Atrophy and primary somatosensory cortical reorganization after unilateral thoracic spinal cord injury: a longitudinal functional magnetic resonance imaging study

Brain region changes following a spinal cord injury

Brain-related complications are common in clinical practice after spinal cord injury (SCI); however, the molecular mechanisms of these complications are still unclear. Here, we reviewed the changes in the brain regions caused by SCI from three perspectives: imaging, molecular analysis, and electrophysiology. Imaging studies revealed abnormal functional connectivity, gray matter volume atrophy, and metabolic abnormalities in brain regions after SCI, leading to changes in the structure and function of brain regions. At the molecular level, chemokines, inflammatory factors, and damage-associated molecular patterns produced in the injured area were retrogradely transmitted through the corticospinal tract, cerebrospinal fluid, or blood circulation to the specific brain area to cause pathologic changes. Electrophysiologic recordings also suggested abnormal changes in brain electrical activity after SCI. Transcranial magnetic stimulation, transcranial direct current stimulation, and deep brain stimulation alleviated pain and improved motor function in patients with SCI; therefore, transcranial therapy may be a new strategy for the treatment of patients with SCI.

Characteristics of corticomuscular coupling during wheelchair Tai Chi in patients with spinal cord injury

BACKGROUND

Wheelchair Tai Chi (WCTC) has been proved to have benefits for the brain and motor system of spinal cord injury (SCI) patients. However, the characteristics of corticomuscular coupling during WCTC are scarcely known. We aimed to investigate changes following SCI on corticomuscular coupling, and further compare the coupling characteristics of WCTC with aerobic exercise in SCI patients.

METHODS

A total of 15 SCI patients and 25 healthy controls were recruited. The patients had to perform aerobic exercise and WCTC, while healthy controls needed to complete a set of WCTC. The participants accomplished the test following the tutorial video in a sitting position. The upper limb muscle activation was measured from upper trapezius, medial deltoid, biceps brachii and triceps brachii with surface electromyography. Cortical activity in the prefrontal cortex, premotor cortex, supplementary motor area and primary motor cortex was simultaneously collected by functional near-infrared spectroscopy. The functional connectivity, phase synchronization index and coherence values were then calculated and statistically analyzed.

RESULTS

Compared to healthy controls, changes in functional connectivity and higher muscle activation were observed in the SCI group. There was no significant difference in phase synchronization between groups. Among patients, significantly higher coherence values between the left biceps brachii as well as the right triceps brachii and contralateral regions of interest were found during WCTC than during aerobic exercise.

CONCLUSION

The patients may compensate for the lack of corticomuscular coupling by enhancing muscle activation. This study demonstrated the potential and advantages of WCTC in eliciting corticomuscular coupling, which may optimize rehabilitation following SCI.

Substances for regenerative wound healing during antler renewal stimulated scar-less restoration of rat cutaneous wounds

Scarification is the outcome of cutaneous wound healing under normal conditions. Although considerable effort has been expended in this field, scar-less healing has not been achieved satisfactorily. The lack of a good model of scar-free healing has contributed to this undesirable situation. However, the annual regeneration of deer antlers, which starts from regenerative wound healing over the top of the pedicles (permanent bony protuberances), may provide such a model. Therefore, in this study, we investigated the process of pedicle wound healing at the organ, tissue, cell, and molecular levels. Our results convincingly demonstrate that wounds over the pedicle preceded a regenerative healing process including regeneration of skin appendages, such as hair follicles. Compared to the scar healing in rats, regenerative healing of the pedicle wound exhibited a weaker inflammatory response, lack of myofibroblast induction, and higher ratios of Col III/Col I, TGF-β3/TGF-β1, and MMP/TIMP. Importantly, our periosteal transplantation experiments in vivo revealed that this regenerative healing process was achieved through induction of antler stem cells (ASCs). Further study showed that this effect of ASCs on regenerative healing was not species-specific but more generic and could be applied to other mammalian species, as injection of ASCs stimulated regenerative healing of full-thickness excisional cutaneous wounds in rats. Overall, our findings show that ASCs may have therapeutic potential in enhancing the quality of wound healing and preventing scar formation in clinical settings.

