Cerebral Cortex Research Articles

TRPC6 is a mechanosensitive channel essential for ultrasound neuromodulation in the mammalian brain

Ultrasound neuromodulation has become an innovative technology that enables noninvasive intervention in mammalian brain circuits with high spatiotemporal precision. Despite the expanding utility of ultrasound neuromodulation in the neuroscience research field and clinical applications, the molecular and cellular mechanisms by which ultrasound impacts neural activity in the brain are still largely unknown. Here, we report that transient receptor potential canonical 6 (TRPC6), a mechanosensitive nonselective cation channel, is essential for ultrasound neuromodulation of mammalian neurons in vitro and in vivo. We first demonstrated that ultrasound irradiation elicited rapid and robust Ca2+ transients mediated via extracellular Ca2+ influx in cultured mouse cortical and hippocampal neurons. Ultrasound-induced neuronal responses were massively diminished by blocking either the generation of action potential or synaptic transmission. Importantly, both pharmacological inhibition and genetic deficiency of TRPC6 almost completely abolished neuronal responses to ultrasound. Furthermore, we found that intracerebroventricular administration of a TRPC6 blocker significantly attenuated the number of neuronal firings in the cerebral cortex evoked by transcranial ultrasound irradiation in mice. Our findings indicate that TRPC6 is an indispensable molecule of ultrasound neuromodulation in intact mammalian brains, providing fundamental understanding of biophysical molecular mechanisms of ultrasound neuromodulation as well as insight into its future feasibility in neuroscience and translational research in humans.

Cortical tracking of postural sways during standing balance

Maintaining an upright stance requires the integration of sensory inputs from the visual, vestibular and somatosensory-proprioceptive systems by the central nervous system to develop a corrective postural strategy. However, it is unclear whether and how the cerebral cortex monitors and controls postural sways. Here, we asked whether postural sways are encoded in ongoing cortical oscillations, giving rise to a form of corticokinematic coherence (CKC) in the context of standing balance. Center-of-pressure (CoP) fluctuations and electroencephalographic cortical activity were recorded as young healthy participants performed balance tasks during which sensory information was manipulated, by either removal or alteration. We found that postural sways are represented in ongoing cortical activity during challenging balance conditions, in the form of CKC at 1–6 Hz. Time delays between cortical activity and CoP features indicated that both afferent and efferent pathways contribute to CKC, wherein the brain would monitor the CoP velocity and control its position. Importantly, CKC was behaviorally relevant, as it predicted the increase in instability brought by alteration of sensory information. Our results suggest that human sensorimotor cortical areas take part in the closed-loop control of standing balance in challenging conditions. Importantly, CKC could serve as a neurophysiological marker of cortical involvement in maintaining balance.

Implication of Let7b/AhR/ARNT/HMGB1/RAGE cascade in neuroplasticity disturbances induced by glucocorticoids and the promising reversible effect of 3,3 diindolymethane: Bidirectional crosstalk of Aryl hydrocarbon receptors

Prolonged exposure to glucocorticoids (GC) disrupts neuronal architecture, hinders neuroplasticity, and triggers neuroinflammation. However, the precise underlying mechanisms have not been studied yet. The current study aimed to investigate the mechanisms of GC-induced neuroinflammatory effects by stimulating the miRNA let7b, aryl hydrocarbon receptor (AhR)/ARNT, HMGB1/RAGE, and other downstream targets. Rats were divided into 4 groups; control, GC (20 mg/kg, S.C.), 3,3′-diindolylmethane (DIM) 50 mg/kg/day, and donepezil (DNZ) 4 mg/kg/day for 21 days. Behavioral tests and histopathological investigations of cerebral cortex were done. Let7b, AhR, ARNT, and cytochrome A1A were estimated using qRT-PCR. HMGB1, RAGE, NQO1and NRF2 were estimated using ELISA, whereas GFAP and TNF-α by immunohistochemical analysis. Keap1 was estimated using Western technique. GSH and TBARS were assessed by colorimetric assay. In the current study, GC elevates the gene expressions of let7b, AhR, ARNT, and cytochrome A1A, along with the protein contents of HMGB1, RAGE, NQO1and NRF2. In addition, GC showed increased GFAP, TNF-α, and TBARS, together with decreased Keap1 and GSH. On the other side, DIM and DNZ reversed all the above-mentioned findings. Collectively, the study documents for the first time the effect of GC in upregulating let7b and activating the AhR/ARNT loop which subsequently stimulates RAGE/HMGB1 and NRF2/Keap1 cascade leading to stimulating further inflammatory and oxidative signaling pathways. Certainly, these effects are responsible for the behavioral fluctuations, the brain’s histological disruption, altered neuroplasticity, and neuroinflammation induced by GC. Moreover, DIM conquers GC-induced neuroinflammation due to its characteristic role in modulating AhR and its downstream targets.

