Evaluate the effect of bone density variation on stress distribution at the bone-implant interface using numerical analysis

The current study aims to comprehend how different bone densities affect stress distribution at the bone-implant interface. This will help understand the behaviour and help predict success rates of the implant planted in different bone densities. The process of implantation involves the removal of bone from a small portion of the jawbone to replace either a lost tooth or an infected one and an implant is inserted in the cavity made as a result. Now the extent of fixation due to osseointegration is largely dependent on the condition of the bone in terms of the density. Generally, the density of the bone is classified into four categories namely D1, D2, D3, and D4; with D1 being purely cortical and D4 having higher percentage of cancellous bordered by cortical bone. A bone model with a form closely resembling the actual bone was made using 3D CAD software and was meshed using Hyper Mesh. The model was subjected to an oblique load of 120 N at 70° to the vertical to replicate occlusal loading. A finite element static analysis was done using Abaqus software. The stress distribution contours at the bone-implant contact zone were studied closely to understand the changes as a result of the varying density. It was revealed that as the quantity of the cancellous bone increased from D1 to D4 the cortical peak stress levels dropped. The bone density and the corresponding change in the material characteristics was also responsible for the variation in the peak stress and displacement values.

Intraoperative application and early experience with novel high-resolution, high-channel-count thin-film electrodes for human microelectrocorticography

OBJECTIVE

The study objective was to evaluate intraoperative experience with newly developed high-spatial-resolution microelectrode grids composed of poly(3,4-ethylenedioxythiophene) with polystyrene sulfonate (PEDOT:PSS), and those composed of platinum nanorods (PtNRs).

METHODS

A cohort of patients who underwent craniotomy for pathological tissue resection and who had high-spatial-resolution microelectrode grids placed intraoperatively were evaluated. Patient demographic and baseline clinical variables as well as relevant microelectrode grid characteristic data were collected. The primary and secondary outcome measures of interest were successful microelectrode grid utilization with usable resting-state or task-related data, and grid-related adverse intraoperative events and/or grid dysfunction.

RESULTS

Included in the analysis were 89 cases of patients who underwent a craniotomy for resection of neoplasms (n = 58) or epileptogenic tissue (n = 31). These cases accounted for 94 grids: 58 PEDOT:PSS and 36 PtNR grids. Of these 94 grids, 86 were functional and used successfully to obtain cortical recordings from 82 patients. The mean cortical grid recording duration was 15.3 ± 1.15 minutes. Most recordings in patients were obtained during experimental tasks (n = 52, 58.4%), involving language and sensorimotor testing paradigms, or were obtained passively during resting state (n = 32, 36.0%). There were no intraoperative adverse events related to grid placement. However, there were instances of PtNR grid dysfunction (n = 8) related to damage incurred by suboptimal preoperative sterilization (n = 7) and improper handling (n = 1); intraoperative recordings were not performed. Vaporized peroxide sterilization was the most optimal sterilization method for PtNR grids, providing a significantly greater number of usable channels poststerilization than did steam-based sterilization techniques (median 905.0 [IQR 650.8-935.5] vs 356.0 [IQR 18.0-597.8], p = 0.0031).

CONCLUSIONS

High-spatial-resolution microelectrode grids can be readily incorporated into appropriately selected craniotomy cases for clinical and research purposes. Grids are reliable when preoperative handling and sterilization considerations are accounted for. Future investigations should compare the diagnostic utility of these high-resolution grids to commercially available counterparts and assess whether diagnostic discrepancies relate to clinical outcomes.

Periodic and aperiodic changes to cortical EEG in response to pharmacological manipulation

Cortical electroencephalograms (EEGs) may help understanding of neuropsychiatric illness and new treatment mechanisms. The aperiodic component (1/f) of EEG power spectra is often treated as noise, but recent studies suggest that changes to the aperiodic exponent of power spectra may reflect changes in excitation/inhibition balance, a concept linked to antidepressant effects, epilepsy, autism, and other clinical conditions. One confound of previous studies is behavioral state, because factors associated with behavioral state other than excitation/inhibition ratio may alter EEG parameters. Thus, to test the robustness of the aperiodic exponent as a predictor of excitation/inhibition ratio, we analyzed video-EEG during active exploration in mice of both sexes during various pharmacological manipulations with the fitting oscillations and one over f (FOOOF) algorithm. We found that GABAA receptor (GABAAR)-positive allosteric modulators increased the aperiodic exponent, consistent with the hypothesis that an increased exponent signals enhanced cortical inhibition, but other drugs (ketamine and GABAAR antagonists at subconvulsive doses) did not follow the prediction. To tilt excitation/inhibition ratio more selectively toward excitation, we suppressed the activity of parvalbumin-positive interneurons with Designer Receptors Exclusively Activated by Designer Drugs (DREADDs). Contrary to our expectations, circuit disinhibition with the DREADD increased the aperiodic exponent. We conclude that the aperiodic exponent of EEG power spectra does not yield a universally reliable marker of cortical excitation/inhibition ratio.NEW & NOTEWORTHY Neuropsychiatric illness may be associated with altered excitation/inhibition balance. A single electroencephalogram (EEG) parameter, the aperiodic exponent of power spectra, may predict the ratio between excitation and inhibition. Here, we use cortical EEGs in mice to evaluate this hypothesis, using pharmacological manipulations of known mechanism. We show that the aperiodic exponent of EEG power spectra is not a reliable marker of excitation/inhibition ratio. Thus, alternative markers of this ratio must be sought.

Phenotypic spectrum of Progressive Supranuclear Palsy: Clinical study and APOE effect

Objectives

Progressive supranuclear palsy (PSP)is a rare neurodegenerative disorder encompassing several phenotypes with various motor and cognitive deficits.We aimed to study motor and cognitive characteristics across PSP phenotypes,and assess the influence of the Apolipoprotein E (APOE)gene variants on PSP phenotypic expression.

Materials and Methods

In 20-year-cross-sectional study, we retrospectively reviewed the charts of all patients classified as PSP and re-categorized them into phenotypes using the MDS-2017 criteria. Phenotypes were divided into three subgroups based on the clinical presentation during the first 3 years after symptoms' onset, which defines the early disease stage:Richardson's syndrome (PSP-RS), PSP-cortical (PSP-F+PSP-SL+PSP-CBS) and PSP-subcortical(PSP-P+PSP-PGF+PSP-PI+PSP-OM+PSP-C+PSP-PLS).Data on clinical and neuropsychological assessments were collected.Genotyping of APOE was performed using the RFLP-PCR and verified by Sanger sequencing.

Results

We included 112 PSP patients comprising 10 phenotypes classified into 48PSP-RS, 34PSP-cortical(17.6%PSP-CBS,9.4%PSP-F,8.2%PSP-SL)and 30 PSP-subcortical(11.6%PSP-P,8%PSP-PI, 2.6%PSP-OM,1.8%PSP-PGF,1.8%PSP-C,0.9%PSP-PLS) subgroups. PSP-RS cases had older age of onset(p=0.009)and more akinetic-rigid and levodopa resistant parkinsonism(p=0.006),while PSP-cortical cases had more tremor and asymmetric and/or levodopa responsive parkinsonism(p=0.025).Cognitive domains were significantly less altered among PSP-subcortical subgroup.Overall,PSP-APOEε4 carriers developed parkinsonism earlier (p=0.019),had earlier oculomotor dysfunction(p=0.052) and more altered cognitive profile.It was also associated with younger age of parkinsonism onset in PSP-RS phenotype(p=0.026).

Conclusion

This study demonstrated the wide phenotypic spectrum of PSP among Tunisians.Later disease onset and akinetic-rigid and levodopa resistant parkinsonism were the hallmarks of PSP-RS phenotype,while milder cognitive impairment was characteristic of PSP-subcortical subgroup.APOEε4 allele was associated to earlier parkinsonism and oculomotor dysfunction and seemed to play a role in defining a more altered cognitive profile in PSP patients.

A taxonomy for superficial cerebral cavernous malformations: subtypes of cortical and subcortical lesions

OBJECTIVE

A taxonomy for superficial cerebral cavernous malformations (CMs), those based cortically in gyral gray matter or subcortically in underlying white matter, is proposed to build on the comprehensive, systematic characterization of CMs in the entire brain.

METHODS

Patients with superficial cerebral CMs were retrospectively analyzed from a consecutive surgical series between November 2008 and June 2021 at the authors' center. Superficial cerebral CMs were categorized into 4 subtypes based on their cortical location or, if subcortical, proximity to the nearest cerebral surface: convexity, medial, basal, and sylvian. Lobar location was also included for subtyping: frontal, temporal, parietal, and occipital.