Importance of brain alterations in spinal cord injury

Spinal cord injury (SCI) destroys the sensorimotor pathway and blocks the information flow between the peripheral nerve and the brain, resulting in autonomic function loss. Numerous studies have explored the effects of obstructed information flow on brain structure and function and proved the extensive plasticity of the brain after SCI. Great progress has also been achieved in therapeutic strategies for SCI to restore the "re-innervation" of the cerebral cortex to the limbs to some extent. Although no thorough research has been conducted, the changes of brain structure and function caused by "re-domination" have been reported. This article is a review of the recent research progress on local structure, functional changes, and circuit reorganization of the cerebral cortex after SCI. Alterations of structure and electrical activity characteristics of brain neurons, features of brain functional reorganization, and regulation of brain functions by reconfigured information flow were also explored. The integration of brain function is the basis for the human body to exercise complex/fine movements and is intricately and widely regulated by information flow. Hence, its changes after SCI and treatments should be considered.

An exploratory study to investigate the association between age, physical activity, femoral trochlear cartilage thickness and biomarkers of tissue metabolism in adult males

Purpose

To investigate the association between age, physical activity, femoral trochlear cartilage thickness and biomarkers of tissue metabolism in a cross-sectional sample of adult males. This study utilizes several emerging biomarkers that have been associated with early joint degenerative changes; serum COMP (cartilage oligomeric matrix protein), HA (hyaluronan) and lubricin.

Methods

Eighty-one males (age: mean (range): 43(18–70) years; body mass index: 25.2 (21.0–30.6) kg/m²) volunteered. Resting serum COMP, HA and lubricin concentrations were determined via commercially available enzyme-linked immunosorbent assay (ELISA) and femoral trochlear cartilage thickness via supra-patellar ultrasound imaging. Physical activity levels were assessed using questionnaires. Statistical analyses were performed using correlation and regression analyses.

Results

Age was correlated with lateral trochlear cartilage thickness (r = − 0.372; p < 0.01) and serum COMP (r = 0.342; p < 0.01). 7-day physical activity was correlated with serum COMP (r = 0.357, p < 0.01), and 12-month physical activity with both lateral trochlear cartilage thickness (r = 0.340, p = 0.01) and serum HA (r = 0.296, p < 0.05). Regression analyses revealed that age significantly accounted for the variability in lateral cartilage thickness and serum COMP, following the adjustment for potential cofounders. However, the association between age and lateral trochlear cartilage thickness was not moderated by physical activity levels (all p > 0.05).

Conclusion

This study indicates that older age may be associated with thinner lateral trochlear cartilage and higher cartilage turnover. Being physically active may also be positive for lateral trochlear cartilage thickness. However, overall, both age and physical activity level only account for a small amount of the variability in cartilage thickness and serum biomarkers.

Oncological Ligand-Target Binding Systems and Developmental Approaches for Cancer Theranostics

Targeted treatment of cancer hinges on the identification of specific intracellular molecular receptors on cancer cells to stimulate apoptosis for eventually inhibiting growth; the development of novel ligands to target biomarkers expressed by the cancer cells; and the creation of novel multifunctional carrier systems for targeted delivery of anticancer drugs to specific malignant sites. There are numerous receptors, antigens, and biomarkers that have been discovered as oncological targets (oncotargets) for cancer diagnosis and treatment applications. Oncotargets are critically important to navigate active anticancer drug ingredients to specific disease sites with no/minimal effect on surrounding normal cells. In silico techniques relating to genomics, proteomics, and bioinformatics have catalyzed the discovery of oncotargets for various cancer types. Effective oncotargeting requires high-affinity probes engineered for specific binding of receptors associated with the malignancy. Computational methods such as structural modeling and molecular dynamic (MD) simulations offer opportunities to structurally design novel ligands and optimize binding affinity for specific oncotargets. This article proposes a streamlined approach for the development of ligand-oncotarget bioaffinity systems via integrated structural modeling and MD simulations, making use of proteomics, genomic, and X-ray crystallographic resources, to support targeted diagnosis and treatment of cancers and tumors.

