Subcortical Neurons Research Articles

Macaque V1 responses to 2nd-order contrast-modulated stimuli and the possible subcortical and cortical contributions.

Natural images comprise contours and boundaries defined by 1st-order luminance-modulated (LM) cues that are readily encoded by V1 neurons, and 2nd-order contrast-modulated (CM) cues that carry local, but not over-the-space, luminance changes. The neurophysiological foundations for CM processing remain unsolved. Here we used two-photon calcium imaging to demonstrate that V1 superficial-layer neurons respond to both LM and CM gratings in awake, fixating, macaques, with overall LM responses stronger than CM responses. Furthermore, adaptation experiments revealed that LM responses were similarly suppressed by LM and CM adaptation, with moderately larger effects by iso-orientation adaptation than by orthogonal adaptation, suggesting that LM and CM orientation responses likely share a strong orientation-non-selective subcortical origin. In contrast, CM responses were substantially more suppressed by iso-orientation than by orthogonal LM and CM adaptation, likely suggesting stronger orientation-specific intracortical influences for CM responses than for LM responses, besides shared orientation-non-selective subcortical influences. These results thus may indicate a subcortical-to-V1 filter-rectify-filter mechanism for CM processing: Local luminance changes in CM stimuli are initially encoded by orientation-non-selective subcortical neurons, and the outputs are half-wave rectified, and then summed by V1 neurons to signal CM orientation, which may be further substantially refined by intracortical influences.

Spike Afterhyperpolarizations Govern Persistent Firing Dynamics in Rat Neocortical and Hippocampal Pyramidal Cells.

Persistent firing is commonly reported in both cortical and subcortical neurons under a variety of behavioral conditions. Yet the mechanisms responsible for persistent activity are only partially resolved with support for both intrinsic and synaptic circuit-based mechanisms. Little also is known about physiological factors that enable epochs of persistent firing to continue beyond brief pauses and then spontaneously terminate. In the present study, we used intracellular recordings in rat (both sexes) neocortical and hippocampal brain slices to assess the ionic mechanisms underlying persistent firing dynamics. Previously, we showed that blockade of ether-á-go-go-related gene (ERG) potassium channels abolished intrinsic persistent firing in the presence of low concentrations of muscarinic receptor agonists and following optogenetic activation of cholinergic axons. Here we show the slow dynamics of ERG conductance changes allows persistent firing to outlast the triggering stimulus and even to initiate discharges following ∼7 s poststimulus firing pauses. We find that persistent firing dynamics is regulated by the interaction between ERG conductance and spike afterhyperpolarizations (AHPs). Increasing the amplitude of spike AHPs using either SK channel activators or a closed-loop reactive feedback system allows persistent discharges to spontaneously terminate in both neocortical neurons and hippocampal CA1 pyramidal cells. The interplay between ERG and the potassium channels that mediate spike AHPs grades the duration of persistent firing, providing a novel, generalizable mechanism to explain self-terminating persistent firing modes observed behaving animals.SIGNIFICANCE STATEMENT Many classes of neurons generate prolonged spiking responses to transient stimuli. These discharges often outlast the stimulus by seconds to minutes in some in vitro models of persistent firing. While recent work has identified key synaptic and intrinsic components that enable persistent spiking responses, less is known about mechanisms that can terminate and regulate the dynamics of these responses. The present study identified the spike afterhyperpolarizations as a potent mechanism that regulates the duration of persistent firing. We found that amplifying spike afterpotentials converted bistable persistent firing into self-terminating discharges. Varying the spike AHP amplitude grades the duration of persistent discharges, generating in vitro responses that mimic firing modes associated with neurons associated with short-term memory function.

Selective corticofugal modulation on sound processing in auditory thalamus of awake marmosets.