RESULTS

A total of 362 CMs were resected in 346 patients. CM subtypes were as follows: 132 (36.5%) convexity, 78 (21.5%) medial, 72 (19.9%) basal, and 80 (22.1%) sylvian. Frontal CMs were most common (155 [42.8%]), followed by parietal (89 [24.6%]), temporal (87 [24.0%]), and occipital (31 [8.6%]). Of all CMs, 302 (83.4%) were cortical and 60 (16.6%) were subcortical. The mean subcortical depth of deep lesions was 2.97 cm, and the mean lesion volume was 4.68 cm3. Overall, 228 lesions (63.0%) were resected through a transgyral approach, and 134 (37.0%) were resected through a transsulcal approach. Good outcomes (modified Rankin Scale [mRS] score ≤ 2) were observed in 314 patients (86.7%) and poor outcomes (mRS score > 2) in 25 patients (6.9%), and 23 patients (6.4%) were lost to late follow-up (mean follow-up duration 11.5 months). Relative outcomes were good (unchanged or improved mRS score) in 327 patients (90.3%) and poor (worse or died) in 35 patients (9.7%).

CONCLUSIONS

Superficial cerebral CMs were resected through a gyrus or sulcus to open the subarachnoid dissection corridors, traversing the full extent of sulci to deepen the approach and minimize tissue transgression. Transgyral dissection avoids associated arteries but is inherently transgressive, whereas transsulcal dissection preserves cortical tissue and may reduce morbidity. Superficial cerebral CMs occupy the largest territory of the 7 types, and the size and surface complexity of the cerebrum make taxonomic subtyping valuable for clear anatomical description.

The articular surface technique for lumbar pedicle screw placement: a 3D feasibility study

Background

Traditional pedicle screws (TPSs) and cortical based trajectory pedicle screws each apply stability with fusions of the lumbar spine and have shown good success. However, the technical considerations of each technique imply complications of loosening and failure that either technique is uniquely prone to having. The current study proposes a new pedicle screw technique through the articular surface of the vertebral superior facet. It is hypothesized that this path will allow utilization of a larger screw that rivals that of the TPS technique, while also maintaining the high-density bone encountered in the cortical based trajectory technique.

Methods

Retrospective review of 50 consecutive trauma patients that underwent lumbar computed tomography (CT) scans at a Level 1 Trauma Center in the age range 18-45. These scans were uploaded to Brainlab software for ideal starting point and trajectory mapping of pedicle screws coursing through each superior facet and pedicle of vertebral levels L1-S1 without cortical breach. Satisfactory pedicle screw variables consisted of a medial angle <10 degrees, screw length at least 30 mm, screw width at least 5.0 mm, and starting point measurements such as distance to the inferior articular surface and distance to the lateral articular surface.

Results

A total of 600 virtual pedicle screws were placed, in which 525 were satisfactory and measured with the above variables. The pedicle widths were shown to significantly widen with lower-level vertebra in the lumbar spine. Approximately 72% of unsuccessful pedicle screws were placed in levels L1 and L2 allowing wider pedicle screws to be placed more further down the vertebral column.

Conclusions

The articular surface technique (AST) for pedicle screw placement is a viable alternative in lumbar spinal fusions that offers decreased soft tissue dissection. However, the technique is likely better suited for lower lumbar fusions in L3 to S1.

Sonographic cortical bone thickness measurement: can it predict bone mineral density in the pediatric population?

PURPOSE

To explore sonographic cortical bone thickness (CoT) as a potential indicator of bone mineral density (BMD) measured by dual-energy X-ray absorptiometry for screening and diagnosing pediatric osteoporosis.

METHODS

A prospective study included 41 osteopenic or osteoporotic patients and 52 healthy children. Radius cortical thickness (R-CoT), tibial cortical thickness (T-CoT), and second metatarsal cortical thickness (M-CoT) were measured by B-mode ultrasound; CoT values were compared between groups and the correlation between BMD and CoT was examined.

RESULTS

There were no significant differences in R-CoT (P = 0.433), T-CoT (P = 0.057), and M-CoT (P = 0.978) values between the patient and control groups. No significant correlations were found between BMD T-scores and R-CoT (r = -0.073, P = 0.490), T-CoT (r = -0.154, P = 0.141), and M-CoT (r = 0.047, P = 0.657) values.

CONCLUSION

Sonographic CoT values in children do not correlate with BMD values. Unlike in adults, sonographic CoT measurements do not appear to have a role in assessing BMD in the pediatric population.

Reproducible Differentiation of Human Pluripotent Stem Cells into Two-Dimensional Cortical Neuron Cultures with Checkpoints for Success

The patterning of excitatory cortical neurons from human pluripotent stem cells (hPSCs) is a desired technique for the study of neurodevelopmental disorders, as neurons can be created and compared from control hPSC lines, hPSC lines generated from patients, and CRISPR-modified hPSC lines. Therefore, this technique allows for the examination of disease phenotypes and assists in the development of potential new therapeutics for neurodevelopmental disorders. Many protocols, however, are optimized for use with specific hPSC lines or within a single laboratory, and they often provide insufficient guidance on how to identify positive stages in the differentiation or how to troubleshoot. Here, we present an efficient and reproducible directed differentiation protocol to generate two-dimensional cultures of hPSC-derived excitatory cortical neurons without intermediary embryoid body formation. This novel protocol is supported by our data generated with five independent hPSC lines and in two independent laboratories. Importantly, as neuronal differentiations follow a long time course to reach maturity, we provide extensive guidance regarding morphological and flow cytometry checkpoints allowing for early indications of successful differentiation. We also include extensive troubleshooting tips and support protocols to assist the operator. The goal of this protocol is to assist others in the successful differentiation of excitatory cortical neurons from hPSCs. © 2023 Wiley Periodicals LLC. Basic Protocol: Directed differentiation of hPSCs into excitatory cortical neurons Support Protocol 1: Harvesting and fixing cells for flow cytometry analyses Support Protocol 2: Performing flow cytometry analyses Support Protocol 3: Thawing NPCs from a cryopreserved stock Alternate Protocol 1: Continuing Expansion of NPCs Alternate Protocol 2: Treatment of neurons with Ara-C to ablate radial glia Support Protocol 4: Experimental methods for validation of excitatory cortical neurons.

Auditory Cortex Maturation and Language Development in Children with Hearing Loss and Additional Disabilities

A significant portion of hearing-impaired children have additional disabilities, but data about the maturation of their auditory cortex are scarce. In these children, behavioral tests are often unreliable, and objective tests are needed for diagnostics and follow-up. This study aimed to explore auditory cortical maturation and language development, and the usability of an objective electroencephalogram-based biomarker in children with multiple disabilities. In 65 hearing aid and cochlear implant users (36 females; 36 with multiple disabilities; 44.3 ± 18.5 months of age, mean ± SD), auditory processing was examined using the P1 cortical auditory evoked response biomarker, and language development with the Preschool Language Scales 5th edition (PLS-5). During the study, all of the children received intensive extra language therapy for six months. No significant differences were found between the groups in P1 latency development, the proportion of abnormal P1 latencies, or the number of children whose P1 latencies changed from abnormal to normal during the study. The PLS-5 total language scores, auditory comprehension scores, or expressive communication scores did not differ between groups either. The P1 latencies showed meaningful negative correlations with the language scores. The results suggest that auditory cortex development is similar in hearing-impaired children with/without additional disabilities, and the P1 biomarker is a feasible tool to evaluate central auditory maturation in children with multiple disabilities.

Neural Correlates of Individual Differences in Speech-in-Noise Performance in a Large Cohort of Cochlear Implant Users

OBJECTIVES

Understanding speech-in-noise (SiN) is a complex task that recruits multiple cortical subsystems. Individuals vary in their ability to understand SiN. This cannot be explained by simple peripheral hearing profiles, but recent work by our group ( Kim et al. 2021 , Neuroimage ) highlighted central neural factors underlying the variance in SiN ability in normal hearing (NH) subjects. The present study examined neural predictors of SiN ability in a large cohort of cochlear-implant (CI) users.

DESIGN

We recorded electroencephalography in 114 postlingually deafened CI users while they completed the California consonant test: a word-in-noise task. In many subjects, data were also collected on two other commonly used clinical measures of speech perception: a word-in-quiet task (consonant-nucleus-consonant) word and a sentence-in-noise task (AzBio sentences). Neural activity was assessed at a vertex electrode (Cz), which could help maximize eventual generalizability to clinical situations. The N1-P2 complex of event-related potentials (ERPs) at this location were included in multiple linear regression analyses, along with several other demographic and hearing factors as predictors of SiN performance.

RESULTS

In general, there was a good agreement between the scores on the three speech perception tasks. ERP amplitudes did not predict AzBio performance, which was predicted by the duration of device use, low-frequency hearing thresholds, and age. However, ERP amplitudes were strong predictors for performance for both word recognition tasks: the California consonant test (which was conducted simultaneously with electroencephalography recording) and the consonant-nucleus-consonant (conducted offline). These correlations held even after accounting for known predictors of performance including residual low-frequency hearing thresholds. In CI-users, better performance was predicted by an increased cortical response to the target word, in contrast to previous reports in normal-hearing subjects in whom speech perception ability was accounted for by the ability to suppress noise.

CONCLUSIONS

These data indicate a neurophysiological correlate of SiN performance, thereby revealing a richer profile of an individual's hearing performance than shown by psychoacoustic measures alone. These results also highlight important differences between sentence and word recognition measures of performance and suggest that individual differences in these measures may be underwritten by different mechanisms. Finally, the contrast with prior reports of NH listeners in the same task suggests CI-users performance may be explained by a different weighting of neural processes than NH listeners.

