Comparison of Linear and Nonlinear Twist Extrusion Processes with Crystal Plasticity Finite Element Analysis.

The mechanical characteristics of polycrystalline metallic materials are influenced significantly by various microstructural parameters, one of which is the grain size. Specifically, the strength and the toughness of polycrystalline metals exhibit enhancement as the grain size is reduced. Applying severe plastic deformations (SPDs) has a noticeable result in obtaining metallic materials with ultrafine-grained (UFG) microstructure. SPD, executed through conventional shaping methods like extrusion, plays a pivotal role in the evolution of the texture, which is closely related to the plastic behavior and ductility. A number of SPD processes have been developed to generate ultrafine-grained materials, each having a different shear deformation mechanism. Among these methods, linear twist extrusion (LTE) presents a non-uniform and non-monotonic form of severe plastic deformation, leading to significant shifts in the microstructure. Prior research demonstrates the capability of the LTE process to yield consistent, weak textures in pre-textured copper. However, limitations in production efficiency and the uneven distribution of grain refinement have curbed the widespread use of LTE in industrial settings. This has facilitated the development of an improved novel method, that surpasses the traditional approach, known as the nonlinear twist extrusion procedure (NLTE). The NLTE method innovatively adjusts the channel design of the mold within the twist section to mitigate strain reversal and the rotational movement of the workpiece, both of which have been identified as shortcomings of twist extrusion. Accurate anticipation of texture changes in SPD processes is essential for mold design and process parameter optimization. The performance of the proposed extrusion technique should still be studied. In this context, here, a single crystal (SC) of copper in billet form, passing through both LTE and NLTE, is analyzed, employing a rate-dependent crystal plasticity finite element (CPFE) framework. CPFE simulations were performed for both LTE and NLTE of SC copper specimens having <100> or <111> directions parallel to the extrusion direction initially. The texture evolution as well as the cross-sectional distribution of the stress and strain is studied in detail, and the performance of both processes is compared.

Criticality supports cross-frequency cortical-thalamic information transfer during conscious states.

Consciousness is thought to be regulated by bidirectional information transfer between the cortex and thalamus, but the nature of this bidirectional communication - and its possible disruption in unconsciousness - remains poorly understood. Here, we present two main findings elucidating mechanisms of corticothalamic information transfer during conscious states. First, we identify a highly preserved spectral channel of cortical-thalamic communication that is present during conscious states, but which is diminished during the loss of consciousness and enhanced during psychedelic states. Specifically, we show that in humans, mice, and rats, information sent from either the cortex or thalamus via δ/θ/α waves (∼1-13 Hz) is consistently encoded by the other brain region by high γ waves (52-104 Hz); moreover, unconsciousness induced by propofol anesthesia or generalized spike-and-wave seizures diminishes this cross-frequency communication, whereas the psychedelic 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) enhances this low-to-high frequency interregional communication. Second, we leverage numerical simulations and neural electrophysiology recordings from the thalamus and cortex of human patients, rats, and mice to show that these changes in cross-frequency cortical-thalamic information transfer may be mediated by excursions of low-frequency thalamocortical electrodynamics toward/away from edge-of-chaos criticality, or the phase transition from stability to chaos. Overall, our findings link thalamic-cortical communication to consciousness, and further offer a novel, mathematically well-defined framework to explain the disruption to thalamic-cortical information transfer during unconscious states.

Effect of pre-rolling aging treatment on evolutions of the microstructure and the texture of aluminium alloy 7005 subjected to heavy cold rolling.

Aluminium alloy 7005 is widely used for structural purposes because of its attractive properties such as good weldability and age-hardening capability. However, since the workability of this alloy falls after a short period of natural aging, the application of cold rolling for the production of strain-hardened sheets of this alloy is a challenge. Two solutions proposed to overcome this challenge are as follows: (a) immediate rolling of the alloy after solution treatment and (b) rolling of the alloy after artificial aging. However, there is no comprehensive study comparing the effect of pre-rolling aging treatments on the evolutions of microstructure and texture of the alloy through heavy cold rolling. This subject is the aim of the present study. For this purpose, different pieces of the alloy are subjected to three different heat treatments before rolling, and afterward, they are rolled to obtain a thickness reduction of 80%. Scanning electron microscopy with electron backscattered diffraction observations are applied to study the evolutions of the microstructure and the texture of the alloy. Results show that the progression of pre-rolling aging decreases the incidence of micro-scaled shear bands by rolling. In addition, the rolling texture intensity decreases with the advancement of pre-rolling aging. Mechanisms responsible for this effect are discussed.

