Cross-hemicord spinal fiber reorganization associates with cortical sensory and motor network expansion in the rat model of hemicontusion cervical spinal cord injury

Magnetic resonance imaging plays an important role in characterizing microstructural changes and reorganization after traumatic injuries to the nervous system. In this study, we tested the feasibility of ex-vivo spinal cord diffusion tensor imaging (DTI) in combination with in vivo brain functional MRI to characterize spinal reorganization and its supraspinal association after a hemicontusion cervical spinal cord injury (SCI). DTI parameters (fractional anisotropy [FA], mean diffusion [MD]) and fiber orientation changes related to reorganization in the contused cervical spinal cord were compared to sham specimens. Altered fiber density and fiber directions occurred across the ipsilateral and contralateral hemicords but with only ipsilateral FA and MD changes. The hemicontusion SCI resulted in ipsilateral fiber breaks, voids and vivid fiber reorientations along the injury epicenter. Fiber directional changes below the injury level were primarily inter-hemispheric, indicating prominent below-level cross-hemispheric reorganization. In vivo resting state functional connectivity of the brain from the respective rats before obtaining the spinal cord samples indicated spatial expansion and increased connectivity strength across both the sensory and motor networks after SCI. The consistency of the neuroplastic changes along the neuraxis (both brain and spinal cord) at the single-subject level, indicates that distinctive reorganizational relationships exist between the spinal cord and the brain post-SCI.

Diffuse glioma-induced structural reorganization in close association with preexisting syntax-related networks

Glioma in the left frontal cortex has been reported to cause agrammatic comprehension and induce global functional connectivity alterations within the syntax-related networks. However, it remains unclear to what extent the structural reorganization is affected by preexisting syntax-related networks. We examined 28 patients with a diffuse glioma in the left hemisphere and 23 healthy participants. Syntactic abilities were assessed by a picture-sentence matching task with various sentence types. The lesion responsible for agrammatic comprehension was identified by region-of-interest-based lesion-symptom mapping (RLSM). Cortical structural alterations were examined by surface-based morphometry (SBM), in which the cortical thickness and fractal dimension were measured with three-dimensional magnetic resonance imaging (MRI). Fiber tracking on the human population-averaged diffusion MRI template was performed to examine whether the cortical structural alterations were associated with the syntax-related networks. The RLSM revealed associations between agrammatic comprehension and a glioma in the posterior limb of the left internal capsule. The SBM demonstrated that decreased cortical thickness and/or increased complexity of the right posterior insula were associated not only with agrammatic comprehension of the patients but also with the syntactic abilities of healthy participants. The fiber tracking revealed that the route between these two regions was anatomically integrated into the preexisting syntax-related networks previously identified. These results suggest a potential association between agrammatic comprehension in patients with diffuse glioma and structural variations in specific tracts and cortical regions, which may be closely related to the syntax-related networks.

Enhanced stability of a disaggregated Aβ fibril on removal of ligand inhibits refibrillation: An all atom Molecular Dynamics simulation study

The extraneuronally deposited senile plaques, composed of neurotoxic aggregates of Aβ fibril, define Alzheimer's disease (AD). Natural compounds have been tested for their destabilization potential on Aβ fibril, thereby curing AD. However, the resultant destabilized Aβ fibril, needs to be checked for its irreversibility to the native organized state after removal of the ligand. Herein, we assessed the stability of a destabilized fibril after the ligand (ellagic acid represented as REF) is removed from the complex. The study has been conducted via Molecular Dynamics (MD) simulation of 1 μs for both Aβ-Water (control) and Aβ-REF″ (test or REF removed) system. The increased value of RMSD, R_g, SASA, lower β-sheet content and reduced number of H-bonds explains enhanced destabilization observed in Aβ-REF″ system. The increased inter-chain distance demonstrates breaking of the residual contacts, testifying the drift of terminal chains from the pentamer. The increased SASA along with the ∆G_ps(polar solvation energy) accounts for the reduced interaction amongst residues, and more with solvent molecules, governing irreversibility to native state. The higher Gibb's free energy of the misaligned structure of Aβ-REF″ ensures irreversibility to the organized structure due to its inability to cross such high energy barrier. The observed stability of the disaggregated structure, despite ligand elimination, establishes the effectiveness of the destabilization technique as a promising therapeutic approach towards treating AD.

The pericontused cortex can support function early after TBI but it remains functionally isolated from normal afferent input

Traumatically injured brain functional connectivity (FC) is altered in a region-dependent manner with some regions functionally disconnected while others are hyperconnected after experimental TBI. Remote, homotopic cortical regions become hyperexcitable after injury, and we hypothesize that this results in increased trans-hemispheric cortical inhibition, preventing reorganization of the primary injured hemisphere. Previously we have shown that temporary silencing the contralesional cortex at 1wk normalizes affected forelimb behavioral use, but not at 4wks. To investigate the potential mechanism for this and to determine whether this occurs due to restoration of afferent pathway FC, and/or reorganization of brain circuits, we probed forelimb circuit function with sensorimotor task-evoked-fMRI, resting state fMRI seed-based analysis, and exploratory structural equation modelling (SEM) of directed causal connections due to forelimb task at 1 and 4wks post-injury after temporary, contralateral silencing with intraparenchymal injection of muscimol versus vehicle, as well as from sham rats. As predicted, silencing at 1wk and 4wks post-injury decimated the contralesional cortical forelimb map evoked by stimulation of the opposite, unaffected forelimb compared to vehicle-injected injured rats indicating the success of the intervention. Surprisingly however, this also resulted in activation of the pericontused cortex ipsilateral to the stimulated forelimb at 1wk, yet this same region could not be activated by directly stimulating the opposite, injury-affected forelimb. Underpinning this were significant increases in interhemispheric FC at the level of the cortex but decreases within subcortical regions. Causal SEM analysis confirmed increased corticothalamic connectivity and suggested changes from and to bilateral thalamus are important for the effect. At 4wks post-injury only cortical increases in FC were found in response to silencing indicating a less flexible brain, and ipsilesional cortex evoked activity was mostly absent. The absence of a reinstatement of ipsilesional evoked activity through normal pathways by temporary neuromodulation despite prior data showing behavioral improvements under the same conditions, indicates that while the pericontused cortex does retain function initially after injury, it is too functionally disconnected to be controlled by normal afferent input. More significant alterations in cross-brain FC during neuromodulation at 1wk compared to 4wk post-injury, suggest that more distributed brain activity accounts for prior behavior improvements in sensorimotor function, and that hemispheric imbalance in function is causally involved in early loss of sensorimotor function in this TBI model.

Natural kaolinite-based hierarchical porous microspheres as effective and highly recyclable adsorbent for removal of cationic dyes

The development of efficient, recyclable, and environment-friendly adsorbent for wastewater remediation is considered a challenge. In this study, a hierarchical porous kaolinite microsphere (HPKS) with three-dimensional (3D) structure was fabricated based on natural-layered kaolinite mineral via an environmentally friendly direct hydrothermal strategy. Characterization results revealed that HPKS microsphere with 3D hierarchical porous structure was constructed with numerous nanospheres which are assembled by ultrafine aluminosilicate flakes. HPKS exhibited negative charge feature ranging from strong acid to high alkaline solution. The influence of contact time, solution pH, initial dye concentration, adsorbent dosage, and foreign ions on methylene blue (MB) adsorption capability was systematically investigated. The synthesized HPKS with higher specific surface area (250.6 m²/g) shows an outstanding adsorption capacity towards MB (411.8 mg/g) and excellent selectivity for cationic MB dyes over anionic methyl orange and competitive metal ions. The adsorption kinetic experiment results fit very well with the pseudo-second-order model and reflect the fast adsorption rate of MB on HPKS. The sorption isotherm study reveals the chemisorption of electrostatic attraction between the cationic MB molecules and the negative charged surfaces of HPKS. More importantly, the MB removal efficiency is more than 99% in a broad range of solution pH value. The adsorption capacities of HPKS can be easily recovered by calcination at 600 °C to remove the adsorbed dyes and without obvious diminishment even after six successive cycles. Therefore, the HPKS is a cost-effective and environmentally friendly adsorbent which has is promising to use in practical applications.

Semantic network activation facilitates oral word reading in chronic aphasia

People with aphasia often show partial impairments on a given task. This trial-to-trial variability offers a potential window into understanding how damaged language networks function. We test the hypothesis that successful word reading in participants with phonological system damage reflects semantic system recruitment. Residual semantic and phonological networks were defined with fMRI in 21 stroke participants with phonological damage using semantic- and rhyme-matching tasks. Participants performed an oral word reading task, and activation was compared between correct and incorrect trials within the semantic and phonological networks. The results showed a significant interaction between hemisphere, network activation, and reading success. Activation in the left hemisphere semantic network was higher when participants successfully read words. Residual phonological regions showed no difference in activation between correct and incorrect trials on the word reading task. The results provide evidence that semantic processing supports successful phonological retrieval in participants with phonological impairment.

