bioRxiv Subject Collection: Neuroscience's Journal

An AAV capsid reprogrammed to bind human Transferrin Receptor mediates brain-wide gene delivery
Developing vehicles that efficiently deliver genes throughout the human central nervous system (CNS) will broaden the range of treatable genetic diseases. We engineered an AAV capsid, BI-hTFR1, that binds human Transferrin Receptor (TfR1), a protein expressed on the blood-brain barrier (BBB). BI-hTFR1 was actively transported across a human brain endothelial cell layer and, relative to AAV9, provided 40-50 times greater reporter expression in the CNS of human TFRC knock-in mice. The enhanced tropism was CNS-specific and absent in wild type mice. When used to deliver GBA1, mutations of which cause Gaucher disease and are linked to Parkinson's disease, BI-hTFR1 substantially increased brain and cerebrospinal fluid glucocerebrosidase activity compared to AAV9. These findings establish BI-hTFR1 as a promising vector for human CNS gene therapy.

A Novel Pathway Implicated in Regulating Cognitive disfunction in a DrosophilaAlzheimer's Disease Model through Acer Inhibition and CG2233 Modulation
Alzheimer's disease (AD) is a progressive neurodegenerative disorder, accounting for most dementia cases worldwide. Current therapies for AD have limited effectiveness in slowing disease progression or delivering a cure. As such, there is an immediate need for ongoing research and innovative strategies to tackle this multifaceted disease. Recently, several studies have implicated the renin-angiotensin system (RAS), known to regulate blood pressure, as a possible therapeutic target for AD. RAS-inhibiting drugs, including angiotensin-converting enzyme inhibitors (ACE-Is), have been shown to reduce the incidence and progression of AD. However, the literature describing their beneficial effects is inconsistent, with contradictory findings reporting no effects. How these drugs may function in AD remains poorly understood. Our previous work in Drosophila models expressing AD-related transgenes investigated the benefits of captopril, an ACE-I, and found it effectively rescued AD-related phenotypes including cognitive performance independent of A{beta}42 changes. Importantly, our study implicated Acer, a homolog of mammalian ACE, as a key player. In our current study, we demonstrate that the beneficial outcomes of Acer inhibition depend on preventing its catalytic activity and downstream target processing. We identify CG2233 as a prospective target and reveal its functional interaction with Acer. Furthermore, we show CG2233 is implicated in AD-related pathways in A{beta}42 expressing flies. Together, these findings provide a new avenue to study the role of ACE in AD.

Rab3 mediates cyclic AMP-dependent presynaptic plasticity and olfactory learning
Presynaptic forms of plasticity occur throughout the nervous system and play an important role in learning and memory but the underlying molecular mechanisms are insufficiently understood. Here we show that the small GTPase Rab3 is a key mediator of cyclic AMP (cAMP)-induced presynaptic plasticity in Drosophila. Pharmacological and optogenetic cAMP production triggered concentration-dependent alterations of synaptic transmission, including potentiation and depression of evoked neurotransmitter release, as well as strongly facilitated spontaneous release. These changes correlated with a nanoscopic rearrangement of the active zone protein Unc13A and required Rab3. To link these results to animal behaviour, we turned to the established role of cAMP signalling in memory formation and demonstrate that Rab3 is necessary for olfactory learning. As Rab3 is dispensable for basal synaptic transmission, these findings highlight a molecular pathway specifically dedicated to tuning neuronal communication and adaptive behaviour.

Metabolomics profiling reveals distinct, sex-specific signatures in the serum and brain metabolomes in the mouse models of Alzheimer's disease
INTRODUCTION: Increasing evidence suggests that metabolic impairments contribute to early Alzheimer's disease (AD) mechanisms and subsequent dementia. Signals in metabolic pathways conserved across species provide can facilitate translation. METHODS: We investigated differences of serum and brain metabolites between the early-onset 5XFAD and late-onset LOAD1 (APOE4.Trem2*R47H) mouse models of AD to C57BL/6J controls at six months of age. RESULTS: We identified sex differences for several classes of metabolites, including glycerophospholipids, sphingolipids, and amino acids. Metabolic signatures were notably different between brain and serum in both mouse models. The 5XFAD mice exhibited stronger differences in brain metabolites, whereas LOAD1 mice showed more pronounced differences in serum. DISCUSSION: Several of our findings were consistent with results in humans, showing glycerophospholipids reduction in serum of APOE4 carriers and replicating the serum metabolic imprint of the APOE4 genotype. Our work thus represents a significant step towards translating metabolic dysregulation from model organisms to human AD.