MR-based techniques for intracortical vessel visualization and characterization: understanding the impact of microvascular disease on skeletal health

PURPOSE OF REVIEW

The relationships between bone vasculature and bone microstructure and strength remain incompletely understood. Addressing this gap will require in vivo imaging capabilities. We describe the relevant vascular anatomy of compact bone, review current magnetic resonance imaging (MRI)-based techniques that allow in vivo assessment of intracortical vasculature, and finally present preliminary studies that apply these techniques to investigate changes in intracortical vessels in aging and disease.

RECENT FINDINGS

Ultra-short echo time MRI (UTE MRI), dynamic contrast-enhanced MRI (DCE-MRI), and susceptibility-weighted MRI techniques are able to probe intracortical vasculature. Applied to patients with type 2 diabetes, DCE-MRI was able to find significantly larger intracortical vessels compared to nondiabetic controls. Using the same technique, a significantly larger number of smaller vessels was observed in patients with microvascular disease compared to those without. Preliminary data on perfusion MRI showed decreased cortical perfusion with age.

SUMMARY

Development of in vivo techniques for intracortical vessel visualization and characterization will enable the exploration of interactions between the vascular and skeletal systems, and further our understanding of drivers of cortical pore expansion. As we investigate potential pathways of cortical pore expansion, appropriate treatment and prevention strategies will be clarified.

Differential gene expression in the calvarial and cortical bone of juvenile female mice

Introduction

Both the calvarial and the cortical bones develop through intramembranous ossification, yet they have very different structures and functions. The calvaria enables the rapid while protected growth of the brain, whereas the cortical bone takes part in locomotion. Both types of bones undergo extensive modeling during embryonic and post-natal growth, while bone remodeling is the most dominant process in adults. Their shared formation mechanism and their highly distinct functions raise the fundamental question of how similar or diverse the molecular pathways that act in each bone type are.

Methods

To answer this question, we aimed to compare the transcriptomes of calvaria and cortices from 21-day old mice by bulk RNA-Seq analysis.

Results

The results revealed clear differences in expression levels of genes related to bone pathologies, craniosynostosis, mechanical loading and bone-relevant signaling pathways like WNT and IHH, emphasizing the functional differences between these bones. We further discussed the less expected candidate genes and gene sets in the context of bone. Finally, we compared differences between juvenile and mature bone, highlighting commonalities and dissimilarities of gene expression between calvaria and cortices during post-natal bone growth and adult bone remodeling.

Discussion

Altogether, this study revealed significant differences between the transcriptome of calvaria and cortical bones in juvenile female mice, highlighting the most important pathway mediators for the development and function of two different bone types that originate both through intramembranous ossification.

Spatial Variation in Young Ovine Cortical Bone Properties

Significant effort continues to be made to understand whether differences exist in the structural, compositional, and mechanical properties of cortical bone subjected to different strain modes or magnitudes. We evaluated juvenile sheep femora (age = 4 months) from the anterior and posterior quadrants at three points along the diaphysis as a model system for variability in loading. Micro-CT scans (50 micron) were used to measure cortical thickness and mineral density. Three point bending tests were performed to measure the flexural modulus, strength, and post-yield displacement. There was no difference in cortical thickness or density between anterior or posterior quadrants; however, density was consistently higher in the middle diaphysis. Interestingly, bending modulus and strength were higher in anterior quadrants compared to posterior quadrants. Together, our results suggest that there is a differential spatial response of bone in terms of elastic bending modulus and mechanical strength. The origins of this difference may lie within the variation in ongoing mineralization, in combination with the collagen-rich plexiform structure, and whether this is related to strain mode remains to be explored. These data suggest that in young ovine cortical bone, modulation of strength occurs via potentially complex interactions of both mineral and collagen-components that may be different in regions of bone exposed to variable amounts of strain. Further work is needed to confirm the physiological load state of bone during growth to better elucidate the degree to which these variations are a function of the local mechanical environment.

Abaloparatide prevents immobilization-induced cortical but not trabecular bone loss after spinal cord injury

Spinal cord injury (SCI) causes severe and resistant sublesional disuse bone loss. Abaloparatide, a modified parathyroid hormone related peptide, is an FDA approved drug for treatment of severe osteoporosis with potent anabolic activity. The effects of abaloparatide on SCI-induced bone loss remain undefined. Thus, female mice underwent sham or severe contusion thoracic SCI causing hindlimb paralysis. Mice then received subcutaneous injection of vehicle or 20 μg/kg/day abaloparatide for 35 days. Micro-computed tomography (micro-CT) analysis of the distal and midshaft femoral regions of the SCI-vehicle mice revealed reduced trabecular fractional bone volume (56%), thickness (75%), and cortical thickness (80%) compared to sham-vehicle controls. Treatment with abaloparatide did not prevent SCI-induced changes in trabecular or cortical bone. However, histomorphometry evaluation of the SCI-abaloparatide mice demonstrated that abaloparatide treatment increased osteoblast (241%) and osteoclast (247%) numbers and the mineral apposition rate (131%) compared to SCI-vehicle animals. In another independent experiment, treatment with 80 μg/kg/day abaloparatide significantly attenuated SCI-induced loss in cortical bone thickness (93%) when compared to SCI-vehicle mice (79%) but did not prevent SCI-induced trabecular bone loss or elevation in cortical porosity. Biochemical analysis of the bone marrow supernatants of the femurs showed that SCI-abaloparatide animals had 2.3-fold increase in procollagen type I N-terminal propeptide, a bone formation marker than SCI-vehicle animals. SCI groups had 70% higher levels of cross-linked C-telopeptide of type I collagen, a bone resorption marker, than sham-vehicle mice. These findings suggest that abaloparatide protects the cortical bone against the deleterious effects of SCI by promoting bone formation.

Relationships between Cerebral Vasculopathies and Microinfarcts in a Community-Based Cohort of Older Adults

Cerebral microinfarcts are associated with cognitive impairment and dementia. Small vessel diseases such as cerebral arteriolosclerosis and cerebral amyloid angiography (CAA) have been found to be associated with microinfarcts. Less is known about the associations of these vasculopathies with the presence, numbers, and location of microinfarcts. These associations were examined in the clinical and autopsy data of 842 participants in the Adult Changes in Thought (ACT) study. Both vasculopathies were categorized by severity (none, mild, moderate, and severe) and region (cortical and subcortical). Odds ratios (OR) and 95% CIs for microinfarcts associated with arteriolosclerosis and CAA adjusted for possible modifying covariates such as age at death, sex, blood pressure, APOE genotype, Braak, and CERAD were estimated. 417 (49.5%) had microinfarcts (cortical, 301; subcortical, 249), 708 (84.1%) had cerebral arteriolosclerosis, 320 (38%) had CAA, and 284 (34%) had both. Ors (95% CI) for any microinfarct were 2.16 (1.46-3.18) and 4.63 (2.90-7.40) for those with moderate (n = 183) and severe (n = 124) arteriolosclerosis, respectively. Respective Ors (95% CI) for the number of microinfarcts were 2.25 (1.54-3.30) and 4.91 (3.18-7.60). Similar associations were observed for cortical and subcortical microinfarcts. Ors (95% Cis) for the number of microinfarcts associated with mild (n = 75), moderate (n = 73), and severe (n = 15) amyloid angiopathy were 0.95 (0.66-1.35), 1.04 (0.71-1.52), and 2.05 (0.94-4.45), respectively. Respective Ors (95% Cis) for cortical microinfarcts were 1.05 (0.71-1.56), 1.50 (0.99-2.27), and 1.69 (0.73-3.91). Respective Ors (95% Cis) for subcortical microinfarcts were 0.84 (0.55-1.28), 0.72 (0.46-1.14), and 0.92 (0.37-2.28). These findings suggest a significant association of cerebral arteriolosclerosis with the presence, number, and location (cortical and subcortical) of microinfarcts, and a weak and non-significant association of CAA with each microinfarct, highlighting the need for future research to better understand the role of small vessel diseases in the pathogenesis of cerebral microinfarcts.

Altered microstructure of the contralesional ventral premotor cortex and motor output after stroke

Cortical thickness analyses have provided valuable insights into changes in cortical brain structure after stroke and their association with recovery. Across studies though, relationships between cortical structure and function show inconsistent results. Recent developments in diffusion-weighted imaging of the cortex have paved the way to uncover hidden aspects of stroke-related alterations in cortical microstructure, going beyond cortical thickness as a surrogate for cortical macrostructure. We re-analysed clinical and imaging data of 42 well-recovered chronic stroke patients from 2 independent cohorts (mean age 64 years, 4 left-handed, 71% male, 16 right-sided strokes) and 33 healthy controls of similar age and gender. Cortical fractional anisotropy and cortical thickness values were obtained for six key sensorimotor areas of the contralesional hemisphere. The regions included the primary motor cortex, dorsal and ventral premotor cortex, supplementary and pre-supplementary motor areas, and primary somatosensory cortex. Linear models were estimated for group comparisons between patients and controls and for correlations between cortical fractional anisotropy and cortical thickness and clinical scores. Compared with controls, stroke patients exhibited a reduction in fractional anisotropy in the contralesional ventral premotor cortex (P = 0.005). Fractional anisotropy of the other regions and cortical thickness did not show a comparable group difference. Higher fractional anisotropy of the ventral premotor cortex, but not cortical thickness, was positively associated with residual grip force in the stroke patients. These data provide novel evidence that the contralesional ventral premotor cortex might constitute a key sensorimotor area particularly susceptible to stroke-related alterations in cortical microstructure as measured by diffusion MRI and they suggest a link between these changes and residual motor output after stroke.

