysis revealed a general correlation of handwriting parameters during sitting and lying except of pen pressure during drawing. Writing compared to imagined writing was accompanied by an increased activity of the ipsilateral cerebellum and the contralateral sensorimotor cortex. Executed compared to imagined drawing revealed elevated activity of a fronto–parieto-temporal network. By contrasting writing and drawing directly, executed writing induced an enhanced activation of the left somatosensory and premotor area. The comparison of the MI of these tasks revealed a higher involvement of occipital activation during imagined writing.

Conclusion

The kinematic results pointed to a high comparability of writing in a vertical and horizontal position. Overall, we observed highly overlapping cortical activity except of a higher involvement of motor control areas during motor execution. The sparse difference between writing and drawing can be explained by highly automatized writing in healthy individuals.

The Contribution of Subthalamic Nucleus Deep Brain Stimulation to the Improvement in Motor Functions and Quality of Life

BACKGROUND

Subthalamic nucleus deep brain stimulation (STN-DBS) effectively treats motor symptoms and quality of life (QoL) of advanced and fluctuating early Parkinson's disease. Little is known about the relation between electrode position and changes in symptom control and ultimately QoL.

OBJECTIVES

The relation between the stimulated part of the STN and clinical outcomes, including the motor score of the Unified Parkinson's Disease Rating Scale (UPDRS) and the quality-of-life questionnaire, was assessed in a subcohort of the EARLYSTIM study.

METHODS

Sixty-nine patients from the EARLYSTIM cohort who underwent DBS, with a comprehensive clinical characterization before and 24 months after surgery, were included. Intercorrelations of clinical outcome changes, correlation between the affected functional parts of the STN, and changes in clinical outcomes were investigated. We further calculated sweet spots for different clinical parameters.

RESULTS

Improvements in the UPDRS III and Parkinson's Disease Questionnaire (PDQ-39) correlated positively with the extent of the overlap with the sensorimotor STN. The sweet spots for the UPDRS III (x = 11.6, y = -13.1, z = -6.3) and the PDQ-39 differed (x = 14.8, y = -12.4, z = -4.3) ~3.8 mm.

CONCLUSIONS

The main influence of DBS on QoL is likely mediated through the sensory-motor basal ganglia loop. The PDQ sweet spot is located in a posteroventral spatial location in the STN territory. For aspects of QoL, however, there was also evidence of improvement through stimulation of the other STN subnuclei. More research is necessary to customize the DBS target to individual symptoms of each patient. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Transcranial Sonography Findings in Alzheimer's Disease: A New Imaging Biomarker

OBJECTIVE

 To validate transcranial sonography (TCS) as a novel imaging tool for the assessment of medial temporal lobe (MTL) atrophy (MTA).

MATERIALS AND METHODS

 Participants with Alzheimer's disease (AD, n = 30) and age-sex-matched controls (n = 30) underwent TCS and MRI. On TCS, MTL structures (choroidal fissure (CF) and temporal horn (TH)) were measured and combined to create an MTA score in sonography (MTA-S). Furthermore, both THs and the third ventricle were combined to form the ventricle enlargement score in sonography (VES-S). On MRI, the MTL was evaluated by linear measurements, MTA scale and hippocampal volumetry. Validation was performed by comparing imaging methods and the patient group.

RESULTS

 Intraclass correlations for CF and TH showed substantial intra/inter-rater reliability (> 0.80). TCS and MRI showed strong to moderate correlation regarding TH (right = 0.88, left = 0.89) and CF (right = 0.70, left = 0.47). MTA-S correlated significantly with the hippocampal volume (right = -0.51, left = -0.47), predicted group membership in logistic regression (Exp(B) right = 3.0, left = 2.7), and could separate AD patients from controls (AUC = 0.93). An MTA-S of 6 mm and 10 mm discriminated MRI MTA scores 0-1 (from 2-4) and MTA score 4 (from 0-3) with 100 % specificity, respectively. VES-S also showed a moderate correlation with the hippocampal volume (r = -0.66) and could differentiate AD patients from controls (AUC = 0.93).

CONCLUSION

 Our results suggest that TCS may be an alternative imaging tool for the assessment of MTL atrophy and ventricular enlargement for patients in whom MRI scanning is not possible. Additionally, TCS offers a practical, patient-friendly and inexpensive option for the screening and follow-up of individuals with AD.

Effects of exergaming on hippocampal volume and brain-derived neurotrophic factor levels in Parkinson's disease

BACKGROUND AND OBJECTIVE

Cognitive impairment is among the most burdensome non-motor symptoms in Parkinson's disease (PD) and has been associated with hippocampal atrophy. Exercise has been reported to enhance neuroplasticity in the hippocampus in correlation with an improvement of cognitive function. We present data from the Training-PD study, which was designed to evaluate effects of an "" training protocol on neuronal plasticity in PD.

METHODS

We initiated a 6-week exergaming training program, combining visually stimulating computer games with physical exercise in 17 PD patients and 18 matched healthy controls. Volumetric segmentation of hippocampal subfields on T1- and T2-weighted magnetic resonance imaging and brain-derived neurotrophic factor (BDNF) serum levels were analyzed before and after the training protocol.

RESULTS

The PD group showed a group-dependent significant volume increase of the left hippocampal subfields CA1, CA4/dentate gyrus (DG) and subiculum after the 6-week training protocol. The effect was most pronounced in the left DG of PD patients, who showed a significantly smaller percentage volume compared to healthy controls at baseline, but not at follow-up. Both groups had a significant increase in serum BDNF levels after training.

CONCLUSIONS

The results of the present study indicate that exergaming might be a suitable approach to induce hippocampal volume changes in PD patients. Further and larger studies are needed to verify our findings.

Never too little: Grip and lift forces following probabilistic weight cues in patients with writer's cramp

OBJECTIVE

Planning of voluntary object-related movements requires the estimation of the most probable object properties. We investigated how 14 writer's cramp (WC) patients compared to 14 controls use probabilistic weight cues in a serial grip-lift task.

METHODS

In every grip-lift trial, an object of either light, medium or heavy weight had to be grasped and lifted after a visual cue gave a probabilistic prediction of the object weights (e.g. 32.5% light, 67.5% medium, 0 % heavy). We determined peak (1) grip force GF, (2) load force LF, (3) grip force rate GFR, (4) load force rate LFR, while we registered brain activity with functional magnetic resonance imaging.