The kinematic recovery process of rhesus monkeys after spinal cord injury

After incomplete spinal cord injury (SCI), neural circuits may be plastically reconstructed to some degree, resulting in extensive functional locomotor recovery. The present study aimed to observe the post-SCI locomotor recovery of rhesus monkey hindlimbs and compare the recovery degrees of different hindlimb parts, thus revealing the recovery process of locomotor function. Four rhesus monkeys were chosen for thoracic hemisection injury. The hindlimb locomotor performance of these animals was recorded before surgery, as well as 6 and 12 weeks post-lesion. Via principal component analysis, the relevant parameters of the limb endpoint, pelvis, hindlimb segments, and joints were processed and analyzed. Twelve weeks after surgery, partial kinematic recovery was observed at the limb endpoint, shank, foot, and knee joints, and the locomotor performance of the ankle joint even recovered to the pre-lesion level; the elevation angle of the thigh and hip joints showed no obvious recovery. Generally, different parts of a monkey hindlimb had different spontaneous recovery processes; specifically, the closer the part was to the distal end, the more extensive was the locomotor function recovery. Therefore, we speculate that locomotor recovery may be attributed to plastic reconstruction of the motor circuits that are mainly composed of corticospinal tract. This would help to further understand the plasticity of motor circuits after spinal cord injury.

Large-Scale Network Analysis of Whole-Brain Resting-State Functional Connectivity in Spinal Cord Injury: A Comparative Study

Network analysis based on graph theory depicts the brain as a complex network that allows inspection of overall brain connectivity pattern and calculation of quantifiable network metrics. To date, large-scale network analysis has not been applied to resting-state functional networks in complete spinal cord injury (SCI) patients. To characterize modular reorganization of whole brain into constituent nodes and compare network metrics between SCI and control subjects, fifteen subjects with chronic complete cervical SCI and 15 neurologically intact controls were scanned. The data were preprocessed followed by parcellation of the brain into 116 regions of interest (ROI). Correlation analysis was performed between every ROI pair to construct connectivity matrices and ROIs were categorized into distinct modules. Subsequently, local efficiency (LE) and global efficiency (GE) network metrics were calculated at incremental cost thresholds. The application of a modularity algorithm organized the whole-brain resting-state functional network of the SCI and the control subjects into nine and seven modules, respectively. The individual modules differed across groups in terms of the number and the composition of constituent nodes. LE demonstrated statistically significant decrease at multiple cost levels in SCI subjects. GE did not differ significantly between the two groups. The demonstration of modular architecture in both groups highlights the applicability of large-scale network analysis in studying complex brain networks. Comparing modules across groups revealed differences in number and membership of constituent nodes, indicating modular reorganization due to neural plasticity.

Ketamine changes the local resting-state functional properties of anesthetized-monkey brain

OBJECTIVE

Ketamine is a well-known anesthetic. 'Recreational' use of ketamine common induces psychosis-like symptoms and cognitive impairments. The acute and chronic effects of ketamine on relevant brain circuits have been studied, but the effects of single-dose ketamine administration on the local resting-state functional properties of the brain remain unknown. In this study, we aimed to assess the effects of single-dose ketamine administration on the brain local intrinsic properties.

METHODS

We used resting-state functional magnetic resonance imaging (rs-fMRI) to explore the ketamine-induced alterations of brain intrinsic properties. Seven adult rhesus monkeys were imaged with rs-fMRI to examine the fractional amplitude of low-frequency fluctuation (fALFF) and regional homogeneity (ReHo) in the brain before and after ketamine injection. Paired comparisons were used to detect the significantly altered regions.

RESULTS

Results showed that the fALFF of the prefrontal cortex (p=0.046), caudate nucleus (left side, p=0.018; right side, p=0.025), and putamen (p=0.020) in post-injection stage significantly increased compared with those in pre-injection period. The ReHo of nucleus accumbens (p=0.049), caudate nucleus (p=0.037), and hippocampus (p=0.025) increased after ketamine injection, but that of prefrontal cortex decreased (p<0.05).

CONCLUSIONS

These findings demonstrated that single-dose ketamine administration can change the regional intensity and synchronism of brain activity, thereby providing evidence of ketamine-induced abnormal resting-state functional properties in primates. This evidence may help further elucidate the effects of ketamine on the cerebral resting status.

Combination of kinematic analyses and diffusion tensor tractrography to evaluate the residual motor functions in spinal cord-hemisected monkeys

BACKGROUND

Spinal cord injury (SCI) causes loss of locomotor functions. Nowadays, the relationship between the residual locomotion after SCI and the diffusion tensor tractography (DTT) results still remains unclear.

METHODS

Four rhesus monkeys were suffered thoracic cord hemisection. Kinematic evaluation and DTT were performed prior- and post-SCI (6 and 12 weeks). The longitudinal changes of gait parameters and the DTT parameters were analyzed for the injury-contralateral hindlimb. The correlations between gaits and DTT parameters were also investigated.