Acute effects of neuromuscular electrical stimulation on cortical dynamics and reflex activation

Superimposing neuromuscular electrical stimulation (NMES) on voluntary muscle contractions has shown the potential to improve motor performance even more than voluntary exercise alone. Nevertheless, the neurophysiological and neurocognitive mechanisms underlying this technique are still unclear. The aim of this study was to investigate the acute responses in spinal excitability, and brain activity following three conditions: NMES superimposed on isometric contractions (NMES+ISO), passive NMES, and voluntary isometric contractions (ISO). Each condition involved fifteen intermittent ankle plantar-flexions at submaximal level. Before and after each condition, tibial nerve stimulation was used to elicit H-reflexes, which represent a measure of spinal excitability, and somatosensory evoked potentials (SEPs), which index the activity of subcortical and cortical somatosensory areas. H-reflex amplitudes increased following NMES+ISO and decreased following passive NMES compared to baseline values. Subcortical lemniscal activity remained unaltered after the conditions. Activity in both primary and secondary somatosensory cortices (S1 and S2) increased after the NMES+ISO and decreased after the ISO condition. At later stages of S2 processing, cortical activity increased also after NMES, however the NMES+ISO effect was greater than that produced by NMES alone. These findings indicate that the beneficial effects of the NMES may be mediated by potentiation of the reflex pathways at the spinal level. At the brain level, peripheral input representation in the brainstem was not influenced by the experimental conditions which, conversely, altered cortical activity by affecting the synaptic efficiency through the somatosensory pathway. While the ISO effect was suppressive, the NMES was excitatory, especially if combined with voluntary contractions.

Galvanic Vestibular Stimulation Activates the Parietal and Temporal Cortex in Humans: A functional near-infrared spectroscopy (fNIRS) Study

Galvanic Vestibular Stimulation (GVS) helps stabilize subjects when balance and posture are compromised. This work aimed to define the cortical regions that GVS activates in normal subjects. We used Functional Near-Infrared Spectroscopy (fNIRS) to test the hypothesis that GVS activates similar cortical areas as a passive movement. We used transcranial current stimulation (cathode in the right mastoid process and anode in the FPz frontopolar point) of bipolar direct current (2 mA), false GVS (sham), vibration (neutral stimulus), and back and forth motion (positive control of vestibular movement) in 18 clinically healthy volunteers. Seventy-two brain scans were performed, applying a crossover-type experimental design. We measured the heart rate, blood pressure, body temperature, head capacitance, and resistance before and after the experiment. The hemodynamic changes of the cerebral cortex were recorded with an arrangement of 26 channels in four regions to perform an ROI-level analysis. The back-and-forth motion produced the most significant oxygenated Hemoglobin (HbO₂ ) increase. The response was similar for the GVS stimulus on the anterior and posterior parietal and right temporal regions. Sham and vibrational conditions did not produce significant changes ROI-wise. The results indicate that GVS produces a cortical activation coherent with displacement percept.

Large-scale analysis of structural brain asymmetries in schizophrenia via the ENIGMA consortium

Left-right asymmetry is an important organizing feature of the healthy brain that may be altered in schizophrenia, but most studies have used relatively small samples and heterogeneous approaches, resulting in equivocal findings. We carried out the largest case-control study of structural brain asymmetries in schizophrenia, with MRI data from 5,080 affected individuals and 6,015 controls across 46 datasets, using a single image analysis protocol. Asymmetry indexes were calculated for global and regional cortical thickness, surface area, and subcortical volume measures. Differences of asymmetry were calculated between affected individuals and controls per dataset, and effect sizes were meta-analyzed across datasets. Small average case-control differences were observed for thickness asymmetries of the rostral anterior cingulate and the middle temporal gyrus, both driven by thinner left-hemispheric cortices in schizophrenia. Analyses of these asymmetries with respect to the use of antipsychotic medication and other clinical variables did not show any significant associations. Assessment of age- and sex-specific effects revealed a stronger average leftward asymmetry of pallidum volume between older cases and controls. Case-control differences in a multivariate context were assessed in a subset of the data (N = 2,029), which revealed that 7% of the variance across all structural asymmetries was explained by case-control status. Subtle case-control differences of brain macrostructural asymmetry may reflect differences at the molecular, cytoarchitectonic, or circuit levels that have functional relevance for the disorder. Reduced left middle temporal cortical thickness is consistent with altered left-hemisphere language network organization in schizophrenia.

The relationship between the interictal epileptiform discharge source connectivity and cortical structural couplings in temporal lobe epilepsy

Objective

The objective of this study was to explore the relation between interictal epileptiform discharge (IED) source connectivity and cortical structural couplings (SCs) in temporal lobe epilepsy (TLE).

Methods

High-resolution 3D-MRI and 32-sensor EEG data from 59 patients with TLE were collected. Principal component analysis was performed on the morphological data on MRI to obtain the cortical SCs. IEDs were labeled from EEG data and averaged. The standard low-resolution electromagnetic tomography analysis was performed to locate the source of the average IEDs. Phase-locked value was used to evaluate the IED source connectivity. Finally, correlation analysis was used to compare the IED source connectivity and the cortical SCs.

Results

The features of the cortical morphology in left and right TLE were similar across four cortical SCs, which could be mainly described as the default mode network, limbic regions, connections bilateral medial temporal, and connections through the ipsilateral insula. The IED source connectivity at the regions of interest was negatively correlated with the corresponding cortical SCs.

Significance

The cortical SCs were confirmed to be negatively related to IED source connectivity in patients with TLE as detected with MRI and EEG coregistered data. These findings suggest the important role of intervening IEDs in treating TLE.

Electroencephalography Signatures for Hepatic Encephalopathy in Cirrhosis Patients Treated with Proton Pump Inhibitors: An Exploratory Pilot Study

(1) Background: Hepatic encephalopathy (HE) is a common complication in cirrhosis patients, and recently, clinical evidence indicates that a higher risk of HE is associated with the usage of proton pump inhibitors. However, the cortical mechanism underlying this neurological disorder of HE remains unknown. (2) Methods: We review the medical recordings of 260 patients diagnosed with liver cirrhosis between January 2021 and March 2022 in one tertiary hospital. Logistic regression analyses were performed to identify the risk factor of HE development. To examine the relationship between cortical dynamics and the administration of proton pump inhibitors, resting-state electroencephalograms (EEGs) were conducted in cirrhosis patients who were treated with proton pump inhibitors. (3) Results: About 28.5% (74 out of 260) of participants developed secondary HE in this study. The logistics regression model indicated that multiple risk factors were associated with the incidence of secondary HE, including proton pump inhibitors usage, white blood cell and neutrophil counts, hemoglobin, prothrombin time activity, and blood urea nitrogen. A total of twelve cirrhosis patients who were scheduled to use proton pump inhibitors consented to performing electroencephalogram recordings upon admission, and eight of twelve participants were diagnosed with HE. Spectral analysis revealed that the decrease in alpha oscillation activities was potentially associated with the development of HE. (4) Conclusions: Our data support the susceptibility of secondary HE in cirrhosis patients treated by proton pump inhibitors. One potential cortical mechanism underlying the neurological disease is the suppression of alpha oscillations in the brain.

Large-scale biophysically detailed model of somatosensory thalamocortical circuits in NetPyNE

The primary somatosensory cortex (S1) of mammals is critically important in the perception of touch and related sensorimotor behaviors. In 2015, the Blue Brain Project (BBP) developed a groundbreaking rat S1 microcircuit simulation with over 31,000 neurons with 207 morpho-electrical neuron types, and 37 million synapses, incorporating anatomical and physiological information from a wide range of experimental studies. We have implemented this highly detailed and complex S1 model in NetPyNE, using the data available in the Neocortical Microcircuit Collaboration Portal. NetPyNE provides a Python high-level interface to NEURON and allows defining complicated multiscale models using an intuitive declarative standardized language. It also facilitates running parallel simulations, automates the optimization and exploration of parameters using supercomputers, and provides a wide range of built-in analysis functions. This will make the S1 model more accessible and simpler to scale, modify and extend in order to explore research questions or interconnect to other existing models. Despite some implementation differences, the NetPyNE model preserved the original cell morphologies, electrophysiological responses and spatial distribution for all 207 cell types; and the connectivity properties of all 1941 pathways, including synaptic dynamics and short-term plasticity (STP). The NetPyNE S1 simulations produced reasonable physiological firing rates and activity patterns across all populations. When STP was included, the network generated a 1 Hz oscillation comparable to the original model in vitro-like state. By then reducing the extracellular calcium concentration, the model reproduced the original S1 in vivo-like states with asynchronous activity. These results validate the original study using a new modeling tool. Simulated local field potentials (LFPs) exhibited realistic oscillatory patterns and features, including distance- and frequency-dependent attenuation. The model was extended by adding thalamic circuits, including 6 distinct thalamic populations with intrathalamic, thalamocortical (TC) and corticothalamic connectivity derived from experimental data. The thalamic model reproduced single known cell and circuit-level dynamics, including burst and tonic firing modes and oscillatory patterns, providing a more realistic input to cortex and enabling study of TC interactions. Overall, our work provides a widely accessible, data-driven and biophysically-detailed model of the somatosensory TC circuits that can be employed as a community tool for researchers to study neural dynamics, function and disease.