RESULTS

In both groups, GFR, LFR and GF increased when a higher probability of heavy weights was announced. When a higher probability of light weights was indicated, controls reduced GFR, LFR and GF, while WC patients did not downscale their forces. There were no inter-group differences in blood oxygenation level dependent activation.

CONCLUSIONS

WC patients could not utilize the decision range in motor planning and adjust their force in a probabilistic cued fine motor task.

SIGNIFICANCE

The results support the pathophysiological model of a hyperfunctional dopamine dependent direct basal ganglia pathway in WC.

Increased functional connectivity in a population at risk of developing Parkinson's disease

BACKGROUND

While the concept of prodromal Parkinson's disease (PD) is well established, reliable markers for the diagnosis of this disease stage are still lacking. We investigated the functional connectivity of the putamina in a resting-state functional MRI analysis in persons with at least two prodromal factors for PD, which is considered a high risk for PD (HRPD) group, in comparison to PD patients and controls.

METHODS

We included 16 PD patients, 20 healthy controls and 20 HRPD subjects. Resting state echo planar images and anatomical T1-weighted images were acquired with a Siemens Prisma 3 T scanner. The computation of correlation maps of the left and the right putamen to the rest of the brain was done in a voxel-wise approach using the REST toolbox. Finally, group differences in the correlation maps were compared on voxel-level and summarized in cluster z-statistics.

RESULTS

Compared to both PD patients and healthy controls, the HRPD group showed higher functional connectivity of both putamina to brain regions involved in execution of motion and coordination (cerebellum, vermis, pre- and postcentral gyrus, supplementary motor area) as well as the planning of movement (precuneus, cuneus, superior medial frontal lobe).

CONCLUSIONS

Higher functional connectivity of the putamina of HRPD subjects to other brain regions involved in motor execution and planning may indicate a compensatory mechanism. Follow-up evaluation and independent longitudinal studies should test whether our results reflect a dynamic process associated with a prodromal PD state.

Abnormal effective connectivity in the sensory network in writer's cramp

BACKGROUND

Writer's cramp (WC), a task specific form of dystonia, is considered to be a motor network disorder, but abnormal sensory tactile processing has also been acknowledged. The sensory spatial discrimination threshold (SDT) can be determined with a spatial acuity test (JVP domes). In addition to increased SDT, patients with WC exhibited dysfunctional sensory processing in the sensory cortex, insula, basal ganglia and cerebellum in a functional magnetic resonance imaging (fMRI) study while performing the spatial acuity test.

OBJECTIVES

To assess whether effective connectivity (EC) in the sensory network including cortical, basal ganglia, thalamic and cerebellar regions of interest in WC patients is abnormal.

METHODS

We used fMRI and applied a block design, while 19 WC patients and 13 age-matched healthy controls performed a spatial discrimination task. Before we assessed EC using dynamic causal modelling, we compared three model structures based on the current literature. We enclosed regions of interest that are established for sensory processing during right hand stimulation: Left thalamus, somatosensory, parietal and insular cortex, posterior putamen, and right cerebellum.

RESULTS

The EC analysis revealed task-dependent decreased unidirectional connectivity between the insula and the posterior putamen. The connectivity involving the primary sensory cortex, parietal cortex and cerebellum were not abnormal in WC. The two groups showed no differences in their behavioural data.

CONCLUSIONS

Perception and integration of sensory information requires the exchange of information between the insula cortex and the putamen, a sensory process that was disturbed in WC patients.

White Matter Hyperintensities Are Associated With Severity of Essential Tremor in the Elderly

Background: Essential tremor (ET) occurs with steeply increasing prevalence in the elderly, and apart from disease duration, age is independently associated with an increase of tremor amplitude and a decrease of frequency. White matter hyperintensities (WMHs) are a common finding in the elderly, and their role in the pathophysiology of ET is unknown. The aims of this study were to examine whether ET patients differ in their total or region-specific WMH volumes from healthy controls and to determine the impact of WMH on tremor characteristics. Methods: A total of 47 elderly ET patients with a mean age of 72 years and 39 age-matched healthy controls underwent a thorough clinical assessment and 3T MRI. Total WMH volumes were derived from T2-weighted fluid-attenuated inversion recovery (FLAIR) MR images. Additionally, region of interest-based WMH volumes for the Johns Hopkins University (JHU) white matter tracts and labels were calculated, and WMHs were assessed semiquantitatively using the Fazekas scale. Results: Essential tremor patients and healthy controls did not differ in their total or tract-specific WMH volumes or Fazekas scores. However, WMH volume was significantly positively correlated with tremor severity on the TETRAS scale, and there was a significant negative correlation with the mean accelerometric tremor frequency. In a multiple linear regression model including disease duration, age, and age-adjusted total WMH volume, only the WMH volume significantly predicted tremor severity, while age and disease duration were not significant. Conclusion: We found evidence for a direct association between WMH volume and tremor severity. If confirmed by larger studies, our findings could explain the well-known relation between age and tremor severity.

Association of Hippocampal Subfields, CSF Biomarkers, and Cognition in Patients With Parkinson Disease Without Dementia

OBJECTIVE

To examine whether hippocampal volume loss is primarily associated with cognitive status or pathologic β-amyloid 1-42 (Aβ42) levels, this study compared hippocampal subfield volumes between patients with Parkinson disease (PD) with mild cognitive impairment (PD-MCI) and without cognitive impairment (PD-CN) and between patients with low and high Aβ42 levels, in addition exploring the relationship among hippocampal subfield volumes, CSF biomarkers (Aβ42, phosphorylated and total tau), neuropsychological tests, and activities of daily living.

METHODS

Forty-five patients with PD without dementia underwent CSF analyses and MRI as well as comprehensive motor and neuropsychological examinations. Hippocampal segmentation was conducted using FreeSurfer image analysis suite 6.0. Regression models were used to compare hippocampal subfield volumes between groups, and partial correlations defined the association between variables while controlling for intracranial volume (ICV).