Cortical feedback has long been considered crucial for the modulation of sensory perception and recognition. However, previous studies have shown varying modulatory effects of the primary auditory cortex (A1) on the auditory response of subcortical neurons, which complicate interpretations regarding the function of A1 in sound perception and recognition. This has been further complicated by studies conducted under different brain states. In the current study, we used cryo-inactivation in A1 to examine the role of corticothalamic feedback on medial geniculate body (MGB) neurons in awake marmosets. The primary effects of A1 inactivation were a frequency-specific decrease in the auditory response of most MGB neurons coupled with an increased spontaneous firing rate, which together resulted in a decrease in the signal-to-noise ratio. In addition, we report for the first time that A1 robustly modulated the long-lasting sustained response of MGB neurons, which changed the frequency tuning after A1 inactivation, e.g. some neurons are sharper with corticofugal feedback and some get broader. Taken together, our results demonstrate that corticothalamic modulation in awake marmosets serves to enhance sensory processing in a manner similar to center-surround models proposed in visual and somatosensory systems, a finding which supports common principles of corticothalamic processing across sensory systems.

Subcortical Neuronal Correlates of Sleep in Neurodegenerative Diseases

Sleep disturbance is common among patients with neurodegenerative diseases. Examining the subcortical neuronal correlates of sleep disturbances is important to understanding the early-stage sleep neurodegenerative phenomena. To examine the correlation between the number of important subcortical wake-promoting neurons and clinical sleep phenotypes in patients with Alzheimer disease (AD) or progressive supranuclear palsy (PSP). This longitudinal cohort study enrolled 33 patients with AD, 20 patients with PSP, and 32 healthy individuals from the Memory and Aging Center of the University of California, San Francisco, between August 22, 2008, and December 31, 2020. Participants received electroencephalographic and polysomnographic sleep assessments. Postmortem neuronal analyses of brainstem hypothalamic wake-promoting neurons were performed and were included in the clinicopathological correlation analysis. No eligible participants were excluded from the study. Electroencephalographic and polysomnographic assessment of sleep and postmortem immunohistological stereological analysis of 3 wake-promoting nuclei (noradrenergic locus coeruleus [LC], orexinergic lateral hypothalamic area [LHA], and histaminergic tuberomammillary nucleus [TMN]). Nocturnal sleep variables, including total sleep time, sleep maintenance, rapid eye movement (REM) latency, and time spent in REM sleep and stages 1, 2, and 3 of non-REM (NREM1, NREM2, and NREM3, respectively) sleep, and wake after sleep onset. Neurotransmitter, tau, and total neuronal counts of LC, LHA, and TMN. Among 19 patients included in the clinicopathological correlation analysis, the mean (SD) age at death was 70.53 (7.75) years; 10 patients (52.6%) were female; and all patients were White. After adjusting for primary diagnosis, age, sex, and time between sleep analyses and death, greater numbers of LHA and TMN neurons were correlated with decreased homeostatic sleep drive, as observed by less total sleep time (LHA: r = -0.63; P = .009; TMN: r = -0.62; P = .008), lower sleep maintenance (LHA: r = -0.85; P < .001; TMN: r = -0.78; P < .001), and greater percentage of wake after sleep onset (LHA: r = 0.85; P < .001; TMN: r = 0.78; P < .001). In addition, greater numbers of LHA and TMN neurons were correlated with less NREM2 sleep (LHA: r = -0.76; P < .001; TMN: r = -0.73; P < .001). A greater number of TMN neurons was also correlated with less REM sleep (r = -0.61; P = .01). A greater number of LC neurons was mainly correlated with less total sleep time (r = -0.68; P = .008) and greater REM latency (r = 0.71; P = .006). The AD-predominant group had significantly greater sleep drive, including higher total sleep time (mean [SD], 0.49 [1.18] vs -1.09 [1.37]; P = .03), higher sleep maintenance (mean [SD], 0.18 [1.22] vs -1.53 [1.78]; P = .02), and lower percentage of wake after sleep onset during sleep period time (mean [SD], -0.18 [1.20] vs 1.49 [1.72]; P = .02) than the PSP-predominant group based on unbiased k-means clustering and principal component analyses. In this cohort study, subcortical wake-promoting neurons were significantly correlated with sleep phenotypes in patients with AD and PSP, suggesting that the loss of wake-promoting neurons among patients with neurodegenerative conditions may disturb the control of sleep-wake homeostasis. These findings suggest that the subcortical system is a primary mechanism associated with sleep disturbances in the early stages of neurodegenerative diseases.