RESULTS

Almost gait parameters significantly changed after SCI, meanwhile, the caudal-rostral connection rate of DTT showed negative correlation with all gait parameters, demonstrating that the locomotor changes of the injury-contralateral hindlimb were associated with the ratio of residual fibers.

CONCLUSIONS

The combinatory use of gait analysis and DTT has been demonstrated to be sensitive to locomotion changes after SCI, and may therefore have potential applications in the pre-clinical studies of SCI.

Non-concomitant cortical structural and functional alterations in sensorimotor areas following incomplete spinal cord injury

Brain plasticity, including anatomical changes and functional reorganization, is the physiological basis of functional recovery after spinal cord injury (SCI). The correlation between brain anatomical changes and functional reorganization after SCI is unclear. This study aimed to explore whether alterations of cortical structure and network function are concomitant in sensorimotor areas after incomplete SCI. Eighteen patients with incomplete SCI (mean age 40.94 ± 14.10 years old; male:female, 7:11) and 18 healthy subjects (37.33 ± 11.79 years old; male:female, 7:11) were studied by resting state functional magnetic resonance imaging. Gray matter volume (GMV) and functional connectivity were used to evaluate cortical structure and network function, respectively. There was no significant alteration of GMV in sensorimotor areas in patients with incomplete SCI compared with healthy subjects. Intra-hemispheric functional connectivity between left primary somatosensory cortex (BA1) and left primary motor cortex (BA4), and left BA1 and left somatosensory association cortex (BA5) was decreased, as well as inter-hemispheric functional connectivity between left BA1 and right BA4, left BA1 and right BA5, and left BA4 and right BA5 in patients with SCI. Functional connectivity between both BA4 areas was also decreased. The decreased functional connectivity between the left BA1 and the right BA4 positively correlated with American Spinal Injury Association sensory score in SCI patients. The results indicate that alterations of cortical anatomical structure and network functional connectivity in sensorimotor areas were non-concomitant in patients with incomplete SCI, indicating the network functional changes in sensorimotor areas may not be dependent on anatomic structure. The strength of functional connectivity within sensorimotor areas could serve as a potential imaging biomarker for assessment and prediction of sensory function in patients with incomplete SCI. This trial was registered with the Chinese Clinical Trial Registry (registration number: ChiCTR-ROC-17013566).

Increased Brain Sensorimotor Network Activation after Incomplete Spinal Cord Injury

After complete spinal cord injury (SCI), activation during attempted movement of paralyzed limbs is sharply reduced, but after incomplete SCI-the more common form of human injury-it is unknown how attempts to move voluntarily are accompanied by activation of brain motor and sensory networks. Here, we assessed brain activation during ankle movement in subjects with incomplete SCI, among whom voluntary motor function is partially preserved. Adults with incomplete SCI (n = 20) and healthy controls (n = 15) underwent functional magnetic resonance imaging that alternated rest with 0.3-Hz right ankle dorsiflexion. In both subject groups, ankle movement was associated with bilateral activation of primary and secondary sensory and motor areas, with significantly (p < 0.001) greater activation in subjects with SCI within right hemisphere areas, including primary sensorimotor cortex and pre-motor cortex. This result was further evaluated using linear regression analysis with respect to core clinical variables. Poorer locomotor function correlated with larger activation within several right hemisphere areas, including pre- and post-central gyri, possibly reflecting increased movement complexity and effort, whereas longer time post-SCI was associated with larger activation in left post-central gyrus and bilateral supplementary motor area, which may reflect behaviorally useful adaptations. The results indicate that brain adaptations after incomplete SCI differ sharply from complete SCI, are related to functional behavioral status, and evolve with increasing time post-SCI. The results suggest measures that might be useful for understanding and treating incomplete SCI in human subjects.

Cortical Reorganization Is Associated with Surgical Decompression of Cervical Spondylotic Myelopathy

