Subthalamic responses to motor cortex stimulation:Selective targeting of the subthalamic motor area

Introduction: Over the last decades, it has been shown consistently that deep brain stimulation (DBS) of the subthalamic nucleus (STN) alleviates motor symptoms in Parkinson (PD) patients. However, in a substantial number of patients the beneficial effects of STN DBS are overshadowed by cognitive and/or limbic alterations. These side effects of STN DBS are thought to be caused by stimulation of the associative and limbic pathways that run through the STN. We hypothesize that an optimal effect of STN DBS on the motor symptoms without inducing cognitive and limbic side effects can be achieved by selective stimulation of the STN motor region by improved targeting. To achieve this goal, we made use of the cortico-subthalamic projection. We hypothesize that in PD patients motor cortex stimulation (MCS) evokes a specific response in the dorsolateral part of the STN, supposedly the STN motor area, that can be seen in both single unit activity and local field potentials (LFP). Material and Methods: Here we describe the results of one PD patient in which we performed MCS during the intra-operative STN microrecordings. In total, we measured single unit activity of eight neurons at various locations in the STN and LFP’s at the same locations. Data were analyzed using Matlab. All recordings were high pass filtered, the stimulus artifact was removed by time shifting, peristimulus time histograms were constructed from which significant excitatory and inhibitory responses were determined using the change point analysis. Results: The STN neurons had an average spontaneous firing rate of 64.6±36.3 Hz. Within the STN responses to MCS were seen, while outside the borders of the STN no responses were found. Responses differed between ventro-dorsal regions in the anterior-posterior and medio-lateral plane. In the anterior and lateral electrode at dorsal levels of the STN a significant early excitation (~10-50ms) and subsequent inhibition (50-110ms) were seen. The lateral electrode also showed a late excitation (~115-170ms). The responses we found were partially similar to reports in animal studies, but we did not observe the typical triphasic response. Conclusion: We found responses in the STN during MCS, which were significantly different in the dorsally recorded neurons in the lateral and anterior trajectory compared to the neurons recorded in other regions of the STN. In the near future MCS could be a novel tool to determine the motor area of the STN to optimize targeting for DBS in PD patients, thereby preventing cognitive and limbic side effect

BETULA: Numerically Stable CF-Trees for BIRCH Clustering

BIRCH clustering is a widely known approach for clustering, that has influenced much subsequent research and commercial products. The key contribution of BIRCH is the Clustering Feature tree (CF-Tree), which is a compressed representation of the input data. As new data arrives, the tree is eventually rebuilt to increase the compression. Afterward, the leaves of the tree are used for clustering. Because of the data compression, this method is very scalable. The idea has been adopted for example for k-means, data stream, and density-based clustering. Clustering features used by BIRCH are simple summary statistics that can easily be updated with new data: the number of points, the linear sums, and the sum of squared values. Unfortunately, how the sum of squares is then used in BIRCH is prone to catastrophic cancellation. We introduce a replacement cluster feature that does not have this numeric problem, that is not much more expensive to maintain, and which makes many computations simpler and hence more efficient. These cluster features can also easily be used in other work derived from BIRCH, such as algorithms for streaming data. In the experiments, we demonstrate the numerical problem and compare the performance of the original algorithm compared to the improved cluster features