RESULTS

Linear regressions revealed cognitive group as a statistically significant predictor of both the hippocampal-amygdaloid transition area (HATA; β = -0.23, 95% CI -0.44 to -0.02) and the cornu ammonis 1 region (CA1; β = -0.28, 95% confidence interval [CI] -0.56 to -0.02), independent of disease duration and ICV, with patients with PD-MCI showing significantly smaller volumes than PD-CN. In contrast, no subfields were predicted by Aβ42 levels. Smaller hippocampal volumes were associated with worse performance on memory, language, spatial working memory, and executive functioning tests. The subiculum was negatively correlated with total tau levels (r = -0.37, 95% CI -0.60 to -0.09).

CONCLUSION

Cognitive status, but not CSF Aβ42, predicted hippocampal volumes, specifically the CA1 and HATA. Hippocampal subfields were associated with various cognitive domains, as well as with tau pathology.

Motor, cognitive and mobility deficits in 1000 geriatric patients: protocol of a quantitative observational study before and after routine clinical geriatric treatment - the ComOn-study

BACKGROUND

Motor and cognitive deficits and consequently mobility problems are common in geriatric patients. The currently available methods for diagnosis and for the evaluation of treatment in this vulnerable cohort are limited. The aims of the ComOn (COgnitive and Motor interactions in the Older populatioN) study are (i) to define quantitative markers with clinical relevance for motor and cognitive deficits, (ii) to investigate the interaction between both motor and cognitive deficits and (iii) to assess health status as well as treatment outcome of 1000 geriatric inpatients in hospitals of Kiel (Germany), Brescia (Italy), Porto (Portugal), Curitiba (Brazil) and Bochum (Germany).

METHODS

This is a prospective, explorative observational multi-center study. In addition to the comprehensive geriatric assessment, quantitative measures of reduced mobility and motor and cognitive deficits are performed before and after a two week's inpatient stay. Components of the assessment are mobile technology-based assessments of gait, balance and transfer performance, neuropsychological tests, frailty, sarcopenia, autonomic dysfunction and sensation, and questionnaires to assess behavioral deficits, activities of daily living, quality of life, fear of falling and dysphagia. Structural MRI and an unsupervised 24/7 home assessment of mobility are performed in a subgroup of participants. The study will also investigate the minimal clinically relevant change of the investigated parameters.

DISCUSSION

This study will help form a better understanding of symptoms and their complex interactions and treatment effects in a large geriatric cohort.

Quantitative assessment of posture in healthy controls and patients with Parkinson's disease

INTRODUCTION

A stooped posture is a main clinical feature of Parkinson's disease (PD). The assessment of posture is important to measure treatment effects. The aim of this study was to investigate the reliability of a standardized postural rating tool, to calculate minimal detectable change scores and to assess the role of gender and age.

METHODS

Two independent raters assessed total camptocormia (TCC), upper camptocormia (UCC) and Pisa angles of 192 PD patients and 78 healthy controls (HC) with the free NeuroPostureApp©(http://www.neuroimaging.uni-kiel.de/NeuroPostureApp). Reliabilities and linear models were calculated for different effects. Three subgroups were defined based on two thresholds (mean+2SD of HC and PD): A) normal, B) presumed stooped/lateral bended posture and C) postural disorder.

RESULTS

Intraclass correlation coefficients ranged between 0.71 and 0.95 for the interrater and test-retest reliability of the three angles. The minimal detectable change values in the PD patients were 3.7°, 6.7° and 2.1° for the TCC, UCC and Pisa angles, respectively. Men had a more stooped posture than women (p < 0.05). Patients with PD had a worse posture than HC (p < 0.001) in all three angles. For the TCC angle, 39.1% of the patients had a normal posture (<17.4°), 47.9% a presumed stooped posture (>17.4°, <30.2°) and 6.3° had camptocormia (>30.2°).

CONCLUSIONS

The NeuroPostureApp© is reliable. Our results confirmed gender differences and the progression of postural deviation in PD patients with age and empirically support the ≥30° TCC angle as a defining criterium for camptocormia. Diagnostic criteria for UCC and Pisa syndrome should be further explored in future studies.

The Effect of Medication and Deep Brain Stimulation on Posture in Parkinson's Disease

Introduction: Postural abnormalities are common in Parkinson's disease (PD) and increasing with disease progression. While many studies focus on balance and gait, postural alignment is only infrequently studied.

Purpose: The aim of the present study was to examine the immediate and long-term effects of medication and deep brain stimulation (DBS) in the subthalamic nucleus on postural alignment in PD.

Materials and Methods: PD patients (n = 192) in an advanced stage of disease were videotaped during a standardized l-dopa trial before and after DBS. The patients were tested with and without medication pre-surgical and retested post-surgical (6–24 months) in all treatment combinations of medication and DBS regarding the on and off conditions. The forward bending as total camptocormia (TCC) and upper camptocormia (UCC) angles and lateral bending as Pisa angle were assessed with the free downloadable NeuroPostureApp (http://www.neuroimaging.uni-kiel.de/NeuroPostureApp/). Three subgroups were defined according to normative values of healthy controls and according to clinical criteria: patients with normal posture, with stooped posture, and with postural disorders.

Results: A stooped posture was found in 82% of the patients with regard to the TCC angle and in 54% for the UCC angle. Sixty-two percent had an abnormal Pisa angle. Camptocormia was diagnosed in ~7% and a Pisa syndrome in 1% of the patients. Medication and DBS both significantly improved postural alignment in the entire cohort. Female and male patients benefit similarly by medication and stimulation. Subgroup analyses revealed that the effects were also significant for patients with stooped posture, and the effects were strongest for patients with camptocormia: they led to angles below the diagnostical criterion for camptocormia for 13 of 14 patients with TCC and 11 of 26 patients with UCC. DBS had an additional effect to medication over time for the Pisa angle.

Conclusion: Medication and DBS both improved postural alignment in PD patients, but effects were small for the entire cohort. Patients with camptocormia according to the TCC angle benefit strongest. The large differences of the treatment effects may indicate distinct pathological mechanisms for stooped posture and postural disorders. The TCC angle was shown to be sensitive to change. The UCC angle was less sensitive but may be a useful assessment tool for a subgroup.