Brain mapping of emotional prosody in patients with drug-resistant temporal epilepsy: An indicator of plasticity

INTRODUCTION

Emotional prosody, a suprasegmental component of language, is predominantly processed by right temporo-frontal areas of the cerebral cortex. In temporal lobe epilepsy (TLE), brain disturbances affecting prosody processing frequently occur. This research assesses compensatory brain mechanisms of prosody processing in refractory TLE using fMRI.

METHODS

Patients with focal unilateral epilepsy, right (RTLE) (N = 19), left (LTLE) (N = 19), and healthy controls (CTRL) (N = 20) were evaluated during a prosody decoding fMRI task. The stimuli consisted in spoken numbers with different tones of voice (joy, fear, anger, neutral and silent trials). Participants were instructed to label the emotion with a keypad. "Joy" was removed from the analysis due to a high degree of variability. A lateralization index (LI) was used to see individual differences in the interhemispheric activations of each participant.

RESULTS

Behaviorally, The LTLE and RTLE groups did not differ significantly from each other neither from CTRL. In Negative Emotions versus Baseline contrast, the whole sample analysis showed extensive activations in bilateral superior temporal gyrus, bilateral precentral and post-central gyrus, right putamen, and left cerebellar vermis. Compared to the LTLE and CTRL, RTLE activated similar areas, but to a lesser extent. The LI analysis revealed significant differences in hemispheric laterality of the temporal lobe and the parietal lobe between RTLE compared to LTLE and CTRL, being the RTLE group lateralized towards the left, unlike the other two groups.

DISCUSSION

The LI indicated that, since the CTRL and the LTLE groups recruited putative prosodic regions, the RTLE lateralized prosody processing towards the left, recruiting contralateral nodes, homotopic to the putative areas of the prosody. Considering that the groups did not differ in prosody task performance, the findings suggest that, in the RTLE group, alternative brain nodes were recruited for the task, demonstrating plasticity.

Resolution of corporate insolvency during COVID-19 pandemic. Evidence from France

We investigate how the lockdown enforcement by French authorities is associated with the resolution of corporate insolvency. In this sense, we make a distinction between four legal procedures, namely the amicable liquidation (out-of-court exit), the judicial liquidation (court-driven exit), the restructuring procedure available to non-defaulted firms, and the restructuring procedure available to defaulted firms. Using a sample of 3488 non-listed and non-financial French firms, our estimates yield three major findings. First, the likelihood of judicial liquidation increased after the lifting of the quarantines compared to the pre-pandemic period. Second, the non-defaulted firms had a higher likelihood to reorganize in court during the second lockdown. Third, the lifting of the first lockdown led to a decrease in the probability of restructuring the assets of defaulted firms. Although the main objective of the lockdown was to limit spread of the virus, its enforcement has not encouraged the use of the out-of-court exit path.

Reconfiguration and Reorganization of Bottlebrush Polymer Surfactants

Bottlebrush random copolymers (BRCPs), having randomly distributed hydrophilic and hydrophobic side chains, are shown to reconfigure into hydrophilic-rich and hydrophobic-rich conformations at liquid-liquid interfaces to reduce interfacial energy. Both the degree of polymerization (N_BB ) and extent of grafting in these BRCPs were found to impact surface coverage and assembly kinetics. The time-dependence of the interfacial tension is described as the sum of two exponential relaxation functions characterizing BRCP diffusion, interfacial adsorption, and reorganization. Interfacial tension (γ) and fluorescence recovery after photobleaching (FRAP) results showed that higher molecular weight BRCPs require longer time to adsorb to the water-oil interface, but less time for interfacial reorganization. Overall, this work describes fundamental principles of BRCP assembly at liquid-liquid interfaces, with implications pertaining to polymer design with enhanced understanding of emulsification, adhesion, and related properties in fluids and at interfaces.

Electrophysiologic evidence of reorganization in poststroke aphasia

Electrophysiologic methods have been used to investigate neural changes in individuals with poststroke aphasia. The major types of electrophysiologic measures include the event-related potential (ERP) and spectral power, and aspects of both (including amplitude, topography, and power) have been shown to differ in people with aphasia. Not only that, these measures are sensitive to spontaneous and treatment-induced language change. The purpose of this chapter is to review evidence of poststroke reorganization in the language network that has been identified in the acute and chronic phases of poststroke aphasia. The chapter will begin with a brief introduction to electrophysiologic methods and then focus on evidence from the most commonly studied ERPs and spectral bands in aphasia.

General principles of brain electromagnetic rhythmic oscillations and implications for neuroplasticity

Neuro-plasticity describes the ability of the brain in achieving novel functions, either by transforming its internal connectivity, or by changing the elements of which it is made, meaning that, only those changes, that affect both structural and functional aspects of the system, can be defined as "plastic." The concept of plasticity can be applied to molecular as well as to environmental events that can be recognized as the basic mechanism by which our brain reacts to the internal and external stimuli. When considering brain plasticity within a clinical context-that is the process linked with changes of brain functions following a lesion- the term "reorganization" is somewhat synonymous, referring to the specific types of structural/functional modifications observed as axonal sprouting, long-term synaptic potentiation/inhibition or to the plasticity related genomic responses. Furthermore, brain rewires during maturation, and aging thus maintaining a remarkable learning capacity, allowing it to acquire a wide range of skills, from motor actions to complex abstract reasoning, in a lifelong expression. In this review, the contribution on the "neuroplasticity" topic coming from advanced analysis of EEG rhythms is put forward.

Work changes and employee age, maladaptive coping expectations, and well-being: a Swedish cohort study

Purpose

Older workers are expected to suffer more from work changes than younger ones, but empirical evidence is lacking. Negative responses to work changes may result rather from maladaptive coping expectations. This study examined possible age differences in job and life satisfaction, and sleep disturbances, after work changes (voluntary and involuntary job changes, reorganizations) and the moderating role of maladaptive coping expectations.

Methods

Four biennial waves from the Swedish Longitudinal Occupational Survey of Health (SLOSH) including respondents who participated in all four waves (n = 3084). We used multilevel path analyses to estimate direct and moderated relationships between work changes and outcomes.

Results

Involuntary job changes were associated with lower job and life satisfaction and more sleep disturbances. Reorganizations were only associated with lower job satisfaction. Older employees were more satisfied with their jobs and lives than younger employees and experienced more sleep disturbances. After involuntary job changes, older employees had similar (lower) levels of well-being as younger ones, but they reported more sleep disturbances when having experienced reorganizations. Maladaptive coping expectations were related to lower job and life satisfaction and more sleep disturbances. Employees with maladaptive coping expectations reported more sleep disturbances after involuntary job changes and reorganizations.

Conclusion

Our results suggest that there are few age differences in well-being after work changes. Employee well-being seems to mostly depend on maladaptive coping expectations. Organizations aiming to prepare employees for job changes and reorganizations could focus their efforts on employees with maladaptive expectations rather than on older ones.

Reorganization of rich clubs in functional brain networks of dementia with Lewy bodies and Alzheimer's disease

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DLB and AD had the different functional reorganization patterns.

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Rich club nodes increased in frontal-parietal network in patients with DLB.

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The rich club nodes in temporal lobe decreased and those in cerebellum increased for AD.

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Compared with HC, rich club connectivity was enhanced in the DLB and AD groups.

The purpose of this study was to reveal the patterns of reorganization of rich club organization in brain functional networks in dementia with Lewy bodies (DLB) and Alzheimer’s disease (AD). The study found that the rich club node shifts from sensory/somatomotor network to fronto-parietal network in DLB. For AD, the rich club nodes switch between the temporal lobe with obvious structural atrophy and the frontal lobe, parietal lobe and cerebellum with relatively preserved structure and function. In addition, compared with healthy controls, rich club connectivity was enhanced in the DLB and AD groups. The connection strength of DLB patients was related to cognitive assessment. In conclusion, we revealed the different functional reorganization patterns of DLB and AD. The conversion and redistribution of rich club members may play a causal role in disease-specific outcomes. It may be used as a potential biomarker to provide more accurate prevention and treatment strategies.