Into the gray matter: construction and coupling of multiscale highly-detailed arterial networks in the human cerebral cortex

Stroke-related diseases represent 11% of worldwide deaths. State-of-the-art medical imaging describes many aspects of cerebral circulation. Nevertheless, the limited resolution of these techniques hinders the study of the hemodynamics in smaller vessels. Computational models aid in this problem, providing tools to characterize cerebral hemodynamics in clinical scenarios of interest that are otherwise inaccessible. This work aims to build vascular networks in the human cerebral cortex to study hemodynamics across different regions of the gray matter. The method is based on the Constrained Constructive Optimization method (CCO), called PDCCO, which generates vascular networks following a set of anatomical rules. A patient-specific MRI geometry of the cerebral gray matter is used to register an existing vascular model of the major cerebral vessels in the pial surface of the brain, from where the network is expanded. The brain geometry is partitioned into three territories for each large cerebral artery. The vascular generation is conducted independently for each territory and merged into a single network. First, a thin volume of the pial surface is filled with blood vessels down to the scale of penetrating arterioles of 50 μm. The network is further extended downwards to penetrate the gray matter, and deep vascularization is achieved by appending sub-tree networks to each terminal vessel. These sub-trees are generated separately with vascular properties associated with the gray matter. The final network reaches 234000 vascular segments in the pial network, out of which 116977 are terminal vessels. In turn, each terminal vessel gives rise to a network of 50 terminals, yielding 5 million terminals, and 10 million vascular segments, for each hemisphere. Over the pial surface, the diameters vary between 2100 μm and 26 μm, with terminals between 50 μm and 60 μm, and the pressure drops from 100 mmHg to a range between 50 mmHg and 70 mmHg. The network can be coupled with existing blood flow models of the entire cardiovascular system for the simulation of pulsatile blood flow to study pressure heterogeneities along the cerebral cortex in normal and pathological systemic conditions. This novel approach proposes a strategy for the automatic vascularization of the brain, with the aim of understanding microcirculation under different conditions, allowing the study of the risk of stroke, among other mechanisms involved in the onset and progress of degenerative diseases.

Unraveling Spatiotemporal Metabolic Perturbation of Amino Acids Associated with Ischemia-Reperfusion Injury by MALDI MS Imaging.

Various complex metabolic perturbations are involved in cerebral ischemia-reperfusion (I/R) injury. However, limited data have been reported on dynamic spatiotemporal metabolic perturbations of amino acids (AAs) in I/R injured rat brains. In this work, a combination of laser-assisted chemical transfer (LACT) and hexafluoroisopropanol (HFIP) was applied to the enhancement of on-tissue derivatization of AAs for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) of their dynamic spatiotemporal changes during I/R injury. The spatiotemporal distribution patterns of 15 derivatized AAs in the rat subjected to middle cerebral artery occlusion (MCAO) followed by different periods of reperfusion were unraveled by using MALDI MSI, including excitatory amino acids (e.g., Glu, Asp), inhibitory amino acids (e.g., GABA, Gly) and the other amino acids (e.g., Val, Pro, Gln, Phe). The metabolic perturbations of AAs showed similarities and differences in cerebral cortex (CTX) and striatum (STR) of MCAO rat brains at different periods of I/R injury. Generally, in 0.5-1.5 h of ischemia followed by 1-6 h of reperfusion, I/R triggered a dramatic increase in the levels of some AAs such as Glu, Asp, Gly, GABA, Gln, and Phe in both CTX and STR. After 6 h of reperfusion, AA levels gradually decreased. Immunohistochemistry (IHC) assay further showed that the immunoreactivities of selected enzymes related to Glu and GABA metabolism increased at the later stage of reperfusion. This present work provided spatiotemporal metabolic perturbations of AAs, which will further help us understand the mechanisms of I/R injury and also have great significance in developing region-specific therapeutic drugs and diagnostic markers.

