Probability Of Disconnection Research Articles

Association of disruption of the right posterior arcuate fasciculus with spatial neglect.

Spatial neglect is a debilitating condition observed in patients with right-sided brain injuries in whom there is defective awareness of the contralesional space. Although classically considered a right parietal lobe deficit, there has been increasing interest in the specific white matter (WM) architecture subserving spatial neglect. Patients who have lesions associated with chronic disruptions in visuospatial networks are of significant relevance in elucidating the WM tracts associated with spatial attention. In this study, the authors used two independent analytical methods to examine the relationship between WM connectivity changes and spatial attention. Thirty patients with right-sided glioma underwent diffusion tensor imaging (DTI) tractography and neuropsychological testing prior to tumor resection. Spatial neglect was assessed using the Bells Test. Diffusion connectometry analysis was performed to calculate the probability of injury to 55 WM tracts. Next, quantitative DTI tractography was used to reconstruct 9 major WM tracts and obtain fractional anisotropy (FA) and streamline number values as indices of connectivity. Differences in connectivity were assessed between patients with neglect and controls. Of the WM tracts analyzed by diffusion connectometry, only the right posterior segment of the arcuate fasciculus (psAF) showed a higher probability of disconnection in patients with evidence of hemispatial neglect compared to tract reconstructions of previously published healthy controls (hemineglect: 42% ± 12.5%, vs control: 6.3% ± 4.8% [mean ± SEM]; p < 0.05). Of the WM tracts reconstructed by DTI tractography, only the right psAF demonstrated consistently lower indices of connectivity based on the mean streamline number (hemineglect: 550.35 ± 183.41, vs control: 1407.01 ± 319.93; p < 0.05) and FA value (hemineglect: 0.40 ± 0.013, vs control: 0.44 ± 0.0063; p < 0.05) in patients who demonstrated neglect compared to controls. The right long segment of the arcuate fasciculus, inferior frontooccipital fasciculus, and inferior longitudinal fasciculus also demonstrated a lower streamline number, but not a lower FA value, in patients with evidence of hemineglect. These findings suggest that parietotemporal networks mediated by the right psAF may play a critical role in visuospatial attention. This analysis may help to disentangle the organization of the visuospatial attention networks, predict deficits in patients with glioma, and optimize surgical planning.

OS08.7.A DEPRESSIVE SYMPTOMS IN ASSOCIATION WITH TUMOR LOCATIONS AT DIAGNOSIS IN PATIENTS WITH DIFFUSE GLIOMA

Abstract BACKROUND Depressive symptoms are common in glioma patients and occur more frequent than in patients with other cancer types. The presence of tumors in specific brain regions that potentially disturb brain functions could contribute to this difference. These lesions may cause an inadequate emotional response to an incurable and lethal disease with consequences for patient counseling and neurosurgical strategies. In this study, we examine the association between brain tumor location and depressive symptoms at presentation in patients with diffuse glioma using several methods for lesion symptom mapping. MATERIAL AND METHODS The retrospective cohort consisted of patients with diffuse glioma who had a preoperative MR-scan and completed the Center for Epidemiologic Studies Depression scale (CES-D) before treatment. We classified patients based on unexpectedly low ( ≤6), intermediate (7-20) and unexpectedly high (&amp;gt;20) CES-D scores. Tumors were segmented in 3D and corresponding white matter disconnectomes were derived from normative tractography. We first correlated tumor and disconnectome with CES-D using sparse canonical correlation analysis to identify clusters of associated brain voxels. Next, we assessed the association between tumor locations and CES-D category using Bayesian multivariable categorical regression analysis of patient and tumor characteristics, including the overlap of tumors and disconnectomes with specific brain atlas structures, the probability of disconnection of white matter tracts, and functional network changes in local efficiency and eigenvector centrality. RESULTS We included 201 patients with a median age of 45 years (range 18-81), consisting of 62% males and 29% grade 4 gliomas. CES-D was completed a median of three weeks before surgery, was unexpectedly low in 29% and unexpectedly high in 15% of patients. Tumors located in the left (L) pallidum and right (R) thalamus were related to unexpectedly low CES-D, whereas tumors in the L hippocampus, L nucleus accumbens and R putamen were related to unexpectedly high CES-D. Disconnection of the R temporal subsection of the cingulum bundle, L optic radiation, L superior longitudinal fasciculus I and L uncinate fasciculus (UF) were related to unexpectedly low CES-D, whereas disconnection of the R corticospinal tract, R fornix, and L UF were related to unexpectedly high CES-D. Neither voxel clusters nor network measures were associated with CES-D. CONCLUSION Both unexpectedly low and unexpectedly high depressive symptom burden is common in patients with diffuse glioma at presentation. These dysfunctional emotional responses may be associated with the location of the tumor. Awareness of this phenomenon may be important in patient counseling and neurosurgical strategies. * these authors contributed equally