Predictive masking of an artificial scotoma is associated with a system-wide reconfiguration of neural populations in the human visual cortex

The visual brain has the remarkable capacity to complete our percept of the world even when the information extracted from the visual scene is incomplete. This ability to predict missing information based on information from spatially adjacent regions is an intriguing attribute of healthy vision. Yet, it gains particular significance when it masks the perceptual consequences of a retinal lesion, leaving patients unaware of their partial loss of vision and ultimately delaying diagnosis and treatment. At present, our understanding of the neural basis of this masking process is limited which hinders both quantitative modeling as well as translational application. To overcome this, we asked the participants to view visual stimuli with and without superimposed artificial scotoma (AS). We used fMRI to record the associated cortical activity and applied model-based analyzes to track changes in cortical population receptive fields and connectivity in response to the introduction of the AS. We found that throughout the visual field and cortical hierarchy, pRFs shifted their preferred position towards the AS border. Moreover, extrastriate areas biased their sampling of V1 towards sections outside the AS projection zone, thereby effectively masking the AS with signals from spared portions of the visual field. We speculate that the signals that drive these system-wide population modifications originate in extrastriate visual areas and, through feedback, also reconfigure the neural populations in the earlier visual areas.

Structural and functional reorganization of contralateral hippocampus after temporal lobe epilepsy surgery

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Postoperative changes of contralateral hippocampus in temporal lobe epilepsy.

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No obvious hippocampal volume change was observed after successful surgery.

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Surgical manipulation may lead to a transient functional connectivity reduction.

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Increased functional connectivity mostly involved bilateral frontal regions.

Objective

To explore the structural and functional reorganization of contralateral hippocampus in patients with unilateral mesial temporal lobe epilepsy (mTLE) who achieved seizure-freedom after anterior temporal lobectomy (ATL).

Methods

We obtained high-resolution structural MRI and resting-state functional MRI data in 28 unilateral mTLE patients and 29 healthy controls. Patients were scanned before and three and 24 months after surgery while controls were scanned only once. Hippocampal gray matter volume (GMV) and functional connectivity (FC) were assessed.

Results

No obvious GMV changes were observed in contralateral hippocampus before and after successful surgery. Before surgery, ipsilateral hippocampus showed increased FC with ipsilateral insula (INS) and temporoparietal junction (TPJ), but decreased FC with widespread bilateral regions, as well as contralateral hippocampus. After successful ATL, contralateral hippocampus showed: (1) decreased FC with ipsilateral INS at three months follow-up, without further changes; (2) decreased FC with ipsilateral TPJ, postcentral gyrus and rolandic operculum at three months, with an obvious increase at 24 months follow-up; (3) increased FC with bilateral medial prefrontal cortex (MPFC) and superior frontal gyrus (SFG) at three months follow-up, without further changes.

Conclusions

Successful ATL may not lead to an obvious structural reorganization in contralateral hippocampus. Surgical manipulation may lead to a transient FC reduction of contralateral hippocampus. Increased FC between contralateral hippocampus and bilateral MPFC and SFG may be related to postoperative functional remodeling.

Anteholosticha foissneri n. sp., a marine hypotrich ciliate (Ciliophora: Spirotrichea) from Vietnam: Morphology, morphogenesis, and molecular phylogeny

In a study of marine ciliate diversity, we collected an Anteholosticha monilata-like population from Vietnam. To identify this population, we analyzed its morphology, some morphogenetic stages, and molecular phylogeny. Based on these data, we conclude that the Vietnamese population is new to science. Anteholosticha foissneri n. sp. resembles Anteholosticha monilata-like species considering (1) the number and arrangement of macronuclear nodules and micronuclei; (2) the presence of cortical granules; and (3) the saline habitat. However, the new species can be easily distinguished from these species by the arrangement, color, and shape of the cortical granules. The divisional morphogenesis commences with the de novo proliferation of basal bodies as a single longitudinal patch left of the posteriormost midventral cirral pair. This character state has not been reported before in Anteholosticha (based on check of the available data) and probably reflects a distinct clade within the nuclear small subunit ribosomal RNA gene tree.

An fMRI, DTI and Neurophysiological Examination of Atypical Organization of Motor Cortex in Ipsilesional Hemisphere Following Post-Stroke Recovery

OBJECTIVES

We report a 61-year-old woman who developed left hemiparesis following a right frontal stroke. She underwent rehabilitation and regained function of the left side of her body. Three years after her first stroke, she developed a large left subdural hematoma and again presented with left hemiparesis.

MATERIALS AND METHODS

Prior to the cranioplasty, an fMRI scan involving left and right hand movement, arm movement, and foot peddling were conducted in order to determine whether the patient showed ipsilateral activation for the motor tasks, thus explaining the left hemiparesis following the left subdural hematoma. Diffusion tensor imaging (DTI) tractography was also collected to visualize the motor and sensory tracts.

RESULTS

The fMRI results revealed activation in the expected contralateral left primary motor cortex (M1) for the right-sided motor tasks, and bilateral M1 activation for the left-sided motor tasks. Intraoperative neurophysiology confirmed these findings, whereby electromyography revealed left-sided (i.e., ipsilateral) responses for four of the five electrode locations. The DTI results indicated that the corticospinal tracts and spinothalamic tracts were within normal limits and showed no displacement or disorganization.

CONCLUSIONS

These results suggest that there may have been reorganization of the M1 following her initial stroke, and that the left hemisphere may have become involved in moving the left side of the body thereby leading to left hemiparesis following the left subdural hematoma. The findings suggest that cortical reorganization may occur in stroke patients recovering from hemiparesis, and specifically, that components of motor processing subserved by M1 may be taken over by ipsilateral regions.

Safety in Endoscopy for Patients and Healthcare Workers During the COVID-19 Pandemic

The coronavirus disease 2019 (COVID-19), caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), is still wreaking havoc in many parts of the world and poses a great burden to healthcare systems worldwide. Mitigation and suppression strategies have been implemented globally but the disease has proven to be difficult to contain. Initially many elective gastrointestinal endoscopies were cancelled to reduce the risk of infection and conserve personal protective equipment, but many endoscopy units are now faced with the dilemma of resuming endoscopy service during the pandemic as indefinitely postponing diagnostic procedures may lead to a delay in the diagnosis and treatment of malignancies. Further concerns are surfacing as COVID-19 is now known to affect the gastrointestinal tract and may potentially be spread via the fecal-oral route. Until more effective drugs and vaccines are available, it is unlikely that the pandemic will wind down in the near future. Maintaining a balance between protecting healthcare workers and patients from being infected on the one hand and providing timely and effective clinical care on the other will become increasingly important as the pandemic persists. In this narrative review, the risk of COVID-19 infection for healthcare workers and patients undergoing endoscopy, and recommendations on maintaining safe, high-quality endoscopy practice will be discussed.

Distinct Patterns of Functional Connectivity During the Comprehension of Natural, Narrative Speech

Recent continuous task studies, such as narrative speech comprehension, show that fluctuations in brain functional connectivity (FC) are altered and enhanced compared to the resting state. Here, we characterized the fluctuations in FC during comprehension of speech and time-reversed speech conditions. The correlations of Hilbert envelope of source-level EEG data were used to quantify FC between spatially separate brain regions. A symmetric multivariate leakage correction was applied to address the signal leakage issue before calculating FC. The dynamic FC was estimated based on a sliding time window. Then, principal component analysis (PCA) was performed on individually concatenated and temporally concatenated FC matrices to identify FC patterns. We observed that the mode of FC induced by speech comprehension can be characterized with a single principal component. The condition-specific FC demonstrated decreased correlations between frontal and parietal brain regions and increased correlations between frontal and temporal brain regions. The fluctuations of the condition-specific FC characterized by a shorter time demonstrated that dynamic FC also exhibited condition specificity over time. The FC is dynamically reorganized and FC dynamic pattern varies along a single mode of variation during speech comprehension. The proposed analysis framework seems valuable for studying the reorganization of brain networks during continuous task experiments.

New Drugs Regulatory Program Modernization: Vision, Strategic Objectives, and Impact

In response to a rapid increase in drug development activity during the past two decades, the Food and Drug Administration's Center for Drug Evaluation and Research launched a multi-year effort in 2017 to modernize the program by which new drug products are regulated, known as the New Drugs Regulatory Program. Following a detailed analysis of FDA activities in new drug development, premarket review, and postmarket monitoring, the Office of New Drugs was restructured to therapeutically align its clinical offices and to add new cross-functional offices for regulatory support. An interdisciplinary review process for new drug and biologics applications was rolled out to reduce redundancy and produce review documents that effectively communicate the scientific basis for the regulatory decision. The investigational new drug (IND) review process was also streamlined. During the next 2 years, the modernization initiative will seek to attract and retain new scientific and regulatory staff, improve postmarket safety monitoring, increase efficiency of drug review via technology-enabled workflows, and standardize the capture and use of scientific data to inform future regulatory decisions. The modernization effort will position the New Drugs Regulatory Program to continually improve and adapt to innovations in science, technology, and drug development.