Frontotemporal lobar degeneration with TAR DNA-binding protein 43 (TDP-43): its journey of more than 100years.

Frontotemporal lobar degeneration (FTLD) with TDP-43-immunoreactive inclusions (FTLD-TDP) is a neurodegenerative disease associated with clinical, genetic, and neuropathological heterogeneity. An association between TDP-43, FTLD and amyotrophic lateral sclerosis (ALS) was first described in 2006. However, a century before immunohistochemistry existed, atypical dementias displaying behavioral, language and/or pyramidal symptoms and showing non-specific FTLD with superficial cortical neuronal loss, gliosis and spongiosis were often confused with Alzheimer's or Pick's disease. Initially this pathology was termed dementia lacking distinctive histopathology (DLDH), but this was later renamed when ubiquitinated inclusions originally found in ALS were also discovered in (DLDH), thus warranting a recategorization as FTLD-U (ubiquitin). Finally, the ubiquitinated protein was identified as TDP-43, which aggregates in cortical, subcortical, limbic and brainstem neurons and glial cells. The topography and morphology of TDP-43 inclusions associate with specific clinical syndromes and genetic mutations which implies different pathomechanisms that are yet to be discovered; hence, the TDP-43 journey has actually just begun. In this review, we describe how FTLD-TDP was established and defined clinically and neuropathologically throughout the past century.

Neuromodulatory control of inhibitory network arborization in the developing postnatal neocortex.

Interregional neuronal communication is pivotal to instructing and adjusting cortical circuit assembly. Subcortical neuromodulatory systems project long-range axons to the cortex and affect cortical processing. However, their roles and signaling mechanisms in cortical wiring remain poorly understood. Here, we explored whether and how the cholinergic system regulates inhibitory axonal ramification of neocortical chandelier cells (ChCs), which control spike generation by innervating axon initial segments of pyramidal neurons. We found that acetylcholine (ACh) signaling through nicotinic ACh receptors (nAChRs) and downstream T-type voltage-dependent calcium (Ca2+) channels cell-autonomously controls axonal arborization in developing ChCs through regulating filopodia initiation. This signaling axis shapes the basal Ca2+ level range in varicosities where filopodia originate. Furthermore, the normal development of ChC axonal arbors requires proper levels of activity in subcortical cholinergic neurons. Thus, the cholinergic system regulates inhibitory network arborization in the developing neocortex and may tune cortical circuit properties depending on early-life experiences.

Emotional and cognitive changes in chronic kidney disease

Chronic kidney disease (CKD) leads to cognitive impairment and emotional changes. However, the precise mechanism underlying the crosstalk between the kidneys and the nervous system is not fully understood. Inflammation and cerebrovascular disease can influence the development of depression in CKD. CKD is one of the strongest risk factors for cognitive impairment. Moreover, cognitive impairment occurs in CKD as patients experience the dysregulation of several brain functional domains due to damage caused to multiple cortical regions and to subcortical modulatory neurons. The differences in structural brain changes between CKD and non-CKD dementia may be attributable to the different mechanisms that occur in CKD. The kidney and brain have similar anatomical vascular systems, which may be susceptible to traditional risk factors. Vascular factors are assumed to be involved in the development of cognitive impairment in patients with CKD. Vascular injury induces white matter lesions, silent infarction, and microbleeds. Uremic toxins may also be directly related to cognitive impairment in CKD. Many uremic toxins, such as indoxyl sulfate, are likely to have an impact on the central nervous system. Further studies are required to identify therapeutic targets to prevent changes in the brain in patients with CKD.