Neuroimaging Of Cold Allodynia Reveals A Central Disinhibition Mechanism Of Pain

Purpose

Allodynia refers to pain evoked by physiologically innocuous stimuli. It is a disabling symptom of neuropathic pain following a lesion within the peripheral or central nervous system. In fact, two different pathophysiological mechanisms of cold allodynia (ie, hypersensitivity to innocuous cold) have been proposed. The peripheral sensitization of nociceptive neurons can produce cold allodynia, which can be induced experimentally by a topical application of menthol. An alternative mechanism involves reduced inhibition of central pain processing by innocuous cold stimuli. A model to induce the latter type of allodynia is the conduction block of peripheral A-fiber input.

Patients and methods

In the presented study, functional MRI was used to analyze these two different experimental models of cold allodynia. In order to identify the underlying cerebral activation patterns of both mechanisms, the application of menthol and the induction of a mechanical A-fiber blockade were studied in healthy volunteers.

Results

The block-induced cold allodynia caused significantly stronger activation of the medial polymodal pain processing pathway, including left medial thalamus, anterior cingulate cortex, and medial prefrontal cortex. In contrast, menthol-induced cold allodynia caused significantly stronger activity of the left lateral thalamus as well as the primary and secondary somatosensory cortices, key structures of the lateral discriminative pathway of pain processing. Mean pain intensity did not differ between both forms of cold allodynia.

Conclusion

Experimental cold allodynia is mediated in different cerebral areas depending on the underlying pathophysiology. The activity pattern associated with block-induced allodynia confirms a fundamental integration between painful and non-painful temperature sensation, ie, the cold-induced inhibition of cold pain.

Hippocampal Dentate Gyrus Atrophy Predicts Pattern Separation Impairment in Patients with LGI1 Encephalitis

Day-to-day life involves the perception of events that resemble one another. For the sufficient encoding and correct retrieval of similar information, the hippocampus provides two essential cognitive processes. Pattern separation refers to the differentiation of similar input information, whereas pattern completion reactivates memory representations based on noisy or degraded stimuli. It has been shown that pattern separation specifically relies on the hippocampal dentate gyrus (DG), whereas pattern completion is performed within CA3 networks. Lesions to these hippocampal networks emerging in the course of neurological disorders may thus affect both processes. In anti-leucine-rich, glioma-inactivated 1 (LGI1) encephalitis it has been shown in animal models and human imaging studies that hippocampal DG and CA3 are preferentially involved in the pathophysiology process. Thus, in order to elucidate the structure-function relationship and contribution of hippocampal subfields to pattern separation, we examined patients (n = 15, age range: 36-77 years) with the rare LGI1 encephalitis showing lesions to hippocampal subfields. Patients were tested 3.53 ± 0.65 years after the acute phase of the disease. Structural sequelae were determined by hippocampal subfield volumetry for the DG, CA1, and CA2/3. Patients showed an overall memory deficit including a significant reduction in pattern separation performance (p = 0.016). In volumetry, we found a global hippocampal volume reduction. The deficits in pattern separation performance were best predicted by the DG (p = 0.029), whereas CA1 was highly predictive of recognition memory deficits (p < 0.001). These results corroborate the framework of a regional specialization of hippocampal functions involved in cognitive processing.

White Matter Changes Along the Electrode Lead in Patients Treated With Deep Brain Stimulation

Introduction: Deep brain stimulation (DBS) is an established treatment for various movement disorders. There is little data available about the potential damage to brain parenchyma through DBS treatment. The objective of this study was to investigate the occurrence of signal changes on magnetic resonance imaging (MRI) in patients treated with DBS.

Methods: We retrospectively analyzed MRI scans of 30 DBS patients (21 patients with Parkinson's disease, 3 patients with dystonia and 6 patients with tremor) that had undergone additional MRI scans after DBS surgery (ranging from 2 months to 8 years). Axial T2 sequences were analyzed by two raters using a standardized lesion mapping procedure.

Results: 26 out of 30 analyzed patients showed hyperintense white matter changes surrounding the DBS lead (mean volume = 2.43 ml). Lesions were prominent along the upper half of the electrode lead within the subcortical white matter, with no abnormalities along the lower lead. Their volume was significantly correlated to the time from surgery to MRI and to the number of microelectrodes used in surgery, but was independent from underlying disease (Parkinson's disease, dystonia, tremor), target structure (STN, GPi, VIM), demographical data, or cardiovascular risk factors.

Discussion: White matter changes along the electrode leads in DBS patients are a frequent finding. These changes seem to evolve with certain latency after surgery and might be radiologically classified as a gliosis. Our findings identify the number of intraoperatively used microelectrodes as a risk factor in the formation of gliosis. Therefore, mechanical damage at the time of surgery and an individual tissue response might contribute to their evolution. Further studies are needed to define the exact mechanisms and their clinical impact.

Neural Correlates of Hypokinetic Dysarthria and Mechanisms of Effective Voice Treatment in Parkinson Disease

Background. Hypokinetic dysarthria is highly prevalent in idiopathic Parkinson disease (PD), and effectiveness of high-intensity voice treatment is well established. However, the neural correlates remain largely unknown. Objective. We aimed to specify cerebral pathophysiology of hypokinetic dysarthria and treatment-induced changes using functional magnetic resonance imaging (fMRI). Methods. We used fMRI to investigate healthy controls (HCs) and patients with idiopathic PD–associated dysarthria before and after treatment according to the Lee Silverman Voice Treatment LOUD (LSVT). During fMRI, participants covertly read sentences with normal (eg, conversation in a quiet room) or high (eg, shouting on a windy beach) intensity. In addition, we tested LSVT effects on intelligibility and different speech features (intensity, pitch, articulation). Results. LSVT effectively improved intelligibility, articulation, and pitch in patients. Covert high-intensity speech compared with covert normal-intensity speech led to increased activation of mainly secondary motor areas and bilateral superior and medial temporal regions. Prior to LSVT, patients showed less activity in several speech-associated areas compared with HCs. As a neural correlate of effective LSVT, increased right-sided superior temporal activity correlated with improved intelligibility. Conclusion. This is the first brain imaging study using a covert speech paradigm in PD, which revealed cortical hypoactivation as correlate of hypokinetic dysarthria. Furthermore, cortical correlates of effective LSVT treatment colocalized with the neuronal network, showing increased activation during high- versus normal-intensity speech generation.