Alteration of Resting-state Functional Connectivity in the Sensorimotor Network in Patients with Thalamic Infarction

PURPOSE

To explore changes in functional connectivity (FC) within the sensorimotor network (SMN) and the relationship between the SMN and bilateral thalamus in patients with thalamic infarction (TI) using resting state functional magnetic resonance imaging (rs-fMRI). Also determined was whether those measures are useful for monitoring the functional recovery of somatosensory deficits.

METHODS

The study included 31 patients with TI presenting somatosensory dysfunction and 31 controls who underwent clinical assessments and MRI scanning at 6 months after a stroke. An independent component analysis was used to identify the SMN. The mean time courses of SMN activity were extracted for each subject, and FC with the bilateral thalamus was assessed. Differences in connectivity strength were compared between groups. Finally, we correlated the altered FC values with clinical data from patients with TI.

RESULTS

Compared to controls, patients with TI showed decreases in FC within SMN in the ipsilesional posterior central gyrus (PCG) (Z-score = -4.581, cluster size = 171), but presented increased FC within the SMN in the ipsilesional supplementary motor area (SMA) (Z-score = 4.648, cluster size = 46). The FC values of the ipsilesional SMA correlated with the somatosensory function score of patients with TI (r = 0.426, P = 0.027). Increased FC was observed between the SMN and bilateral thalamus in patients with TI. The region exhibiting increased FC was adjacent to the lesion in the affected thalamus, while the area with increased FC overlapped the location of the lesion when the lesion was mirrored onto the unaffected thalamus.

CONCLUSION

The increased FC in the ipsilesional SMA and between the SMN and perilesional thalamus might reflect functional reorganization in patients with TI presenting somatosensory deficits.

The rapid transformation of cardiac surgery practice in the coronavirus disease 2019 (COVID-19) pandemic: insights and clinical strategies from a centre at the epicentre

OBJECTIVES

The onset of the coronavirus disease 2019 (COVID-19) pandemic has forced our cardiac surgery programme and hospital to enact drastic measures that has forced us to change how we care for cardiac surgery patients, assist with COVID-19 care and enable support for the hospital in terms of physical resources, providers and resident training.

METHODS

In this review, we review the cardiovascular manifestations of COVID-19 and describe our system-wide adaptations to the pandemic, including the use of telemedicine, how a severe reduction in operative volume affected our programme, the process of redeployment of staff, repurposing of residents into specific task teams, the creation of operation room intensive care units, and the challenges that we faced in this process.

RESULTS

We offer a revised set of definitions of surgical priority during this pandemic and how this was applied to our system, followed by specific considerations in coronary/valve, aortic, heart failure and transplant surgery. Finally, we outline a path forward for cardiac surgery for the near future.

CONCLUSIONS

We recognize that individual programmes around the world will eventually face COVID-19 with varying levels of infection burden and different resources, and we hope this document can assist programmes to plan for the future.

Rapid motor cortical reorganization following subacute spinal cord dysfunction

OBJECTIVE

Damage to the spinal cord is known to be associated with a posterior shift of the motor cortical upper limb representation, i.e. towards the somatosensory cortex. Due to missing pre-traumatic data, knowledge resulted from comparing findings between patients and healthy subjects. Here, we present a case of transient spinal cord injury resulting in a left-sided hemiparesis for 4 weeks. By chance, this patient had a pre-lesional navigated transcranial magnetic stimulation (nTMS) motor mapping 2 years before. Hence, nTMS mapping was repeated during the acute (after 1 day), sub-acute (after 10 days) and chronic (after 2 years) phase to trace the cortical reorganization following this incident.

METHODS

Acute clinical work-up included magnetic resonance imaging and navigated transcranial magnetic stimulation (nTMS). Motor mapping was performed with 110% of the abductor pollicis brevis muscle (APB) resting motor threshold (rMT). Amplitudes and latencies of the motor-evoked potential (MEPs) were recorded and analyzed. In addition, motor function was evaluated by the Medical Research Council (MRC) scale, a standard Purdue Pegboard test and by a reaction time (RT) task.

RESULTS

MRI revealed no aberrant findings. nTMS mapping, however, showed a posterior shift of the APB representation from the anatomical hand knob towards the somatosensory cortex in the acute in comparison to the pre-lesional phase. Concomitantly, there was an increase of rMT (6%). Within 10 days, there was an incomplete reversal of the posterior shift in parallel with improvement of the clinical motor function. Long-term follow-up revealed a complete restitution of nTMS cortical mapping and motor function.

CONCLUSION

The present case report thoroughly documents a rapid cortical reorganization within a few days after a transient spinal shock. Our data adds further evidence to the literature suggesting a posterior shift of motor cortical representation following spinal cord injury. For the first time, 52 cortical reorganization was shown idiosyncratically in a single patient arising from the fortuitous fact of having a pre - lesional nTMS map.

A conceptual framework for plasticity in the developing brain

In this chapter, we highlight the various definitions of early brain plasticity commonly used in the scientific literature. We then present a conceptual framework of early brain plasticity that focuses on plasticity at the level of the synapse (synaptic plasticity) and the level of the network (connectivity). The proposed framework is organized around three main domains through which current theories and principles of early brain plasticity can be integrated: (1) the mechanisms of plasticity and constraints at the synaptic level and network connectivity, (2) the importance of temporal considerations related to the development of the immature brain, and (3) the functions early brain plasticity serve. We then apply this framework to discuss some clinical disorders caused by and/or associated with impaired plasticity mechanisms. We propose that a careful examination of the relationship between mechanisms, constraints, and functions of early brain plasticity in health and disease may provide an integrative understanding of the current theories and principles generated by experimental and observational studies.

Work-unit organizational changes and risk of cardiovascular disease: a prospective study of public healthcare employees in Denmark

PURPOSE

The impact of organizational change at work on cardiovascular disease (CVD) among employees is poorly understood. We examined the longitudinal associations between different types of work-unit organizational changes and risk of CVD among employees.

METHODS

We used multilevel mixed-effects parametric survival models to assess the risk of incident ischemic heart disease and stroke (72 events) during 2014 according to organizational changes in 2013 among 14,788 employees working in the same work unit from January through December 2013. We excluded employees with pre-existing CVD events between 2009 and 2013. Data on organizational changes defined as mergers, split-ups, relocations, change in management, employee layoffs, and budget cuts were obtained from work-unit managers (59% response).

RESULTS

There was an excess risk of CVD in the year following change in management (HR 2.04, 95% CI 1.10-3.78) and employee layoff (HR 2.44, 95% CI 1.29-4.59) in the work unit relative to no change. Exposure to any organizational change also suggested increased risk of CVD (HR 1.48, 95% CI 0.91-2.43). Including perceived stress as mediator in the regression models attenuated the point risk estimates only slightly, indicating no important mediation through this psychosocial factor.

CONCLUSIONS

Work-unit organizational change may be associated with excess risk of incident CVD among the employees relative to stable workplaces.

Axonal regeneration and functional recovery driven by endogenous Nogo receptor antagonist LOTUS in a rat model of unilateral pyramidotomy

The adult mammalian central nervous system (CNS) rarely recovers from injury. Myelin fragments contain axonal growth inhibitors that limit axonal regeneration, thus playing a major role in determining neural recovery. Nogo receptor-1 (NgR1) and its ligands are among the inhibitors that limit axonal regeneration. It has been previously shown that the endogenous protein, lateral olfactory tract usher substance (LOTUS), antagonizes NgR1-mediated signaling and accelerates neuronal plasticity after spinal cord injury and cerebral ischemia in mice. However, it remained unclear whether LOTUS-mediated reorganization of descending motor pathways in the adult brain is physiologically functional and contributes to functional recovery. Here, we generated LOTUS-overexpressing transgenic (LOTUS-Tg) rats to investigate the role of LOTUS in neuronal function after damage. After unilateral pyramidotomy, motor function in LOTUS-Tg rats recovered significantly compared to that in wild-type animals. In a retrograde tracing study, labeled axons spanning from the impaired side of the cervical spinal cord to the unlesioned hemisphere of the red nucleus and sensorimotor cortex were increased in LOTUS-Tg rats. Anterograde tracing from the unlesioned cortex also revealed enhanced ipsilateral connectivity to the impaired side of the cervical spinal cord in LOTUS-Tg rats. Moreover, electrophysiological analysis showed that contralesional cortex stimulation significantly increased ipsilateral forelimb movement in LOTUS-Tg rats, which was consistent with the histological findings. According to these data, LOTUS overexpression accelerates ipsilateral projection from the unlesioned cortex and promotes functional recovery after unilateral pyramidotomy. LOTUS could be a future therapeutic option for CNS injury.

