Longitudinal Recordings Reveal Transient Increase of Alpha/Low-Beta Power in the Subthalamic Nucleus Associated With the Onset of Parkinsonian Rest Tremor

Functional magnetic resonance imaging studies suggest that different subcortico-cortical circuits control different aspects of Parkinsonian rest tremor. The basal ganglia were proposed to drive tremor onset, and the cerebellum was suggested to be responsible for tremor maintenance (“dimmer-switch” hypothesis). Although several electrophysiological correlates of tremor have been described, it is currently unclear whether any of these is specific to tremor onset or maintenance. In this study, we present data from a single patient measured repeatedly within 2 years after implantation of a deep brain stimulation (DBS) system capable of recording brain activity from the target. Local field potentials (LFPs) from the subthalamic nucleus and the scalp electroencephalogram were recorded 1 week, 3 months, 6 months, 1 year, and 2 years after surgery. Importantly, the patient suffered from severe rest tremor of the lower limbs, which could be interrupted voluntarily by repositioning the feet. This provided the unique opportunity to record many tremor onsets in succession. We found that tremor onset and tremor maintenance were characterized by distinct modulations of subthalamic oscillations. Alpha/low-beta power increased transiently immediately after tremor onset. In contrast, beta power was continuously suppressed during tremor maintenance. Tremor maintenance was additionally associated with subthalamic and cortical power increases around individual tremor frequency. To our knowledge, this is the first evidence of distinct subthalamic LFP modulations in tremor onset and tremor maintenance. Our observations suggest the existence of an acceleration signal for Parkinsonian rest tremor in the basal ganglia, in line with the “dimmer-switch” hypothesis

Multimodale Vermessung technischer Strukturen mittels moderner Holographie- und Mikroskopieverfahren

Zunehmende Anforderungen an die zerstörungsfreie Bildgebung erfordern eine stetige Weiterentwicklung optischer Systeme. Dabei können multimodale Messsysteme, die mehrere Messvorgänge zusammenführen und dadurch verschiedene Objekteigenschaften untersuchen, eine große Rolle spielen. In dieser Arbeit werden unterschiedliche Mikroskopie- und Holographiesysteme, sowie ihre Eigenschaften und Beiträge zur multimodalen Bildgebung vorgestellt. Das linsenlose holographische Mikroskop, eine schnelle und kostengünstige Methode, um Amplituden- und Phaseninformationen einer Probe zu erhalten, wird am Beispiel des enzymatischen Plastikabbaus demonstriert. Ein multimodales System aus konfokaler Mikroskopie und Photostromspektroskopie wird erstmals um die Messtechnik der digitalen Holographie erweitert, um zusätzliche Informationen über vergrabene Strukturen zu erlangen. Dabei vereint es die Vorteile einer hohen lateralen und axialen Auflösung, hoher Selektivität und Amplituden- und Phaseninformationen

Contrast Enhancement for Topographic Imaging in Confocal Laser Scanning Microscopy

The influence of the axial pinhole position in a confocal microscope in terms of the contrast of the image is analyzed. The pinhole displacement method is introduced which allows to increase the contrast for topographic imaging. To demonstrate this approach, the simulated data of a confocal setup as well as experimental data is shown. The simulated data is verified experimentally by a custom stage scanning reflective microscopy setup using a semiconductor test target with low contrast structures of sizes between 200 nm and 500 nm. With the introduced technique, we are able to achieve a contrast enhancement of up to 80% without loosing diffraction limited resolution. We do not add additional components to the setup, thus our concept is applicable for all types of confocal microscopes. Furthermore, we show the application of the contrast enhancement in imaging integrated circuits

Guanine quantum defects in carbon nanotubes for biosensing

Fluorescent single wall carbon nanotubes (SWCNTs) are used as nanoscale biosensors in diverse applications. Selectivity is built in by non-covalent functionalization with polymers such as DNA. In general, fluorescence sensing with SWCNTs would benefit from covalent DNA-conjugation but it is not known how changes in conformational flexibility and photophysics affect the sensing mechanism. Recently, covalent functionalization was demonstrated by conjugating guanine bases of adsorbed DNA to the SWCNT surface as guanine quantum defects (g-defects). Here, we create guanine defects in (GT)10 coated SWCNTs (Gd-SWCNTs) and explore how this affects molecular sensing. We vary the defect densities, which shifts the E11 fluorescence emission by 55 nm to max = 1049 nm for the highest defect density. Furthermore, the difference between absorption maximum and emission maximum (Stokes shift) increases with increasing defect density by 0.87 nm per nm of absorption shift and up to 27 nm in total. Gd-SWCNTs represent sensitive sensors and increase their fluorescence >70 % in response to the important neurotransmitter dopamine and decrease 93 % in response to riboflavin. Additionally, cellular uptake of Gd-SWCNTs decreases. These results show how physiochemical properties alter with guanine defects and that Gd-SWCNTs constitute a versatile optical biosensor platform