Contribution of structural brain phenotypes to the variance in resting energy expenditure in healthy Caucasian subjects

Brain gray (GM) and white matter (WM) volumes are related to weight changes. The impact of structural variations in GM and WM on the variance in resting energy expenditure (REE) and the REE-on-fat-free mass (FFM) association is unknown. The aim of this study was to address this in healthy Caucasian subjects. Cross-sectional data analysis of 493 healthy Caucasian subjects (age range 6–80 years; 3 age groups) was conducted with comprehensive information on FFM, organ and tissue masses, and detailed brain composition as assessed by whole body magnetic resonance imaging and REE (assessed by indirect calorimetry). REE was calculated (REEc) using organ and tissue masses times their specific metabolic rates. FFM was the major determinant of REE (70.6%); individual masses of liver, total brain, and heart explained a further 2.1% of the variance in REE. Replacing total brain with GM and WM did not change the total R2. Nevertheless, GM added more to the variance in REE (5.6%) and corresponding residuals (12.5%) than did total brain. Additionally, up to 12% was explained by age and sex (<2%). There was a systematic bias between REE and REEc with positive values in younger subjects but negative values in older ones. This bias remained after substituting the specific metabolic rate of brain with the specific metabolic rates of GM and WM. In healthy Caucasian subjects, GM and WM contributed to the variance in REE. Detailed brain structures do not explain the bias between REE and REEc.

NEW & NOTEWORTHY Detailed brain composition (gray and white matter) contributed to the variances of resting energy expenditure (REE) and REE-on-fat-free mass residuals. Gray matter explained most of the variances, and for future studies on energy expenditure, brain compartments should be analyzed separately with regard to their different energy needs.

Decoding Pedophilia: Increased Anterior Insula Response to Infant Animal Pictures

Previous research found increased brain responses of men with sexual interest in children (i.e., pedophiles) not only to pictures of naked children but also to pictures of child faces. This opens the possibly that pedophilia is linked (in addition to or instead of an aberrant sexual system) to an over-active nurturing system. To test this hypothesis we exposed pedophiles and healthy controls to pictures of infant and adult animals during functional magnetic resonance imaging of the brain. By using pictures of infant animals (instead of human infants), we aimed to elicit nurturing processing without triggering sexual processing. We hypothesized that elevated brain responses to nurturing stimuli will be found - in addition to other brain areas - in the anterior insula of pedophiles because this area was repeatedly found to be activated when adults see pictures of babies. Behavioral ratings confirmed that pictures of infant or adult animals were not perceived as sexually arousing neither by the pedophilic participants nor by the heathy controls. Statistical analysis was applied to the whole brain as well as to the anterior insula as region of interest. Only in pedophiles did infants relative to adult animals increase brain activity in the anterior insula, supplementary motor cortex, and dorsolateral prefrontal areas. Within-group analysis revealed an increased brain response to infant animals in the left anterior insular cortex of the pedophilic participants. Currently, pedophilia is considered the consequence of disturbed sexual or executive brain processing, but details are far from known. The present findings raise the question whether there is also an over-responsive nurturing system in pedophilia.

Network effects and pathways in Deep brain stimulation in Parkinson's disease

Deep brain stimulation of subthalamic nucleus (STN-DBS) became a standard therapeutic option in Parkinson's disease (PD), even though the underlying modulated network of STN-DBS is still poorly described. Probabilistic tractography and connectivity analysis as derived from diffusion tensor imaging (DTI) were performed together with modelling of implanted electrode positions and linked postoperative clinical outcome. Fifteen patients with idiopathic PD without dementia were selected for DBS treatment. After pre-processing, probabilistic tractography was run from cortical and subcortical seeds of the hypothesized network to targets represented by the positions of the active DBS contacts. The performed analysis showed that the projections of the stimulation site to supplementary motor area (SMA) and primary motor cortex (M1) are mainly involved in the network effects of STN-DBS. An involvement of the "hyperdirected pathway" and a clear delimitation of the cortico-spinal tract were demonstrated. This study shows the effects of STN-DBS in PD distinctly rely on the network connections of the stimulated region to M1 and SMA, motor and premotor regions.

Topography of essential tremor

INTRODUCTION

Topography of tremor manifestations is poorly investigated in essential tremor. The present study explores the prevalence and clinical correlates of head and/or voice tremor in essential tremor.

METHODS

Out of a prospectively designed registry of 972 patients, 884 patients with definite and probable essential tremor had complete information on tremor localization. Demographic and clinical characteristics were compared among four subgroups: group A (without head or voice tremor, n = 619), B (with head but without voice tremor, n = 155), C (with voice but without head tremor, n = 47), and D (with both head and voice tremor, n = 63).

RESULTS

In our patients, total prevalence of tremor was 24.7% for head, 12.4% for voice and 7.1% for the combination of head and voice. Logistic regression analyses showed that female gender is strongly associated with head tremor, which was confirmed by an additional meta-analysis. Severe hand tremor was the only factor associated with voice tremor. Both female gender and severe hand tremor increase the odds for having the combination of head and voice tremor. For males, hand tremor severity is significantly increased among those with head and voice tremor alone and in combination, but for females only for the combination. Patients with both head and voice tremor have more frequent involvement of legs and other localizations and are less responsive to β-blockers.

CONCLUSIONS

Female gender and severe hand tremor may increase the odds of head and/or voice tremor in essential tremor. The association of hand tremor severity with midline tremor is stronger for males than females.

Assessing paedophilia based on the haemodynamic brain response to face images

OBJECTIVES

Objective assessment of sexual preferences may be of relevance in the treatment and prognosis of child sexual offenders. Previous research has indicated that this can be achieved by pattern classification of brain responses to sexual child and adult images. Our recent research showed that human face processing is tuned to sexual age preferences. This observation prompted us to test whether paedophilia can be inferred based on the haemodynamic brain responses to adult and child faces.

METHODS

Twenty-four men sexually attracted to prepubescent boys or girls (paedophiles) and 32 men sexually attracted to men or women (teleiophiles) were exposed to images of child and adult, male and female faces during a functional magnetic resonance imaging (fMRI) session.

RESULTS

A cross-validated, automatic pattern classification algorithm of brain responses to facial stimuli yielded four misclassified participants (three false positives), corresponding to a specificity of 91% and a sensitivity of 95%.