Refined Functional Magnetic Resonance Imaging and Magnetoencephalography Mapping Reveals Reorganization in Language-Relevant Areas of Lesioned Brains

BACKGROUND

Neurosurgical decisions regarding interventions close to brain areas with language-related functions remain highly challenging because of the risk of postoperative dysfunction. To minimize these risks, improvements in the preoperative mapping of language-related regions are required, especially as space-occupying lesions often lead to altered cortical topography and language area reorganization.

METHODS

The degree of deviation and language area reorganization were investigated in 26 functional magnetic resonance imaging- and magnetoencephalography-dissociable cortical sub-areas displaying language-related activations in each of 18 patients with brain lesions and 3 healthy volunteers (during visual language tasks).

RESULTS

Both modalities showed good congruency of the language areas. The mean spatial distance of the centroids and maxima was 9.06 mm and 10.58 mm, respectively, allowing us to define more specific anatomical positions. Postoperatively, language abilities increased in 11% (2 of 18) of the patients, remained unchanged in 83% (15 of 18) of the patients, and decreased in 6% (1 of 18) of the patients, respectively. Signs of language function reorganization detected on both functional magnetic resonance imaging and magnetoencephalography were present in 29% (5 of 17) of the patients. Attenuation of neurovascular coupling was found postoperatively in 17% (3 of 18) of the patients. Monohemispheric language processing cannot be assumed always in patients with brain lesions.

CONCLUSIONS

The more detailed subdivision of language-relevant brain areas shown in this study can help to achieve more radical tumor resection without postoperative language deficits.

Reorganization of the brain in spinal cord injury: a meta-analysis of functional MRI studies

PURPOSE

Reorganization of the brain is considered the key mechanism of functional recovery in patients after spinal cord injury (SCI). This meta-analysis assessed abnormal brain activation in SCI patients to understand the pattern of reorganization in the brain after SCI.

METHODS

Functional magnetic resonance imaging (fMRI) studies that compared SCI patients with controls and were published before August 30, 2018, were extracted from the PubMed, Web of Science, and EMBASE databases. Voxel-wise whole-brain meta-analysis and region-of-interest meta-analysis of group differences were separately performed. Then, meta-regression analysis was conducted with several clinical characteristics as regressors.

RESULTS

Sixteen studies that met the inclusion criteria were identified. Compared with control individuals, SCI patients showed increased activation in the sensorimotor cortex in both whole-brain and region-of-interest (ROI) analyses. In addition, whole-brain meta-analysis revealed increased activation in the cerebellum, and this increase was positively correlated with lesion level and injury severity.

CONCLUSION

Our results demonstrated that reorganization occurred mainly in the sensorimotor system of the brain after SCI, implying that brain functions involved in sensorimotor demands can still be preserved in this condition. These findings provide opportunities for future studies in terms of therapeutic strategies and prognosis assessment.

Reorganization of the somatosensory pathway after subacute incomplete cervical cord injury

Objective

The main purpose of the present study was to investigate the possible somatosensory-related brain functional reorganization after traumatic spinal cord injury (SCI).

Methods

Thirteen patients with subacute incomplete cervical cord injury (ICCI) and thirteen age- and sex-matched healthy controls (HCs) were recruited. Eleven patients and all the HCs underwent both sensory task-related brain functional scanning and whole brain structural scanning on a 3.0 Tesla MRI system, and two patients underwent only structural scanning; the process of structural scanning was completed on thirteen patients, while functional scanning was only applied to eleven patients. We performed sensory task-related functional MRI (fMRI) to investigate the functional changes in the brain. In addition, voxel-based morphometry (VBM) was applied to explore whether any sensory-related brain structural changes occur in the whole brain after SCI.

Results

Compared with HCs, ICCI patients exhibited decreased activation in the left postcentral gyrus (postCG), the brainstem (midbrain and right pons) and the right cerebellar lobules IV-VI. Moreover, a significant positive association was found between the activation in the left PostCG and the activation in both the brainstem and the right cerebellar lobules IV-VI. Additionally, the decrease in gray matter volume (GMV) was detected in the left superior parietal lobule (SPL). The decrease of white matter volume (WMV) was observed in the right temporal lobe, the right occipital lobe, and the right calcarine gyrus. No structural change in the primary sensory cortex (S1), the secondary somatosensory cortex (S2) or the thalamus was detected.

Conclusion

These functional and structural findings may demonstrate the existence of an alternative pathway in the impairment of somatosensory function after SCI, which consists of the ipsilateral cerebellum, the brainstem and the contralateral postCG. It provides a new theoretical basis for the mechanism of sensory-related brain alteration in SCI patients and the rehabilitation therapy based on this pathway in the future.

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We found that sensory-related brain reorganization may not occur in the thalamus in patients with ICCI.

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We found that brain structural reorganization did not occur in the S1 or the S2 in patients with ICCI.

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We observed that SCI can cause brain structural reorganization in non-sensory-related areas.

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We observed that an alternative pathway may exist in the impairment of somatosensory function after SCI.

Different patterns of white matter changes after successful surgery of mesial temporal lobe epilepsy

Objectives

To explore the dynamic changes of white matters following anterior temporal lobectomy (ATL) in mesial temporal lobe epilepsy (MTLE) patients who achieved seizure-free at two-year follow-up.

Methods

Diffusion tensor imaging (DTI) was obtained in ten MTLE patients at five serial time points: before surgery, three months, six months, 12 months and 24 months after surgery, as well as in 11 age- and sex-matched healthy controls at one time point. Regions with significant postoperative fractional anisotropy (FA) changes and their dynamic changes were confirmed by comparing all preoperative and postoperative data using Tract-Based Spatial Statistics (TBSS).

Results

After successful ATL, significant FA changes were found in widespread ipsilateral and contralateral white matter regions (P <.05, FWE correction). Ipsilateral external capsule, cingulum, superior corona radiate, body of corpus callosum, inferior longitudinal fasciculus, optic radiation and contralateral inferior cerebellar peduncle, inferior longitudinal fasciculus showed significant FA decrease at three months after surgery, without further changes. Ipsilateral superior cerebellar peduncle and contralateral corpus callosum, anterior corona radiate, external capsule, optic radiation showed significant FA decrease at three months follow up but increase later. Ipsilateral cerebral peduncle and contralateral middle cerebellar peduncle showed significant FA decrease at three months follow up, with further decrease after that. While ipsilateral posterior limb of internal capsule, retrolenticular part of internal capsule and contralateral posterior corona radiate showed significant FA increase after surgery.

Conclusions

FA changes after successful ATL presented as four distinct patterns, reflecting different structural adaptions following epilepsy surgery. Some FA increases indicated the reversibility of preoperative diffusion abnormalities and the possibility of structural reorganization, especially in the contralateral hemisphere.

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Widespread white matter abnormalities existed in mesial temporal lobe epilepsy.

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We explored longitudinal DTI changes at five serial time points before and after anterior temporal lobectomy.

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We found four distinct patterns of diffusion changes, reflecting different structural adaptions following epilepsy surgery.

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Structural reorganization did occur after surgery, especially in contralateral hemisphere.

Contralateral functional reorganization of the speech supplementary motor area following neurosurgical tumor resection

We evaluated plasticity in speech supplemental motor area (SMA) tissue in two patients using functional magnetic resonance imaging (fMRI), following resection of tumors in or associated with the dominant hemisphere speech SMA. Patient A underwent resection of a anaplastic astrocytoma NOS associated with the left speech SMA, experienced SMA syndrome related mutism postoperatively, but experienced full recovery 14 months later. FMRI performed 32 months after surgery demonstrated a migration of speech SMA to homologous contralateral hemispheric regional tissue. Patient B underwent resection of a oligodendroglioma NOS in the left speech SMA, and postoperatively experienced speech hesitancy, latency and poor fluency, which gradually resolved over 18 months. FMRI performed at 64 months after surgery showed a reorganization of speech SMA to the contralateral hemisphere. These data support the hypothesis of dynamic, time based plasticity in speech SMA tissue, and may represent a noninvasive neural marker for SMA syndrome recovery.