Development of a non-invasive novel individual marmoset holder for evaluation by awake functional magnetic resonance brain imaging
Background: Although functional MRI (fMRI) in awake marmosets (Callithrix jacchus) is fascinating for functional brain mapping and evaluation of brain disease models, it is difficult to launch awake fMRI on scanners with less than 15 cm of bore size. A universal marmoset holder for the small-bore size MRI was designed, and evaluated whether this holder could conduct auditory stimulation fMRI in the awake state. New Method: The marmoset holder was designed with an outer diameter of 71.9 mm. A holder was designed to allow adjustment according to the individual head shape, enabling to use the holder universally. An awake fMRI study of auditory response was conducted to evaluate the practicality of the new holder. Whole-brain activation was investigated when marmosets heard the marmoset social communication phee call, an artificial tone sound, music (bossa nova), and reversed of those. Results: The prefrontal cortex was significantly activated in response to phee calls, whereas only the auditory cortex was activated in response to pure tones. In response to bossa nova, visual and auditory cortices of the marmosets were activated. In contrast, the auditory response was decreased when marmosets heard phee calls and bossa nova music played backward. Their stimulus-specific responses indicated they perceived and differentiated sound characteristics in the fMRI environment. Comparison with Existing Methods: A holder does not require surgical intervention or custom-made helmet to minimize head movement in small space. Conclusion: Our newly developed holder made it possible to perform longitudinal fMRI experiments on multiple marmosets in a less invasive manner.

Transcriptional and Cellular Response of hiPSC-derived Microglia-Neural Progenitor Co-Cultures Exposed to IL-6
Elevated interleukin (IL-)6 levels during prenatal development have been linked to increased risk for neurodevelopmental disorders (NDD) in the offspring, but the mechanism remains unclear. Human-induced pluripotent stem cell (hiPSC) models offer a valuable tool to study the effects of IL-6 on features relevant for human neurodevelopment in vitro. We previously reported that hiPSC-derived microglia-like cells (MGLs) respond to IL-6, but neural progenitor cells (NPCs) in monoculture do not. We therefore investigated whether co-culturing hiPSC-derived MGLs with NPCs would trigger a cellular response to IL-6 stimulation via secreted factors from the MGLs. Using N=4 donor lines without psychiatric diagnosis, we first confirmed that NPCs can respond to IL-6 through trans-signalling when recombinant IL-6Ra is present, and that this response is dose-dependent. In response to IL-6, MGLs secreted soluble IL-6R, but at lower levels than found in vivo and below that needed to activate trans-signalling in NPCs. Among other cytokines, MGLs also increased Tumour necrosis factor (TNF) alpha secretion into the co-culture environment. Despite this, whilst transcriptomic analysis confirmed that MGLs undergo substantial transcriptomic changes after IL-6 exposure, NPCs in co-culture with MGLs exhibited a minimal transcriptional response. Furthermore, there were no significant cell fate-acquisition changes when differentiated into post-mitotic cultures, nor alterations in synaptic densities in mature neurons. These findings highlight the need to investigate if trans-IL-6 signalling to NPCs is a relevant disease mechanism linking prenatal IL-6 exposure to increased risk for psychiatric disorders. Moreover, our findings underscore the importance of establishing more complex in vitro human models with diverse cell types, which may show cell-specific responses to microglia-released cytokines to fully understand how IL-6 exposure may influence human neurodevelopment.

CSF plasma cell expansion in LGI1-/CASPR2-autoimmune encephalitis is associated with loss of regulatory MAIT cells
Anti Leucine rich glioma inactivated 1 (LGI1) and anti contactin associated protein 2 (CASPR2) associated autoimmune encephalitis (AIE) variants are characterized by directly pathogenic autoantibodies present in serum and CSF. The dynamics and drivers of intrathecal and systemic autoantibody production are incompletely understood. We aimed to elucidate the immunologic basis of the LGI1 /CASPR2 associated AIE variants by performing multiomic profiling of CSF/blood in untreated patients. We validated findings by flow cytometry in independent cohorts and confirmed functionality using rodent immunization. We identified clonal IgG2 and IgG4 plasma cell expansion and affinity maturation in the CSF together with clonally restricted, activated, antigen-experienced CD8 and CD4 T cells as a hallmark of these encephalitis variants. Using recombinant cloning, we confirmed that expanded CSF plasma cell clones almost exclusively bound the respective neuronal autoantigen. In addition, we found a loss of regulatory mucosa associated invariant T (MAIT) cells and gamma delta T cells in the CSF and to a lesser degree in blood. We validated the functional role of these invariant T cells using a novel murine active immunization paradigm using both autoantigens: MAIT cells suppressed systemic formation of LGI1 and CASPR2 specific anti neuronal antibodies. We propose that loss of systemic and intrathecal regulatory mechanisms mediated by innate like T cells promote plasma cell expansion and autoantibody production as a shared mechanism in AIE.