Regulation and function of a polarly localized lignin barrier in the exodermis

AbstractMulticellular organisms control environmental interactions through specialized barriers in specific cell types. A conserved barrier in plant roots is the endodermal Casparian strip (CS), a ring-like structure made of polymerized lignin that seals the endodermal apoplastic space. Most angiosperms have another root cell type, the exodermis, that is reported to form a barrier. Our understanding of exodermal developmental and molecular regulation and function is limited as this cell type is absent from Arabidopsis thaliana. We demonstrate that in tomato (Solanum lycopersicum), the exodermis does not form a CS. Instead, it forms a polar lignin cap (PLC) with equivalent barrier function to the endodermal CS but distinct genetic control. Repression of the exodermal PLC in inner cortical layers is conferred by the SlSCZ and SlEXO1 transcription factors, and these two factors genetically interact to control its polar deposition. Several target genes that act downstream of SlSCZ and SlEXO1 in the exodermis are identified. Although the exodermis and endodermis produce barriers that restrict mineral ion uptake, the exodermal PLC is unable to fully compensate for the lack of a CS. The presence of distinct lignin structures acting as apoplastic barriers has exciting implications for a root’s response to abiotic and biotic stimuli.

Digital instrument simulator to optimize the development of hyperspectral systems: application for intraoperative functional brain mapping.

Intraoperative optical imaging is a localization technique for the functional areas of the human brain cortex during neurosurgical procedures. These areas can be assessed by monitoring cerebral hemodynamics and metabolism. Robust quantification of these biomarkers is complicated to perform during neurosurgery due to the critical context of the operating room. In actual devices, the inhomogeneities of the optical properties of the exposed brain cortex are poorly taken into consideration, which introduce quantification errors of biomarkers of brain functionality. Moreover, the best choice of spectral configuration is still based on an empirical approach. We propose a digital instrument simulator to optimize the development of hyperspectral systems for intraoperative brain mapping studies. This simulator can provide realistic modeling of the cerebral cortex and the identification of the optimal wavelengths to monitor cerebral hemodynamics (oxygenated and deoxygenated hemoglobin Hb) and metabolism (oxidized state of cytochromes and and cytochrome-c-oxidase oxCytb, oxCytc, and oxCCO). The digital instrument simulator is computed with white Monte Carlo simulations of a volume created from a real image of exposed cortex. We developed an optimization procedure based on a genetic algorithm to identify the best wavelength combinations in the visible and near-infrared range to quantify concentration changes in , Hb, oxCCO, and the oxidized state of cytochrome and (oxCytb and oxCytc). The digital instrument allows the modeling of intensity maps collected by a camera sensor as well as images of path length to take into account the inhomogeneities of the optical properties. The optimization procedure helps to identify the best wavelength combination of 18 wavelengths that reduces the quantification errors in , Hb, and oxCCO by 47%, 57%, and 57%, respectively, compared with the gold standard of 121 wavelengths between 780 and 900nm. The optimization procedure does not help to resolve changes in cytochrome and in a significant way but helps to better resolve oxCCO changes. We proposed a digital instrument simulator to optimize the development of hyperspectral systems for intraoperative brain mapping studies. This digital instrument simulator and this optimization framework could be used to optimize the design of hyperspectral imaging devices.

Group-common and individual-specific effects of structure–function coupling in human brain networks with graph neural networks

Abstract The human cerebral cortex is organized into functionally segregated but synchronized regions bridged by the structural connectivity of white matter pathways. While structure–function coupling has been implicated in cognitive development and neuropsychiatric disorders, it remains unclear to what extent the structure–function coupling reflects a group-common characteristic or varies across individuals, at both the global and regional brain levels. By leveraging two independent, high-quality datasets, we found that the graph neural network accurately predicted unseen individuals’ functional connectivity from structural connectivity, reflecting a strong structure–function coupling. This coupling was primarily driven by network topology and was substantially stronger than that of the correlation approaches. Moreover, we observed that structure–function coupling was dominated by group-common effects, with subtle yet significant individual-specific effects. The regional group and individual effects of coupling were hierarchically organized across the cortex along a sensorimotor-association axis, with lower group and higher individual effects in association cortices. These findings emphasize the importance of considering both group and individual effects in understanding cortical structure–function coupling, suggesting insights into interpreting individual differences of the coupling and informing connectivity-guided therapeutics.

A Subset of Cortical Areas Exhibit Adult-like Functional Network Patterns in Early Childhood.