Temporal relations between peripheral and central arousals in good and poor sleepers

Good sleepers and patients with insomnia symptoms (poor sleepers) were tracked with two measures of arousal; conventional polysomnography (PSG) for electroencephalogram (EEG) assessed cortical arousals, and a peripheral arterial tonometry device was used for the detection of peripheral nervous system (PNS) arousals associated with vasoconstrictions. The relationship between central (cortical) and peripheral (autonomic) arousals was examined by evaluating their close temporal dynamics. Cortical arousals almost invariably were preceded and followed by peripheral activations, while large peripheral autonomic arousals were followed by cortical arousals only half of the time. The temporal contiguity of these two types of arousals was altered in poor sleepers, and poor sleepers displayed a higher number of cortical and peripheral arousals compared with good sleepers. Given the difference in the number of peripheral autonomic arousals between good and poor sleepers, an evaluation of such arousals could become a means of physiologically distinguishing poor sleepers.

A Platform for Spatiotemporal "Matrix" Stimulation in Brain Networks Reveals Novel Forms of Circuit Plasticity

Here we demonstrate a facile method by which to deliver complex spatiotemporal stimulation to neural networks in fast patterns, to trigger interesting forms of circuit-level plasticity in cortical areas. We present a complete platform by which patterns of electricity can be arbitrarily defined and distributed across a brain circuit, either simultaneously, asynchronously, or in complex patterns that can be easily designed and orchestrated with precise timing. Interfacing with acute slices of mouse cortex, we show that our system can be used to activate neurons at many locations and drive synaptic transmission in distributed patterns, and that this elicits new forms of plasticity that may not be observable via traditional methods, including interesting measurements of associational and sequence plasticity. Finally, we introduce an automated "network assay" for imaging activation and plasticity across a circuit. Spatiotemporal stimulation opens the door for high-throughput explorations of plasticity at the circuit level, and may provide a basis for new types of adaptive neural prosthetics.

Differential Diagnosis between Child Abuse and Infantile Cortical Hyperostosis: A Case Report and Literature Review

Child abuse is a major public health problem that can lead to critical consequences for the child and family. However, early identification of abuse may be difficult. An 8-month-old boy presented with extensive periosteal reaction in both upper and lower long bones. There was no specific history of injury. Caffey disease was initially considered as the diagnosis because the patient displayed fever and hyperostosis of multiple bones with elevated erythrocyte sedimentation rates and C-reactive protein and alkaline phosphatase levels. However, we suspected child abuse based on the clinical and radiological features. We eventually found out that the child had been injured through child abuse and were able to treat him. We report this case because child abuse cases may be confused with Caffey disease. This case report can, therefore, help distinguish between Caffey disease and child abuse.

Nutrients, Cognitive Function, and Brain Aging: What We Have Learned from Dogs

Due to a difference in genetics, environmental factors, and nutrition, just like in people, dogs age at different rates. Brain aging in people and dogs share similar morphological changes including irreversible cortical atrophy, cerebral amyloid angiopathy, and ventricular enlargement. Due to severe and irreversible brain atrophy, some aging dogs develop cognitive dysfunction syndrome (CDS), which is equivalent to dementia or Alzheimer’s disease (AD) in people. The risk factors and causes of CDS in dogs have not been fully investigated, but age, gender, oxidative stress, and deficiency of sex hormones appears to be associated with increased risk of accelerated brain aging and CDS in dogs. Both AD and CDS are incurable diseases at this moment, therefore more efforts should be focused on preventing or reducing brain atrophy and minimizing the risk of AD in people and CDS in dogs. Since brain atrophy leads to irreversible cognitive decline and dementia, an optimal nutritional solution should be able to not only enhance cognitive function during aging but also reduce irreversible brain atrophy. Up to now, only one nutritional intervention has demonstrated both cognition-enhancing benefits and atrophy-reducing benefits.

Neonatal Hypoxia-Ischemia Causes Persistent Intracortical Circuit Changes in Layer 4 of Rat Auditory Cortex

The connection between early brain injury and subsequent development of disorders is unknown. Neonatal hypoxia-ischemia (HI) alters circuits associated with subplate neurons (SPNs). SPNs are among the first maturing cortical neurons, project to thalamorecipient layer 4 (L4), and are required for the development of thalamocortical connections. Thus, early HI might influence L4 and such influence might persist. We investigated functional circuits to L4 neurons in neonatal rat HI models of different severities (mild and moderate) shortly after injury and at adolescence. We used laser-scanning photostimulation in slices of auditory cortex during P5-10 and P18-23. Mild injuries did not initially (P6/P7) alter the convergence of excitatory inputs from L2/3, but hyperconnectivity emerged by P8-10. Inputs from L4 showed initial hypoconnectivity which resolved by P8-10. Moderate injuries resulted in initial hypoconnectivity from both layers which resolved by P8-10 and led to persistent strengthening of connections. Inhibitory inputs to L4 cells showed similar changes. Functional changes were mirrored by reduced dendritic complexity. We also observed a persistent increase in similarity of L4 circuits, suggesting that HI interferes with developmental circuit refinement and diversification. Altogether, our results show that neonatal HI injuries lead to persistent changes in intracortical connections.

Preliminary image findings of lower limb stress fractures to aid ultrasonographic diagnoses: A systematic review and narrative synthesis

INTRODUCTION

This systematic review investigates which image appearances are most common when diagnosing lower limb stress fractures using ultrasound imaging, with the aim of outlining an image critique guideline for operators to support confident diagnoses.

METHOD

A comprehensive literature search of medical databases and handsearching was undertaken to identify relevant studies. All studies were critically examined for quality using the CASP critical appraisal tool. Results from eight studies were combined and interpreted using a narrative synthesis.

FINDINGS

A clear outline of common stress fracture appearances using ultrasound were identified in a combined total of 119 participants. Each finding was ranked according to its popularity. Periosteal thickening (78/119) and cortical disruption/irregularity (83/119) were noted in all eight studies. Hypervascularity of the periosteum visualised by colour Doppler imaging (66/119) was reported in six of the eight studies. Soft tissue hypervascularity (13/119), bony callus formation (5/119) and cortical break (22/119) were seen in three studies.

CONCLUSIONS

Based on the findings, we offer a guideline of the most significant preliminary image findings to be utilised by operators when examining athletes suspected of having lower limb stress fractures. The results show a gap in research for evaluating changes in appearance depending on the injury severity. Further research into distinguishing stress fractures from pathological involvement may in future reduce reliance on plain film radiography.

Voluntary running of defined distances alters bone microstructure in C57BL/6 mice fed a high-fat diet

Obesity increases the risk for pathological conditions such as bone loss. On the other hand, physical exercise reduces body adiposity. To test the hypothesis that physical activity improves bone quality, we evaluated voluntary running of defined distances on trabecular and cortical microstructure in mice fed a high-fat diet (HFD). Sedentary mice were fed the standard AIN93G diet or the HFD. Mice fed the HFD remained sedentary or were assigned to unrestricted running or 75%, 50%, and 25% of unrestricted running with an average running activity at 8.3, 6.3, 4.2, and 2.1 km per day, respectively. The bone structural differences found in sedentary mice were that HFD, compared with the AIN93G diet, resulted in a lower bone volume fraction (BV/TV) and a higher structure model index (SMI) in vertebrae. Running had a greater effect on trabecular microstructure in femurs than in vertebrae; the decrease in SMI and an increase in trabecular thickness (Tb.Th) were in dose-dependent manners. Running was positively correlated with BV/TV and Tb.Th and inversely correlated with SMI in femurs. The HFD increased plasma concentrations of tartrate-resistant acid phosphatase 5b, a marker of bone resorption, in sedentary mice, while running decreased it in a dose-dependent manner. The findings show that voluntary running improves bone quality in young adult mice fed an HFD. Novelty: The high-fat diet alters bone microstructure by increasing bone resorption. Quantitative voluntary running improves bone microstructure through its attenuation of bone resorption in mice fed a high-fat diet.