Specific inhibition and disinhibition in the higher-order structure of a cortical connectome
Neuronal network activity is thought to be structured around the activation of assemblies, or low-dimensional manifolds describing states of activity. Both views describe neurons acting not independently, but in concert, likely facilitated by strong recurrent excitation between them. The role of inhibition in these frameworks - if considered at all - is often reduced to blanket inhibition with no specificity with respect to which excitatory neurons are targeted. We analyzed the structure of excitation and inhibition in the MICrONS dataset, an electron microscopic reconstruction of a piece of cortical tissue. We found that excitation was structured around a feed-forward flow in non-random motifs of seven or more neurons. This revealed a structure of information flow from a small number of sources to a larger number of potential targets that became only visible when larger motifs were considered instead of individual pairs. Inhibitory neurons targeted and were targeted by neurons in specific sequential positions of these motifs. Additionally, disynaptic inhibition was strongest between target motifs excited by the same group of source neurons, implying competition between them. The structure of this inhibition was also highly specific and symmetrical, contradicting the idea of non-specific blanket inhibition. None of these trends are detectable in only pairwise connectivity, demonstrating that inhibition is specifically structured by these large motifs. Further, we found that these motifs represent higher order connectivity patterns which are present, but to a lesser extent in a recently released, detailed computational model, and not at all in a distance-dependent control. These findings have important implications for how synaptic plasticity reorganizes neocortical connectivity to implement learning and for the specific role of inhibition in this process.

Anhedonia severity mediates the relationship between attentional networks recruitment and emotional blunting during music listening
Recent studies have reported atypical emotional processing in individuals with greater levels of anhedonic depressive symptoms. However, the relationship between brain networks dynamics and moment-to-moment affective responses to naturalistic paradigms, as emotions are unfolding, remains unclear. In this study, we used the unique temporal characteristics of music to investigate behavioural and brain network dynamics as a function of anhedonic depressive symptoms severity in healthy adults during an emotionally provocative music listening task. Thirty-one neurotypical participants aged 18-30 years were required to continuously rate happy, neutral and sad pieces of music whilst undergoing MRI scanning. They were also asked to fill in questionnaires assessing their levels of anhedonic depressive symptoms. Using a novel fMRI analysis method called Leading Eigenvector Dynamics Analysis (LEiDA), we found an increased probability of occurrence of attentional networks and a blunted emotional response to both happy and sad pieces of music in participants with greater levels of anhedonic depressive symptoms. More specifically, anhedonic depressive symptoms mediated the relationship between attentional networks recruitment and emotional blunting. Furthermore, the elevated recruitment of attentional networks during emotional pieces of music carried over into subsequent neutral music. Future studies are needed to investigate whether these findings could be generalised to a clinical population (i.e., Major Depressive Disorder).

Bi-allelic variants in WDR47 lead to neuronal loss causing a rare neurodevelopmental syndrome with corpus callosum dysgenesis in humans.
The corpus callosum (CC) is the largest interhemispheric connection that is largely formed by the axons of layer 2/3 callosal projection neurons (CPNs) through a series of tightly regulated cellular events, including neuronal specification, migration, axon extension and branching. Defects in any of those steps may prevent the proper development of the corpus callosum resulting in a spectrum of disorders collectively referred to as corpus callosum dysgenesis (CCD). Here, we report four unrelated families carrying bi-allelic variants in WDR47 presenting with CCD together with other neuroanatomical phenotypes such as microcephaly, cerebellar abnormalities and hydrocephalus. Using a combination of in vitro and in vivo mouse models and complementation assays, we show that independently from its previously identified functions in neuronal migration and axonal extension, WDR47 is required for survival of callosal neurons by contributing to the maintenance of mitochondrial and microtubule homeostasis. We further provide evidence that severity of the CCD phenotype is determined by the degree of the loss of function caused by the human variants. Taken together, we identify WDR47 as a causative gene of a new neurodevelopmental syndrome characterized by corpus callosum abnormalities and other neuroanatomical malformations.