The human cerebral cortex contains groups of areas that support sensory, motor, cognitive, and affective functions, often categorized into functional networks. These networks show stronger internal and weaker external functional connectivity (FC), with FC profiles more similar within the same network. Previous studies have shown these networks develop from nascent forms before birth to their mature, adult-like structures in childhood. However, these analyses often rely on adult functional network definitions. This study assesses the potential misidentification of infant functional networks when using adult models and explores the consequences and possible solutions to this problem. Our findings suggest that although adult networks only marginally describe infant FC organization better than chance, misidentification is primarily driven by specific areas. Restricting functional networks to areas with adult-like network clustering revealed consistent within-network FC across scans and throughout development. These areas are also near locations with low network identity variability. Our results highlight the implications of using adult networks for infants and offer guidance for selecting and utilizing functional network models based on research questions and scenarios.

Cell-autonomous action of Slit2 in radial migration of cortical projection neurons.

Neuronal radial migration is a fundamental process for cortical development, the disruption of which causes neurological and psychiatric dysfunctions. SLIT2 plays diverse functions in brain development and is a well-known axon guidance molecule. In this study, we investigated the radial migration of projection neurons in the developing cerebral cortex by in utero knockdown (KD) of Slit2 in mice. KD of Slit2 did not interfere with the neurogenesis and fate-determination but led to the accumulation of the transfected cells in the intermediate zone (IZ), suggesting that the expression of Slit2 is crucial for the radial migration of the cortical neurons. KD of Slit2 hindered the transition of cells from a multipolar to a bipolar shape, which is necessary for glia-guided locomotion. Interestingly, reducing Slit2 did not affect the migration of neighboring untransfected cells, indicating a cell-autonomous action by SLIT2. In addition, the action of SLIT2 KD was mimicked by a dominant negative mutant of ROBO2, a canonical membrane receptor of SLIT2, supporting that SLIT2 acted locally as a secretory molecule. Our results suggest that SLIT2 is indispensable for the radial migration of cortical neurons through an autocrine signaling mechanism.

Isolation and Molecular Profiling of Nuclei of Specific Neuronal Types from Human Cerebral Cortex and Striatum.

Most pathological conditions of the central nervous system do not affect all cell types to the same extent. Delineation of molecular events underlying disease symptoms, including genetic, epigenetic, and transcriptional changes, thus relies on the ability to characterize a specific cell type separately from others. We have developed a methodology for the collection of nuclear RNA and genomic DNA of specific cell types from frozen post-mortem striatum and cerebral cortex. This allows deep transcriptomic profiling of specific cell populations and characterization of their genomes and epigenetic properties. The method is based on the purification of cell nuclei, followed by fluorescence-activated sorting of nuclei (FANS) labeled with nucleic acid probes or antibodies binding to targets present in specific cell types. The protocol describes in detail the procedure for isolating and labeling neuronal and glial nuclei from human brain tissue, the steps that can be taken to extract RNA and genomic DNA, a way to combine the procedure with ATAC-seq to yield information about chromatin accessibility, as well as computational measures for assessing the quality of cell type-specific RNA-seq and ATAC-seq datasets. © 2024 The Author(s). Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Tissue homogenization, isolation of cell nuclei by ultracentrifugation and formaldehyde-fixation Basic Protocol 2: Antibody-based labeling and isolation of nuclei of specific neocortical neuron types Support Protocol 1: Generation of ATAC-seq libraries from the nuclei of specific neuron types of the cerebral cortex Basic Protocol 3: Nucleic acid hybridization-based labeling and isolation of nuclei of specific striatal projection neuron types Alternate Protocol 1: Labeling and isolation of nuclei of specific striatal interneuron types Support Protocol 2: Generation of ATAC-seq libraries from the nuclei of specific striatal neuron types Basic Protocol 4: Extraction of genomic DNA and nuclear RNA and preparation of sequencing libraries Basic Protocol 5: Processing and quality control of FANS-seq and ATAC-seq data.

Functional architecture of cerebral cortex during naturalistic movie watching.

Characterizing the functional organization of cerebral cortex is a fundamental step in understanding how different kinds of information are processed in the brain. However, it is still unclear how these areas are organized during naturalistic visual and auditory stimulation. Here, we used high-resolution functional MRI data from 176 human subjects to map the macro-architecture of the entire cerebral cortex based on responses to a 60-min audiovisual movie stimulus. A data-driven clustering approach revealed a map of 24 functional areas/networks, each explicitly linked to a specific aspect of sensory or cognitive processing. Novel features of this map included an extended scene-selective network in the lateral prefrontal cortex, separate clusters responsive to human-object and human-human interaction, and a push-pull interaction between three executive control (domain-general) networks and domain-specific regions of the visual, auditory, and language cortex. Our cortical parcellation provides a comprehensive and unified map of functionally defined areas in the human cerebral cortex.