Predicting their past: Machine language learning can discriminate the brains of chimpanzees with different early-life social rearing experiences

Early life experiences, including separation from caregivers, can result in substantial, persistent effects on neural, behavioral, and physiological systems as is evidenced in a long-standing literature and consistent findings across species, populations, and experimental models. In humans and other animals, differential rearing conditions can affect brain structure and function. We tested for whole brain patterns of morphological difference between 108 chimpanzees reared typically with their mothers (MR; N = 54) and those reared decades ago in a nursery with peers, human caregivers, and environmental enrichment (NR; N = 54). We applied support vector machine (SVM) learning to archival MRI images of chimpanzee brains to test whether we could, with any degree of significant probability, retrospectively classify subjects as MR and NR based on variation in gray matter within the entire brain. We could accurately discriminate MR and NR chimpanzee brains with nearly 70% accuracy. The combined brain regions discriminating the two rearing groups were widespread throughout the cortex. We believe this is the first report using machine language learning as an analytic method for discriminating nonhuman primate brains based on early rearing experiences. In this sense, the approach and findings are novel, and we hope they stimulate application of the technique to studies on neural outcomes associated with early experiences. The findings underscore the potential for infant separation from caregivers to leave a long-term mark on the developing brain.

Nonepileptic, Stereotypical, and Intermittent Symptoms After Subdural Hematoma Evacuation

Transient neurological deficits can occur in the setting of subdural hemorrhages with subsequent unremarkable electrodiagnostic and radiological evaluation. This scenario is rare and can be difficult for physicians to interpret. These transient neurological deficits are thought to result from relative ischemia, secondary to a lesser-known concept known as cortical spreading depolarization. These transient neurological deficits are thought to result from relative ischemia, secondary to a lesser-known concept known as cortical spreading depolarization, which may present clinically as nonepileptic, stereotypical, and intermittent symptoms (NESIS). In these instances, patients are often misdiagnosed as epileptics and committed to long-term antiseizure drugs. We present a 51-year-old patient developing acute global aphasia following the evacuation of a subdural hematoma, with no significant findings on laboratory, microbiological, electrodiagnostic, or radiological evaluation. The patient experienced spontaneous improvement and returned to baseline in the subsequent weeks. Increased awareness of NESIS as a cortical spreading depolarization phenomenon can improve patient care and prevent both unnecessary, extended medical evaluations and therapeutic trials.

Accurate Decoding of Imagined and Heard Melodies

Music perception requires the human brain to process a variety of acoustic and music-related properties. Recent research used encoding models to tease apart and study the various cortical contributors to music perception. To do so, such approaches study temporal response functions that summarise the neural activity over several minutes of data. Here we tested the possibility of assessing the neural processing of individual musical units (bars) with electroencephalography (EEG). We devised a decoding methodology based on a maximum correlation metric across EEG segments (maxCorr) and used it to decode melodies from EEG based on an experiment where professional musicians listened and imagined four Bach melodies multiple times. We demonstrate here that accurate decoding of melodies in single-subjects and at the level of individual musical units is possible, both from EEG signals recorded during listening and imagination. Furthermore, we find that greater decoding accuracies are measured for the maxCorr method than for an envelope reconstruction approach based on backward temporal response functions (bTRF_env). These results indicate that low-frequency neural signals encode information beyond note timing, especially with respect to low-frequency cortical signals below 1 Hz, which are shown to encode pitch-related information. Along with the theoretical implications of these results, we discuss the potential applications of this decoding methodology in the context of novel brain-computer interface solutions.

Prevalence of acute dizziness and vertigo in cortical stroke

BACKGROUND AND PURPOSE

In posterior circulation stroke, vertigo can be a presenting feature. However, whether isolated hemispheric strokes present with vertigo is less clear, despite a few single case reports in the literature. Here, (a) the prevalence of vertigo/dizziness in acute stroke is explored and (b) the cortical distribution of the lesions in relation to both the known vestibular cortex and the evolution of the symptoms, are considered.

METHODS

Structured interviews were conducted in 173 consecutive unselected patients admitted to the hyperacute stroke unit at the University College London Hospitals. The interview was used to evaluate whether the patient was suffering from dizziness and/or vertigo before the onset of the stroke and at the time of the stroke (acute dizziness/vertigo), and the nature of these symptoms.

RESULTS

In all, 53 patients had cortical infarcts, of which 21 patients reported acute dizziness. Out of these 21, five patients reported rotational vertigo. Seventeen of the total 53 patients had lesions in known vestibular cortical areas distributed within the insular and parietal opercular cortices.

CONCLUSIONS

The prevalence of vertigo in acute cortical strokes was 9%, with no single locus of lesion overlap. There is growing evidence supporting a lateralized vestibular cortex, with speculation that cortical strokes affecting the right hemisphere are more likely to cause vestibular symptoms than left hemispheric strokes. A trend was observed for this association, with the right hemisphere affected in four of five patients who reported spinning vertigo at the onset of the stroke.

Glucocorticoid-induced dose-related and site-specific bone remodelling, microstructure, and mechanical changes in cancellous and cortical bones

The study investigated the effects of long-term glucocorticoid (GC) administration on bone remodelling, microstructure, and biomechanical strength in cortical and cancellous (trabecular) bones. Thirty-one female Sprague-Dawley rats were randomly divided into three dexamethasone (Dex) dosage groups, 1.0, 2.5, and 5.0 mg/kg twice a week for 8 weeks, and one control group treated with saline. At the end of the experiment, the tibia of one side and the fourth lumbar vertebrae were processed into sections for a histomorphometric analysis, while the femur of the same side and the fifth vertebrae were isolated for a biomechanical test. A dose-dependent decline in bone formation was observed in both trabecular and cortical (periosteal and endosteal) bones. In contrast, bone resorption was inhibited only in cancellous bone in the two higher dose groups and not dose-related. The ratio of Node/Termini increased, while marrow star volume (MSV) decreased in all Dex groups in metaphyseal trabecular bones, both of which were dose-dependent. Subendosteal cortex porosity increased in parallel with non-uniform trabecular distribution, but cortical thickness remained unchanged. Interestingly, there were no significant changes in microstructure or mechanical strength in lumbar trabecular bone. The cortical elastic load was dose-independently reduced in all three Dex groups when compared with the control group. In summary, bone remodelling was dose-dependently inhibited in cancellous bones but enhanced in intracortical bones. The non-uniform distribution of trabecular bone and increased porosity in the inner edge of cortical bone were both in parallel with GC dosage, and the porosity increase was more likely to occur, leading to reduced cortical mechanical strength.

Specialized coding patterns among dorsomedial prefrontal neuronal ensembles predict conditioned reward seeking

Non-overlapping cell populations within dorsomedial prefrontal cortex (dmPFC), defined by gene expression or projection target, control dissociable aspects of reward seeking through unique activity patterns. However, even within these defined cell populations, considerable cell-to-cell variability is found, suggesting that greater resolution is needed to understand information processing in dmPFC. Here, we use two-photon calcium imaging in awake, behaving mice to monitor the activity of dmPFC excitatory neurons throughout Pavlovian reward conditioning. We characterize five unique neuronal ensembles that each encodes specialized information related to a sucrose reward, reward-predictive cues, and behavioral responses to those cues. The ensembles differentially emerge across daily training sessions – and stabilize after learning – in a manner that improves the predictive validity of dmPFC activity dynamics for deciphering variables related to behavioral conditioning. Our results characterize the complex dmPFC neuronal ensemble dynamics that stably predict reward availability and initiation of conditioned reward seeking following cue-reward learning.

New Cortical Neurodegenerative Pathways in the Hypertensive Rat Brain

Hypertension is a risk factor for neurodegenerative diseases. We hypothesized that chronic hypertension underlies neurodegeneration. In this study, we examined the expression of brain cortical proteins involved in homeostasis, apoptosis, and brain functions in Spontaneously Hypertensive Rats (SHR) compared with normotensive Wistar-Kyoto (WKY) rats. We used paraffin-embedded brain sections of 8-month-old SHR and WKY rats, immunohistochemically stained and analyzed by image processing. In SHR, cytochrome c oxidase subunit 7A increased, indicative of hypoxia; heat shock protein 40, the chaperon for refolding proteins, decreased, leading to accumulation of misfolded proteins; the levels of both voltage-gated sodium channels, Na1.2, 1.6, decreased, reflecting attenuation of the action potential, causing axonal injury; autophagy-related protein 4A (Atg4a), an essential protein of autophagy, decreased, reducing the removal of misfolded proteins; demyelination, the hallmark of neurodegeneration, was shown; modulation of both histone deacetylases 2 and histone acetyltransferase 1 was shown, indicative of altered regulation of gene transcription; increased activated (cleaved) caspase-3, indicative of apoptosis. These new findings suggest that chronic hypertension induces hypoxia and oxidative stress, axonal injury, accelerates the accumulation of misfolded proteins and apoptosis, pathways preceding neurodegeneration.

The Clinical Features of FLAIR-Hyperintense Lesions in Anti-MOG Antibody Associated Cerebral Cortical Encephalitis with Seizures: Case Reports and Literature Review

Background

The presence of fluid attenuated inversion recovery (FLAIR)-hyperintense lesions in anti-myelin oligodendrocyte glycoprotein (MOG) antibody-associated cerebral cortical encephalitis with seizures (FLAMCES) was recently reported. However, the clinical characteristics and outcome of this rare clinico-radiographic syndrome remain unclear.

