Restoring SRSF3 in Kupffer cells attenuates obesity-related insulin resistance.

BACKGROUND AND AIMS: In obesity, depletion of KCs expressing CRIg (complement receptor of the Ig superfamily) leads to microbial DNA accumulation, which subsequently triggers tissue inflammation and insulin resistance. However, the mechanism underlying obesity-mediated changes in KC complement immune functions is largely unknown. APPROACH AND RESULTS: Using KC-specific deactivated Cas9 transgenic mice treated with guide RNA, we assessed the effects of restoring CRIg or the serine/arginine-rich splicing factor 3 (SRSF3) abundance on KC functions and metabolic phenotypes in obese mice. The impacts of weight loss on KC responses were evaluated in a diet switch mouse model. The role of SRSF3 in regulating KC functions was also evaluated using KC-specific SRSF3 knockout mice. Here, we report that overexpression of CRIg in KCs of obese mice protects against bacterial DNA accumulation in metabolic tissues. Mechanistically, SRSF3 regulates CRIg expression, which is essential for maintaining the CRIg+ KC population. During obesity, SRSF3 expression decreases, but it is restored with weight loss through a diet switch, normalizing CRIg+ KCs. KC SRSF3 is also repressed in obese human livers. Lack of SRSF3 in KCs in lean and obese mice decreases their CRIg+ population, impairing metabolic parameters. During the diet switch, the benefits of weight loss are compromised due to SRSF3 deficiency. Conversely, SRSF3 overexpression in obese mice preserves CRIg+ KCs and improves metabolic responses. CONCLUSIONS: Restoring SRSF3 abundance in KCs offers a strategy against obesity-associated tissue inflammation and insulin resistance by preventing bacterial DNA accumulation.

Nuclear receptor 5A2 regulation of Agrp underlies olanzapine-induced hyperphagia.

Antipsychotic (AP) drugs are efficacious treatments for various psychiatric disorders, but excessive weight gain and subsequent development of metabolic disease remain serious side effects of their use. Increased food intake leads to AP-induced weight gain, but the underlying molecular mechanisms remain unknown. In previous studies, we identified the neuropeptide Agrp and the transcription factor nuclear receptor subfamily 5 group A member 2 (Nr5a2) as significantly upregulated genes in the hypothalamus following AP-induced hyperphagia. While Agrp is expressed specifically in the arcuate nucleus of the hypothalamus and plays a critical role in appetite stimulation, Nr5a2 is expressed in both the CNS and periphery, but its role in food intake behaviors remains unknown. In this study, we investigated the role of hypothalamic Nr5a2 in AP-induced hyperphagia and weight gain. In hypothalamic cell lines, olanzapine treatment resulted in a dose-dependent increase in gene expression of Nr5a2 and Agrp. In mice, the pharmacological inhibition of NR5A2 decreased olanzapine-induced hyperphagia and weight gain, while the knockdown of Nr5a2 in the arcuate nucleus partially reversed olanzapine-induced hyperphagia. Chromatin-immunoprecipitation studies showed for the first time that NR5A2 directly binds to the Agrp promoter region. Lastly, the analysis of single-cell RNA seq data confirms that Nr5a2 and Agrp are co-expressed in a subset of neurons in the arcuate nucleus. In summary, we identify Nr5a2 as a key mechanistic driver of AP-induced food intake. These findings can inform future clinical development of APs that do not activate hyperphagia and weight gain.

Inhibition of YTHDF1 prevents hypoxia-induced pulmonary artery smooth muscle cell proliferation by regulating Foxm1 translation in an m6A-dependent manner.

Pulmonary arterial hypertension (PAH) is a chronic disease characterized by pulmonary vascular remodeling. It refers to the abnormal proliferation of pulmonary artery smooth muscle cells (PASMCs), and hypoxia is an important risk factor for this progression. The present study aims to investigate the role of YTHDF1 in the regulation of hypoxic PASMC proliferation and the underlying mechanism. Human PASMCs were transfected with si-YTHDF1/2/3 followed by treatment of hypoxia, and the PASMC proliferation and Foxm1 expression were detected. Through RNA pull-down, RNA immunoprecipitation, and protein synthesis assay, the mechanism of YTHDF1 regulating Foxm1 was explored. Next, Foxm1 was inhibited by thiostrepton, and cell proliferation was detected. In vivo, mice received a tail vein injection of adenovirus containing si-YTHDF1 and were exposed to hypoxia treatment. Pulmonary vascular changes, right ventricular systolic pressure (RVSP), and genes involving proliferation were analyzed. YTHDF1 silencing reduced more hypoxic PASMC proliferation and Foxm1 protein level than YTHDF2/3 silencing. Mechanical results showed that YTHDF1 interacted with Foxm1 mRNA and up-regulated Foxm1 protein level by enhancing the translation efficiency in an m6A-dependent manner. Furthermore, YTHDF1 facilitated hypoxic PASMC proliferation and proliferation marker expressions through up-regulation of Foxm1 in an m6A-dependent manner. In vivo, the YTHDF1 silencing alleviated pulmonary vascular changes and fibrosis, reduced RVSP, inhibited the interaction of YTHDF1 and Foxm1, and reduced proliferation marker levels, as compared to the PAH group. In conclusion, YTHDF1 silencing inhibits hypoxic PASMC proliferation by regulating Foxm1 translation in an m6A-dependent manner.