Age and duration of obesity modulate the inflammatory response and expression of neuroprotective factors in mammalian female brain.

Obesity has become a global epidemic and is associated with comorbidities, including diabetes, cardiovascular, and neurodegenerative diseases, among others. While appreciable insight has been gained into the mechanisms of obesity-associated comorbidities, effects of age, and duration of obesity on the female brain remain obscure. To address this gap, adolescent and mature adult female mice were subjected to a high-fat diet (HFD) for 13 or 26 weeks, whereas age-matched controls were fed a standard diet. Subsequently, the expression of inflammatory cytokines, neurotrophic/neuroprotective factors, and markers of microgliosis and astrogliosis were analyzed in the hypothalamus, hippocampus, and cerebral cortex, along with inflammation in visceral adipose tissue. HFD led to a typical obese phenotype in all groups independent of age and duration of HFD. However, the intermediate duration of obesity induced a limited inflammatory response in adolescent females' hypothalamus while the hippocampus, cerebral cortex, and visceral adipose tissue remained unaffected. In contrast, the prolonged duration of obesity resulted in inflammation in all three brain regions and visceral adipose tissue along with upregulation of microgliosis/astrogliosis and suppression of neurotrophic/neuroprotective factors in all brain regions, denoting the duration of obesity as a critical risk factor for neurodegenerative diseases. Importantly, when female mice were older (i.e., mature adult), even the intermediate duration of obesity induced similar adverse effects in all brain regions. Taken together, our findings suggest that (1) both age and duration of obesity have a significant impact on obesity-associated comorbidities and (2) early interventions to end obesity are critical to preserving brain health.

Vitamin D3 Exerts a Neuroprotective Effect in Metabolic Syndrome Rats: Role of BDNF/TRKB/Akt/GS3Kβ Pathway.

Metabolic syndrome (MetS) is usually associated with cognitive impairment, neuropathic pain, and reduced brain-derived neurotrophic factor (BDNF) levels. BDNF via tropomyosin receptor kinase B (TrkB) exerts neuroprotection by activating protein kinase B (Akt) to inhibit glycogen synthase kinase-3β (GSK3β). Although Vitamin D3 (VitD3) has demonstrated favorable metabolic and neuronal outcomes in MetS, the precise molecular mechanisms underlying its neuroprotective effects remain poorly elucidated. We aimed to test the hypothesis that VitD3 mitigates MetS-induced cognition deficits and neuropathic pain via modulating the BDNF/TRKB/Akt/GS3Kβ signaling pathway. MetS was induced in male rats by 10% fructose-supplemented water and 3% salt-enriched diet. After 6 weeks, normal and MetS rats received either vehicle or VitD3 (10 µg/kg/day) for an additional 6 weeks. Glycemic status, lipid profile, and behavioral changes were assessed. The advanced glycation end products (AGEs), and markers of inflammation (TNF-α and NF-κB), oxidative stress (malondialdehyde), and apoptosis (caspase3), as well as BDNF, TrkB, PI3K, Akt, GSK3β, phosphorylated tau, and amyloid beta (Aβ) were assessed in the cerebral cortex. MetS rats had deteriorated glycemic and lipid profiles, higher AGEs, reduced levels of BDNF, TrkB, PI3K, and active Akt, along with increased GSK3β levels, inflammation, oxidative stress, and apoptosis. These changes were associated with higher levels of cognitive impairment markers phosphorylated tau and Aβ, as well as behavioral changes indicative of cognitive impairment and neuropathic pain. VitD3 improved the cognitive and behavioral alterations, while mitigating the associated molecular derangements. Our results indicate that VitD3 may exert neuroprotective effects by modulating the BDNF/TrkB/PI3K/Akt/GSK3β signaling pathway.