Organization of area hV5/MT+ in subjects with homonymous visual field defects

Damage to the primary visual cortex (V1) leads to a visual field loss (scotoma) in the retinotopically corresponding part of the visual field. Nonetheless, a small amount of residual visual sensitivity persists within the blind field. This residual capacity has been linked to activity observed in the middle temporal area complex (V5/MT+). However, it remains unknown whether the organization of hV5/MT+ changes following early visual cortical lesions. We studied the organization of area hV5/MT+ of five patients with dense homonymous defects in a quadrant of the visual field as a result of partial V1+ or optic radiation lesions. To do so, we developed a new method, which models the boundaries of population receptive fields directly from the BOLD signal of each voxel in the visual cortex. We found responses in hV5/MT+ arising inside the scotoma for all patients and identified two possible sources of activation: 1) responses might originate from partially lesioned parts of area V1 corresponding to the scotoma, and 2) responses can also originate independent of area V1 input suggesting the existence of functional V1-bypassing pathways. Apparently, visually driven activity observed in hV5/MT+ is not sufficient to mediate conscious vision. More surprisingly, visually driven activity in corresponding regions of V1 and early extrastriate areas including hV5/MT+ did not guarantee visual perception in the group of patients with post-geniculate lesions that we examined. This suggests that the fine coordination of visual activity patterns across visual areas may be an important determinant of whether visual perception persists following visual cortical lesions.

Cell based therapy enhances activation of ventral premotor cortex to improve recovery following primary motor cortex injury

Stroke results in enduring damage to the brain which is accompanied by innate neurorestorative processes, such as reorganization of surviving circuits. Nevertheless, patients are often left with permanent residual impairments. Cell based therapy is an emerging therapeutic that may function to enhance the innate neurorestorative capacity of the brain. We previously evaluated human umbilical tissue-derived cells (hUTC) in our non-human primate model of cortical injury limited to the hand area of primary motor cortex. Injection of hUTC 24 h after injury resulted in significantly enhanced recovery of fine motor function compared to vehicle treated controls (Moore et al., 2013). These monkeys also received an injection of Bromodeoxyuridine (BrdU) 8 days after cortical injury to label cells undergoing replication. This was followed by 12 weeks of behavioral testing, which culminated 3 h prior to perfusion in a final behavioral testing session using only the impaired hand. In this session, the neuronal activity initiating hand movements leads to the upregulation of the immediate early gene c-Fos in activated cells. Following perfusion-fixation of the brain, sections were processed using immunohistochemistry to label c-Fos activated cells, pre-synaptic vesicle protein synaptophysin, and BrdU labeled neuroprogenitor cells to investigate the hypothesis that hUTC treatment enhanced behavioral recovery by facilitating reorganization of surviving cortical tissues. Quantitative analysis revealed that c-Fos activated cells were significantly increased in the ipsi- and contra-lesional ventral premotor but not the dorsal premotor cortices in the hUTC treated monkeys compared to placebo controls. Furthermore, the increase in c-Fos activated cells in the ipsi- and contra-lesional ventral premotor cortex correlated with a decrease in recovery time and improved grasp topography. Interestingly, there was no difference between treatment groups in the number of synaptophysin positive puncta in either ipsi- or contra-lesional ventral or dorsal premotor cortices. Nor was there a significant difference in the density of BrdU labeled cells in the subgranular zone of the hippocampus or the subventricular zone of the lateral ventricle. These findings support the hypothesis that hUTC treatment enhances the capacity of the brain to reorganize after cortical injury and that bilateral plasticity in ventral premotor cortex is a critical locus for this recovery of function. This reorganization may be accomplished through enhanced activation of pre-existing circuits within ventral premotor, but it could also reflect ventral premotor projections to the brainstem or spinal cord.

Motor Cortex Reorganization in Patients with Glioma Assessed by Repeated Navigated Transcranial Magnetic Stimulation-A Longitudinal Study

OBJECTIVE

Evidence for cerebral reorganization after resection of low-grade glioma has mainly been obtained by serial intraoperative cerebral mapping. Noninvasively collected data on cortical plasticity in tumor patients over a surgery-free period are still scarce. The present study therefore aimed at evaluating motor cortex reorganization by navigated transcranial magnetic stimulation (nTMS) in patients after perirolandic glioma surgery.

METHODS

nTMS was performed preoperatively and postoperatively in 20 patients, separated by 26.1 ± 24.8 months. Further nTMS mapping was conducted in 14 patients, resulting in a total follow-up period of 46.3 ± 25.4 months. Centers of gravity (CoGs) were calculated for every muscle representation area, and Euclidian distances between CoGs over time were defined. Results were compared with data from 12 healthy individuals, who underwent motor cortex mapping by nTMS in 2 sessions.

RESULTS

Preoperatively and postoperatively pooled CoGs from the area of the dominant abductor pollicis brevis muscle and of the nondominant leg area differed significantly compared with healthy individuals (P < 0.05). Most remarkably, during the ensuing follow-up period, a reorganization of all representation areas was observed in 3 patients, and a significant shift of hand representation areas was identified in further 3 patients. Complete functional recovery of postoperative motor deficits was exclusively associated with cortical reorganization.

CONCLUSIONS

Despite the low potential of remodeling within the somatosensory region, long-term reorganization of cortical motor function can be observed. nTMS is best suited for a noninvasive evaluation of this reorganization.

Loss of inhibition in ipsilateral somatosensory areas following altered afferent nerve signaling from the hand

Cutaneous stimulation of the hand results in increased neural activity in the contralateral primary somatosensory cortex (S1) in humans, whereas an inhibition of neurons is seen in the ipsilateral S1. The aim of this study was to assess changes in neural activity in the S1 bilaterally, with a focus on the ipsilateral hemisphere, following altered afferent nerve signaling from the hand. Three cohorts, all with altered afferent nerve signaling from the hand, participated in the study. There were: 18 patients with traumatic median nerve injury, 10 patients with vibration induced neuropathy and 11 healthy subjects who had their dominant hand and wrist immobilized for 72 h. In addition, 36 healthy subjects were included as controls. Each subject was examined using functional magnetic resonance imaging at 3 T. All three study cohorts showed enlarged activation in the contralateral S1 during tactile stimulation compared to healthy controls. Moreover, inhibition of the ipsilateral S1 was significantly decreased or completely lost. Thus, somatosensory areas of both hemispheres respond to changed afferent nerve signaling from the hand. The loss of inhibition of neurons in the ipsilateral S1 suggests an important role of the ipsilateral hemisphere in the cerebral adaptation following a change in afferent nerve signaling.

Neuroimaging of stroke recovery from aphasia - Insights into plasticity of the human language network

The role of left and right hemisphere brain regions in language recovery after stroke-induced aphasia remains controversial. Here, we summarize how neuroimaging studies increase the current understanding of functional interactions, reorganization and plasticity in the language network. We first discuss the temporal dynamics across the time course of language recovery, with a main focus on longitudinal studies from the acute to the chronic phase after stroke. These studies show that the functional contribution of perilesional and spared left hemisphere as well as contralesional right hemisphere regions to language recovery changes over time. The second section introduces critical variables and recent advances on early prediction of subsequent outcome. In the third section, we outline how multi-method approaches that combine neuroimaging techniques with non-invasive brain stimulation elucidate mechanisms of plasticity and reorganization in the language network. These approaches provide novel insights into general mechanisms of plasticity in the language network and might ultimately support recovery processes during speech and language therapy. Finally, the neurobiological correlates of therapy-induced plasticity are discussed. We argue that future studies should integrate individualized approaches that might vary the combination of language therapy with specific non-invasive brain stimulation protocols across the time course of recovery. The way forward will include the combination of such approaches with large data sets obtained from multicentre studies.

Reorganized neural activation in motor cortex following subdural fluid collection: an fMRI and DTI study

We report a patient with a cavernous malformation involving the right lentiform nucleus. Pre-surgical planning included fMRI localization of language, motor, and sensory processing, and DTI of white matter tracts. fMRI results revealed no activation near the planned resection zone. However, post-surgery the patient developed a subdural fluid collection, which applied pressure to the primary motor cortex (M1). Follow-up scans revealed that motor activation had shifted due to pressure, and then shifted to a new location after the fluid collection subsided. This case report suggests that long-term neural reorganization can occur in response to short term compression in the cortex.