Cyfip2 controls the acoustic startle threshold through FMRP, actin polymerization, and GABAB receptor function.
Animals process a constant stream of sensory input, and to survive they must detect and respond to dangerous stimuli while ignoring innocuous or irrelevant ones. Behavioral responses are elicited when certain properties of a stimulus such as its intensity or size reach a critical value, and such behavioral thresholds can be a simple and effective mechanism to filter sensory information and determine if a response is appropriate. For example, the acoustic startle response is a conserved and stereotyped defensive behavior induced by sudden loud sounds, but dysregulation of the threshold to initiate this behavior can result in startle hypersensitivity that is associated with sensory processing disorders including schizophrenia and autism. Through a previous forward genetic screen for regulators of the startle threshold a nonsense mutation in Cytoplasmic Fragile X Messenger Ribonucleoprotein (FMRP)-interacting protein 2 (cyfip2) was found that causes startle hypersensitivity in zebrafish larvae, but the molecular mechanisms by which Cyfip2 establishes the acoustic startle threshold are unknown. Here we use conditional transgenic rescue and CRISPR/Cas9 gene knockdown approaches to determine that Cyfip2 requires both Rac1 and FMRP pathways, but not the closely related FXR1 or FXR2, to regulate the acoustic startle threshold in early neurodevelopment. Using a candidate-based drug screen we find that Cyfip2 also acts acutely to maintain the startle threshold through Arp2/3-mediated branched actin polymerization and N-methyl D-aspartate receptors (NMDARs). To identify proteins and pathways that may be targets of Cyfip2-FMRP-mediated translational regulation, we then performed discovery proteomics and determined that loss of Cyfip2 alters cytoskeletal and extracellular matrix components and disrupts oxidative phosphorylation and GABA receptor signaling. Finally, we validated our proteomics findings by showing that the GABAB receptor agonist baclofen, but not the GABAA agonist muscimol, restores normal startle sensitivity in cyfip2 mutants. Together, these data reveal that Cyfip2 acts through multiple pathways to regulate excitatory/inhibitory balance in the startle circuit to control the processing of acoustic information.

Adaptive responding to stimulus-outcome associations requires noradrenergic transmission in the medial prefrontal cortex
A dynamic environment, such as the one we inhabit, requires organisms to continuously update their knowledge of the setting. While the prefrontal cortex is recognized for its pivotal role in regulating such adaptive behavior, the specific contributions of each prefrontal area remain elusive. In the current work, we investigated the direct involvement of two major prefrontal subregions, the medial prefrontal cortex (mPFC) and the ventrolateral orbitofrontal cortex (vlOFC), in updating Pavlovian stimulus-outcome (S-O) associations following contingency degradation. Specifically, animals had to learn that a specific cue, previously fully predicting the delivery of a specific reward, was no longer a reliable predictor. First, we found that chemogenetic inhibition of mPFC, but not of vlOFC, neurons altered rats ability to adaptively respond to degraded and non-degraded cues. Next, given the growing evidence pointing at noradrenaline (NA) as a main neuromodulator of adaptive behavior, we decided to investigate the possible involvement of NA projections to the two subregions in this higher-order cognitive process. Employing a pair of novel retrograde vectors, we traced NA projections from the locus coeruleus (LC) to both structures and observed an equivalent yet relatively segregated amount of inputs. Then, we showed that chemogenetic inhibition of NA projections to the mPFC, but not to the vlOFC, also impaired the rats ability to adaptively respond to the degradation procedure. Altogether, our findings provide important evidence of functional parcellation within the prefrontal cortex and point at mPFC-NA as key for updating Pavlovian S-O associations.

Syntax through rapid synaptic changes
Syntax is a central organizing component of human language but few models explain how it may be implemented in neurons. We combined two rapid synaptic rules to demonstrate how neurons can implement a simple grammar. Words bind to syntactic roles (e.g. 'dog' as subject or object) and the roles obey ordering rules (e.g. subject [->] verb [->] object), guided by predefined syntactic knowledge. We find that, like humans, the model recalls sentences better than shuffled word-lists, and it can serialize words to express an idea as a sentence. The model also supports order-free morphemic languages, exhibits syntactic priming and demonstrates typical patterns of aphasia when damaged. Crucially, it achieves these using an intuitive representation where words fill roles, allowing structured cognition.

Post-synaptic competition between calcineurin and PKA regulates mammalian sleep-wake cycles
Phosphorylation of synaptic proteins is a pivotal biochemical reaction that controls the sleep-wake cycle in mammals. Protein phosphorylation in vivo is reversibly regulated by kinases and phosphatases. In this study, we investigated a pair of kinases and phosphatases that reciprocally regulate sleep duration. Through comprehensive screening of Protein kinase A (PKA) and phosphoprotein phosphatase (PPP) family genes via the generation of 40 gene knockout mouse lines including post-natal CRISPR targeting, we identified a regulatory subunit of PKA (Prkar2b), a regulatory subunit of protein phosphatase (PP) 1 (Pppr1r9b), and catalytic and regulatory subunits of PP2B (calcineurin) (Ppp3ca and Ppp3r1) as sleep control genes. AAV-mediated stimulation of PKA and PP1/calcineurin activities confirmed PKA as a wake-promoting kinase, while PP1 and calcineurin function as sleep-promoting phosphatases. The importance of these phosphatases in sleep regulation is supported by the dramatic changes in sleep duration associated with their increased and decreased activity, ranging from approximately 17.3 hours/day (PP1 expression) to 6.7 hours/day (post-natal CRISPR targeting of calcineurin). For these phosphatases to exert their sleep-promoting effects, localization signals to the excitatory post-synapse were necessary. Furthermore, the wake-promoting effect of PKA localized to the excitatory post-synapse negated the sleep-promoting effect of calcineurin, suggesting that PKA and calcineurin construct a hierarchical phosphorylation control network for sleep regulation at excitatory post-synapses.

