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We recommend a new term, "primary age-related tauopathy" (PART), to describe a pathology that is commonly observed in the brains of aged individuals. Many autopsy studies have reported brains with neurofibrillary tangles (NFTs) that are indistinguishable from those of Alzheimer's disease (AD), in the absence of amyloid (Aβ) plaques. For these "NFT+/Aβ-" brains, for which formal criteria for AD neuropathologic changes are not met, the NFTs are mostly restricted to structures in the medial temporal lobe, basal forebrain, brainstem, and olfactory areas (bulb and cortex). Symptoms in persons with PART usually range from normal to amnestic cognitive changes, with only a minority exhibiting profound impairment. Because cognitive impairment is often mild, existing clinicopathologic designations, such as "tangle-only dementia" and "tangle-predominant senile dementia", are imprecise and not appropriate for most subjects. PART is almost universally detectable at autopsy among elderly individuals, yet this pathological process cannot be specifically identified pre-mortem at the present time. Improved biomarkers and tau imaging may enable diagnosis of PART in clinical settings in the future. Indeed, recent studies have identified a common biomarker profile consisting of temporal lobe atrophy and tauopathy without evidence of Aβ accumulation. For both researchers and clinicians, a revised nomenclature will raise awareness of this extremely common pathologic change while providing a conceptual foundation for future studies. Prior reports that have elucidated features of the pathologic entity we refer to as PART are discussed, and working neuropathological diagnostic criteria are proposed.

Efforts to understand nervous system structure and function have received new impetus from the federal Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative. Comparative analyses can contribute to this effort by leading to the discovery of general principles of neural circuit design, information processing, and gene-structure-function relationships that are not apparent from studies on single species. We here propose to extend the comparative approach to nervous system 'maps' comprising molecular, anatomical, and physiological data. This research will identify which neural features are likely to generalize across species, and which are unlikely to be broadly conserved. It will also suggest causal relationships between genes, development, adult anatomy, physiology, and, ultimately, behavior. These causal hypotheses can then be tested experimentally. Finally, insights from comparative research can inspire and guide technological development. To promote this research agenda, we recommend that teams of investigators coalesce around specific research questions and select a set of 'reference species' to anchor their comparative analyses. These reference species should be chosen not just for practical advantages, but also with regard for their phylogenetic position, behavioral repertoire, well-annotated genome, or other strategic reasons. We envision that the nervous systems of these reference species will be mapped in more detail than those of other species. The collected data may range from the molecular to the behavioral, depending on the research question. To integrate across levels of analysis and across species, standards for data collection, annotation, archiving, and distribution must be developed and respected. To that end, it will help to form networks or consortia of researchers and centers for science, technology, and education that focus on organized data collection, distribution, and training. These activities could be supported, at least in part, through existing mechanisms at NSF, NIH, and other agencies. It will also be important to develop new integrated software and database systems for cross-species data analyses. Multidisciplinary efforts to develop such analytical tools should be supported financially. Finally, training opportunities should be created to stimulate multidisciplinary, integrative research into brain structure, function, and evolution.

Background: The primary histological characteristic of Alzheimer's disease is the presence of neurofibrillary tangles, which are large aggregates of tau protein. Aging is the primary risk factor for the development of Alzheimer's disease, however, the underlying causes of tau protein aggregation and toxicity are unclear. Aims: Here we investigated tau aggregation and toxicity under the conditions of compromised protein homeostasis. Methods: We used heterologous expression of human tau protein in the unicellular eukaryote yeast Saccharomyces cerevisiae with evolutionarily conserved protein quality control pathways and examined tau‐dependent toxicity and aggregation using growth assays, fluorescence microscopy, and a split luciferase‐based reporter NanoBiT. Results: Tau protein expressed in yeast under mild proteotoxic stress, or in mutants with impaired pathways for proteotoxic stress response, did not lead to synthetic toxicity or the formation of obvious aggregates. Chronologically old cells also did not develop observable tau aggregates. Our examination of tau oligomerization in living cells using NanoBiT reporter suggests that tau does not form significant levels of oligomers under basal conditions or under mild proteotoxic stress. Conclusion: Together our data suggest that human tau protein does not represent a major burden to the protein quality control system in yeast cells. When expressed in yeast Saccharomyces cerevisiae cell model under the conditions of compromised protein homeostasis, human tau protein does not form visible aggregates or result in toxicity. [ABSTRACT FROM AUTHOR]

The evolutionary history of canids and felids is marked by a deep time separation that has uniquely shaped their behavior and phenotype toward refined predatory abilities. The caudate nucleus is a subcortical brain structure associated with both motor control and cognitive, emotional, and executive functions. We used a combination of three‐dimensional imaging, allometric scaling, and structural analyses to compare the size and shape characteristics of the caudate nucleus. The sample consisted of MRI scan data obtained from six canid species (Canis lupus lupus, Canis latrans, Chrysocyon brachyurus, Lycaon pictus, Vulpes vulpes, Vulpes zerda), two canid subspecies (Canis lupus familiaris, Canis lupus dingo), as well as three felids (Panthera tigris, Panthera uncia, Felis silvestris catus). Results revealed marked conservation in the scaling and shape attributes of the caudate nucleus across species, with only slight deviations. We hypothesize that observed differences in caudate nucleus size and structure for the domestic canids are reflective of enhanced cognitive and emotional pathways that possibly emerged during domestication. [ABSTRACT FROM AUTHOR]