Methods

The present study reported two new cases. In addition, cases in the literature were systematically reviewed to investigate the clinical symptoms, magnetic resonance imaging (MRI) abnormalities, treatments and prognosis for this rare clinico-radiographic syndrome.

Results

A total of 21 cases were identified during a literature review, with a mean patient age at onset of 26.8 years. The primary clinicopathological characteristics included seizures (100%), headache (71.4%), fever (52.3%) and other cortical symptoms associated with the encephalitis location (61.9%). The common seizure types were focal to bilateral tonic-clonic seizures (28.6%) and unknown-onset tonic-clonic seizures (38.1%). The cortical abnormalities on MRI FLAIR imaging were commonly located in the frontal (58.8%), parietal (70.6%) and temporal (64.7%) lobes. In addition, pleocytosis in the cerebrospinal fluid was reported in the majority of the patients (95.2%). All patients received a treatment regimen of corticosteroids and 9 patients received anti-epileptic drugs. Clinical improvement was achieved in all patients; however, one-third of the patients reported relapse following recovery from cortical encephalitis.

Conclusions

FLAMCES is a rare phenotype of MOG-associated disease. Thus, the wider recognition of this rare syndrome may enable timely diagnosis and the development of suitable treatment regimens.

The Impact of Strategic White Matter Hyperintensity Lesion Location on Language

OBJECTIVE

The impact of white matter hyperintensities (WMH) on language possibly depends on lesion location through disturbance of strategic white matter tracts. We examined the impact of WMH location on language in elderly Asians.

DESIGN

Cross-sectional.

SETTING

Population-based.

PARTICIPANTS

Eight-hundred nineteen residents of Singapore, ages (≥65 years).

MEASUREMENTS

Clinical, cognitive and 3T magnetic resonance imaging assessments were performed on all participants. Language was assessed using the Modified Boston Naming Test (MBNT) and Verbal Fluency (VF). Hypothesis-free region-of-interest-based (ROI) analyses based on major white matter tracts were used to determine the association between WMH location and language. Conditional dependencies between the regional WMH volumes and language were examined using Bayesian-network analysis.

RESULTS

ROI-based analyses showed that WMH located within the anterior thalamic radiation (mean difference: -0.12, 95% confidence interval [CI]: -0.22; -0.02, p = 0.019) and uncinate fasciculus (mean difference: -0.09, 95% CI: -0.18; -0.01, p = 0.022) in the left hemisphere were significantly associated with worse VF but did not survive multiple testing. Conversely, WMH volume in the left cingulum of cingulate gyrus was significantly associated with MBNT performance (mean difference: -0.09, 95% CI: -0.17; -0.02, p = 0.016). Bayesian-network analyses confirmed the left cingulum of cingulate gyrus as a direct determinant of MBNT performance.

CONCLUSION

Our findings identify the left cingulum of cingulate gyrus as a strategic white matter tract for MBNT, suggesting that language - is sensitive to subcortical ischemic damage. Future studies on the role of sporadic ischemic lesions and vascular cognitive impairment should not only focus on total WMH volume but should also take WMH lesion location into account when addressing language.

Neural Correlates of Freezing of Gait in Parkinson's Disease: An Electrophysiology Mini-Review

Freezing of gait (FoG) is a disabling symptom characterized as a brief inability to step or by short steps, which occurs when initiating gait or while turning, affecting over half the population with advanced Parkinson's disease (PD). Several non-competing hypotheses have been proposed to explain the pathophysiology and mechanism behind FoG. Yet, due to the complexity of FoG and the lack of a complete understanding of its mechanism, no clear consensus has been reached on the best treatment options. Moreover, most studies that aim to explore neural biomarkers of FoG have been limited to semi-static or imagined paradigms. One of the biggest unmet needs in the field is the identification of reliable biomarkers that can be construed from real walking scenarios to guide better treatments and validate medical and therapeutic interventions. Advances in neural electrophysiology exploration, including EEG and DBS, will allow for pathophysiology research on more real-to-life scenarios for better FoG biomarker identification and validation. The major aim of this review is to highlight the most up-to-date studies that explain the mechanisms underlying FoG through electrophysiology explorations. The latest methodological approaches used in the neurophysiological study of FoG are summarized, and potential future research directions are discussed.

Abnormal Striatal Development Underlies the Early Onset of Behavioral Deficits in Shank3B-/- Mice

The neural substrates and pathophysiological mechanisms underlying the onset of cognitive and motor deficits in autism spectrum disorders (ASDs) remain unclear. Mutations in ASD-associated SHANK3 in mice (Shank3B^−/−) result in the accelerated maturation of corticostriatal circuits during the second and third postnatal weeks. Here, we show that during this period, there is extensive remodeling of the striatal synaptic proteome and a developmental switch in glutamatergic synaptic plasticity induced by cortical hyperactivity in striatal spiny projection neurons (SPNs). Behavioral abnormalities in Shank3B^−/− mice emerge during this stage and are ameliorated by normalizing excitatory synapse connectivity in medial striatal regions by the downregulation of PKA activity. These results suggest that the abnormal postnatal development of striatal circuits is implicated in the onset of behavioral deficits in Shank3B^−/− mice and that modulation of postsynaptic PKA activity can be used to regulate corticostriatal drive in developing SPNs of mouse models of ASDs and other neurodevelopmental disorders.

Peixoto et al. show that the onset of behavioral deficits in Shank3B^−/− mice occurs during early postnatal development and that these can be ameliorated by reducing the glutamatergic synaptic drive in medial regions of the striatum by the downregulation of PKA activity.

Cortical and medullary morphology of the tibia

Bone resorption caused by stress shielding and insufficient bone-implant contact continues to be problematic for orthopedic endoprostheses that utilize osseointegration (OI) for skeletal fixation. Morphologic analyses have helped combat this issue by defining anatomic parameters to optimize endoprosthesis loading by maximizing bone-implant contact. These studies have not typically included diaphyseal medullary morphology, as this region is not pertinent to total joint replacement. To the contrary, percutaneous OI endoprostheses for prosthetic limb attachment are placed in the diaphysis of the long bone. This study examined the cortical and medullary morphology of 116 fresh-frozen human cadaveric tibia using computed tomography. Anatomic landmarks were selected and custom MATLAB scripts were used to analyze the cross-sectional cortical and medullary morphology normalized to biomechanical length (BML). BML measured the distance between the tibial plateau and the tibial plafond. Properties such as cortical thickness, medullary diameter, and circularity of the medullary canal were quantified. We tested the influence of sex and laterality on morphology, and examined variations along the length of the bone. Results showed that while both sex and laterality impacted the location of anatomic landmarks, only sex influenced cross-sectional morphology. Overall, morphology significantly affected shape along the length of the bone for all examined properties except medullary circularity. This analysis found that distal to 35% BML, the canal is conducive to a circular implant, with medullary diameter ranging from 13 to 32 mm between 20 and 80% BML. A large size range is necessary for sufficient implant contact in order to accommodate residual limb length after amputation.

Cortical Representations of Conspecific Sex Shape Social Behavior

A central question related to virtually all social decisions is how animals integrate sex-specific cues from conspecifics. Using microendoscopic calcium imaging in mice, we find that sex information is represented in the dorsal medial prefrontal cortex (dmPFC) across excitatory and inhibitory neurons. These cells form a distributed code that differentiates the sex of conspecifics and is strengthened with social experience. While males and females both represent sex in the dmPFC, male mice show stronger encoding of female cues, and the relative strength of these sex representations predicts sex preference behavior. Using activity-dependent optogenetic manipulations of natively active ensembles, we further show that these specific representations modulate preference behavior toward males and females. Together, these results define a functional role for native representations of sex in shaping social behavior and reveal a neural mechanism underlying male- versus female-directed sociality.

Age-Related Compensation Mechanism Revealed in the Cortical Representation of Degraded Speech

Older adults understand speech with comparative ease in quiet, but signal degradation can hinder speech understanding much more than it does in younger adults. This difficulty may result, in part, from temporal processing deficits related to the aging process and/or high-frequency hearing loss that can occur in listeners who have normal- or near-normal-hearing thresholds in the speech frequency range. Temporal processing deficits may manifest as degraded neural representation in peripheral and brainstem/midbrain structures that lead to compensation, or changes in response strength in auditory cortex. Little is understood about the process by which the neural representation of signals is improved or restored by age-related cortical compensation mechanisms. Therefore, we used vocoding to simulate spectral degradation to compare the behavioral and neural representation of words that contrast on a temporal dimension. Specifically, we used the closure duration of the silent interval between the vowel and the final affricate /t∫/ or fricative /ʃ/ of the words DITCH and DISH, respectively. We obtained perceptual identification functions and electrophysiological neural measures (frequency-following responses (FFR) and cortical auditory-evoked potentials (CAEPs)) to unprocessed and vocoded versions of these words in young normal-hearing (YNH), older normal- or near-normal-hearing (ONH), and older hearing-impaired (OHI) listeners. We found that vocoding significantly reduced the slope of the perceptual identification function in only the OHI listeners. In contrast to the limited effects of vocoding on perceptual performance, vocoding had robust effects on the FFRs across age groups, such that stimulus-to-response correlations and envelope magnitudes were significantly lower for vocoded vs. unprocessed conditions. Increases in the P1 peak amplitude for vocoded stimuli were found for both ONH and OHI listeners, but not for the YNH listeners. These results suggest that while vocoding substantially degrades early neural representation of speech stimuli in the midbrain, there may be cortical compensation in older listeners that is not seen in younger listeners.