Scaling of ventral hippocampal activity during anxiety
Background The hippocampus supports a multiplicity of functions, with the dorsal region contributing to memory-related spatial representations, while the ventral hippocampus (vH) is primarily involved in emotional processing. While spatial encoding has been extensively investigated, how the vH activity is tuned to emotional states, e.g. to different anxiety levels, is not well understood. Methods We developed an adjustable linear track maze (aLTM) for mice to induce different anxiety levels within the same spatial environment. Through in vivo single-unit recordings, optogenetic manipulations, and the application of a convolutional classifier, we examined the changes and causal effects of vH activity at different anxiety levels. Results We found that anxiogenic experiences activated the vH and that this activity scaled with increasing anxiety levels within the same spatial environment. We identified two processes that contributed to this scaling of anxiety-related activity: rate remapping and the successive recruitment of neurons. Moreover, optogenetic inhibition of the vH reduced anxiety across different levels, while anxiety-related activity scaling could be decoded using a convolutional classifier. Conclusions Our findings position the vH as a critical limbic region that functions as an "anxiometer" by scaling its activity based on perceived anxiety levels. Our discoveries go beyond the traditional theory of cognitive maps in the hippocampus underlying spatial navigation and memory, by identifying hippocampal mechanisms selectively regulating anxiety.

Concurrent representations of reinstated and transformed memories and their modulation by reward
An integral part of episodic retrieval is the reinstatement of neural activity that was present in the medial temporal lobe during encoding. However, neural memory representations do not remain static. Consolidation promotes the transformation of representations that are specific to individual episodes towards more generalized representations that reflect commonalities across episodes. Moreover, reward has been shown to augment episodic memory by enhancing consolidation, and it may accelerate the transformation of neural memory representations. We investigated this account with n=40 human participants using fMRI and an associative memory task. They encoded pictures of objects, each with one of four recurring scenes. Two scenes led to high reward, two led to low reward. The next day, participants encountered the objects again and retrieved the scenes from memory. Using representational similarity analysis, we demonstrate that retrieval is concurrently accompanied by the reinstatement of original neural representations and the activation of transformed, more generalized memories. Specifically, the parahippocampal cortex reinstates scene-specific patterns from the encoding phase during successful retrieval. In contrast, activity patterns in the medial prefrontal cortex and anterior hippocampus reflect transformed memories: They become more similar to each other for memories sharing the same scene, independent of memory success. Importantly, high reward enhances memory transformation in the anterior hippocampus. The brain thus maintains complementary memory representations: An episodic representation that resembles the original encoding pattern, and a generalized representation that summarizes commonalities across memories - in part for particularly valuable information.

Task-Switch Related Reductions in Neural Distinctiveness in Children and Adults: Commonalities and Differences
Goal-directed behavior requires the ability to flexibly switch between task sets with changing environmental demands. Switching between tasks generally comes at the cost of slower and less accurate responses. Compared to adults, children show greater switch costs, presumably reflecting the protracted development of the ability to flexibly update task-set representations. To examine whether the distinctiveness of neural task-set representations is more strongly affected by a task switch in children compared to adults, we examined multi-voxel patterns of fMRI activation in 88 children (8-11 years, 49 girls) and 53 adults (20-30 years, 28 women) during a task-switching paradigm. Using multivariate pattern analysis (MVPA), we investigated whether task-set representations were less distinct on switch than on repeat trials across frontoparietal, cingulo-opercular, and temporo-occipital regions. Children and adults showed lower accuracy and longer response times on switch than on repeat trials, with higher accuracy costs in children. Decoding accuracy across regions was lower on switch than repeat trials, consistent with the notion that switching reduces the distinctiveness of task-set representations. Reliable age differences in switch-related representational distinctiveness reductions were absent, pointing to a remarkable degree of maturity of neural representations of task-relevant information in late childhood. However, we also observed that switch-related reductions in distinctiveness were more highly correlated across frontoparietal and cingulo-opercular regions in children than in adults, potentially reflecting the ongoing specialization of different control networks with respect to the representation of task features.