HYPOXIC BRAIN DAMAGEIN PREMATURE INFANTS (MORPHOLOGICAL STUDY)

The aim of the study was to investigate the morphological signs of hypoxic damage to the central nervous system (CNS) in premature infants. Material and methods: The autopsy reports of 20 premature infants were analyzed. The mean gestational age was 25.9±3.7 weeks, median birth weight was 650 [535;940] grams, and height was 32.6±5.4 cm. We analyzed clinical assessment of the infant's condition at birth, the course of the neonatal period, blood gases and acid-base status, the mode and parameters of mechanical lung ventilation, as well as the oxygenation index (OI) and oxygen saturation index (OSI). Macroscopic and histological signs of damage to various brain structures were studied during pathological anatomical examination. Cortex, parietal subcortex, hippocampus, striatum, cerebellum, foci of hemorrhage were examined. Results: The main causes of mortality in premature infants were severe asphyxia and its sequelae such as combined ischemic and hemorrhagic brain and spinal cord damage (45%). Severe hypoxia was confirmed by laboratory investigations. Critical lactate and acid-base blood values corresponding to decompensated lactate acidosis were registered in newborns including hyperlactatemia up to 9±3.6 mmol/l, pH 7.01±0.21, BE (-12.3) [-30; -7.9] mmol/l. The OI and OSI, indicating severity of hypoxia, were significantly elevated with their medians being 13.7[9.6;19.8] and 31.8[9.6;16.2], respectively. All infants had central nervous system lesions of varying severity with the underlying morphological immaturity. Pericellular and perivascular cerebral edema, unilateral or bilateral subcortical and subependymal hemorrhages, intraventricular hemorrhages of various degrees, up to tamponade and blood leakage into the cisterna magna, and cerebral leukomalacia were the most frequent findings. In all patients, altered neuronal shape and size as well as hyperchromic nuclei were revealed in the subcortical zone. Changes in all cell structures (cytoplasm, nuclei, and nucleoli), as well as satellitosis and neuronophagy, were characteristic. Conclusion: Polymorphic morphological changes were observed in the brain structures of premature infants who died as a result of perinatal hypoxia. Along with signs of morphological immaturity, irreversible changes in cortical and subcortical neurons were found. The magnitude of changes is associated with the severity of perinatal hypoxia and decompensated lactate acidosis.

Intranasal delivery of insulin for the restoration of memory signaling in Alzheimer's disease

Alzheimer's disease(AD), is progressive, degenerative brain disease characterized by marked atrophy of cerebral cortex and loss of cortical and sub-cortical neurons. Weakening of insulin receptor signaling is involved in ageing-related brain degeneration like AD. Objective of this study is to develop delivery-system to overcome BBB by employing novel, non-invasive approach via nasal route i.e. delivery of antibody appended Insulin encapsulated carrier, PEGylated nanoparticle coated with chitosan to facilitate nasal absorption for efficient transfer to brain.

THE RESULTS OF THE SEARCH FOR LABORATORY SIGNS OF AUTOIMMUNE REACTIONS TO CEREBRAL AND EXTRACEREBRAL AUTOANTIGENS IN CHILDREN WITH AUTISM SPECTRUM DISORDERS ASSOCIATED WITH GENETIC DEFICIENCY OF THE FOLATE CYCLE