Combining the Inner Self with the Map of the Body: Evidence for White Matter Contribution to the Relation Between Interoceptive Sensibility and Nonaction-oriented Body Representation

Very recent studies on healthy individuals suggest that changes in the sensibility toward internal bodily sensations across the lifespan affect the ability to mentally represent one’s body, in terms of action-oriented and nonaction-oriented body representation (BR). Little is known about the neural correlates of this relation. Here we fill this gap using the neuropsychological model provided by focal brain damage. Sixty-five patients with unilateral stroke (20 with left and 45 with right brain damage, LBD and RBD, respectively) participated in this study. Both action-oriented BR and nonaction-oriented BR were tested; interoceptive sensibility was assessed as well. First, we tested whether interoceptive sensibility predicted action-oriented BR and nonaction-oriented BR, in RBD and LBD separately. Then, a track-wise hodological lesion-deficit analysis was performed in a subsample of twenty-four patients to test the brain network supporting this relation. We found that interoceptive sensibility predicted the performances in the task tapping nonaction-oriented BR. The higher interoceptive sensibility was, the worse patients performed. This relation was associated with the disconnection probability of the corticospinal tract, the fronto-insular tract, and the pons. We expand over the previous findings on healthy individuals, supporting the idea that high levels of interoceptive sensibility negatively affect BR. Specific frontal projections and frontal u-shaped tracts may play a pivotal role in such an effect, likely affecting the development of a first-order representation of the self within the brainstem autoregulatory centers and posterior insula and of a second-order representation of the self within the anterior insula and higher-order prefrontal areas.

Neural correlates of verbal fluency revealed by longitudinal T1, T2 and FLAIR imaging in stroke

Diffusion-weighted imaging has been widely used in the research on post-stroke verbal fluency but acquiring diffusion data is not always clinically feasible. Achieving comparable reliability for detecting brain variables associated with verbal fluency impairments, based on more readily available anatomical, non-diffusion images (T1, T2 and FLAIR), enables clinical practitioners to have complementary neurophysiological information at hand to facilitate diagnosis and treatment of language impairment. Meanwhile, although the predominant focus in the stroke recovery literature has been on cortical contributions to verbal fluency, it remains unclear how subcortical regions and white matter disconnection are related to verbal fluency. Our study thus utilized anatomical scans of ischaemic stroke survivors (n = 121) to identify longitudinal relationships between subcortical volume, white matter tract disconnection, and verbal fluency performance at 3- and 12-months post-stroke. Subcortical grey matter volume was derived from FreeSurfer. We used an indirect probabilistic approach to quantify white matter disconnection in terms of disconnection severity, the proportion of lesioned voxel volume to the total volume of a tract, and disconnection probability, the probability of the overlap between the stroke lesion and a tract. These disconnection variables of each subject were identified based on the disconnectome map of the BCBToolkit. Using a linear mixed multiple regression method with 5-fold cross-validations, we correlated the semantic and phonemic fluency scores with longitudinal measurements of subcortical grey matter volume and 22 bilateral white matter tracts, while controlling for demographic variables (age, sex, handedness and education), total brain volume, lesion volume, and cortical thickness. The results showed that the right subcortical grey matter volume was positively correlated with phonemic fluency averaged over 3 months and 12 months. The finding generalized well on the test data. The disconnection probability of left superior longitudinal fasciculus II and left posterior arcuate fasciculus was negatively associated with semantic fluency only on the training data, but the result aligned with our previous study using diffusion scans in the same clinical population. In sum, our results presented evidence that routinely acquired anatomical scans can serve as a reliable source for deriving neural variables of post-stroke verbal fluency performance. The use of this method might provide an ecologically valid and more readily implementable analysis tool.