CUX2 deficiency causes facilitation of excitatory synaptic transmission onto hippocampus and increased seizure susceptibility to kainate.

CUX2 gene encodes a transcription factor that controls neuronal proliferation, dendrite branching and synapse formation, locating at the epilepsy-associated chromosomal region 12q24 that we previously identified by a genome-wide association study (GWAS) in Japanese population. A CUX2 recurrent de novo variant p.E590K has been described in patients with rare epileptic encephalopathies and the gene is a candidate for the locus, however the mutation may not be enough to generate the genome-wide significance in the GWAS and whether CUX2 variants appear in other types of epilepsies and physiopathological mechanisms are remained to be investigated. Here in this study, we conducted targeted sequencings of CUX2, a paralog CUX1 and its short isoform CASP harboring a unique C-terminus on 271 Japanese patients with a variety of epilepsies, and found that multiple CUX2 missense variants, other than the p.E590K, and some CASP variants including a deletion, predominantly appeared in patients with temporal lobe epilepsy (TLE). The CUX2 variants showed abnormal localization in human cell culture analysis. While wild-type CUX2 enhances dendritic arborization in fly neurons, the effect was compromised by some of the variants. Cux2- and Casp-specific knockout mice both showed high susceptibility to kainate, increased excitatory cell number in the entorhinal cortex, and significant enhancement in glutamatergic synaptic transmission to the hippocampus. CASP and CUX2 proteins physiologically bound to each other and co-expressed in excitatory neurons in brain regions including the entorhinal cortex. These results suggest that CUX2 and CASP variants contribute to the TLE pathology through a facilitation of excitatory synaptic transmission from entorhinal cortex to hippocampus.

The Early Introduction of Extracorporeal Membrane Oxygenation for Postcardiotomy Cardiogenic Shock Does Not Improve 30-Day Mortality Rates in Low-Volume Centers.

Background and objective Postcardiotomy cardiogenic shock (PCS) is one of the most critical conditions observed in cardiac surgery. Recently, the early initiation of venoarterial extracorporeal membrane oxygenation (VA-ECMO) has been recommended for PCS patients to ensure end-organ perfusion, especially in high-volume centers. In this study, we investigated the effectiveness of earlier initiation of VA-ECMO for PCS in low-volume centers. Methods We retrospectively assessed patients admitted in two of our related facilities from April 2014 to March 2019. The patients who underwent VA-ECMO during peri- or post-cardiac surgery (within 48 hours) were included. We divided the patients into two groups according to the timing of VA-ECMO initiation. In the early initiation of VA-ECMO group, the "early ECMO group," VA-ECMO was initiated when patients needed high-dose inotropic support with high-dose catecholamines, such as epinephrine, without waiting for PCS recovery. In the late initiation of VA-ECMO group, the "late ECMO group," VA-ECMO was delayed until PCS was not controlled with high-dose catecholamines, with the intent of avoiding severe bleeding complications. Results A total of 30 patients were included in the analysis (early ECMO group/late ECMO group: 19/11 patients). Thirty-day mortality in the entire cohort was 60% (n=18), and there was no significant difference between the two groups (early ECMO group/late ECMO group: 64%/55%, p=0.712). Thirteen and six patients died without being weaned off in the early ECMO (43%) and late ECMO groups (55%), respectively; there was no significant difference between the two groups (p=0.696). The median duration of ECMO support was five days (IQR: 1.5-6.5). Conclusions The early initiation of ECMO did not contribute to patients' 30-day outcomes in low-volume centers. To improve outcomes of ECMO therapy in patients with PCS, centralization of low-volume centers may be required.

Corrosion Behavior of Ultrafine-Grained CoCrFeMnNi High-Entropy Alloys Fabricated by High-Pressure Torsion.