A systematic classification and accepted nomenclature of neuron types is much needed but is currently lacking. This article describes a possible taxonomical solution for classifying GABAergic interneurons of the cerebral cortex based on a novel, web-based interactive system that allows experts to classify neurons with pre-determined criteria. Using Bayesian analysis and clustering algorithms on the resulting data, we investigated the suitability of several anatomical terms and neuron names for cortical GABAergic interneurons. Moreover, we show that supervised classification models could automatically categorize interneurons in agreement with experts' assignments. These results demonstrate a practical and objective approach to the naming, characterization and classification of neurons based on community consensus.

Oligomeric β-amyloid (Aβ) has recently been linked to synaptic plasticity deficits, which play a major role in progressive cognitive decline in Alzheimer's disease (AD). Here we present evidence that chronic oral administration of carvedilol, a nonselective β-adrenergic receptor blocker, significantly attenuates brain oligomeric β-amyloid content and cognitive deterioration in 2 independent AD mouse models. We found that carvedilol treatment significantly improved neuronal transmission, and that this improvement was associated with the maintenance of number of the less stable "learning" thin spines in the brains of AD mice. Our novel observation that carvedilol interferes with the neuropathologic, biochemical, and electrophysiological mechanisms underlying cognitive deterioration in AD supports the potential development of carvedilol as a treatment for AD.

Brain aging has been associated with aberrant DNA methylation patterns, and changes in the levels of DNA methylation and associated markers have been observed in the brains of Alzheimer’s disease (AD) patients. DNA hydroxymethylation, however, has been sparsely investigated in aging and AD. We have previously reported robust decreases in 5-methylcytosine (5-mC) and 5-hydroxymethylcytosine (5-hmC) in the hippocampus of AD patients compared to non-demented controls. In the present study, we investigated 3- and 9-month-old APPswe/PS1ΔE9 transgenic and wild-type mice for possible age-related alterations in 5-mC and 5-hmC levels in three hippocampal sub-regions using quantitative immunohistochemistry. While age-related increases in levels of both 5-mC and 5-hmC were found in wild-type mice, APPswe/PS1ΔE9 mice showed decreased levels of 5-mC at 9 months of age and no age-related changes in 5-hmC throughout the hippocampus. Altogether, these findings suggest that aberrant amyloid processing impact on the balance between DNA methylation and hydroxymethylation in the hippocampus during aging in mice.

In the current study we employed immunohistochemical techniques to investigate the localisation of three calcium-binding proteins (parvalbumin, calbindin, and calretinin) in 10 neuronal structures of the cerebellar cortex (stellate cells, basket cells, parallel fibres, climbing fibres, Purkinje cells, granule cells, Golgi type II cells, Lugaro neurons, unipolar brush neurons, and mossy fibres) in 143 species from across themammalian radiation. Most often, parvalbumin was localised in the neural structures of themolecular and Purkinje cell layers but was absent in the granule cell layer. Calbindin was most often immunolocalised in the neural structures of the Purkinje cell layer and mossy fibres, whereas calretinin was most often immunolocalised in the climbing fibres of the molecular layer and all neural structures of the granule cell layer. Despite this general consistency, variations in the localisation of these three calcium-binding proteins were found in every lineage, and almost every species, the one exception being the western tree hyrax that showed the full suite of most often observed calcium-binding protein chemoarchitecture for the mammalian cerebellar cortex. These consistencies and variances in the calcium-binding protein chemoarchitecture of the cerebellar cortex of mammals may play significant roles in the species-specific learning and refining of motor, perceptual, and cognitive skills and capacities required to survive in the environments they inhabit. [ABSTRACT FROM AUTHOR]

Aims: Considering the substantial variability in treatment response across patients with spinal muscular atrophy (SMA), reliable markers for monitoring response to therapy and predicting treatment responders need to be identified. The study aimed to determine if measured concentrations of disease biomarkers (total tau protein, neurofilament light chain, and S100B protein) correlate with the duration of nusinersen treatment and with scores obtained using functional scales for the assessment of motor abilities. Methods: A total of 30 subjects with SMA treated with nusinersen between 2017 and 2021 at the Department of Pediatrics, University Hospital Centre Zagreb, Croatia, were included in this study. Cerebrospinal fluid (CSF) samples were collected by lumbar puncture prior to intrathecal application of nusinersen. Protein concentrations in CSF samples were determined by enzyme‐linked immunosorbent assay in 26 subjects. The motor functions were assessed using functional motor scales. Results: The main finding was significantly decreased total tau correlating with the number of nusinersen doses and motor improvement in the first 18–24 months of treatment (in all SMA patients and SMA type 1 patients). Neurofilament light chain and S100B were not significantly changed after administration of nusinersen. Conclusions: The measurement of total tau concentration in CSF is a reliable index for monitoring the biomarker and clinical response to nusinersen therapy in patients with SMA. [ABSTRACT FROM AUTHOR]