UV-radiation and health

Jaarlijks krijgen meer dan 51.000 mensen in Nederland te horen dat ze huidkanker hebben en overlijden ruim 900 mensen aan de gevolgen ervan. Sinds 1990 is het aantal gevallen verviervoudigd. Deze stijging is veel sterker dan bij andere vormen van kanker, en een verdere stijging dreigt (met een factor 2 tot 5). De gevaarlijkste vorm van huidkanker komt in Nederland relatief vaak voor, en binnen Europa behoort Nederland tot de koplopers. Blootstelling van de huid aan UV-straling is de voornaamste oorzaak van het ontstaan van huidkanker, en dan vooral door onverstandig zongedrag. De vergrijzing en de aantasting van de ozonlaag blijken slechts een deel van de toename aan huidkanker te verklaren. Het blootstellingsgedrag lijkt de hoofdrol te spelen en daarbij zijn het dragen van minder bedekkende kleding, meer vrije tijd en langere (zon/strand) vakanties van belang, maar ook klimaatverandering en het gebruik van kunstmatige UV-bronnen voor bruining dragen mogelijk bij. De belangrijkste manier om huidkanker te voorkomen is dan ook ervoor te zorgen dat de huid niet verbrandt door de zon of zonnebank. Maar ook zonder te verbranden kan de huid beschadigd raken. Daarom is het verstandig om de huiddelen die veelvuldig worden blootgesteld extra te beschermen en om daarbij rekening te houden met de zonkracht en de duur van het verblijf in de zon. Bij een hoogstaande (zomer)zon tussen 11 en 16 uur is meer bescherming nodig dan 's morgens vroeg en in de namiddag. Behalve aan huidkanker draagt UV-straling bij aan de vorming van staar en veroorzaakt het huidveroudering en sneeuwblindheid. Het is niet wenselijk om de zonblootstelling volledig te vermijden, omdat UV-blootstelling van de huid ook de voornaamste bron is van vitamine D. Deze vitamine is essentieel voor gezonde botten en spieren. Bovendien zijn er aanwijzingen dat vitamine D de kans op darmkanker kan verkleinen. Momenteel is er een felle wetenschappelijke discussie gaande welke hoeveelheid vitamine D de meeste gezondheidswinst oplevert. De kosten van de medische behandeling van huidkanker bedragen naar schatting circa 325 (250-400) miljoen euro per jaar. De kosten voor de behandeling van door UV veroorzaakte staar, worden geschat op 75-150 miljoen euro per jaar. De kosten zijn grotendeels vermijdbaar door verstandiger (zon)gedrag. De actuele zonkrachtmetingen (www.rivm.nl/zonkracht) en betere kennis over (ontwikkelingen in) blootstellingsgedrag en gezondheidseffecten dragen bij aan een goede voorlichting en preventie. Er is alle reden de kennisopbouw met betrekking tot UV-stralingsbescherming te versterken.Every year more than 51,000 new cases of skin cancer are diagnosed in the Netherlands and over 900 fatalities are reported. The number of new skin cancer cases is rising rapidly and since 1990 a fourfold increase has been observed. This increase is much stronger than for other types of cancer, and a further increase is expected (with a factor of 2-5). The incidence of melanoma of the skin in the Netherlands is among the highest in Europe. Exposure of the skin to UV-radiation is the primary cause of skin cancer, and sun-exposure is the primary source of UV-exposure. The increase in skin cancer incidence that has been observed is only partly explained by the ageing of the Dutch population and the depletion of the ozone layer. A change in exposure behaviour is probably the most dominant factor that could explain a major part of the increased skin cancer incidence. Changes in fashion, with more of the body exposed, shorter working hours and longer vacations, including an increase in summer holidays spent in southern Europe are likely causes. Climate change and the use of artificial tanning devices may also contribute. Skin cancer prevention should be focused on the avoidance of UV-induced erythema (sunburn) in solar and artificial exposures. Limiting the chronic exposure of the most exposed skin parts is also very important, because damage to the skin also occurs below the threshold of erythemal doses. It is, therefore, important to provide additional protection for the parts of the skin that are chronically exposed. Solar exposure is the most important UV-source and protection is most needed when the sun is high in the sky, in the summer months between 11:00 am and 16:00 (4 pm). The UV-index is a good indicator; it is much lower in the early morning or late afternoon/early evening. UV-exposure also contributes to the incidence of cataract and causes skin ageing and snow blindness (photokeratitis). Exposure of the skin to solar UV from the sun should not be completely avoided, however, as it is an important source of vitamin D. Vitamin D is essential for healthy bones and muscles, and there are indications that a high vitamin D status lowers the risk of developing colon cancer, and may also be a factor in the development of a number of other cancers and chronic diseases. At present, a scientific debate is ongoing regarding the minimally required and optimal levels of vitamin D, and how to best achieve them. In the Netherlands the estimated costs for medical treatments of skin cancer and precancerous skin lesions amount to 325 million Euro (250-400). Estimated medical costs for the UV-contribution to cataract formation are 75-150 million Euro per year. These costs can be substantially reduced if (solar) UV-exposure is restricted. Prevention is supported by Solar UV-index measurements (www.rivm.nl/zonkracht), and improved knowledge on UV-radiation exposure and associated health effects. Strengthening the knowledge building and dissemination of information about UV-radiation protection is vitally important.Ministerie van VW