The influence of the nanocrystalline structure produced by severe plastic deformation (SPD) on the corrosion behavior of CoCrFeMnNi alloys with Cr contents ranging from 0 to 20 at.% was investigated in aqueous 0.5 M H2SO4 and 3.5% NaCl solutions. The resistance to general corrosion and pitting became higher in both the solutions, with higher passivation capability observed with increasing Cr content, and it is believed that the high corrosion resistance of CoCrFeMnNi alloys can be attributed to the incorporation of the Cr element. However, the impact of the nanocrystalline structure produced by SPD on the corrosion behavior was negligibly small. This is inconsistent with reports on nanocrystalline binary Fe-Cr alloys and stainless steels processed by SPD, where grain refinement by SPD results in higher corrosion resistance. The small change in the corrosion behavior with respect to grain refinement is discussed, based on the passivation process of Fe-Cr alloys and on the influence of the core effects of HEAs on the passivation process.

Endovascular Reintervention for Stent-Graft Dislocation after Open Surgical Conversion for Thoracoabdominal Aortic Aneurysm Treated by Thoracic Endovascular Aortic Repair.

Complex anatomical restrictions can lead to further interventions after the emergence of a postoperative aneurysm enlargement in thoracic endovascular aortic repair (TEVAR) for a thoracoabdominal aortic aneurysm (TAAA). A 75-year-old male underwent a TEVAR for a Crawford extent I TAAA. The main device and the distal extension were placed using a fenestrated technique, outside of the instructions for use. The aneurysm expanded because of an endoleak and stent graft migration; and was surgically repaired by fully salvaging the previous endografts 38 months after the first TEVAR. However, the distal extension, which was the proximal anastomosis site with a prosthetic graft, became completely dislocated from the main device eight months after the open surgical conversion, resulting again in the enlargement of the aneurysm. An additional TEVAR was successfully performed to correct the dislocated stent graft. An appropriate treatment strategy is crucial to prevent multiple reinterventions for TAAA with complex anatomical restrictions.

Brain-specific heterozygous loss-of-function of ATP2A2, endoplasmic reticulum Ca2+ pump responsible for Darier's disease, causes behavioral abnormalities and a hyper-dopaminergic state.

A report of a family of Darier's disease with mood disorders drew attention when the causative gene was identified as ATP2A2 (or SERCA2), which encodes a Ca2+ pump on the endoplasmic reticulum (ER) membrane and is important for intracellular Ca2+ signaling. Recently, it was found that loss-of-function mutations of ATP2A2 confer a risk of neuropsychiatric disorders including depression, bipolar disorder and schizophrenia. In addition, a genome-wide association study found an association between ATP2A2 and schizophrenia. However, the mechanism of how ATP2A2 contributes to vulnerability to these mental disorders is unknown. Here, we analyzed Atp2a2 heterozygous brain-specific conditional knockout (hetero cKO) mice. The ER membranes prepared from the hetero cKO mouse brain showed decreased Ca2+ uptake activity. In Atp2a2 heterozygous neurons, decays of cytosolic Ca2+ level were slower than control neurons after depolarization. The hetero cKO mice showed altered behavioral responses to novel environments and impairments in fear memory, suggestive of enhanced dopamine signaling. In vivo dialysis demonstrated that extracellular dopamine levels in the NAc were indeed higher in the hetero cKO mice. These results altogether indicate that the haploinsufficiency of Atp2a2 in the brain causes prolonged cytosolic Ca2+ transients, which possibly results in enhanced dopamine signaling, a common feature of mood disorders and schizophrenia. These findings elucidate how ATP2A2 mutations causing a dermatological disease may exert their pleiotropic effects on the brain and confer a risk for mental disorders.

Kv3.1 channels regulate the rate of critical period plasticity.