CONCLUSIONS

These results indicate that the functional response to facial stimuli can be reliably used for fMRI-based classification of paedophilia, bypassing the problem of showing child sexual stimuli to paedophiles.

Clinical Definition of Camptocormia in Parkinson's Disease

Background

Clinical key aspects of camptocormia in patients with idiopathic Parkinson's disease (PD) await further definition.

Methods

Based on a self-assessment of PD patients, we performed an observational study, asking patients with subjectively felt involuntary forward bending to return a questionnaire and provide photographs showing their axial disorder. Forty-two matched PD patients without subjective signs of camptocormia were recruited as controls.

Results

The stooped posture of patients with advanced PD without camptocormia is characterized by a forward bending angle of always less than 30 degrees. Of the 145 camptocormia patients in our study, 70% had an angle ≥30 degrees. The patients with a more-severe forward bending angle were more severely affected in daily life than those with an angle of less than 30 degrees. Back pain was more frequent (81% vs. 43%) and more severe in PD patients with camptocormia than in controls. Back diseases in camptocormia PD patients were also significantly more frequent than in the PD control patients (55% vs. 26%). Camptocormia is a relevant burden in everyday life. Seventy-seven percent of patients needed walking aids and 85% reported specific disabilities attributed to camptocormia (e.g. increased risk of falling, dyspnea, problems in eating or swallowing).

Conclusions

Camptocormia cannot be clinically defined based on the forward bending angle alone, but an angle larger than 30 degrees is only found in camptocormia. Back pain is an essential aspect of camptocormia in PD. Back diseases can be seen as a risk factor in these patients.

Altered brain activation in a reversal learning task unmasks adaptive changes in cognitive control in writer's cramp

Previous receptor binding studies suggest dopamine function is altered in the basal ganglia circuitry in task-specific dystonia, a condition characterized by contraction of agonist and antagonist muscles while performing specific tasks. Dopamine plays a role in reward-based learning. Using fMRI, this study compared 31 right-handed writer's cramp patients to 35 controls in reward-based learning of a probabilistic reversal-learning task. All subjects chose between two stimuli and indicated their response with their left or right index finger. One stimulus response was rewarded 80%, the other 20%. After contingencies reversal, the second stimulus response was rewarded in 80%. We further linked the DRD2/ANKK1-TaqIa polymorphism, which is associated with 30% reduction of the striatal dopamine receptor density with reward-based learning and assumed impaired reversal learning in A + subjects. Feedback learning in patients was normal. Blood-oxygen level dependent (BOLD) signal in controls increased with negative feedback in the insula, rostral cingulate cortex, middle frontal gyrus and parietal cortex (pFWE < 0.05). In comparison to controls, patients showed greater increase in BOLD activity following negative feedback in the dorsal anterior cingulate cortex (BA32). The genetic status was not correlated with the BOLD activity. The Brodmann area 32 (BA32) is part of the dorsal anterior cingulate cortex (dACC) that plays an important role in coordinating and integrating information to guide behavior and in reward-based learning. The dACC is connected with the basal ganglia-thalamo-loop modulated by dopaminergic signaling. This finding suggests disturbed integration of reinforcement history in decision making and implicate that the reward system might contribute to the pathogenesis in writer's cramp.

Metabolic Topology of Neurodegenerative Disorders: Influence of Cognitive and Motor Deficits

Parkinson disease with and without dementia (PDD and PD, respectively), dementia with Lewy bodies (DLB), and Alzheimer dementia (AD) traditionally have been viewed as distinct clinical and pathologic entities. However, intriguing overlaps in biochemical, clinical, and imaging findings question the concept of distinct entities and suggest a continuous spectrum in which individual patients express PD-typical patterns and AD-typical patterns to a variable degree.

METHODS

Following this concept, we built a topological map based on regional patterns of the cerebral metabolic rate of glucose as measured with (18)F-FDG PET to rank and localize single subjects' disease status according to PD-typical (PD vs. controls) and AD-typical (AD vs. controls) pattern expression in patients clinically characterized as PD, PDD, DLB, amnestic mild cognitive impairment, and AD.

RESULTS

The topology generally confirmed an indivisible spectrum of disease manifestation according to 2 separable expression patterns. The expression values derived from the first pattern were highly correlated with individual cognitive, but not motor, disability. The opposite was found for the corresponding expression values of the second pattern.

CONCLUSION

The metabolic imaging analysis supports the notion that there is a continuous spectrum of neurodegeneration between AD and PD. Furthermore, PDD and DLB may in fact represent 1 overlapping disease entity, characterized by the presence of mixed neuropathology and only different by the time course.

The (in)consistency of changes in brain macrostructure in male paedophiles: A combined T1-weighted and diffusion tensor imaging study

Thus far, four studies have used magnetic resonance imaging (MRI) to test for differences in brain structure between paedophilic (i.e. sexually attracted to pre-pubescent children) and teleiophilic (i.e. sexually attracted to adults) men, revealing divergent results. To re-examine this issue, we acquired high resolution structural T1-weighted and diffusion MRI scans of the brain in 24 paedophilic and 32 teleiophilic men. We performed voxel-based morphometry (VBM) of the T1-weighted images and tract-based spatial statistics (TBSS) of the diffusion tensor imaging data to search for grey and white matter differences between groups. In contrast to previous studies, less than half of the individuals in our paedophilic group had a record of sexual offences against children, as subjects were partially recruited from two outpatient facilities of a child sexual abuse prevention project for self-acknowledged paedophiles. After adjustment for multiple comparisons and controlling for important confounding factors, we did not find any significant grey or white matter differences between the paedophilic and teleiophilic subjects. Together with the inconsistencies in the literature, these results argue against consistent structural differences at the macroanatomical scale between paedophiles and teleiophiles.