Homological landscape of human brain functional sub-circuits
Human whole-brain functional connectivity networks have been shown to exhibit both local/quasilocal (e.g., set of functional sub-circuits induced by node or edge attributes) and non-local (e.g., higher-order functional coordination patterns) properties. Nonetheless, the non-local properties of topological strata induced by local/quasilocal functional sub-circuits have yet to be addressed. To that end, we proposed a homological formalism that enables the quantification of higher-order characteristics of human brain functional sub-circuits. Our results indicated that each homological order uniquely unravels diverse, complementary properties of human brain functional sub-circuits. Noticeably, the H1 homological distance between rest and motor task were observed at both whole-brain and sub-circuit consolidated level which suggested the self-similarity property of human brain functional connectivity unraveled by homological kernel. Furthermore, at the whole-brain level, the rest-task differentiation was found to be most prominent between rest and different tasks at different homological orders: i) Emotion task (H0), ii) Motor task (H1), and iii) Working memory task (H2). At the functional sub-circuit level, the rest-task functional dichotomy of default mode network is found to be mostly prominent at the first and second homological scaffolds. Also at such scale, we found that the limbic network plays a significant role in homological reconfiguration across both task- and subject- domain which sheds light to subsequent investigations on the complex neuro-physiological role of such network. From a wider perspective, our formalism can be applied, beyond brain connectomics, to study non-localized coordination patterns of localized structures stretching across complex network fibers.

A direct estrogenic involvement in the expression of human hypocretin
Background: Hypocretin-1 may play an important role in depression, which was increased in female depression in LHA in our previous study. Estrogen acts through its nuclear transcriptional receptors. Methods: We studied the possibility of a direct action of estrogen receptors on the expression of human hypocretin. To explore the activation of ERs by hypocretin, we first investigated the potential presence of co-localization of the estrogen receptors (ERs) in hypocretin-immunoreactive neurons in the lateral hypothalamic area (LHA) in human and nuclear ERs in hypocretin immunoreactive neuroblastoma SK-N-SH cells. We investigated the relationship between E2 and hypocretin in female rats. After we explored the regulating role of exogenous estrogen on hypocretin gene expression via ERs through Chromatin immunoprecipitation, Electrophoretic mobility shift assay and Luciferase assay. Results: We found that hypocretin-1 plasma level was significantly higher in female depression. Estrogen receptors (ER and ER{beta}) and hypocretin are co-localized in female depression LHA, PC12 and SK-N-SH cell lines. The estrogen receptor response elements (EREs) existing in the hypocretin promoter region may directly regulate the expression of hypocretin, the synchronicity of change of hypocretin and estradiol both in hypothalamus and plasma was verified in female rats. With the presence of estradiol, there is specific binding between human ER and the Hypocretin-ERE. Expression of ER combined with estradiol repressed hypocretin promoter activity through the ERE. Conclusions: we defined that estradiol may affect hypocretin neurons in the human hypothalamus via ER binding to the Hypocretin-ERE directly, which may thus lead to the sex-specific pathogenesis of depression.

Sequential Transitions of Male Sexual Behaviours Driven by Dual Acetylcholine-Dopamine Dynamics
In mammals, males execute a stereotypical and organized sequence of sexual behaviours, such as mounting, intromission, and ejaculation, to successfully complete copulation. However, the neural mechanisms that govern the sequential transitions of male copulatory behaviours remain unclear. Here, we report that dopamine (DA) and acetylcholine (ACh) dynamics in the ventral shell of the nucleus accumbens (vsNAc) closely align with serial transitions of sexual behaviours in male mice. In particular, the vsNAc exhibits a unique pattern of 1.5--2.2 Hz dual ACh/DA rhythms that correspond to the pelvic thrust rhythm during intromission. The dual ACh/DA rhythms are generated locally by reciprocal regulation between ACh and DA signalling via nicotinic acetylcholine (nAChR) and dopamine D2 (D2R) receptors, respectively. Knockdown of choline acetyltransferase (ChAT) and D2R expression in the vsNAc diminishes intromission and ejaculation. We showed that ACh signalling promotes the initiation of intromission, whereas DA signalling sustains intromission by inhibiting the activities of D2R--expressing neurons in the vsNAc. Moreover, optogenetic activation of ChATvsNAc neurons during intromission slows down the DA rhythm, a specific activity signature that precedes ejaculation, and leads to immediate ejaculation. Taken together, dual ACh/DA dynamics in the vsNAc coordinate sequential transitions of male copulatory behaviours from intromission to ejaculation.

Cannabidiol improves learning and memory deficits and alleviates anxiety in 12-month-old SAMP8 Mice
Cannabidiol (CBD) has gained a lot of interest in recent years for its purported medicinal properties. CBD has been investigated for the treatment of anxiety, depression, epilepsy, neuroinflammation, and pain. Recently there has been an interest in CBD as a possible treatment for age-related disorders such as Alzheimers disease and related disorders (ADRD). Here we tested the hypothesis that chronic CBD administration would improve learning and memory in the SAMP8 mouse model of Alzheimers disease. SAMP8 mice aged 11 months (at the start of the study) were administered vehicle or CBD (3 or 30 mg/Kg) daily via oral gavage for 2 months. Vehicle-treated young SAMP8 mice (age 3 months at the start of the study) served as unimpaired controls. After 30 days of treatment (4 and 12 months of age), learning and memory, activity, anxiety, strength and dexterity were assessed. High dose CBD treatment significantly improved learning and memory of the 12-month-old mice in the T maze. Novel object recognition memory was also improved by CBD in aged CBD treated mice. Aged CBD treated mice also displayed less anxiety in the elevated plus maze test compared to controls. However, activity and strength levels were similar between groups. Biochemical analysis revealed decreased markers of oxidative stress, providing a possible mechanism by which CBD treatment impacts learning, memory, and anxiety. These results highlight the potential use of CBD as a therapeutic for age related cognitive impairment and dementia.