Experience-dependent plasticity within visual cortex is controlled by postnatal maturation of inhibitory circuits, which are both morphologically diverse and precisely connected. Gene-targeted disruption of the voltage-dependent potassium channel Kv3.1 broadens action potentials and reduces net inhibitory function of parvalbumin (PV)-positive GABA subtypes within the neocortex. In mice lacking Kv3.1, the rate of input loss from an eye deprived of vision was slowed two-fold, despite otherwise normal critical period timecourse and receptive field properties. Rapid ocular dominance plasticity was restored by local or systemic enhancement of GABAergic transmission with acute benzodiazepine infusion. Diazepam instead exacerbated a global suppression of slow-wave oscillations during sleep described previously in these mutant mice, which therefore did not account for the rescued plasticity. Rapid ocular dominance shifts closely reflected Kv3.1 gene dosage that prevented prolonged spike discharge of their target pyramidal cells in vivo or the spike amplitude decrement of fast-spiking cells during bouts of high-frequency firing in vitro. Late postnatal expression of this unique channel in fast-spiking interneurons thus subtly regulates the speed of critical period plasticity with implications for mental illnesses.

Analysis of a Methanogen and an Actinobacterium Dominating the Thermophilic Microbial Community of an Electromethanogenic Biocathode.

Electromethanogenesis refers to the bioelectrochemical synthesis of methane from CO2 by biocathodes. In an electromethanogenic system using thermophilic microorganisms, metagenomic analysis along with quantitative real-time polymerase chain reaction and fluorescence in situ hybridization revealed that the biocathode microbiota was dominated by the methanogen Methanothermobacter sp. strain EMTCatA1 and the actinobacterium Coriobacteriaceae sp. strain EMTCatB1. RNA sequencing was used to compare the transcriptome profiles of each strain at the methane-producing biocathodes with those in an open circuit and with the methanogenesis inhibitor 2-bromoethanesulfonate (BrES). For the methanogen, genes related to hydrogenotrophic methanogenesis were highly expressed in a manner similar to those observed under H2-limited conditions. For the actinobacterium, the expression profiles of genes encoding multiheme c-type cytochromes and membrane-bound oxidoreductases suggested that the actinobacterium directly takes up electrons from the electrode. In both strains, various stress-related genes were commonly induced in the open-circuit biocathodes and biocathodes with BrES. This study provides a molecular inventory of the dominant species of an electromethanogenic biocathode with functional insights and therefore represents the first multiomics characterization of an electromethanogenic biocathode.

Down syndrome cell adhesion molecule like-1 (DSCAML1) links the GABA system and seizure susceptibility.

The Ihara epileptic rat (IER) is a mutant model with limbic-like seizures whose pathology and causative gene remain elusive. In this report, via linkage analysis, we identified Down syndrome cell adhesion molecule-like 1(Dscaml1) as the responsible gene for IER. A single base mutation in Dscaml1 causes abnormal splicing, leading to lack of DSCAML1. IERs have enhanced seizure susceptibility and accelerated kindling establishment. Furthermore, GABAergic neurons are severely reduced in the entorhinal cortex (ECx) of these animals. Voltage-sensitive dye imaging that directly presents the excitation status of brain slices revealed abnormally persistent excitability in IER ECx. This suggests that reduced GABAergic neurons may cause weak sustained entorhinal cortex activations, leading to natural kindling via the perforant path that could cause dentate gyrus hypertrophy and epileptogenesis. Furthermore, we identified a single nucleotide substitution in a human epilepsy that would result in one amino acid change in DSCAML1 (A2105T mutation). The mutant DSCAML1A2105T protein is not presented on the cell surface, losing its homophilic cell adhesion ability. We generated knock-in mice (Dscaml1A2105T) carrying the corresponding mutation and observed reduced GABAergic neurons in the ECx as well as spike-and-wave electrocorticogram. We conclude that DSCAML1 is required for GABAergic neuron placement in the ECx and suppression of seizure susceptibility in rodents. Our findings suggest that mutations in DSCAML1 may affect seizure susceptibility in humans.

CRISPR/dCas9-based Scn1a gene activation in inhibitory neurons ameliorates epileptic and behavioral phenotypes of Dravet syndrome model mice.