Structural disconnections associated with language impairments in chronic post-stroke aphasia using disconnectome maps

Inconsistent findings have been reported about the impact of structural disconnections on language function in post-stroke aphasia. This study investigated patterns of structural disconnections associated with chronic language impairments using disconnectome maps.Seventy-six individuals with post-stroke aphasia underwent a battery of language assessments and a structural MRI scan. Support-vector regression disconnectome-symptom mapping analyses were performed to examine the correlations between disconnectome maps, representing the probability of disconnection at each white matter voxel and different language scores. To further understand whether significant disconnections were primarily representing focal damage or a more extended network of seemingly preserved but disconnected areas beyond the lesion site, results were qualitatively compared to support-vector regression lesion-symptom mapping analyses.Part of the left white matter perisylvian network was similarly disconnected in 90% of the individuals with aphasia. Surrounding this common left perisylvian disconnectome, specific structural disconnections in the left fronto-temporo-parietal network were significantly associated with aphasia severity and with lower performance in auditory comprehension, syntactic comprehension, syntactic production, repetition and naming tasks. Auditory comprehension, repetition and syntactic processing deficits were related to disconnections in areas that overlapped with and extended beyond lesion sites significant in SVR-LSM analyses. In contrast, overall language abilities as measured by aphasia severity and naming seemed to be mostly explained by focal damage at the level of the insular and central opercular cortices, given the high overlap between SVR-DSM and SVR-LSM results for these scores.While focal damage seems to be sufficient to explain broad measures of language performance, the structural disconnections between language areas provide additional information on the neural basis of specific and persistent language impairments at the chronic stage beyond lesion volume. Leveraging routinely available clinical data, disconnectome mapping furthers our understanding of anatomical connectivity constraints that may limit the recovery of some language abilities in chronic post-stroke aphasia.

Evaluating the rare cases of cortical vertigo using disconnectome mapping

In rare cases, cortical infarcts lead to vertigo. We evaluated structural and functional disconnection in patients with acute vertigo due to unilateral ischemic cortical infarcts compared to infarcts without vertigo in a similar location with a focus on the connectivity of the vestibular cortex, i.e., the parieto-opercular (retro-)insular cortex (PIVC). Using lesion maps from the ten published case reports, we computed lesion–functional connectivity networks in a set of healthy individuals from the human connectome project. The probability of lesion disconnection was evaluated by white matter disconnectome mapping. In all ten cases with rotational vertigo, disconnections of interhemispheric connections via the corpus callosum were present but were spared in lesions of the PIVC without vertigo. Further, the arcuate fascicle was affected in 90% of the lesions that led to vertigo and spared in lesions that did not lead to vertigo. The lesion–functional connectivity network included vestibulo-cerebellar hubs, the vestibular nuclei, the PIVC, the retro-insular and posterior insular cortex, the multisensory vestibular ventral intraparietal area, motion-sensitive areas (temporal area MT+ and cingulate visual sulcus) as well as hubs for ocular motor control (lateral intraparietal area, cingulate and frontal eye fields). However, this was not sufficient to differentiate between lesions with and without vertigo. Disruption of interhemispheric connections of both PIVC via the corpus callosum and intra-hemispheric disconnection via the arcuate fascicle might be the distinguishing factor between vestibular cortical network lesions that manifest with vertigo compared to those without vertigo.

Optimal Beam Association for High Mobility mmWave Vehicular Networks: Lightweight Parallel Reinforcement Learning Approach

In intelligent transportation systems (ITS), vehicles are expected to feature with advanced applications and services which demand ultra-high data rates and low-latency communications. For that, the millimeter wave (mmWave) communication has been emerging as a very promising solution. However, incorporating the mmWave into ITS is particularly challenging due to the high mobility of vehicles and the inherent sensitivity of mmWave beams to dynamic blockages. This article addresses these problems by developing an optimal beam association framework for mmWave vehicular networks under high mobility. Specifically, we use the semi-Markov decision process to capture the dynamics and uncertainty of the environment. The Q-learning algorithm is then often used to find the optimal policy. However, Q-learning is notorious for its slow-convergence. Instead of adopting deep reinforcement learning structures (like most works in the literature), we leverage the fact that there are usually multiple vehicles on the road to speed up the learning process. To that end, we develop a lightweight yet very effective parallel Q-learning algorithm to quickly obtain the optimal policy by simultaneously learning from various vehicles. Extensive simulations demonstrate that our proposed solution can increase the data rate by 47% and reduce the disconnection probability by 29% compared to other solutions.