Exploring the wider societal impacts of sexual health issues and interventions to build a framework for research and policy:a qualitative study based on in-depth semi-structured interviews with experts in OECD member countries

ObjectivesSexual health is a complex public health challenge and can generate wide-ranging health, social and economic impacts both within and beyond the health sector (ie, intersectoral costs and benefits). Methods are needed to capture these intersectoral impacts in economic studies to optimally inform policy/decision-making. The objectives of this study were (1) to explore the different intersectoral costs and benefits associated with sexual health issues and interventions, (2) to categorise these into sectors and (3) to develop a preliminary framework to better understand these impacts and to guide future research and policy.DesignA qualitative study based on in-depth semi-structured online interviews.SettingOECD (Organisation for Economic Co-operation and Development) member countries.ParticipantsProfessionals with expertise in the field of sexual health including clinicians, medical practitioners, sexologists, researchers, professionals working for international governmental or non-governmental health (policy) organisations and professionals involved in implementation and/or evaluation of sexual health interventions/programmes.MethodsSampling of participants was undertaken purposively. We conducted in-depth semi-structured online interviews to allow for a systemic coverage of key topics and for new ideas to emerge. We applied a Framework approach for thematic data analysis.Results28 experts were interviewed. Six themes emerged from the interviews: (1) Interconnections to other areas of health (ie, reproductive health, mental health), (2) Relationships and family, (3) Productivity and labour, (4) Education, (5) Criminal justice/sexual violence, (6) Housing, addiction and other sectors. The findings confirm that sexual health is complex and can generate wide-ranging impacts on other areas of health and other non-health sectors of society.ConclusionThese different sectors need to be considered when evaluating interventions and making policy decisions. The preliminary framework can help guide future research and policy/decision-making. Future research could explore additional sectors not covered in this study and expand the preliminary framework

BrainCycles : Experimental Setup for the Combined Measurement of Cortical and Subcortical Activity in Parkinson's Disease Patients during Cycling

Recently, it has been demonstrated that bicycling ability remains surprisingly preserved in Parkinson's disease (PD) patients who suffer from freezing of gait. Cycling has been also proposed as a therapeutic means of treating PD symptoms, with some preliminary success. The neural mechanisms behind these phenomena are however not yet understood. One of the reasons is that the investigations of neuronal activity during pedaling have been up to now limited to PET and fMRI studies, which restrict the temporal resolution of analysis, and to scalp EEG focused on cortical activation. However, deeper brain structures like the basal ganglia are also associated with control of voluntary motor movements like cycling and are affected by PD. Deep brain stimulation (DBS) electrodes implanted for therapy in PD patients provide rare and unique access to directly record basal ganglia activity with a very high temporal resolution. In this paper we present an experimental setup allowing combined investigation of basal ganglia local field potentials (LFPs) and scalp EEG underlying bicycling in PD patients. The main part of the setup is a bike simulator consisting of a classic Dutch-style bicycle frame mounted on a commercially available ergometer. The pedal resistance is controllable in real-time by custom software and the pedal position is continuously tracked by custom Arduino-based electronics using optical and magnetic sensors. A portable bioamplifier records the pedal position signal, the angle of the knee, and the foot pressure together with EEG, EMG, and basal ganglia LFPs. A handlebar-mounted display provides additional information for patients riding the bike simulator, including the current and target pedaling rate. In order to demonstrate the utility of the setup, example data from pilot recordings are shown. The presented experimental setup provides means to directly record basal ganglia activity not only during cycling but also during other movement tasks in patients who have undergone DBS treatment. Thus, it can facilitate studies comparing bicycling and walking, to elucidate why PD patients often retain the ability to bicycle despite severe freezing of gait. Moreover it can help clarifying the mechanism through which cycling may have therapeutic benefits.publishe