Host Cell Vimentin Restrains Toxoplasma gondii Invasion and Phosphorylation of Vimentin is Partially Regulated by Interaction with TgROP18

The obligate intracellular parasite, Toxoplasma gondii, manipulates the cytoskeleton of its host cells to facilitate infection. A significant rearrangement of host cell vimentin around Toxoplasma parasitophorous vacuoles is observed during the course of infection. ROP18 (TgROP18) is a serine-threonine kinase secreted by T. gondii rhoptry and a major virulence factor; however, the mechanisms by which this kinase modulates host factors remain poorly understood. Different and dynamic patterns of vimentin solubility, phosphorylation, and expression levels were observed in host cells infected with T. gondii strain RH and RH Δrop18 strains, suggesting that TgROP18 contributes to the regulation of these dynamic patterns. Additionally, host cell vimentin was demonstrated to interact with and be phosphorylated by TgROP18. A significant increase in T. gondii infection rate was observed in vimentin knockout human brain microvessel endothelial cells (HBMEC), while vimentin knockout or knock down in host cells had no impact on parasite proliferation and egress. These results indicate that host cell vimentin can inhibit T. gondii invasion. Interestingly, western blotting of different mouse tissues indicated that the lowest vimentin expression level was present in the brain, which may explain the mechanism underlying the nervous system tropism of T. gondii, and the phenomenon of huge cyst burdens developing in the mouse brain during chronic infection.

Rehabilitation and the Neural Network After Stroke

Stroke remains a major cause of disability throughout the world: paralysis, cognitive impairment, aphasia, and so on. Surgical or medical intervention is curative in only a small number of cases. Nearly all stroke cases require rehabilitation. Neurorehabilitation generally improves patient outcome, but it sometimes has no effect or even a mal-influence. The aim of this review is the clarification of the mechanisms of neurorehabilitation. We systematically reviewed recently published articles on neural network remodeling, especially from 2014 to 2016. Finally, we summarize progress in neurorehabilitation and discuss future prospects.

Reorganization of brain function after a short-term behavioral intervention for stuttering

This study investigated changes in brain function that occurred over a 7-day behavioral intervention for adults who stutter (AWS). Thirteen AWS received the intervention (AWS+), and 13 AWS did not receive the intervention (AWS-). There were 13 fluent controls (FC-). All participants were scanned before and after the intervention. Whole-brain analysis pre-intervention showed significant differences in task-related brain activation between AWS and FC- in the right inferior frontal cortex (IFC) and left middle temporal cortex, but there were no differences between the two AWS groups. Across the 7-day period of the intervention, AWS+ alone showed a significant increase of brain activation in the left ventral IFC/insula. There were no changes in brain function for the other two groups. Further analysis revealed that the change did not correlate with resting-state functional connectivity (RSFC) that AWS showed in the cerebellum (Lu et al., 2012). However, both changes in task-related brain function and RSFC correlated with changes in speech fluency level. Together, these findings suggest that functional reorganization in a brain region close to the left IFC that shows anomalous function in AWS, occurs after a short-term behavioral intervention for stuttering.

Functional reorganization after hemispherectomy in humans and animal models: What can we learn about the brain's resilience to extensive unilateral lesions?

Hemispherectomy (HS) is an effective surgical procedure aimed at managing otherwise intractable epilepsy in cases of diffuse unihemispheric pathologies. Neurological recovery in subjects treated with HS is not limited to seizure reduction, rather, sensory-motor and behavioral improvement is often observed. This outcome highlights the considerable capability of the brain to react to such an extensive lesion, by functionally reorganizing and rewiring the cerebral cortex, especially early in life. In this narrative review, we summarize the animal studies as well as the human neurophysiological and neuroimaging studies dealing with the reorganizational processes that occur after HS. These topics are of particular interest in understanding mechanisms of functional recovery after brain injury. HS offers the chance to investigate contralesional hemisphere activity in controlling ipsilateral limb movements, and the role of transcallosal interactions, before and after the surgical procedure. These post-injury neuroplastic phenomena actually differ from those observed after less extensive brain damage. Therefore, they illustrate how different lesions could lead the contralesional hemisphere to play the "good" or "bad" role in functional recovery. These issues may have clinical implications and could inform rehabilitation strategies aiming to improve functional recovery following unilateral hemispheric lesions. Future studies, involving large cohorts of hemispherectomized patients, will be necessary in order to obtain a greater understanding of how cerebral reorganization can contribute to residual sensorimotor, visual and auditory functions.

Primary visual cortical remapping in patients with inherited peripheral retinal degeneration

Human studies addressing the long-term effects of peripheral retinal degeneration on visual cortical function and structure are scarce. Here we investigated this question in patients with Retinitis Pigmentosa (RP), a genetic condition leading to peripheral visual degeneration. We acquired functional and anatomical magnetic resonance data from thirteen patients with different levels of visual loss and twenty-two healthy participants to study primary (V1) visual cortical retinotopic remapping and cortical thickness. We identified systematic visual field remapping in the absence of structural changes in the primary visual cortex of RP patients. Remapping consisted in a retinotopic eccentricity shift of central retinal inputs to more peripheral locations in V1. Importantly, this was associated with changes in visual experience, as assessed by the extent of the visual loss, with more constricted visual fields resulting in larger remapping. This pattern of remapping is consistent with expansion or shifting of neuronal receptive fields into the cortical regions with reduced retinal input. These data provide evidence for functional changes in V1 that are dependent on the magnitude of peripheral visual loss in RP, which may be explained by rapid cortical adaptation mechanisms or long-term cortical reorganization. This study highlights the importance of analyzing the retinal determinants of brain functional and structural alterations for future visual restoration approaches.

Dynamic Reorganization and Enzymatic Remodeling of Type IV Collagen at Cell-Biomaterial Interface

Vascular basement membrane remodeling involves assembly and degradation of its main constituents, type IV collagen (Col IV) and laminin, which is critical during development, angiogenesis, and tissue repair. Remodeling can also occur at cell-biomaterials interface altering significantly the biocompatibility of implants. Here we describe the fate of adsorbed Col IV in contact with endothelial cells adhering on positively charged NH2 or hydrophobic CH3 substrata, both based on self-assembly monolayers (SAMs) and studied alone or mixed in different proportions. AFM studies revealed distinct pattern of adsorbed Col IV, varying from single molecular deposition on pure NH2 to network-like assembly on mixed SAMs, turning to big globular aggregates on bare CH3. Human umbilical endothelial cells (HUVECs) interact better with Col IV adsorbed as single molecules on NH2 surface and readily rearrange it in fibril-like pattern that coincide with secreted fibronectin fibrils. The cells show flattened morphology and well-developed focal adhesion complexes that are rich on phosphorylated FAK while expressing markedly low pericellular proteolytic activity. Conversely, on hydrophobic CH3 substrata HUVECs showed abrogated spreading and FAK phosphorylation, combined with less reorganization of the aggregated Col IV and significantly increased proteolytic activity. The later involves both MMP-2 and MMP-9, as measured by zymography and FITC-Col IV release. The mixed SAMs support intermediate remodeling activity. Taken together these results show that chemical functionalization combined with Col IV preadsorption provides a tool for guiding the endothelial cells behavior and pericellular proteolytic activity, events that strongly affect the fate of cardiovascular implants.

Post-Surgical Language Reorganization Occurs in Tumors of the Dominant and Non-Dominant Hemisphere

PURPOSE

Surgical resection of brain tumors may shift the location of cortical language areas. Studies of language reorganization primarily investigated left-hemispheric tumors irrespective of hemispheric language dominance. We used functional magnetic resonance imaging (fMRI) to investigate how tumors influence post-surgical language reorganization in relation to the dominant language areas.

METHODS

A total of, 17 patients with brain tumors (16 gliomas, one metastasis) in the frontotemporal and lower parietal lobes planned for awake surgery underwent pre-surgical and post-surgical language fMRI. Language activation post-to-pre surgery was evaluated visually and quantitatively on the statistically thresholded images on patient-by-patient basis. Results were qualitatively compared between three patient groups: temporal, with tumors in the dominant temporal lobe, frontal, with tumors in the dominant frontal lobe and remote, with tumors in the non-dominant hemisphere.

RESULTS

Post-to-pre-surgical distributions of activated voxels changed in all except the one patient with metastasis. Changes were more pronounced in the dominant hemisphere for all three groups, showing increased number of activated voxels and also new activation areas. Tumor resection in the dominant hemisphere (frontal and temporal) shifted the activation from frontal towards temporal, whereas tumor resection in the non-dominant hemisphere shifted the activation from temporal towards frontal dominant areas.

CONCLUSION

Resection of gliomas in the dominant and in the non-dominant hemisphere induces postsurgical shifts and increase in language activation, indicating that infiltrating gliomas have a widespread influence on the language network. The dominant hemisphere gained most of the language activation irrespective of tumor localization, possibly reflecting recovery of pre-surgical tumor-induced suppression of these activations.