EFRADIR: An Enhanced FRAmework for DIsaster Resilience

This paper focuses on how to increase the availability of a backbone network with minimal cost. In particular, the new framework focuses on resilience against natural disasters and is an evolution of the FRADIR/FRADIR-II framework. It targets three different directions, namely: network planning, failure modeling, and survivable routing. The steady state network planning is tackled by upgrading a sub-network (a set of links termed the spine) to achieve the targeted availability threshold. A new two-stage approach is proposed: a heuristic algorithm combined with a mixed-integer linear problem to optimize the availability upgrade cost. To tackle the disaster-resilient network planning problem, a new integer linear program is presented for the optimal link intensity tolerance upgrades together with an efficient heuristic scheme to reduce the running time. Failure modeling is improved by considering more realistic disasters. In particular, we focus on earthquakes using the historical data of the epicenters and the moment magnitudes. The joint failure probabilities of the multi-link failures are estimated, and the set of shared risk link groups is defined. The survivable routing aims to improve the network’s connectivity during these shared risk link group failures. Here, a generalized dedicated protection algorithm is used to protect against all the listed failures. Finally, the experimental results demonstrate the benefits of the refined eFRADIR framework in the event of disasters by guaranteeing low disconnection probabilities even during large-scale natural disasters.

The effect of adaptive behavior on risk propagation in industrial symbiosis networks

The complex symbiotic relationship in the industrial symbiosis network (ISN) may cause new risks for firms. In view of this problem, previous studies mainly regard the ISN as a static system, without considering the adaptive behavior of firms. This paper establishes a risk propagation model of the ISN based on the change of firm state, proposes four kinds of reconnection strategies to model the adaptive behavior, and uses numerical simulation to investigate the effect of adaptive behavior on risk propagation. The results demonstrate that all the reconnection strategies play an inhibitory role in the risk propagation. Therein, the effectiveness of PP strategy is the best, followed by RR strategy, and DP (SP) strategy. In any case, the effect of reconnection strategies on risk propagation will improve with the increase of the disconnection probability and network resilience. Additionally, the more decentralized weight distribution will weaken the inhibition of adaptive behavior on risk propagation.

Topological and hodological aspects of body representation in right brain damaged patients

The triadic taxonomy posits that three distinct types of body representations do exist, namely the body schema (BS), which corresponds to the representation derived from multiple sensory and motor inputs, the body structural representation (BSR), which corresponds to the structural description of spatial relations among the body parts, and the body semantics (SEM), which corresponds to the lexical-semantic representation of the body. Although several studies have assessed neural correlates of these representations, no study has compared them in brain-damaged patients, controlling for deficits in other cognitive domains. Also, little is known about the contribution of the right hemisphere to different body representations. Here we used a computerized battery to test these three body representations in twenty-six right brain damaged patients, controlling for other cognitive deficits by means of tests tapping similar spatial and lexical processes on non-body related stimuli. Residual scores corresponding to the BS, the BSR and the SEM were used to test neural correlates, which were assessed by integrating topological and hodological approaches to lesion-deficit analyses. We found that the BSR was associated with lesion of the superior temporal gyrus, the insula, the supramarginal gyrus and the temporo-parietal junction, extending also to the Rolandic operculum and the inferior frontal gyrus. Also, it was associated with the disconnection probability of the posterior arcuate segment. The BS was associated with a small cluster of voxels in the precentral and postcentral gyri, whereas the SEM was associated with white matter lesion at the boundary between the parietal and temporal lobes. Overall, these results provide strong support to the regional and connectional contribution of the right hemisphere to body representation, and more specifically to the BSR.