Comparison of causality analysis on simultaneously measured fMRI and NIRS signals during motor tasks

Brain activity can be measured using different modalities. Since most of the modalities tend to complement each other, it seems promising to measure them simultaneously. In to be presented research, the data recorded from Functional Magnetic Resonance Imaging (fMRI) and Near Infrared Spectroscopy (NIRS), simultaneously, are subjected to causality analysis using time-resolved partial directed coherence (tPDC). Time-resolved partial directed coherence uses the principle of state space modelling to estimate Multivariate Autoregressive (MVAR) coefficients. This method is useful to visualize both frequency and time dynamics of causality between the time series. Afterwards, causality results from different modalities are compared by estimating the Spearman correlation. In to be presented study, we used directionality vectors to analyze correlation, rather than actual signal vectors. Results show that causality analysis of the fMRI correlates more closely to causality results of oxy-NIRS as compared to deoxy-NIRS in case of a finger sequencing task. However, in case of simple finger tapping, no clear difference between oxy-fMRI and deoxy-fMRI correlation is identified.

Increased volume and impaired function: the role of the basal ganglia in writer's cramp

INTRODUCTION

The pathophysiology of writer's cramp, a task-specific dystonia, remains unclear. The objective of this study was to investigate the basal ganglia circuit and the cerebellum during a complex motor sequence learning task carried out with the nonaffected hand in writer's cramp patients.

METHODS

We applied structural and functional imaging in 22 writer's cramp patients and 28 matched controls using 3T MRI. With the asymptomatic left hand all participants learned a complex, sequential, five-element sequence-tapping task as accurately and quickly as possible. Functional imaging was measured during a repeated (15 times), fixed block design with tapping (30 sec) and rest (30 sec). Additionally, gray matter volume of the basal ganglia was analyzed using voxel-based morphometry (VBM).

RESULTS

While behavior was comparable between groups, after small volume correction the anterior part of the right putamen and the left globus pallidus exhibited reduced blood oxygen level-dependent (BOLD) activity in patients during the sequential finger-tapping task. VBM analysis showed larger gray matter volume bilateral in the posterior part of the putamen and globus pallidus. There were no group differences in the cerebellum.

CONCLUSION

The results indicate an impairment of anterior basal ganglia loops involved in producing complex sequential movements of the unaffected hand. These findings are in line with previous reports of reduced neuronal activity in the globus pallidus internus. Higher gray matter volume of the putamen and globus pallidus may stem from elevated activity of the direct pathway, which could reflect a compensatory phenomenon or a primary predisposition, that is, endophenotypic trait.

Human face processing is tuned to sexual age preferences

Human faces can motivate nurturing behaviour or sexual behaviour when adults see a child or an adult face, respectively. This suggests that face processing is tuned to detecting age cues of sexual maturity to stimulate the appropriate reproductive behaviour: either caretaking or mating. In paedophilia, sexual attraction is directed to sexually immature children. Therefore, we hypothesized that brain networks that normally are tuned to mature faces of the preferred gender show an abnormal tuning to sexual immature faces in paedophilia. Here, we use functional magnetic resonance imaging (fMRI) to test directly for the existence of a network which is tuned to face cues of sexual maturity. During fMRI, participants sexually attracted to either adults or children were exposed to various face images. In individuals attracted to adults, adult faces activated several brain regions significantly more than child faces. These brain regions comprised areas known to be implicated in face processing, and sexual processing, including occipital areas, the ventrolateral prefrontal cortex and, subcortically, the putamen and nucleus caudatus. The same regions were activated in paedophiles, but with a reversed preferential response pattern.

Relation of lead trajectory and electrode position to neuropsychological outcomes of subthalamic neurostimulation in Parkinson's disease: results from a randomized trial

Deep brain stimulation of the subthalamic nucleus improves motor functions in patients suffering from advanced Parkinson's disease but in some patients, it is also associated with a mild decline in cognitive functioning about one standard deviation from the preoperative state. We assessed the impact of the cortical lead entry point, the subcortical electrode path and the position of the active electrode contacts on neuropsychological changes after subthalamic nucleus-deep brain stimulation compared to a control group of patients receiving best medical treatment. Sixty-eight patients with advanced Parkinson's disease were randomly assigned to have subthalamic nucleus-deep brain stimulation or best medical treatment for Parkinson's disease. All patients had a blinded standardized neuropsychological exam (Mattis Dementia Rating scale, backward digit span, verbal fluency and Stroop task performance) at baseline and after 6 months of treatment. Patients with subthalamic nucleus-deep brain stimulation were defined as impaired according to a mild decline of one or more standard deviations compared to patients in the best medical treatment group. The cortical entry point of the electrodes, the electrode trajectories and the position of the active electrode contact were transferred into a normalized brain volume by an automated, non-linear registration algorithm to allow accurate statistical group analysis using pre- and postoperative magnetic resonance imaging data. Data of 31 patients of the subthalamic nucleus-deep brain stimulation group and 31 patients of the best medical treatment group were analysed. The subthalamic nucleus-deep brain stimulation group showed impaired semantic fluency compared with the best medical treatment group 6 months after surgery (P = 0.02). Electrode trajectories intersecting with caudate nuclei increased the risk of a decline in global cognition and working memory performance. Statistically, for every 0.1 ml overlap with a caudate nucleus, the odds for a decline >1 standard deviation increased by a factor of 37.4 (odds ratio, confidence interval 2.1-371.8) for the Mattis Dementia Rating Scale and by a factor of 8.8 (odds ratio, confidence interval 1.0-70.9) for the backward digit span task. Patients with subthalamic nucleus-deep brain stimulation who declined in semantic verbal fluency, Stroop task and the backward digit span task performance showed a position of the active electrode outside the volume built by the active electrodes of stable performers. Passage of the chronic stimulation lead through the head of the caudate increases the risk of global cognitive decline and working memory performance after subthalamic nucleus-deep brain stimulation in Parkinson's disease. Therefore the electrode path should be planned outside the caudate nuclei, whenever possible. This study also stresses the importance of precise positioning of the active stimulating contact within the subthalamic volume to avoid adverse effects on semantic verbal fluency and response inhibition.