Congenital foot deformation alters the topographic organization in the primate somatosensory system

Limbs may fail to grow properly during fetal development, but the extent to which such growth alters the nervous system has not been extensively explored. Here we describe the organization of the somatosensory system in a 6-year-old monkey (Macaca radiata) born with a deformed left foot in comparison to the results from a normal monkey (Macaca fascicularis). Toes 1, 3, and 5 were missing, but the proximal parts of toes 2 and 4 were present. We used anatomical tracers to characterize the patterns of peripheral input to the spinal cord and brainstem, as well as between thalamus and cortex. We also determined the somatotopic organization of primary somatosensory area 3b of both hemispheres using multiunit electrophysiological recording. Tracers were subcutaneously injected into matching locations of each foot to reveal their representations within the lumbar spinal cord, and the gracile nucleus (GrN) of the brainstem. Tracers injected into the representations of the toes and plantar pads of cortical area 3b labeled neurons in the ventroposterior lateral nucleus (VPL) of the thalamus. Contrary to the orderly arrangement of the foot representation throughout the lemniscal pathway in the normal monkey, the plantar representation of the deformed foot was significantly expanded and intruded into the expected representations of toes in the spinal cord, GrN, VPL, and area 3b. We also observed abnormal representation of the intact foot in the ipsilateral spinal cord and contralateral area 3b. Thus, congenital malformation influences the somatotopic representation of the deformed as well as the intact foot.

Disconnection and hyper-connectivity underlie reorganization after TBI: A rodent functional connectomic analysis

While past neuroimaging methods have contributed greatly to our understanding of brain function after traumatic brain injury (TBI), resting state functional MRI (rsfMRI) connectivity methods have more recently provided a far more unbiased approach with which to monitor brain circuitry compared to task-based approaches. However, current knowledge on the physiologic underpinnings of the correlated blood oxygen level dependent signal, and how changes in functional connectivity relate to reorganizational processes that occur following injury is limited. The degree and extent of this relationship remain to be determined in order that rsfMRI methods can be fully adapted for determining the optimal timing and type of rehabilitative interventions that can be used post-TBI to achieve the best outcome. Very few rsfMRI studies exist after experimental TBI and therefore we chose to acquire rsfMRI data before and at 7, 14 and 28 days after experimental TBI using a well-known, clinically-relevant, unilateral controlled cortical impact injury (CCI) adult rat model of TBI. This model was chosen since it has widespread axonal injury, a well-defined time-course of reorganization including spine, dendrite, axonal and cortical map changes, as well as spontaneous recovery of sensorimotor function by 28 d post-injury from which to interpret alterations in functional connectivity. Data were co-registered to a parcellated rat template to generate adjacency matrices for network analysis by graph theory. Making no assumptions about direction of change, we used two-tailed statistical analysis over multiple brain regions in a data-driven approach to access global and regional changes in network topology in order to assess brain connectivity in an unbiased way. Our main hypothesis was that deficits in functional connectivity would become apparent in regions known to be structurally altered or deficient in axonal connectivity in this model. The data show the loss of functional connectivity predicted by the structural deficits, not only within the primary sensorimotor injury site and pericontused regions, but the normally connected homotopic cortex, as well as subcortical regions, all of which persisted chronically. Especially novel in this study is the unanticipated finding of widespread increases in connection strength that dwarf both the degree and extent of the functional disconnections, and which persist chronically in some sensorimotor and subcortically connected regions. Exploratory global network analysis showed changes in network parameters indicative of possible acutely increased random connectivity and temporary reductions in modularity that were matched by local increases in connectedness and increased efficiency among more weakly connected regions. The global network parameters: shortest path-length, clustering coefficient and modularity that were most affected by trauma also scaled with the severity of injury, so that the corresponding regional measures were correlated to the injury severity most notably at 7 and 14 days and especially within, but not limited to, the contralateral cortex. These changes in functional network parameters are discussed in relation to the known time-course of physiologic and anatomic data that underlie structural and functional reorganization in this experiment model of TBI.

The neurophysiology of language: Insights from non-invasive brain stimulation in the healthy human brain

With the advent of non-invasive brain stimulation (NIBS), a new decade in the study of language has started. NIBS allows for testing the functional relevance of language-related brain activation and enables the researcher to investigate how neural activation changes in response to focal perturbations. This review focuses on the application of NIBS in the healthy brain. First, some basic mechanisms will be introduced and the prerequisites for carrying out NIBS studies of language are addressed. The next section outlines how NIBS can be used to characterize the contribution of the stimulated area to a task. In this context, novel approaches such as multifocal transcranial magnetic stimulation and the condition-and-perturb approach are discussed. The third part addresses the combination of NIBS and neuroimaging in the study of plasticity. These approaches are particularly suited to investigate short-term reorganization in the healthy brain and may inform models of language recovery in post-stroke aphasia.

Lithium-induced developmental anomalies in the spirotrich ciliate Stylonychia lemnae (Ciliophora, Hypotrichida)

Lithium is known to have profound biological effects of varying intensity in different life forms. In the present investigation, the effect of lithium was studied on the spirotrich ciliate Stylonychia lemnae. Lithium treatment brings about quantitative changes in the patterning of ciliary structures in S. lemnae. The dorsal surface of the affected cells develops supernumerary ciliary kineties due to excessive proliferation of the kinetosomes. The ventral surface on the other hand develops fewer than normal cirri formed from reduced numbers of ciliary primordia. The adoral zone of membranelles (AZM) fails to remodel properly as, in certain segments, membranelles become disarranged and misaligned. Lithium-induced changes are transitory as the normal pattern is restored during recovery after the cells are shifted to normal medium, suggesting non-genic regulation of cortical pattern. Lithium also affects the process of cell proliferation as the number of cells undergoing division is negligible as compared to reorganizing cells. The results point to the extremely complex and heterogeneous organization of the cellular cortex (plasma membrane and cytoskeleton) which is capable of exerting autonomous control over the phenotype and cortical pattern.

Nonlinear population receptive field changes in human area V5/MT+ of healthy subjects with simulated visual field scotomas

There is extensive controversy over whether the adult visual cortex is able to reorganize following visual field loss (scotoma) as a result of retinal or cortical lesions. Functional magnetic resonance imaging (fMRI) methods provide a useful tool to study the aggregate receptive field properties and assess the capacity of the human visual cortex to reorganize following injury. However, these methods are prone to biases near the boundaries of the scotoma. Retinotopic changes resembling reorganization have been observed in the early visual cortex of normal subjects when the visual stimulus is masked to simulate retinal or cortical scotomas. It is not known how the receptive fields of higher visual areas, like hV5/MT+, are affected by partial stimulus deprivation. We measured population receptive field (pRF) responses in human area V5/MT+ of 5 healthy participants under full stimulation and compared them with responses obtained from the same area while masking the left superior quadrant of the visual field (“artificial scotoma” or AS). We found that pRF estimations in area hV5/MT+ are nonlinearly affected by the AS. Specifically, pRF centers shift towards the AS, while the pRF amplitude increases and the pRF size decreases near the AS border. The observed pRF changes do not reflect reorganization but reveal important properties of normal visual processing under different test-stimulus conditions.

Differences in AMPA and GABAA/B receptor subunit expression between the chronically reorganized cortex and brainstem of adult squirrel monkeys

The primate somatosensory neuraxis provides a highly translational model system with which to investigate adult neural plasticity. Here, we report immunohistochemical staining data for AMPA and GABAA/B receptor subunits of area 3b cortex and cuneate nucleus of adult squirrel monkeys one to five years after median and ulnar nerve transection. In Area 3B cortex, the expression of GluR1 AMPAR subunits in reorganized regions are significantly increased, while the expression of GluR2/3 AMPAR subunits are not. GABAA α1 subunit expression in the reorganized region is not significantly different from control regions. Presynaptic GABABR1a subunit expression was also not significantly different between reorganized and control regions, while postsynaptic GABABR1b subunit expression was significantly decreased. In the cuneate nucleus of the brainstem, the expression of GluR1 AMPAR subunits in reorganized regions was not significantly different, while GluR2/3 AMPAR subunit expression was significantly elevated. GABAA α1 subunit expression in the reorganized region was significantly decreased. Presynaptic GABABR1a subunit expression was not significantly different, while postsynaptic GABABR1b subunit expression was significantly decreased. When subunit expression is compared, brainstem and cortical patterns diverge over longer periods of recovery. Persistent patterns of change in the cortex are stable by 1-year. Alternatively, subunit expression in the cuneate nucleus one to five years after nerve injury is similar to that seen 1-month after a reorganizing injury. This suggests that cortical plasticity continues to change over many months as receptive field reorganization occurs, while brainstem plasticity obtains a level of stable persistence by one month.