Duration reproduction in regular and irregular contexts after unilateral brain damage: Evidence from voxel-based lesion-symptom mapping and atlas-based hodological analysis

It has been proposed that not completely overlapping brain networks support interval timing depending on whether or not an external, predictable temporal cue is provided during the task, aiding time estimation. Here we tested this hypothesis in a neuropsychological study, using both a topological approach – through voxel-based lesion-symptom mapping (VLSM), that assesses the relation between continuous behavioral scores and lesion information on a voxel-by-voxel basis – and a hodological approach, using an atlas-based tractography. A group of patients with unilateral focal brain lesions and their matched controls performed a duration reproduction task assessing time processing in two conditions, namely with regularly spaced stimuli during encoding and reproduction (Regular condition), and with irregularly spaced stimuli during the same task (Irregular condition). VLSM analyses showed that scores in the two conditions were associated with lesions involving partly separable clusters of voxels, with lower performance only in the Irregular condition being related to lesions involving the right insular cortex. Performance in both conditions correlated with the probability of disconnection of the right frontal superior longitudinal tract, and of the superior and middle branches of the right superior longitudinal fasciculus. These findings suggest that the dissociation between timing in regular and irregular contexts is not complete, since performance in both conditions relies on the integrity of a common suprasecond timing network. Furthermore, they are consistent with the hypothesis that tracking time without the aid of external cues selectively relies on the integration of psychophysiological changes in the right insula.

Блокировка несанкционированного срабатывания быстродействующих выключателей в тяговой сети постоянного тока

Electric railway is a system of very complex interconnected technical structures. High-quality operation of the power supply system depends on successful solution of a number of technical tasks by applying an integrated approach and introducing various scientific-technical measures. The traction network state is becoming of special importance. When an electric locomotive’s pantograph moves along the branches of the insulating air gap and when a transition is made from one power supply zone to another, there is a high probability of false disconnection of power supply to the branch the electric stock drives in. This may happen due to specific characteristics according to which the protection devices come in action. In this case, an electric arc emerges between the moving pantograph of the electric locomotive and the branch it leaves; this arc burns out the contact system wires. A device ensuring uninterrupted operation of DC traction network elements when an electric locomotive passes the insulating air gap is presented. The protective device in the form of a differential shunt relay, the use of which makes it possible to disconnect the traction network feeding line at a small value of a rapidly changing short-circuit current, serves as a prototype. The results from simulating a transient that occurs under such conditions in the traction network feeding lines are presented. Based on the obtained data, the parameters of a circuit for interlocking false disconnections performed by high-speed circuit breakers in the traction network adjacent feeding lines have been developed

Experimental realization of electromigration at high power for copper wires

The electromigration phenomenon is a topical concern in all types of interconnects in power systems for both low and high voltages, low and large power ranges, for instance, in fabrication and manufacturing of Integrated Circuits, electronics of the power modules, power grid interconnects etc. Due to distributed generation units, in particular, renewable energy sources, which are commonly connected to already existing infrastructures, the considered issues related to the electromigration impact will result to a potential reduction of the electrical interconnection failure risks. Thus, the design of the integrated systems has to perform at highly efficient level with low probability of disconnections. The presented study considers the effect of the electromigration in terms of the spatial direction of the currents by observing directions of the sparks under certain arrangements of copper wires’ connections. The experimental setup has been developed in order to realize and observe the theoretical expectations. The experimental results were conducted at around 500 A, and the corresponding observations match theoretical expectations.

Water Distribution Network Reliability Assessment and Isolation Valve System

Mechanical reliability analysis of water distribution networks (WDNs) refers to the assessment to provide correct service to customers under abnormal functioning conditions due to system component failures. Mechanical reliability depends on the isolation valve system (IVS) effectiveness in isolating a network segment and on the failure probability. The main aim of this work was the formal development of reliability indicators considering pressure-driven analysis (PDA) for customer demand and topological changes. Three factors influencing reliability were identified: (1) the hydraulic behavior of the still-connected network; (2) the topological performance of the IVS; and (3) the topological performance of the IVS with respect to unintended isolation. The reliability performance assessment of the network over time depends on the hydraulic capacity of the WDN under abnormal functioning conditions and on two IVS performance topological indicators of the risk of disconnection and unintended isolations. The hydraulic capacity was computed using PDA, whereas the topological risks were computed considering the unsupplied demand in the isolated segment and the normalized failure probability, i.e., the probability of a segment disconnection for an assumed failure occurrence in the network. The development of a modularity index for an IVS was achieved in a consistent framework and the integrated design of an IVS and district metering areas was introduced. The framework allows the analysis of the isolation valve failure. A real Apulian WDN was used to discuss and demonstrate the theoretical findings.