Acute mitragynine administration suppresses cortical oscillatory power and systems theta coherence in rats

BACKGROUND

Mitragynine is the major alkaloid of Mitragyna speciosa (kratom) with potential as a therapeutic in pain management and in depression. There has been debate over the potential side effects of the drug including addiction risk and cognitive decline.

AIMS

To evaluate the effects of mitragynine on neurophysiological systems function in the prefrontal cortex (PFC), cingulate cortex (Cg), orbitofrontal cortex, nucleus accumbens (NAc), hippocampus (HIP), thalamus (THAL), basolateral amygdala (BLA) and ventral tegmental area of rats.

METHODS

Local field potential recordings were taken from animals at baseline and for 45 min following mitragynine administration (10 mg/kg, intraperitoneally). Drug-induced changes in spectral power and coherence between regions at specific frequencies were evaluated. Mitragynine-induced changes in c-fos expression were also analyzed.

RESULTS

Mitragynine increased delta power and reduced theta power in all three cortical regions that were accompanied by increased c-fos expression. A transient suppression of gamma power in PFC and Cg was also evident. There were no effects of mitragynine on spectral power in any of the other regions. Mitragynine induced a widespread reduction in theta coherence (7-9 Hz) that involved disruptions in cortical and NAc connectivity with the BLA, HIP and THAL.

CONCLUSIONS

These findings show that mitragynine induces frequency-specific changes in cortical neural oscillatory activity that could potentially impact cognitive functioning. However, the absence of drug effects within regions of the mesolimbic pathway may suggest either a lack of addiction potential, or an underlying mechanism of addiction that is distinct from other opioid analgesic agents.

CD44 impacts glomerular parietal epithelial cell changes in the aged mouse kidney

CD44 contributes to the activation of glomerular parietal epithelial cells (PECs). Although CD44 expression is higher in PECs of healthy aged mice, the biological role of CD44 in PECs in this context remains unclear. Accordingly, young (4 months) and aged (24 months) CD44-/- mice were compared to age-matched CD44+/+ mice, both aged in a nonstressed environment. Parietal epithelial cell densities were similar in both young and aged CD44+/+ and CD44-/- mice. Phosphorylated ERK 1/2 (pERK) was higher in aged CD44+/+ mice. Vimentin and α-SMA, markers of changes to the epithelial cell phenotype, were present in PECs in aged CD44+/+ mice, but absent in aged CD44-/- mice in both outer cortical (OC) and juxtamedullary (JM) glomeruli. Because age-related glomerular hypertrophy was lower in CD44-/- mice, mTOR activation was assessed by phospho-S6 ribosomal protein (pS6RP) staining. Parietal epithelial cells and glomerular tuft staining for pS6RP was lower in aged CD44-/- mice compared to aged CD44+/+ mice. Podocyte density was higher in aged CD44-/- mice in both OC and JM glomeruli. These changes were accompanied by segmental and global glomerulosclerosis in aged CD44+/+ mice, but absent in aged CD44-/- mice. These results show that the increase in CD44 in PECs in aged kidneys contributes to several changes to the glomerulus during healthy aging in mice, and may involve ERK and mTOR activation.

Cortical Strut Graft for Enigmatic Thigh Pain in Uncemented Total Hip Replacement

Aims

Enigmatic thigh pain in uncemented femoral components of a total hip replacement can be severe and disabling. Treatment can be conservative or surgical with cortical strut graft or revision of the femoral stem. Cortical strut grafting may offer good results with reduced morbidity. The aim of this study was to report the functional and radiographic outcomes of four patients with enigmatic thigh pain treated with cortical strut allograft.

Materials and Methods

Between 2016 and 2018, four women underwent cortical strut allografting at two centres. All patients had an uncemented, proximally porous S-ROM femoral implant (DePuy, Warsaw, In, USA). All other causes of anterolateral thigh pain were excluded. The mean age was 36.7 years (range: 29-51 years). Patients were followed up for a minimum of 14 months (range: 14-38 months). The University of California, Los Angles (UCLA) activity score, pain scores, complications, and radiographs at six weeks, three months, six months, nine months and one year were recorded.

Results

Mean UCLA activity scores increased from 3.2 (range: 2-4) to 6.2 (range: 6-7) post-operatively. Radiologically, all four patients had complete osseointegration of their strut grafts. Pain scores decreased at six weeks and at six months. One deep venous thrombosis occurred. One patient experienced recurrence of anterolateral thigh pain 26 months post-strut graft, which resolved with protected weight-bearing and analgesia for three months.

Conclusions

In uncemented femoral prostheses, cortical strut grafting to treat enigmatic thigh pain can reduce symptoms and increase activity without the need to revise a well-fixed femoral stem. We add to the growing body of evidence that this can be a successful surgical technique.

If Human Brain Organoids Are the Answer to Understanding Dementia, What Are the Questions?

Because our beliefs regarding our individuality, autonomy, and personhood are intimately bound up with our brains, there is a public fascination with cerebral organoids, the "mini-brain," the "brain in a dish". At the same time, the ethical issues around organoids are only now being explored. What are the prospects of using human cerebral organoids to better understand, treat, or prevent dementia? Will human organoids represent an improvement on the current, less-than-satisfactory, animal models? When considering these questions, two major issues arise. One is the general challenge associated with using any stem cell-generated preparation for in vitro modelling (challenges amplified when using organoids compared with simpler cell culture systems). The other relates to complexities associated with defining and understanding what we mean by the term "dementia." We discuss 10 puzzles, issues, and stumbling blocks to watch for in the quest to model "dementia in a dish."

BMD-Related Genetic Risk Scores Predict Site-Specific Fractures as Well as Trabecular and Cortical Bone Microstructure

CONTEXT

It is important to identify patients at highest risk of fractures.

OBJECTIVE

To compare the separate and combined performances of bone-related genetic risk scores (GRSs) for prediction of forearm, hip and vertebral fractures separately, as well as of trabecular and cortical bone microstructure parameters separately.

DESIGN, SETTING, AND PARTICIPANTS

Using 1103 single nucleotide polymorphisms (SNPs) independently associated with estimated bone mineral density of the heel (eBMD), we developed a weighted GRS for eBMD and determined its contribution to fracture prediction beyond 2 previously developed GRSs for femur neck BMD (49 SNPs) and lumbar spine BMD (48 SNPs). Associations between these GRSs and forearm (ncases = 1020; ncontrols = 2838), hip (ncases = 1123; ncontrols = 2630) and vertebral (ncases = 288; ncontrols = 1187) fractures were evaluated in 3 Swedish cohorts. Associations between the GRSs and trabecular and cortical bone microstructure parameters (n = 426) were evaluated in the MrOS Sweden cohort.

RESULTS

We found that eBMDGRS was the only significant independent predictor of forearm and vertebral fractures while both FN-BMDGRS and eBMDGRS were significant independent predictors of hip fractures. The eBMDGRS was the major GRS contributing to prediction of trabecular bone microstructure parameters while both FN-BMDGRS and eBMDGRS contributed information for prediction of cortical bone microstructure parameters.

CONCLUSIONS

The eBMDGRS independently predicts forearm and vertebral fractures while both FN-BMDGRS and eBMDGRS contribute independent information for prediction of hip fractures. We propose that eBMDGRS captures unique information about trabecular bone microstructure useful for prediction of forearm and vertebral fractures. These findings may facilitate personalized medicine to predict site-specific fractures as well as cortical and trabecular bone microstructure separately.

Distinct Genetic Signatures of Cortical and Subcortical Regions Associated with Human Memory

Despite the discovery of gene variants linked to memory performance, understanding the genetic basis of adult human memory remains a challenge. Here, we devised an unsupervised framework that relies on spatial correlations between human transcriptome data and functional neuroimaging maps to uncover the genetic signatures of memory in functionally-defined cortical and subcortical memory regions.

Despite the discovery of gene variants linked to memory performance, understanding the genetic basis of adult human memory remains a challenge. Here, we devised an unsupervised framework that relies on spatial correlations between human transcriptome data and functional neuroimaging maps to uncover the genetic signatures of memory in functionally-defined cortical and subcortical memory regions. Results were validated with animal literature and showed that our framework is highly effective in identifying memory-related processes and genes compared to a control cognitive function. Genes preferentially expressed in cortical memory regions are linked to memory-related processes such as immune and epigenetic regulation. Genes expressed in subcortical memory regions are associated with neurogenesis and glial cell differentiation. Genes expressed in both cortical and subcortical memory areas are involved in the regulation of transcription, synaptic plasticity, and glutamate receptor signaling. Furthermore, distinct memory-associated genes such as PRKCD and CDK5 are linked to cortical and subcortical regions, respectively. Thus, cortical and subcortical memory regions exhibit distinct genetic signatures that potentially reflect functional differences in health and disease, and nominates gene candidates for future experimental investigations.