Grid cells perform path integration in multiple reference frames during self-motion-based navigation
With their periodic firing pattern, grid cells are considered a fundamental unit of a neural network performing path integration. The periodic firing patterns of grid cells have been observed mainly during behaviors with little navigational demands, and the firing patterns of grid cells in animals navigating 2D environments using path integration are largely unknown. Here, we recorded the activity of grid cells in mice performing the AutoPI task, a task assessing homing based on path integration. Using artificial deep neural networks to decode the animal's moment-to-moment movement vectors, we found that grid cells perform path integration over short trajectories and change their reference frames within single trials. More specifically, grid cell modules re-anchor to a task-relevant object via a translation of the grid pattern. The code for movement direction in grid modules drifts as the animal navigates using self-motion cues, and this drift predicts the homing direction of the mouse. These results reveal the computations in grid cell circuits during self-motion-based navigation.

Western diet feeding since adolescence impairs functional hyperemia probed by functional ultrasound imaging at adulthood and middle age: rescue by a balanced ω-3:ω-6 polyunsaturated fatty acids ratio in the diet
Obesity is a devastating worldwide metabolic disease, with the highest prevalence in children and adolescence. Obesity impacts neuronal function but the fate of functional hyperemia, a vital mechanism making possible cerebral blood supply to active brain areas, is unknown in organisms fed a high caloric Western Diet (WD) since adolescence. We mapped changes in cerebral blood volume (CBV) in the somatosensory cortex in response to whiskers stimulation in adolescent, adult and middle-aged mice fed a WD since adolescence. To this aim, we used non-invasive and high-resolution functional ultrasound imaging (fUS). Functional hyperemia is compromised as early as 3 weeks of WD and remains impaired thereafter. Starting WD in adult mice does not trigger the profound impairment in sensory-evoked CBV observed in young mice, suggesting a cerebrovascular vulnerability to WD during adolescence. A balanced {omega}-6:{omega}-3 polyunsaturated fatty acids ratio in WD achieved by docosahexaenoic acid supplementation is efficient to restore glucose homeostasis and functional hyperemia in adults.

The intracellular C-terminus confers compartment-specific targeting of voltage-gated Ca2+ channels
To achieve the functional polarization that underlies brain computation, neurons sort protein material into distinct compartments. Ion channel composition, for example, differs between axons and dendrites, but the molecular determinants for their polarized trafficking remain obscure. Here, we identify the mechanisms that target voltage-gated Ca2+ channels (CaVs) to distinct subcellular compartments. In hippocampal neurons, CaV2s trigger neurotransmitter release at the presynaptic active zone, and CaV1s localize somatodendritically. After knockout of all three CaV2s, expression of CaV2.1, but not of CaV1.3, restores neurotransmitter release. Chimeric CaV1.3 channels with CaV2.1 intracellular C-termini localize to the active zone, mediate synaptic vesicle exocytosis, and render release fully sensitive to blockade of CaV1 channels. This dominant targeting function of the CaV2.1 C-terminus requires an EF hand in its proximal segment, and replacement of the CaV2.1 C-terminus with that of CaV1.3 abolishes CaV2.1 active zone localization. We conclude that the intracellular C-termini mediate compartment-specific CaV targeting.