Use of Variable Fuzzy Clustering to Quantify the Vulnerability of a Power Grid to Earthquake Damage

The power grid is a critical component of city infrastructure. If it is damaged by an earthquake, there can be a huge impact on the safety and well-being of society and individuals. Identifying nodes in the grid that are highly vulnerable to earthquake damage is significant for effective pre-earthquake damage prevention, emergency response, and post-earthquake relief. Three indicators, the probability of node disconnection, the node hierarchical level, and the node critical threshold, were chosen, and their combined ability to represent node vulnerability to damage from an earthquake event was analyzed. A variable fuzzy clustering model was used to classify and order the nodes in the grid. The 20-node power grid of a city was used as an example to show how highly vulnerable nodes were identified, and how the reasons for the high vulnerability of these nodes were drawn out of the analysis. Countermeasures were given to reduce network vulnerability. The variable fuzzy clustering method used in this paper offers a new perspective on network vulnerability, and it quantifies the vulnerability of grid nodes more comprehensively than existing methods of assessing grid vulnerability. This research is significant as a baseline reference for future studies of grid vulnerability.

Approximation Theory for Connectivity of Ad Hoc Wireless Networks With Node Faults

In this letter, we propose an approximation theory for connectivity of general random geometric graphs (RGGs) with stochastic node faults, which is regarded as an abstract model of ad hoc wireless sensor networks (WSNs) with unreliable nodes. In the model, each node in an RGG is independently at fault and the disconnection probability of a resulting survival network is evaluated. The proposed approximation formula for the probability is asymptotically correct and reveals the phase transition phenomena of connectivity in the model. In addition, we obtain phase transition thresholds of a practical Rayleigh single-input single-output (SISO) model and Rayleigh multiple-input multiple-output (MIMO) model, which shows the effectiveness of the MIMO system against attenuation and random node faults. The numerical results in Rayleigh MIMO model show that the approximation formula well estimates the connection probability even for finite graphs and that it provides useful information for design of WSN immune to node faults.

The freshwater biome gradient framework: predicting macroscale properties based on latitude, altitude, and precipitation

AbstractUnderstanding global ecological patterns and processes, from biogeochemical to biogeographical, requires broad‐scale macrosystems context for comparing and contrasting ecosystems. Climate gradients (precipitation and temperature) and other continental‐scale patterns shape freshwater environments due to their influences on terrestrial environments and their direct and indirect effects on the abiotic and biotic characteristics of lakes, streams, and wetlands. We combined literature review, analyses of open access data, and logical argument to assess abiotic and biotic characters of freshwater systems across gradients of latitude and elevation that drive precipitation, temperature, and other variability. We explored the predictive value of analyzing patterns in freshwater ecosystems at the global macrosystems scale. We found many patterns based on climate, particularly those dependent upon hydrologic characteristics and linked to characteristics of terrestrial biomes. For example, continental waters of dry areas will generally be widely dispersed and have higher probability of drying and network disconnection, greater temperatures, greater inorganic turbidity, greater salinity, and lower riparian canopy cover relative to areas with high precipitation. These factors will influence local community composition and ecosystem rates. Enough studies are now available at the continental or global scale to start to characterize patterns under a coherent conceptual framework, though considerable gaps exist in the tropics and less developed regions. We present illustrative global‐scale trends of abiotic, biotic, and anthropogenic impacts in freshwater ecosystems across gradients of precipitation and temperature to further understanding of broad‐scale trends and to aid prediction in the face of global change. We view freshwater systems as occurring across arrays of multiple gradients (including latitude, altitude, and precipitation) rather than areas with specific boundaries. While terrestrial biomes capture some variability along these gradients that influence freshwaters, other features such as, slope, geology, and historical glaciation also influence freshwaters. Our conceptual framework is not so much a single hypothesis as a way to logically characterize patterns in freshwaters at scales relevant to (1) evolutionary processes that give rise to freshwater biodiversity, (2) regulatory units that influence freshwater ecosystems, and (3) the current scope of anthropogenic impacts on freshwaters and the vital ecosystem services they provide.