Regulation of neuronal fate specification and connectivity of the thalamic reticular nucleus by the Ascl1-Isl1 transcriptional cascade

The thalamic reticular nucleus (TRN) is an anatomical and functional hub that modulates the flow of information between the cerebral cortex and thalamus, and its dysfunction has been linked to sensory disturbance and multiple behavioral disorders. Therefore, understanding how TRN neurons differentiate and establish connectivity is crucial to clarify the basics of TRN functions. Here, we showed that the regulatory cascade of the transcription factors Ascl1 and Isl1 promotes the fate of TRN neurons and concomitantly represses the fate of non-TRN prethalamic neurons. Furthermore, we found that this cascade is necessary for the correct development of the two main axonal connections, thalamo-cortical projections and prethalamo-thalamic projections. Notably, the disruption of prethalamo-thalamic axons can cause the pathfinding defects of thalamo-cortical axons in the thalamus. Finally, forced Isl1 expression can rescue disruption of cell fate specification and prethalamo-thalamic projections in in vitro primary cultures of Ascl1-deficient TRN neurons, indicating that Isl1 is an essential mediator of Ascl1 function in TRN development. Together, our findings provide insights into the molecular mechanisms for TRN neuron differentiation and circuit formation.

GLP-1 receptor signaling restores aquaporin 4 subcellular polarization in reactive astrocytes and promotes amyloid β clearance in a mouse model of Alzheimer's disease.

The physiological actions of a gut hormone, glucagon-like peptide-1 (GLP-1), in Alzheimer's disease (AD) brain remain poorly understood, although GLP-1 receptor (GLP-1R) expression in this organ has been shown in several experimental studies. Therefore, we explored whether the GLP-1R signaling promotes the clearance of amyloid β (Aβ) (1-42) which is a core pathological hallmark of AD, focusing on the water channel protein aquaporin 4 (AQP4) localized to astrocyte endfeet perivascular membranes in intact brain. First, we confirmed that Glp1r mRNA is predominantly expressed at perivascular site of astrocytes in normal mouse cerebral cortex through in situ hybridization analysis. Next, we observed that 20-week subcutaneous administration of a GLP-1R agonist (GLP-1RA) liraglutide significantly reduced Aβ (1-42) accumulation in the cerebral cortex and improved spatial working memory in an AD mouse model, AppNL-G-F/NL-G-F mice. Furthermore, our current data revealed that the 4-week liraglutide treatment relocalized subcellular AQP4 in morphologically injured reactive astrocytes of AppNL-G-F/NL-G-F mice to the cell surface perivascular site through PKA-mediated AQP4 phosphorylation. Such translocation of phosphorylated AQP4 to astrocyte cell surface following incubation with liraglutide was observed also in the present in vitro study using the cell line in which AQP4 cDNA was introduced into immortalized human astrocyte. These results suggest that enhanced intracerebral GLP-1R signaling following peripheral administration of GLP-1RA restores AQP4 subcellular polarization in reactive astrocytes and would promote Aβ excretion possibly through increasing AQP4-mediated intracerebral water flux in the brain in AD.

Euonymus hamiltonianus Extract Improves Amnesia in APPswe/Tau Transgenic and Scopolamine-Induced Dementia Models.

Dementia is a syndrome exhibiting progressive impairments on cognition and behavior beyond the normal course of aging, and Alzheimer's disease (AD) is one of the neurodegenerative diseases known to cause dementia. We investigated the effect of KGC07EH, the 30% ethanol extract of Euonymus hamiltonianus, against amyloid-β (Aβ) production and cognitive dysfunction in dementia models. KGC07EH was treated on Hela cells expressing the Swedish mutant form of amyloid precursor protein (APP), and the AD triple transgenic (3× TG) mice were given KGC07EH orally during 11-14 months of age (100 and 300mg/kg/day). SH-SY5Y cell line was used to test KGC07EH on scopolamine-induced elevation of acetylcholinesterase (AChE) activity. ICR mice were intraperitoneally injected with scopolamine, and KGC07EH was administered orally (50, 100, and 200mg/kg/day) for 4 weeks. KGC07EH treatment decreased Aβ, sAPPβ-sw, and sAPPβ-wt levels and APP protein expressions while sAPPα was increased in Swedish mutant-transfected HeLa cells. KGC07EH treatment also significantly reduced the accumulation of Aβ plaques and tau tangles in the brain of 3× TG mice as well as improving the cognitive function. In SH-SY5Y cells cultured with scopolamine, KGC07EH dose-dependently attenuated the increase of AChE activity. KGC07EH also improved scopolamine-induced learning and memory impairment in scopolamine-injected mice, and in their cerebral cortex and hippocampus, the expression levels of p-ERK, p-CREB, p-Akt, and BDNF were attenuated. KGC07EH inhibits APP processing and Aβ production both in vitro and in vivo, while enhancing acetylcholine signaling and cognitive dysfunction which are the major symptoms of dementia.