Background. Cervical spondylotic myelopathy (CSM) results in sensorimotor limb deficits, bladder, and bowel dysfunction, but mechanisms underlying motor plasticity changes before and after surgery are unclear. Methods. We studied 24 patients who underwent decompression surgery and 15 healthy controls. Patients with mixed upper and lower limb dysfunction (Group A) and only lower limb dysfunction (Group B) were then analysed separately. Results. The sum amplitude of motor evoked potentials sMEP (p < 0.01) and number of focal points where MEPs were elicited (N) (p < 0.001) were significantly larger in CSM patients compared with controls. For Group A (16 patients), sMEP (p < 0.01) and N (p < 0.001) showed similar findings. However, for Group B (8 patients), only N (p = 0.03) was significantly larger in patients than controls. Group A had significantly increased grip strength (p = 0.02) and reduced sMEP (p = 0.001) and N (p = 0.003) after surgery. Changes in sMEP (cMEP) significantly correlated inversely with improved feeding (p = 0.03) and stacking (p = 0.04) times as was the change in number of focal points (NDiff) with improved writing times (p = 0.03). Group B did not show significant reduction in sMEP or N after surgery, or significant correlation of cMEP or NDiff with all hand function tests. No significant differences in H reflex parameters obtained from the flexor carpi radialis, or central motor conduction time changes, were noted after surgery. Discussion. Compensatory expansion of motor cortical representation occurs largely at cortical rather than spinal levels, with a tendency to normalization after surgery. These mirrored improvements in relevant tasks requiring utilization of intrinsic hand muscles.

Alteration of brain regional homogeneity of monkeys with spinal cord injury: A longitudinal resting-state functional magnetic resonance imaging study

PURPOSE

To investigate the longitudinal brain regional homogeneity (ReHo) changes in nonhuman primate after spinal cord injury (SCI) by resting-state functional magnetic resonance imaging (fMRI).

METHODS

Three adult female rhesus monkeys underwent unilateral thoracic cord injury. A resting-state fMRI examination was performed in the healthy stage and 4, 8, and 12 weeks after the injury. The ReHo value of each voxel in the monkey brain was calculated and compared between pre- and post-SCI monkeys with paired t test. The regions of interest (ROIs) in the significantly changed ReHo regions were set. The correlations between the ReHo change and the time after injury were also determined.

RESULTS

Compared with those in healthy period, the ReHo values of the left premotor cortex and the anterior cingulate cortex (ACC) in post-SCI rhesus monkeys significantly increased in 4-week follow-up examinations. The ReHo values of posterior cingulate cortex, left precuneus, left temporal parietooccipital area, and bilateral superior parietal lobules decreased at 8-week follow-up examinations. In 12-week follow-up examinations, the ReHo values of the left postcentral gyrus, right caudate nucleus, and superior temporal gyrus increased. Correlation analysis showed positive correlations between left ACC and the postoperative time.

CONCLUSION

SCI can change the regional synchronism of brain activity in sensorimotor system and the default mode network. These findings may help us to understand the potential pathophysiological changes in the central nervous system after SCI.

Enhancement of bilateral cortical somatosensory evoked potentials to intact forelimb stimulation following thoracic contusion spinal cord injury in rats

The adult central nervous system is capable of significant reorganization and adaptation following neurotrauma. After a thoracic contusive spinal cord injury (SCI) neuropathways that innervate the cord below the epicenter of injury are damaged, with minimal prospects for functional recovery. In contrast, pathways above the site of injury remain intact and may undergo adaptive changes in response to injury. We used cortical somatosensory evoked potentials (SSEPs) to evaluate changes in intact forelimb pathways. Rats received a midline contusion SCI, unilateral contusion SCI, or laminectomy with no contusion at the T8 level and were monitored for 28 days post-injury. In the midline injury group, SSEPs recorded from the contralateral forelimb region of the primary somatosensory cortex were 59.7% (CI 34.7%, 84.8%; c(2) = 21.9; dof = 1; p = 2.9 ×10(-6)) greater than the laminectomy group; SSEPs from the ipsilateral somatosensory cortex were 47.6% (CI 18.3%, 77%; c(2) = 10.1; dof = 1; p = 0.001) greater. Activation of the ipsilateral somatosensory cortex was further supported by BOLD-fMRI, which showed increased oxygenation at the ipsilateral hemisphere at day seven post-injury. In the unilateral injury group, ipsilesional side was compared to the contralesional side. SSEPs on day 14 (148%; CI 111%, 185%) and day 21 (137%; CI 110%, 163%) for ipsilesional forelimb stimulation were significantly increased over baseline (100%). SSEPs recorded from the hindlimb sensory cortex upon ipsilesional stimulation were 33.9% (CI 14.3%, 53.4%; c(2) = 11.6; dof = 1; p = 0.0007) greater than contralesional stimulation. Therefore, these results demonstrate the ability of SSEPs to detect significant enhancements in the activation of forelimb sensory pathways following both midline and unilateral contusive SCI at T8. Reorganization of forelimb pathways may occur after thoracic SCI, which SSEPs can monitor to aid the development of future therapies.