Photomyogenic response in Niemann–Pick type C: a case report

Contains fulltext : 98214.pdf (publisher's version ) (Closed access)1 maart 201

Combining gamma with Alpha and Beta power modulation for enhanced cortical mapping in patients with focal epilepsy

About one third of patients with epilepsy have seizures refractory to the medical treatment. Electrical stimulation mapping (ESM) is the gold standard for the identification of "eloquent" areas prior to resection of epileptogenic tissue. However, it is time-consuming and may cause undesired side effects. Broadband gamma activity (55-200 Hz) recorded with extraoperative electrocorticography (ECoG) during cognitive tasks may be an alternative to ESM but until now has not proven of definitive clinical value. Considering their role in cognition, the alpha (8-12 Hz) and beta (15-25 Hz) bands could further improve the identification of eloquent cortex. We compared gamma, alpha and beta activity, and their combinations for the identification of eloquent cortical areas defined by ESM. Ten patients with intractable focal epilepsy (age: 35.9 ± 9.1 years, range: 22-48, 8 females, 9 right handed) participated in a delayed-match-to-sample task, where syllable sounds were compared to visually presented letters. We used a generalized linear model (GLM) approach to find the optimal weighting of each band for predicting ESM-defined categories and estimated the diagnostic ability by calculating the area under the receiver operating characteristic (ROC) curve. Gamma activity increased more in eloquent than in non-eloquent areas, whereas alpha and beta power decreased more in eloquent areas. Diagnostic ability of each band was close to 0.7 for all bands but depended on multiple factors including the time period of the cognitive task, the location of the electrodes and the patient's degree of attention to the stimulus. We show that diagnostic ability can be increased by 3-5% by combining gamma and alpha and by 7.5-11% when gamma and beta were combined. We then show how ECoG power modulation from cognitive testing can be used to map the probability of eloquence in individual patients and how this probability map can be used in clinical settings to optimize ESM planning. We conclude that the combination of gamma and beta power modulation during cognitive testing can contribute to the identification of eloquent areas prior to ESM in patients with refractory focal epilepsy.info:eu-repo/semantics/publishedVersio

Data Stream Clustering for Real-Time Anomaly Detection: An Application to Insider Threats

Insider threat detection is an emergent concern for academia, industries, and governments due to the growing number of insider incidents in recent years. The continuous streaming of unbounded data coming from various sources in an organisation, typically in a high velocity, leads to a typical Big Data computational problem. The malicious insider threat refers to anomalous behaviour(s) (outliers) that deviate from the normal baseline of a data stream. The absence of previously logged activities executed by users shapes the insider threat detection mechanism into an unsupervised anomaly detection approach over a data stream. A common shortcoming in the existing data mining approaches to detect insider threats is the high number of false alarms/positives (FPs). To handle the Big Data issue and to address the shortcoming, we propose a streaming anomaly detection approach, namely Ensemble of Random subspace Anomaly detectors In Data Streams (E-RAIDS), for insider threat detection. E-RAIDS learns an ensemble of p established outlier detection techniques [Micro-cluster-based Continuous Outlier Detection (MCOD) or Anytime Outlier Detection (AnyOut)] which employ clustering over continuous data streams. Each model of the p models learns from a random feature subspace to detect local outliers, which might not be detected over the whole feature space. E-RAIDS introduces an aggregate component that combines the results from the p feature subspaces, in order to confirm whether to generate an alarm at each window iteration. The merit of E-RAIDS is that it defines a survival factor and a vote factor to address the shortcoming of high number of FPs. Experiments on E-RAIDS-MCOD and E-RAIDS-AnyOut are carried out, on synthetic data sets including malicious insider threat scenarios generated at Carnegie Mellon University, to test the effectiveness of voting feature subspaces, and the capability to detect (more than one)-behaviour-all-threat in real-time. The results show that E-RAIDS-MCOD reports the highest F1 measure and less number of false alarm = 0 compared to E-RAIDS-AnyOut, as well as it attains to detect approximately all the insider threats in real-time