Directionality analysis on functional magnetic resonance imaging during motor task using Granger causality

Directionality analysis of signals originating from different parts of brain during motor tasks has gained a lot of interest. Since brain activity can be recorded over time, methods of time series analysis can be applied to medical time series as well. Granger Causality is a method to find a causal relationship between time series. Such causality can be referred to as a directional connection and is not necessarily bidirectional. The aim of this study is to differentiate between different motor tasks on the basis of activation maps and also to understand the nature of connections present between different parts of the brain. In this paper, three different motor tasks (finger tapping, simple finger sequencing, and complex finger sequencing) are analyzed. Time series for each task were extracted from functional magnetic resonance imaging (fMRI) data, which have a very good spatial resolution and can look into the sub-cortical regions of the brain. Activation maps based on fMRI images show that, in case of complex finger sequencing, most parts of the brain are active, unlike finger tapping during which only limited regions show activity. Directionality analysis on time series extracted from contralateral motor cortex (CMC), supplementary motor area (SMA), and cerebellum (CER) show bidirectional connections between these parts of the brain. In case of simple finger sequencing and complex finger sequencing, the strongest connections originate from SMA and CMC, while connections originating from CER in either direction are the weakest ones in magnitude during all paradigms.

Sensorimotor skills and focal dystonia are linked to putaminal grey-matter volume in pianists

BACKGROUND

Focal hand dystonia has been associated with morphometric changes and distorted somatotopic representations in the putamen.

OBJECTIVE

The authors used voxel-based morphometry (VBM) to identify regions in the putamen where grey-matter volume is associated with musician's dystonia (MD) or the skill level of piano playing in professional pianists.

METHODS

In 11 pianists with MD affecting the right hand and 12 healthy pianists without dystonia, the authors performed high-resolution T1-weighted MRI of the brain. The authors also measured the temporal variability of key strokes during scale playing with the right hand to characterise the individual skill level of piano playing. Statistical comparisons of the normalised and smoothed grey-matter maps were performed to test for dystonia and performance-related structural changes in the putamen.

RESULTS

During scale playing, the timing of consecutive key strokes was more variable in MD patients than in non-dystonic pianists. Regional grey-matter volume in the middle part of left and right putamen increased with timing variability during piano playing in pianists with and without MD. Between-group comparisons revealed that MD patients had a larger grey-matter volume in the right middle putamen compared with healthy musicians.

CONCLUSION

In highly trained pianists with and without MD, the volume of the associative motor territory in the middle putamen reflects both the skill level of piano playing and the presence of dystonia. While a smaller volume is associated with better timing skills, a relative expansion is correlated with the presence of focal task-specific hand dystonia.

Assessment of pedophilia using hemodynamic brain response to sexual stimuli

CONTEXT

Accurately assessing sexual preference is important in the treatment of child sex offenders. Phallometry is the standard method to identify sexual preference; however, this measure has been criticized for its intrusiveness and limited reliability.

OBJECTIVE

To evaluate whether spatial response pattern to sexual stimuli as revealed by a change in the blood oxygen level-dependent signal facilitates the identification of pedophiles.

DESIGN

During functional magnetic resonance imaging, pedophilic and nonpedophilic participants were briefly exposed to same- and opposite-sex images of nude children and adults. We calculated differences in blood oxygen level-dependent signals to child and adult sexual stimuli for each participant. The corresponding contrast images were entered into a group analysis to calculate whole-brain difference maps between groups. We calculated an expression value that corresponded to the group result for each participant. These expression values were submitted to 2 different classification algorithms: Fisher linear discriminant analysis and κ -nearest neighbor analysis. This classification procedure was cross-validated using the leave-one-out method.

SETTING

Section of Sexual Medicine, Medical School, Christian Albrechts University of Kiel, Kiel, Germany.

PARTICIPANTS

We recruited 24 participants with pedophilia who were sexually attracted to either prepubescent girls (n = 11) or prepubescent boys (n = 13) and 32 healthy male controls who were sexually attracted to either adult women (n = 18) or adult men (n = 14).

MAIN OUTCOME MEASURES

Sensitivity and specificity scores of the 2 classification algorithms.

RESULTS

The highest classification accuracy was achieved by Fisher linear discriminant analysis, which showed a mean accuracy of 95% (100% specificity, 88% sensitivity).

CONCLUSIONS

Functional brain response patterns to sexual stimuli contain sufficient information to identify pedophiles with high accuracy. The automatic classification of these patterns is a promising objective tool to clinically diagnose pedophilia.

Manual activity shapes structure and function in contralateral human motor hand area

From longitudinal voxel-based morphometry (VBM) studies we know that relatively short periods of training can increase regional grey matter volume in trained cortical areas. In 14 right-handed patients with writer's cramp, we employed VBM to test whether suppression (i.e., immobilization) or enhancement (i.e., training) of manual activity lead to opposing changes in grey matter in the contralateral primary motor hand area (M1(HAND)). We additionally used transcranial magnetic stimulation (TMS) to evaluate concurrent changes in regional excitability. Patients were recruited from a clinical trial which was designed to improve handwriting-associated dystonia. Initially the dystonic hand was immobilized for 4 weeks with the intention to reverse faulty plasticity. After immobilization, patients accomplished a motor re-training for 8 weeks. T1-weighted MRIs of the whole brain and single-pulse TMS measurements of the resting motor threshold (RMT) were performed every 4 weeks. Immobilization of the right hand resulted in a relative grey matter decrease in the contralateral left M1(HAND) along with a decrease in corticomotor excitability as indexed by an increase in RMT. Subsequent training reversed the effects of immobilization, causing an increase in regional grey matter density and excitability of left M1(HAND). The relative changes in grey matter correlated with the relative shifts in RMT. This prospective within-subject VBM study in task-specific hand dystonia shows that the grey matter density of M1(HAND) is dynamically shaped by the level of manual activity. This bi-directional structural plasticity is functionally relevant as local grey matter changes are mirrored by changes in regional excitability.

Mapping brain activity on the verge of a photically induced generalized tonic-clonic seizure

In a photosensitive patient intermittent photic stimulation (IPS) accidentally provoked a generalized tonic-clonic seizure during simultaneous recordings of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). Before seizure onset, IPS consistently induced generalized photoparoxysmal responses (PPRs). These PPRs were associated with increases in blood oxygen level dependent (BOLD) signal in the visual cortex, the thalamus, and both superior colliculi, and a decrease in BOLD signal in the frontoparietal areas. The BOLD signal in the visual cortex increased in magnitude during consecutive epochs of IPS associated with PPRs. We propose that repeated IPS led to an excessive amount of neuronal activity in the visual cortex that evoked PPRs and finally exceeded a critical threshold and triggered a generalized seizure.