White matter tracts lesions and decline of verbal fluency after deep brain stimulation in Parkinson's disease.

Decline of verbal fluency (VF) performance is one of the most systematically reported neuropsychological adverse effects after subthalamic nucleus deep brain stimulation (STN-DBS). It has been suggested that this worsening of VF may be related to a microlesion due to the electrode trajectories. We describe the disruption of surrounding white matter tracts following electrode implantation in Parkinson's disease (PD) patients with STN-DBS and assess whether damage of fiber pathways is associated with VF impairment after surgery. We retrospectively analyzed 48 PD patients undergoing bilateral STN DBS. The lesion mask along the electrode trajectory transformed into the MNI 152 coordinate system, was compared with white matter tract atlas in Tractotron software, which provides a probability and proportion of fibers disconnection. Combining tract- and atlas-based analysis reveals that the trajectory of the electrodes intersected successively with the frontal aslant tract, anterior segment of arcuate tract, the long segment of arcuate tract, the inferior longitudinal fasciculus, the superior longitudinal fasciculus, the anterior thalamic radiation, and the fronto striatal tract. We found no association between the proportion fiber disconnection and the severity of VF impairment 6 months after surgery. Our findings demonstrated that microstructural injury associated with electrode trajectories involved white matter bundles implicated in VF networks.

Recovery time from supplementary motor area syndrome: relationship to postoperative day 7 paralysis and damage of the cingulum.

Supplementary motor area (SMA) syndrome is defined as temporary paralysis after the resection of brain tumor localized in the SMA. Although in most cases paralysis induced by SMA resection resolves within a short period, the time until complete recovery varies and has not been precisely analyzed to date. In this study, the authors investigated factors for predicting the time required for recovery from paralysis after SMA resection. Data from 20 cases were analyzed. All 20 patients (mean age 54.9 ± 12.6 years) had undergone resection of frontal lobe glioma involving the SMA. The severity of postoperative paralysis was recorded until complete recovery using the Brunnstrom recovery stage index. To investigate factors associated with recovery time, the authors performed multivariate analysis with the following potentially explanatory variables: age, severity of paralysis after the surgery, resected volume of the SMA, and probability of disconnection of fibers running through or near the SMA. Moreover, voxel-based lesion symptom analysis was performed to clarify the resected regions related to prolonged recovery. In most cases of severe to moderate paralysis, there was substantial improvement within the 1st postoperative week, but 2-9 weeks were required for complete recovery. Significantly delayed recovery from paralysis was associated with resection of the cingulate cortex and its deep regions. The factors found to influence recovery time from paralysis were stage of paralysis at postoperative day 7 and disconnection probability of the cingulum (adjusted R2 = 0.63, p < 0.0001). Recovery time from paralysis due to SMA syndrome can be predicted by the severity of paralysis at postoperative day 7 and degree of damage to the cingulum.

Long-Term Routing Stability of Wireless Sensor Networks in a Real-World Environment

The reliability of a wireless sensor network (WSN) is often assessed on node-to-node communication performance through link characterization. Long-term routing stability is an aspect of a WSN that is often overlooked in routing protocol implementations. In this paper, we investigate the routing stability of ZigBee PRO implemented WSN nodes that are deployed in a real-world environment. Frequent changes in next hops along routing paths between source and destination nodes can result in an increase in undesired energy consumption of the WSN. Hence, the relative routing path usage count, usage rate of unique next hop and switching frequency count are proposed as routing stability indicators. Our findings show that routing stability is subjected to not only the quality of a link but also to the implemented routing protocols, deployed environment and routing options available. More importantly, next hops with low usage rates are shown to experience a higher probability of disconnection from the Neighbor Table of respective source nodes, causing them to be short-lived. The need to avoid these links shows the importance of evaluating routing stability and identifying network bottlenecks.