Relevance. The results of five meta-analyzes of randomized controlled clinical trials indicate an association between genetic deficiency of the folate cycle (GDFC) and autism spectrum disorders (ASD) in children. Autoimmune mechanisms play a special role in the pathogenesis of encephalopathy in children with ASD associated with GDFC. Objective: to study the structure of autoimmune reactions in children with ASD associated with GDFC, according to the accumulated evidence base and to identify associations of laboratory signs of autoimmunity and microorganisms to improve understanding of encephalopathy pathogenesis and diagnostic, monitoring and treatment algorithms. Materials and methods. The medical data of 225 children aged 2 to 9 years with GDFC, who had clinical manifestations of ASD (183 boys and 42 girls) were retrospectively analyzed. The diagnosis of ASD was made by child psychiatrists according to the criteria DSM-IV-TR (Diagnostic and Statistical Manual of mental disorders) and ICD-10 (The International Statistical Classification of Diseases and Related Health Problems) (study group; SG). The control group (CG) included 51 clinically healthy children (37 boys and 14 girls) of similar age and gender distribution who did not suffer from GDFC and ASD. Pathogenic polymorphic variants of folate cycle genes were determined by PCR with restriction (Sinevo, Ukraine). Autoantibodies to autoantigens of CNS subcortical ganglion neurons in blood serum were determined using a Cunningham panel (Moleculera Labs, Inc, USA). Serum autoantibodies to neurons of the mesolimbic system of the brain were identified by ELISA (MDI Limbach Berlin GmbH, Germany). Autoimmunization to myelin was assessed by serum autoantibody titer to basic myelin protein (ELISA) and signs of neutrophil and CD8+ T-lymphocyte sensitization to hemispheric white matter autoantigens (cell-based assay; department of neuroimmunology at the Neurosurgery Institute; Ukraine). Serum autoantibodies to nuclei of connective tissue cells and striated muscle proteins were determined by western blot analysis (Sinevo, Ukraine). To determine the significance of the differences between the indicators in the observation groups, we used the Student's parametric T-test with the confidence probability p and the nonparametric criterion – the number of signs Z according to Urbach Yu.V. The odds ratio (OR) and the 95% confidence interval (95% CI) were used to study the associations between the studied indicators. The study was performed as a fragment of research work commissioned by the Ministry of Health of Ukraine (№ state registration 0121U107940). Research. Positive results of the Cunningham panel occurred in 32%, laboratory signs of autoimmunization to neurons of the mesolimbic system – 36%, myelin of white matter of the hemispheres – 43%, nuclei autoantigens of connective tissue cells – 53%, proteins of striated muscles – 48% of cases among children SG (in general – 68% of cases; p &lt; 0.05; Z &lt; Z0.05). Serological signs of autoimmunization to autoantigens of the subcortical ganglia of the cerebral hemispheres were associated with Streptococcus pyogenes and Borrelia, to neurons of the mesolimbic system – EBV, HHV-6, HHV-7, Toxoplasma and TTV, to CNS myelin – EBV, HHV-6, HHV-7, Borrelia and TTV, to the nuclei of connective tissue cells and striated muscles – EBV, HHV-6, HHV-7, Borrelia and TTV. Conclusions. In children with ASD associated with GDFC laboratory sings of microbial-induced autoimmunity to a number of cerebral and extracerebral autoantigens has been evaluated, which affects the mental and physical health of patients and is a potential target for effective therapeutic interventions.

When and How Does the Auditory Cortex Influence Subcortical Auditory Structures? New Insights About the Roles of Descending Cortical Projections.

For decades, the corticofugal descending projections have been anatomically well described but their functional role remains a puzzling question. In this review, we will first describe the contributions of neuronal networks in representing communication sounds in various types of degraded acoustic conditions from the cochlear nucleus to the primary and secondary auditory cortex. In such situations, the discrimination abilities of collicular and thalamic neurons are clearly better than those of cortical neurons although the latter remain very little affected by degraded acoustic conditions. Second, we will report the functional effects resulting from activating or inactivating corticofugal projections on functional properties of subcortical neurons. In general, modest effects have been observed in anesthetized and in awake, passively listening, animals. In contrast, in behavioral tasks including challenging conditions, behavioral performance was severely reduced by removing or transiently silencing the corticofugal descending projections. This suggests that the discriminative abilities of subcortical neurons may be sufficient in many acoustic situations. It is only in particularly challenging situations, either due to the task difficulties and/or to the degraded acoustic conditions that the corticofugal descending connections bring additional abilities. Here, we propose that it is both the top-down influences from the prefrontal cortex, and those from the neuromodulatory systems, which allow the cortical descending projections to impact behavioral performance in reshaping the functional circuitry of subcortical structures. We aim at proposing potential scenarios to explain how, and under which circumstances, these projections impact on subcortical processing and on behavioral responses.