Dravet syndrome is a severe infantile-onset epileptic encephalopathy which begins with febrile seizures and is caused by heterozygous loss-of-function mutations of the voltage-gated sodium channel gene SCN1A. We designed a CRISPR-based gene therapy for Scn1a-haplodeficient mice using multiple guide RNAs (gRNAs) in the promoter regions together with the nuclease-deficient Cas9 fused to transcription activators (dCas9-VPR) to trigger the transcription of SCN1A or Scn1a in vitro. We tested the effect of this strategy in vivo using an adeno-associated virus (AAV) mediated system targeting inhibitory neurons and investigating febrile seizures and behavioral parameters. In both the human and mouse genes multiple guide RNAs (gRNAs) in the upstream, rather than downstream, promoter region showed high and synergistic activities to increase the transcription of SCN1A or Scn1a in cultured cells. Intravenous injections of AAV particles containing the optimal combination of 4 gRNAs into transgenic mice with Scn1a-haplodeficiency and inhibitory neuron-specific expression of dCas9-VPR at four weeks of age increased Nav1.1 expression in parvalbumin-positive GABAergic neurons, ameliorated their febrile seizures and improved their behavioral impairments. Although the usage of transgenic mice and rather modest improvements in seizures and abnormal behaviors hamper direct clinical application, our results indicate that the upregulation of Scn1a expression in the inhibitory neurons can significantly improve the phenotypes, even when applied after the juvenile stages. Our findings also suggest that the decrease in Nav1.1 is directly involved in the symptoms seen in adults with Dravet syndrome and open a way to improve this condition.

Scn2a haploinsufficient mice display a spectrum of phenotypes affecting anxiety, sociability, memory flexibility and ampakine CX516 rescues their hyperactivity.

Background: Mutations of the SCN2A gene encoding a voltage-gated sodium channel alpha-II subunit Nav1.2 are associated with neurological disorders such as epilepsy, autism spectrum disorders, intellectual disability, and schizophrenia. However, causal relationships and pathogenic mechanisms underlying these neurological defects, especially social and psychiatric features, remain to be elucidated. Methods: We investigated the behavior of mice with a conventional or conditional deletion of Scn2a in a comprehensive test battery including open field, elevated plus maze, light-dark box, three chambers, social dominance tube, resident-intruder, ultrasonic vocalization, and fear conditioning tests. We further monitored the effects of the positive allosteric modulator of AMPA receptors CX516 on these model mice. Results: Conventional heterozygous Scn2a knockout mice (Scn2aKO/+) displayed novelty-induced exploratory hyperactivity and increased rearing. The increased vertical activity was reproduced by heterozygous inactivation of Scn2a in dorsal-telencephalic excitatory neurons but not in inhibitory neurons. Moreover, these phenotypes were rescued by treating Scn2aKO/+ mice with CX516. Additionally, Scn2aKO/+ mice displayed mild social behavior impairment, enhanced fear conditioning, and deficient fear extinction. Neuronal activity was intensified in the medial prefrontal cortex of Scn2aKO/+ mice, with an increase in the gamma band. Conclusions: Scn2aKO/+ mice exhibit a spectrum of phenotypes commonly observed in models of schizophrenia and autism spectrum disorder. Treatment with the CX516 ampakine, which ameliorates hyperactivity in these mice, could be a potential therapeutic strategy to rescue some of the disease phenotypes.

Impaired cortico-striatal excitatory transmission triggers epilepsy.

STXBP1 and SCN2A gene mutations are observed in patients with epilepsies, although the circuit basis remains elusive. Here, we show that mice with haplodeficiency for these genes exhibit absence seizures with spike-and-wave discharges (SWDs) initiated by reduced cortical excitatory transmission into the striatum. Mice deficient for Stxbp1 or Scn2a in cortico-striatal but not cortico-thalamic neurons reproduce SWDs. In Stxbp1 haplodeficient mice, there is a reduction in excitatory transmission from the neocortex to striatal fast-spiking interneurons (FSIs). FSI activity transiently decreases at SWD onset, and pharmacological potentiation of AMPA receptors in the striatum but not in the thalamus suppresses SWDs. Furthermore, in wild-type mice, pharmacological inhibition of cortico-striatal FSI excitatory transmission triggers absence and convulsive seizures in a dose-dependent manner. These findings suggest that impaired cortico-striatal excitatory transmission is a plausible mechanism that triggers epilepsy in Stxbp1 and Scn2a haplodeficient mice.

Nav1.2 haplodeficiency in excitatory neurons causes absence-like seizures in mice.