Presenilin-dependent regulation of tau pathology via the autophagy/proteasome pathway
Autosomal dominant inherited mutations in the presenilin (PS/PSEN) genes cause early-onset familial Alzheimers disease (AD) by enhancing cerebral accumulation of amyloid-{beta}(A{beta}) and microtubule-associated protein tau, although the precise cellular mechanisms by which PS dysfunction drives neuronal tau pathology remain still unclear. Here, we investigated the mechanisms linking PS/{gamma}-secretase-dependent tau pathology and autophagy by using molecular, imaging and pathological approaches in brains, fibroblasts and induced pluripotent stem cells (iPSCs)-derived neurons from mutant PSEN1 carriers, as well as in a novel tauopathy mouse model lacking PS in glutamatergic neurons. We found colocalization of phosphorylated tau with the autophagy marker p62 in the hippocampus of tauopathy patients with PSEN1 mutations, corticobasal degeneration and Pick disease. Remarkably, disrupted autophagic clearance of pathological tau was evidenced by increased autophagy markers and accumulation of total and AD-associated phosphorylated tau species (pTau 181, 202, 217) in hippocampal lysates and autophagosomes of familial AD-linked PSEN1 patients and PS-deficient tau transgenic mice. Human iPSC-derived neurons harboring the familial AD-linked PSEN1 G206D mutation are less sensitive to autophagy inhibition, reduce tau release and accumulate intracellular tau oligomers. Human primary fibroblasts from PSEN1 G206D and/or L286P carriers show elevated LC3 and autolysosomes indicating that these familial AD-linked PSEN1 mutations disrupt autophagy flux. PS is required for efficient autophagy-mediated tau degradation in neurons through a dual mechanism involving autophagy induction via blockage of Akt/PRAS40-dependent mTORC1 activation and promoting autophagosome/lysosome fusion. Surprisingly, pharmacological proteasome inhibition decreases tau accumulation in neurons by promoting tau release through a mechanism that requires functional PS. In conclusion, PS is required for autophagy/proteasome-mediated tau elimination in neurons, while familial AD-linked PSEN1 mutations cause progressive tau pathology by disrupting autophagy. These findings may impact on the development of new therapeutic targets for tauopathy dementias.

The Effects of Multi-Colour Light Filtering Glasses on Human Brain Wave Activity
The prevalence of electronic screens in modern society has significantly increased our exposure to high-energy blue and violet light wavelengths. Accumulating evidence links this exposure to adverse visual and cognitive effects and sleep disturbances. To mitigate these effects, the optical industry has introduced a variety of light-filtering glasses. Yet, the scientific validation of these glasses has often been based on subjective reports and a narrow range of objective measures, casting doubt on their true efficacy. In this study, we used electroencephalography (EEG) to record brain wave activity to evaluate the effects of glasses that filter multiple wavelengths (blue, violet, indigo, and green) on human brain function. Our results demonstrate that wearing these multi-colour light filtering glasses significantly reduces beta wave power (13-30 Hz) compared to control glasses or no glasses at all. This reduction suggests that such glasses can calm heightened mental states, such as anxiety, thereby promoting relaxation. This investigation is innovative in applying neuroimaging techniques to confirm that light-filtering glasses can induce measurable changes in brain activity.

Kappa Opioid Receptors in Mesolimbic Terminals Mediate Escalation of Cocaine Consumption
Increases in drug consumption over time, also known as escalation, is a key behavioral component of substance use disorder (SUD) that is related to potential harm to users, such as overdose. Studying escalation also allows researchers to investigate the transition from casual drug use to more SUD-like drug use. Understanding the neurobiological systems that drive this transition will inform therapeutic treatments in the aim to prevent increases in drug use and the development of SUD. The kappa opioid receptor (KOR) system is typically known for its role in negative affect, which is commonly found in SUD as well. Furthermore, the KOR system has also been implicated in drug use and importantly, modulating the negative effects of drug use. However, the specific neuronal subpopulation expressing KOR involved has not been identified. Here, we first demonstrated that pharmacologically inhibiting KOR in the nucleus accumbens core (NAcC), as a whole, blocks cocaine escalation under long-access self-administration conditions. We then demonstrated that KOR expressed on ventral tegmental area (VTA) neurons but not NAcC neurons is sufficient for blocking cocaine escalation by utilizing a novel virally-mediated CRISPR-SaCas9 knock-out of the oprk1 gene. Together, this suggests that activation of KOR on VTA terminals in the NAcC drives the transition to the SUD-like phenotype of escalation of cocaine consumption.

Assessing cross-contamination in spike-sorted electrophysiology data
Recent advances in extracellular electrophysiology now facilitate the recording of spikes from hundreds or thousands of neurons simultaneously. This has necessitated both the development of new computational methods for spike sorting and better methods to determine spike sorting accuracy. One longstanding method of assessing the false discovery rate (FDR) of spike sorting - the rate at which spikes are misassigned to the wrong cluster - has been the rate of inter-spike-interval (ISI) violations. Despite their near ubiquitous usage in spike sorting, our understanding of how exactly ISI violations relate to FDR, as well as best practices for using ISI violations as a quality metric, remain limited. Here, we describe an analytical solution that can be used to predict FDR from ISI violation rate. We test this model in silico through Monte Carlo simulation, and apply it to publicly available spike-sorted electrophysiology datasets. We find that the relationship between ISI violation rate and FDR is highly nonlinear, with additional dependencies on firing rate, the correlation in activity between neurons, and contaminant neuron count. Predicted median FDRs in public datasets were found to range from 3.1% to 50.0%. We find that stochasticity in the occurrence of ISI violations as well as uncertainty in cluster-specific parameters make it difficult to predict FDR for single clusters with high confidence, but that FDR can be estimated accurately across a population of clusters. Our findings will help the growing community of researchers using extracellular electrophysiology assess spike sorting accuracy in a principled manner.