Amyloidogenic, neuroinflammatory and memory dysfunction effects of HIV-1 gp120

Human immunodeficiency virus 1 (HIV-1) infection can cause several HIV-associated neurocognitive disorders a variety of neurological impairments characterized by the loss of cortical and subcortical neurons and decreased cognitive and motor function. HIV-1 gp120, the major envelope glycoprotein on viral particles, acts as a binding protein for viral entry and is known to be an agent of neuronal cell death. To determine the mechanism of HIV-1 gp120-induced memory dysfunction, we performed mouse intracerebroventricular (i.c.v.) infusion with HIV-1 gp120 protein (300 ng per mouse) and investigated memory impairment and amyloidogenesis. Infusion of the HIV-1 gp120 protein induced memory dysfunction, which was evaluated using passive avoidance and water maze tests. Infusion of HIV-1 gp120 induced neuroinflammation, such as the release of iNOS and COX-2 and the activation of astrocytes and microglia and increased the mRNA and protein levels of IL-6, ICAM-1, M-CSF, TIM, and IL-2. In particular, we found that the infusion of HIV-1 gp120 induced the accumulation of amyloid plaques and signs of elevated amyloidogenesis, such as increased expression of amyloid precursor protein and BACE1 and increased β-secretase activity. Therefore, these studies suggest that HIV-1 gp120 may induce memory impairment through Aβ accumulation and neuroinflammation.

Neural Population Computing: Parallel Distributed Processing, the Basal Ganglia, and Evolution

Representations in the central nervous system are population encoded. Understanding the computational processes subserved by pools of cortical and connected subcortical neurons constitutes one of the major challenges facing systems neuroscience. The science of parallel distributed processing (PDP) combines neural plausibility, theoretical coherence, and a demonstrated ability to account for an enormous range of phenomena in normal and damaged human brains.

Inferring spikes from calcium imaging in dopamine neurons.

Calcium imaging has led to discoveries about neural correlates of behavior in subcortical neurons, including dopamine (DA) neurons. However, spike inference methods have not been tested in most populations of subcortical neurons. To address this gap, we simultaneously performed calcium imaging and electrophysiology in DA neurons in brain slices and applied a recently developed spike inference algorithm to the GCaMP fluorescence. This revealed that individual spikes can be inferred accurately in this population. Next, we inferred spikes in vivo from calcium imaging from these neurons during Pavlovian conditioning, as well as during navigation in virtual reality. In both cases, we quantitatively recapitulated previous in vivo electrophysiological observations. Our work provides a validated approach to infer spikes from calcium imaging in DA neurons and implies that aspects of both tonic and phasic spike patterns can be recovered.

G392E neuroserpin causing the dementia FENIB is secreted from cells but is not synaptotoxic

Familial encephalopathy with neuroserpin inclusion bodies (FENIB) is a progressive neurodegenerative disease caused by point mutations in the gene for neuroserpin, a serine protease inhibitor of the nervous system. Different mutations are known that are responsible for mutant neuroserpin polymerization and accumulation as inclusion bodies in many cortical and subcortical neurons, thereby leading to cell death, dementia and epilepsy. Many efforts have been undertaken to elucidate the molecular pathways responsible for neuronal death. Most investigations have concentrated on analysis of intracellular mechanisms such as endoplasmic reticulum (ER) stress, ER-associated protein degradation (ERAD) and oxidative stress. We have generated a HEK-293 cell model of FENIB by overexpressing G392E-mutant neuroserpin and in this study we examine trafficking and toxicity of this polymerogenic variant. We observed that a small fraction of mutant neuroserpin is secreted via the ER-to-Golgi pathway, and that this release can be pharmacologically regulated. Overexpression of the mutant form of neuroserpin did not stimulate cell death in the HEK-293 cell model. Finally, when treating primary hippocampal neurons with G392E neuroserpin polymers, we did not detect cytotoxicity or synaptotoxicity. Altogether, we report here that a polymerogenic mutant form of neuroserpin is secreted from cells but is not toxic in the extracellular milieu.

SH-SY5Y-derived neurons: a human neuronal model system for investigating TAU sorting and neuronal subtype-specific TAU vulnerability.