Mutations in the SCN2A gene encoding a voltage-gated sodium channel Nav1.2 are associated with epilepsies, intellectual disability, and autism. SCN2A gain-of-function mutations cause early-onset severe epilepsies, while loss-of-function mutations cause autism with milder and/or later-onset epilepsies. Here we show that both heterozygous Scn2a-knockout and knock-in mice harboring a patient-derived nonsense mutation exhibit ethosuximide-sensitive absence-like seizures associated with spike-and-wave discharges at adult stages. Unexpectedly, identical seizures are reproduced and even more prominent in mice with heterozygous Scn2a deletion specifically in dorsal-telencephalic (e.g., neocortical and hippocampal) excitatory neurons, but are undetected in mice with selective Scn2a deletion in inhibitory neurons. In adult cerebral cortex of wild-type mice, most Nav1.2 is expressed in excitatory neurons with a steady increase and redistribution from proximal (i.e., axon initial segments) to distal axons. These results indicate a pivotal role of Nav1.2 haplodeficiency in excitatory neurons in epilepsies of patients with SCN2A loss-of-function mutations.

Variant Intestinal-Cell Kinase in Juvenile Myoclonic Epilepsy.

BACKGROUND: In juvenile myoclonic epilepsy, data are limited on the genetic basis of networks promoting convulsions with diffuse polyspikes on electroencephalography (EEG) and the subtle microscopic brain dysplasia called microdysgenesis. METHODS: Using Sanger sequencing, we sequenced the exomes of six members of a large family affected with juvenile myoclonic epilepsy and confirmed cosegregation in all 37 family members. We screened an additional 310 patients with this disorder for variants on DNA melting-curve analysis and targeted real-time DNA sequencing of the gene encoding intestinal-cell kinase ( ICK). We calculated Bayesian logarithm of the odds (LOD) scores for cosegregating variants, odds ratios in case-control associations, and allele frequencies in the Genome Aggregation Database. We performed functional tests of the effects of variants on mitosis, apoptosis, and radial neuroblast migration in vitro and conducted video-EEG studies in mice lacking a copy of Ick. RESULTS: A variant, K305T (c.914A→C), cosegregated with epilepsy or polyspikes on EEG in 12 members of the family affected with juvenile myoclonic epilepsy. We identified 21 pathogenic ICK variants in 22 of 310 additional patients (7%). Four strongly linked variants (K220E, K305T, A615T, and R632X) impaired mitosis, cell-cycle exit, and radial neuroblast migration while promoting apoptosis. Tonic-clonic convulsions and polyspikes on EEG resembling seizures in human juvenile myoclonic epilepsy occurred more often in knockout heterozygous mice than in wild-type mice (P=0.02) during light sleep with isoflurane anesthesia. CONCLUSIONS: Our data provide evidence that heterozygous variants in ICK caused juvenile myoclonic epilepsy in 7% of the patients included in our analysis. Variant ICK affects cell processes that help explain microdysgenesis and polyspike networks observed on EEG in juvenile myoclonic epilepsy. (Funded by the National Institutes of Health and others.).

DYRK1A-haploinsufficiency in mice causes autistic-like features and febrile seizures.

Mutations and copy number variants affecting DYRK1A gene encoding the dual-specificity tyrosine phosphorylation-regulated kinase 1A are among the most frequent genetic causes of neurodevelopmental disorders including autism spectrum disorder (ASD) associated with microcephaly, febrile seizures and severe speech acquisition delay. Here we developed a mouse model harboring a frame-shift mutation in Dyrk1a resulting in a protein truncation and elimination of its kinase activity site. Dyrk1a+/- mice showed significant impairments in cognition and cognitive flexibility, communicative ultrasonic vocalizations, and social contacts. Susceptibility to hyperthermia-induced seizures was also significantly increased in these mice. The truncation leading to haploinsufficiency of DYRK1A in mice thus recapitulates the syndromic phenotypes observed in human patients and constitutes a useful model for further investigations of the mechanisms leading to ASD, speech delay and febrile seizures.

Potentiation of excitatory synaptic transmission ameliorates aggression in mice with Stxbp1 haploinsufficiency.