Cell type census in cerebral cortex reveals species-specific brain function and connectivity

The cerebral cortex contains a diverse array of functional regions that are conserved across species, such as primary somatosensory and primary visual cortex. However, despite this conservation, these regions exhibit different connectivity and functions in various species. It is hypothesized that these differences arise from distinct cell types within the conserved regions. To uncover these species-specific differences, investigating gene expression at the cellular level can reveal unique cell types. In this review, we highlight recent research on the molecular mechanisms that govern the formation of specific cell types in the rodent primary somatosensory cortex. Furthermore, we explore how these conserved molecular mechanisms are observed across different brain regions in various species. These findings offer new insights into the diversity and evolutionary background of neural circuit formation in the mammalian cortex.

Vascular Development of Fetal and Postnatal Neocortex of the Pig, the European Wild Boar Susscrofa.

The development of the brain's vascular system is a predominantly prenatal process in mammalian species and is required for neurogenesis and further brain development. Our recent work on fetal pig has revealed that many neurodevelopmental processes start well before birth and proceed rapidly reaching near-mature status already around birth. Here, we analyzed the development of neocortical vasculature from embryonic day (E) 45 onward (gestation in pig lasts 114 days) using qualitative and quantitative image analyses and protein blots. In all cortical layers, vessel volume from total brain volume at E100 resembled that of a postnatal day (P) 30 piglet. Endothelial cells expressed the tight junction protein claudin-5 from E45 onward. GFAP+ and AQP4+ astrocytes, PDGFRβ+ pericytes, and α-SMA+ smooth muscle cells are detectable near vessels at E60 suggesting an early assembly of blood-brain barrier components. The vascular system in the visual cortex is advanced before birth with an almost mature pattern at E100. Findings were confirmed by blots that showed a steady increase of expression of tight junction and angiogenesis-related proteins (claudin-5, occludin, VE-cadherin, PECAM-1/CD31) from E65 onward until P90. The expression profile was similar in visual and somatosensory cortex. Together, we report a rapid maturation of the vascular system in pig cortex.

Single‐nucleus multi‐ome profiling of epigenomic modifications and transcriptome characterization of heterogeneity in early and late‐stage Alzheimer’s disease

AbstractBackgroundAlzheimer’s disease (AD), characterized by tau lesions and amyloid plaques, has traditionally been investigated within the cortical domain. Recent neuroimaging studies have implicated micro‐ and macrostructural abnormalities in cortical layers during the progression of AD. While examinations from diverse brain regions have contributed to comprehending the regional severity, these approaches have constrained the ability to delineate cortical alterations in AD. Our study employed a single‐cell resolution approach to characterize transcriptomic and epigenomic alternations in the human brain affected by the disease.MethodWe conducted a comprehensive analysis utilizing snRNA‐Seq and single‐nucleus epigenomic profiling on samples obtained from more than 2 million cells over 100 individuals with early and late‐stage AD cases, along with controls. Four samples were procured from each participant, derived from the human pre‐frontal cortex (PFC) and temporal cortex (TCX). Our analysis utilized multi‐ome profiling, which simultaneously profiles gene expression and epigenomic changes. Data processing utilized Scanpy and Signac for gene expression and histone processing. Cicero identified cis‐regulatory elements (cCREs), overlaid with GWAS variants, creating a genome‐wide map. Transcription factor (TF) footprinting was done for cell types and disease‐associated subclusters.ResultUMAP and Leiden clustering on batch‐corrected data identified discrete cell‐type clusters from snRNA‐Seq and additional multi‐ome profiling. Enhancer‐promoter links were identified, constructing disease‐enriched, region‐specific, and shared TF regulatory networks in AD. Pseudotime trajectory analysis revealed changes from early to late‐stage AD.ConclusionThe single nucleus multi‐ome data produced in this study represents a valuable asset for the AD research community. Compared to bulk ATAC‐seq, our single‐nucleus epigenomic data provides precise insights into active and repressive activities. The study illuminates crucial TFs and their roles in AD, offering insights into cell‐specific and region‐specific mechanisms in AD pathology. Experimental validation underscores the functional relevance of the targeted TF in AD, highlighting its potential medical significance.