The microtubule-associated protein (MAP) TAU is mainly sorted into the axon of healthy brain neurons. Somatodendritic missorting of TAU is a pathological hallmark of many neurodegenerative diseases, including Alzheimer's disease (AD). Cause, consequence and (patho)physiological mechanisms of TAU sorting and missorting are understudied, in part also because of the lack of readily available human neuronal model systems. The human neuroblastoma cell line SH-SY5Y is widely used for studying TAU physiology and TAU-related pathology in AD and related tauopathies. SH-SY5Y cells can be differentiated into neuron-like cells (SH-SY5Y-derived neurons) using various substances. This review evaluates whether SH-SY5Y-derived neurons are a suitable model for (i)investigating intracellular TAU sorting in general, and (ii) with respect to neuron subtype-specific TAU vulnerability. (I) SH-SY5Y-derived neurons show pronounced axodendritic polarity, high levels of axonally localized TAU protein, expression of all six human brain isoforms and TAU phosphorylation similar to the human brain. As SH-SY5Y cells are highly proliferative and readily accessible for genetic engineering, stable transgene integration and leading-edge genome editing are feasible. (II) SH-SY5Y-derived neurons display features of subcortical neurons early affected in many tauopathies. This allows analyzing brain region-specific differences in TAU physiology, also in the context of differential vulnerability to TAU pathology. However, several limitations should be considered when using SH-SY5Y-derived neurons, e.g., thelack of clearly defined neuronal subtypes, or the difficulty of mimicking age-related tauopathy risk factors invitro. In brief, this review discusses the suitability of SH-SY5Y-derived neurons for investigating TAU (mis)sorting mechanisms and neuron-specific TAU vulnerability in disease paradigms.

Epiplexus phagocytes of nervous tissue in experimental brain contusion

Neuroinflammation is known to participate in pathogenesis of intracranial brain injury (TBI), e.g., brain contusion or concussion. In view of high overall prevalence of these conditions, there is a need for nosological verification of the mild- and moderate-severity neuroinflammation. Our research in immune regulation of blood flow in TBI, including a role of Kolmer cells in pathogenesis of neuroinflammation, is now at the stage of collecting research data and requires adequate experimental study. Purpose of our study was as follows: to assess the state of Kolmer cells in vascular plexus of brain ventricles in experimental model of mild traumatic brain contusion (mTBC). mTBC was reproduced in male Wistar rats using a model of a falling load weighing 200 g. Immunohistochemical study was performed in order to assess CD45 receptor expression on the brain cells. During acute period after mTBC, we observed constriction of blood vessels and pericellular edema of the brain tissues. Expression of CD45 cytodifferentiation receptors markers characteristic of the hematopoietic cell pools was found in parenchymal areas of neocortex and on the surface of choroid plexuses in brain ventricles. These data suggest participation of epiplexus and parenchymal macrophages in the pronounced pericellular edema of the brain. On the 8th day of observation, the spasm of the blood vessels persists, along with significantly weaker pericellular edema. In all the brain sections, leukocyte infiltration of tissues was not seen, and there was no expression of CD45 receptors, whereas increased number and size of nucleoli was found in the neurons. The results of our study confirm the role of cerebral vasospasm as a severe complication of neuroinflammation developing after mTBI. Acute inflammation is characterized by a series of vascular changes, manifesting by development of vasospasm, arterial, venous hyperemia and stasis. Venous hyperemia is characterized by further vasodilation, tissue plethora, the phenomenon of the marginal leukocyte stasis and their emigration, along with increased exudation processes. Innervation from subcortical neurons or local cortical interneurons to parenchymal arterioles and cortical microvessels provides minimal contact and predominantly targets the surrounding astrocytes and other cells. During acute period of mTBC, the inflammatory process is confirmed by the presence in parenchyma and on the surface of ependymal Kolmer cells and by expression of CD45 receptors. This finding points to inflammatory reasons for altered tone of pial blood vessels, capillaries of neocortex and ependymal areas, and changed depth of subarachnoid space. Response of astrocytes to the brain trauma could be another factor of neuroinflammation.

Glutamatergic Neurons in the Preoptic Hypothalamus Promote Wakefulness, Destabilize NREM Sleep, Suppress REM Sleep, and Regulate Cortical Dynamics.