Genetic studies point to a major role of de novo mutations in neurodevelopmental disorders of intellectual disability, autism spectrum disorders, and epileptic encephalopathy. The STXBP1 gene encodes the syntaxin-binding protein 1 (Munc18-1) that critically controls synaptic vesicle exocytosis and synaptic transmission. This gene harbors a high frequency of de novo mutations, which may play roles in these neurodevelopmental disorders. However, the system and behavioral-level pathophysiological changes caused by these genetic defects remain poorly understood. Constitutional (Stxbp1+/-), dorsal-telencephalic excitatory (Stxbp1fl/+/Emx), or global inhibitory neuron-specific (Stxbp1fl/+/Vgat) mice were subjected to a behavioral test battery examining locomotor activity, anxiety, fear learning, and social interactions including aggression. Furthermore, measurements of local field potentials in multiple regions of the brain were performed. Stxbp1+/- male mice exhibited enhanced aggressiveness and impaired fear learning associated with elevated gamma activity in several regions of the brain including the prefrontal cortex. Stxbp1fl/+/Emx mice showed fear-learning deficits, but neither Stxbp1fl/+/Emx nor Stxbp1fl/+/Vgat mice showed increased aggressiveness. Pharmacological potentiation of the excitatory transmission at active synapses via the systemic administration of ampakine CX516, which enhances the excitatory postsynaptic function, ameliorated the aggressive phenotype of Stxbp1+/- mice. These findings suggest that synaptic impairments of the dorsal telencephalic and subcortical excitatory neurons cause learning deficits and enhanced aggression in Stxbp1+/- mice, respectively. Additionally, normalizing the excitatory synaptic transmission is a potential therapeutic option for managing aggressiveness in patients with STXBP1 mutations.

Regulation of spinogenesis in mature Purkinje cells via mGluR/PKC-mediated phosphorylation of CaMKIIß.

Dendritic spines of Purkinje cells form excitatory synapses with parallel fiber terminals, which are the primary sites for cerebellar synaptic plasticity. Nevertheless, how density and morphology of these spines are properly maintained in mature Purkinje cells is not well understood. Here we show an activity-dependent mechanism that represses excessive spine development in mature Purkinje cells. We found that CaMKIIß promotes spine formation and elongation in Purkinje cells through its F-actin bundling activity. Importantly, activation of group I mGluR, but not AMPAR, triggers PKC-mediated phosphorylation of CaMKIIß, which results in dissociation of the CaMKIIß/F-actin complex. Defective function of the PKC-mediated CaMKIIß phosphorylation promotes excess F-actin bundling and leads to abnormally numerous and elongated spines in mature IP3R1-deficient Purkinje cells. Thus, our data suggest that phosphorylation of CaMKIIß through the mGluR/IP3R1/PKC signaling pathway represses excessive spine formation and elongation in mature Purkinje cells.

Ts1Cje Down syndrome model mice exhibit environmental stimuli-triggered locomotor hyperactivity and sociability concurrent with increased flux through central dopamine and serotonin metabolism.

Ts1Cje mice have a segmental trisomy of chromosome 16 that is orthologous to human chromosome 21 and display Down syndrome-like cognitive impairments. Despite the occurrence of affective and emotional impairments in patients with Down syndrome, these parameters are poorly documented in Down syndrome mouse models, including Ts1Cje mice. Here, we conducted comprehensive behavioral analyses, including anxiety-, sociability-, and depression-related tasks, and biochemical analyses of monoamines and their metabolites in Ts1Cje mice. Ts1Cje mice showed enhanced locomotor activity in novel environments and increased social contact with unfamiliar partners when compared with wild-type littermates, but a significantly lower activity in familiar environments. Ts1Cje mice also exhibited some signs of decreased depression like-behavior. Furthermore, Ts1Cje mice showed monoamine abnormalities, including increased extracellular dopamine and serotonin, and enhanced catabolism in the striatum and ventral forebrain. This study constitutes the first report of deviated monoamine metabolism that may help explain the basis for abnormal behaviors, including the environmental stimuli-triggered hyperactivity, increased sociability and decreased depression-like behavior in Ts1Cje mice.