Decreased haemodynamic response and decoupling of cortical gamma-band activity and tissue oxygen perfusion after striatal interleukin-1 injection

Sensory adaptation in the barrel cortex during active sensation in the behaving mouse

Sensory Adaptation (SA) is a prominent aspect of how neurons respond to sensory signals, ubiquitous across species and modalities. However, SA depends on the activation state of the brain and the extent to which SA is expressed in awake, behaving animals during active sensation remains unclear. Here, we addressed this question by training head-fixed mice to detect an object using their whiskers and recording neuronal activity from barrel cortex whilst simultaneously imaging the whiskers in 3D. We found that neuronal responses decreased during the course of whisker-object touch sequences and that this was due to two factors. First, a motor effect, whereby, during a sequence of touches, later touches were mechanically weaker than early ones. Second, a sensory encoding effect, whereby neuronal tuning to touch became progressively less sensitive during the course of a touch sequence. The sensory encoding effect was whisker-specific. These results show that SA does occur during active whisker sensing and suggest that SA is fundamental to sensation during natural behaviour.

Clinical and molecular correlates of the ASPECTS in the acute phase of stroke

BACKGROUND

The Alberta Stroke Program Early CT Score (ASPECTS) scale was developed for monitoring early ischemic changes on CT, being associated with clinical outcomes. The ASPECTS can also associate with peripheral biomarkers that reflect the pathophysiological response of the brain to the ischemic stroke.

OBJECTIVE

To investigate the association between peripheral biomarkers with the Alberta Stroke Program Early CT Score (ASPECTS) in individuals after ischemic stroke.

METHODS

Patients over 18 years old with acute ischemic stroke were enrolled in this study. No patient was eligible for thrombolysis. The patients were submitted to non-contrast CT in the first 24 hours of admission, being the Alberta Stroke Program Early CT Score and clinical and molecular evaluations applied on the same day. The National Institutes of Health Stroke Scale (NIHSS), modified Rankin scale and the Mini-Mental State Examination for clinical evaluation were also applied to all subjects. Plasma levels of BDNF, VCAM-1, VEGF, IL-1β, sTNFRs and adiponectin were determined by ELISA.

RESULTS

Worse neurological impairment (NIHSS), cognitive (MEEM) and functional (Rankin) performance was observed in the group with changes in the NCTT. Patients with NCTT changes also exhibited higher levels of IL-1β and adiponectin. In the linear multivariate regression, an adjusted R coefficient of 0.515 was found, indicating adiponectin and NIHSS as independent predictors of ASPECTS.

CONCLUSION

Plasma levels of adiponectin are associated with the ASPECTS scores.

Longitudinal study of hemodynamics and dendritic membrane potential changes in the mouse cortex following a soft cranial window installation

The soft cranial window using polydimethylsiloxane allows direct multiple access to neural tissue during long-term monitoring. However, the chronic effects of soft window installation on the brain have not been fully studied. Here, we investigate the long-term effects of soft window installation on sensory-evoked cerebral hemodynamics and neuronal activity. We monitored the brain tissue immunocytohistology for 6 weeks postinstallation. Heightened reactive astrocytic and microglia levels were found at 2 weeks postinstallation. By 6 weeks postinstallation, mice had expression levels similar to those of normal animals. We recorded sensory-evoked hemodynamics of the barrel cortex and LFP during whisker stimulation at these time points. Animals at 6 weeks postinstallation showed stronger hemodynamic responses and focalized barrel mapping than 2-week postoperative mice. LFP recordings of 6-week postoperative mice also showed higher neural activity at the barrel column corresponding to the stimulated whisker. Furthermore, the expression level of interleukin- 1 β was highly upregulated at 2 weeks postinstallation. When we treated animals postoperatively with minocycline plus N-acetylcystein, a drug-suppressing inflammatory cytokine, these animals did not show declined hemodynamic responses and neuronal activities. This result suggests that neuroinflammation following soft window installation may alter hemodynamic and neuronal responses upon sensory stimulation.

How much is enough-Can resting state fMRI provide a demarcation for neurosurgical resection in glioma?

This study represents a systematic review of the insights provided by resting state functional MRI (rs-fMRI) use in the glioma population. Following PRISMA guidelines, 45 studies were included in the review and were classified in glioma-related neuronal changes (n=28) and eloquent area localization (n=17). Despite the heterogeneous nature of the studies, there is considerable evidence of diffuse functional reorganization occurring in the setting of gliomas with local and interhemispheric functional connectivity alterations involving different functional networks. The studies showed evidence of decreased long distance functional connectivity and increased global local efficiency occurring in the setting of gliomas. The tumour grade seems to correlate with distinct functional connectivity changes. Overall, there is a potential clinical utility of rs-fMRI for identifying the functional brain network disruptions occurring in the setting of gliomas. Further studies utilizing standardized analytical methods are required to elucidate the mechanism through which gliomas induce global changes in brain connectivity.

Role of pattern recognition receptors of the neurovascular unit in inflamm-aging

Aging is associated with chronic inflammation partly mediated by increased levels of damage-associated molecular patterns, which activate pattern recognition receptors (PRRs) of the innate immune system. Furthermore, many aging-related disorders are associated with inflammation. PRRs, such as Toll-like receptors (TLRs) and nucleotide-binding oligomerization domain-like receptors (NLRs), are expressed not only in cells of the innate immune system but also in other cells, including cells of the neurovascular unit and cerebral vasculature forming the blood-brain barrier. In this review, we summarize our present knowledge about the relationship between activation of PRRs expressed by cells of the neurovascular unit-blood-brain barrier, chronic inflammation, and aging-related pathologies of the brain. The most important damage-associated molecular pattern-sensing PRRs in the brain are TLR2, TLR4, and NLR family pyrin domain-containing protein-1 and pyrin domain-containing protein-3, which are activated during physiological and pathological aging in microglia, neurons, astrocytes, and possibly endothelial cells and pericytes.

Translocator Protein-18 kDa (TSPO) Positron Emission Tomography (PET) Imaging and Its Clinical Impact in Neurodegenerative Diseases

In vivo exploration of activated microglia in neurodegenerative diseases is achievable by Positron Emission Tomography (PET) imaging, using dedicated radiopharmaceuticals targeting the translocator protein-18 kDa (TSPO). In this review, we emphasized the major advances made over the last 20 years, thanks to TSPO PET imaging, to define the pathophysiological implication of microglia activation and neuroinflammation in neurodegenerative diseases, including Parkinson’s disease, Huntington’s disease, dementia, amyotrophic lateral sclerosis, multiple sclerosis, and also in psychiatric disorders. The extent and upregulation of TSPO as a molecular biomarker of activated microglia in the human brain is now widely documented in these pathologies, but its significance, and especially its protective or deleterious action regarding the disease’s stage, remains under debate. Thus, we exposed new and plausible suggestions to enhance the contribution of TSPO PET imaging for biomedical research by exploring microglia’s role and interactions with other cells in brain parenchyma. Multiplex approaches, associating TSPO PET radiopharmaceuticals with other biomarkers (PET imaging of cellular metabolism, neurotransmission or abnormal protein aggregates, but also other imaging modalities, and peripheral cytokine levels measurement and/or metabolomics analysis) was considered. Finally, the actual clinical impact of TSPO PET imaging as a routine biomarker of neuroinflammation was put into perspective regarding the current development of diagnostic and therapeutic strategies for neurodegenerative diseases.