Clinical and experimental data from the last nine decades indicate that the preoptic area of the hypothalamus is a critical node in a brain network that controls sleep onset and homeostasis. By contrast, we recently reported that a group of glutamatergic neurons in the lateral and medial preoptic area increases wakefulness, challenging the long-standing notion in sleep neurobiology that the preoptic area is exclusively somnogenic. However, the precise role of these subcortical neurons in the control of behavioral state transitions and cortical dynamics remains unknown. Therefore, in this study, we used conditional expression of excitatory hM3Dq receptors in these preoptic glutamatergic (Vglut2+) neurons and show that their activation initiates wakefulness, decreases non-rapid eye movement (NREM) sleep, and causes a persistent suppression of rapid eye movement (REM) sleep. We also demonstrate, for the first time, that activation of these preoptic glutamatergic neurons causes a high degree of NREM sleep fragmentation, promotes state instability with frequent arousals from sleep, decreases body temperature, and shifts cortical dynamics (including oscillations, connectivity, and complexity) to a more wake-like state. We conclude that a subset of preoptic glutamatergic neurons can initiate, but not maintain, arousals from sleep, and their inactivation may be required for NREM stability and REM sleep generation. Further, these data provide novel empirical evidence supporting the hypothesis that the preoptic area causally contributes to the regulation of both sleep and wakefulness.SIGNIFICANCE STATEMENT Historically, the preoptic area of the hypothalamus has been considered a key site for sleep generation. However, emerging modeling and empirical data suggest that this region might play a dual role in sleep-wake control. We demonstrate that chemogenetic stimulation of preoptic glutamatergic neurons produces brief arousals that fragment sleep, persistently suppresses REM sleep, causes hypothermia, and shifts EEG patterns toward a "lighter" NREM sleep state. We propose that preoptic glutamatergic neurons can initiate, but not maintain, arousal from sleep and gate REM sleep generation, possibly to block REM-like intrusions during NREM-to-wake transitions. In contrast to the long-standing notion in sleep neurobiology that the preoptic area is exclusively somnogenic, we provide further evidence that preoptic neurons also generate wakefulness.

The nonhuman primate neuroimaging and neuroanatomy project

Multi-modal neuroimaging projects such as the Human Connectome Project (HCP) and UK Biobank are advancing our understanding of human brain architecture, function, connectivity, and their variability across individuals using high-quality non-invasive data from many subjects. Such efforts depend upon the accuracy of non-invasive brain imaging measures. However, ‘ground truth’ validation of connectivity using invasive tracers is not feasible in humans. Studies using nonhuman primates (NHPs) enable comparisons between invasive and non-invasive measures, including exploration of how “functional connectivity” from fMRI and “tractographic connectivity” from diffusion MRI compare with long-distance connections measured using tract tracing. Our NonHuman Primate Neuroimaging & Neuroanatomy Project (NHP_NNP) is an international effort (6 laboratories in 5 countries) to: (i) acquire and analyze high-quality multi-modal brain imaging data of macaque and marmoset monkeys using protocols and methods adapted from the HCP; (ii) acquire quantitative invasive tract-tracing data for cortical and subcortical projections to cortical areas; and (iii) map the distributions of different brain cell types with immunocytochemical stains to better define brain areal boundaries. We are acquiring high-resolution structural, functional, and diffusion MRI data together with behavioral measures from over 100 individual macaques and marmosets in order to generate non-invasive measures of brain architecture such as myelin and cortical thickness maps, as well as functional and diffusion tractography-based connectomes. We are using classical and next-generation anatomical tracers to generate quantitative connectivity maps based on brain-wide counting of labeled cortical and subcortical neurons, providing ground truth measures of connectivity. Advanced statistical modeling techniques address the consistency of both kinds of data across individuals, allowing comparison of tracer-based and non-invasive MRI-based connectivity measures. We aim to develop improved cortical and subcortical areal atlases by combining histological and imaging methods. Finally, we are collecting genetic and sociality-associated behavioral data in all animals in an effort to understand how genetic variation shapes the connectome and behavior.

Intranasal delivery of insulin for the restoration of memory signaling in Alzheimer disease

Alzheimer's disease(AD), a form of dementia, is progressive, degenerative brain disease characterized by marked atrophy of cerebral cortex and loss of cortical and sub-cortical neurons. Weakening of insulin receptor signaling is involved in ageing-related brain degeneration such as AD. Objective of this study is to develop delivery-system to overcome BBB by employing novel, non-invasive approach via nasal route. The olfactory neural pathway provides both intraneuronal and extraneuronal pathway into brain.