Litter mixing promoted decomposition and altered microbial community in common bean root litter.

BACKGROUND: Decomposition of plant litter is a key driver of carbon and nutrient cycling in terrestrial ecosystems. Mixing litters of different plant species may alter the decomposition rate, but its effect on the microbial decomposer community in plant litter is not fully understood. Here, we tested the effects of mixing with maize (Zea mays L.) and soybean [Glycine max (Linn.) Merr.] stalk litters on the decomposition and microbial decomposer communities of common bean (Phaseolus vulgaris L.) root litter at the early decomposition stage in a litterbag experiment. RESULTS: Mixing with maize stalk litter, soybean stalk litter, and both of these litters increased the decomposition rate of common bean root litter at 56 day but not 14 day after incubation. Litter mixing also increased the decomposition rate of the whole liter mixture at 56 day after incubation. Amplicon sequencing found that litter mixing altered the composition of bacterial (at 56 day after incubation) and fungal communities (at both 14 and 56 day after incubation) in common bean root litter. Litter mixing increased the abundance and alpha diversity of fungal communities in common bean root litter at 56 day after incubation. Particularly, litter mixing stimulated certain microbial taxa, such as Fusarium, Aspergillus and Stachybotrys spp. In addition, a pot experiment with adding litters in the soil showed that litter mixing promoted growth of common bean seedlings and increased soil nitrogen and phosphorus contents. CONCLUSIONS: This study showed that litter mixing can promote the decomposition rate and cause shifts in microbial decomposer communities, which may positively affect crop growth.

CRIg+ Macrophages Prevent Gut Microbial DNA-Containing Extracellular Vesicle-Induced Tissue Inflammation and Insulin Resistance.

BACKGROUND & AIMS: Liver CRIg+ (complement receptor of the immunoglobulin superfamily) macrophages play a critical role in filtering bacteria and their products from circulation. Translocation of microbiota-derived products from an impaired gut barrier contributes to the development of obesity-associated tissue inflammation and insulin resistance. However, the critical role of CRIg+ macrophages in clearing microbiota-derived products from the bloodstream in the context of obesity is largely unknown. METHODS: We performed studies with CRIg-/-, C3-/-, cGAS-/-, and their wild-type littermate mice. The CRIg+ macrophage population and bacterial DNA abundance were examined in both mouse and human liver by either flow cytometric or immunohistochemistry analysis. Gut microbial DNA-containing extracellular vesicles (mEVs) were adoptively transferred into CRIg-/-, C3-/-, or wild-type mice, and tissue inflammation and insulin sensitivity were measured in these mice. After coculture with gut mEVs, cellular insulin responses and cGAS/STING-mediated inflammatory responses were evaluated. RESULTS: Gut mEVs can reach metabolic tissues in obesity. Liver CRIg+ macrophages efficiently clear mEVs from the bloodstream through a C3-dependent opsonization mechanism, whereas obesity elicits a marked reduction in the CRIg+ macrophage population. Depletion of CRIg+ cells results in the spread of mEVs into distant metabolic tissues, subsequently exacerbating tissue inflammation and metabolic disorders. Additionally, in vitro treatment of obese mEVs directly triggers inflammation and insulin resistance of insulin target cells. Depletion of microbial DNA blunts the pathogenic effects of intestinal EVs. Furthermore, the cGAS/STING pathway is crucial for microbial DNA-mediated inflammatory responses. CONCLUSIONS: Deficiency of CRIg+ macrophages and leakage of intestinal EVs containing microbial DNA contribute to the development of obesity-associated tissue inflammation and metabolic diseases.

Cumulative latency advance underlies fast visual processing in desynchronized brain state.

Fast sensory processing is vital for the animal to efficiently respond to the changing environment. This is usually achieved when the animal is vigilant, as reflected by cortical desynchronization. However, the neural substrate for such fast processing remains unclear. Here, we report that neurons in rat primary visual cortex (V1) exhibited shorter response latency in the desynchronized state than in the synchronized state. In vivo whole-cell recording from the same V1 neurons undergoing the two states showed that both the resting and visually evoked conductances were higher in the desynchronized state. Such conductance increases of single V1 neurons shorten the response latency by elevating the membrane potential closer to the firing threshold and reducing the membrane time constant, but the effects only account for a small fraction of the observed latency advance. Simultaneous recordings in lateral geniculate nucleus (LGN) and V1 revealed that LGN neurons also exhibited latency advance, with a degree smaller than that of V1 neurons. Furthermore, latency advance in V1 increased across successive cortical layers. Thus, latency advance accumulates along various stages of the visual pathway, likely due to a global increase of membrane conductance in the desynchronized state. This cumulative effect may lead to a dramatic shortening of response latency for neurons in higher visual cortex and play a critical role in fast processing for vigilant animals.

Targeting Clic1 for the treatment of obesity: A novel therapeutic strategy to reduce food intake and body weight.

OBJECTIVE: Despite great advances in obesity therapeutics in recent years, there is still a need to identify additional therapeutic targets for the treatment of this disease. We previously discovered a signature of genes, including Chloride intracellular channel 1 (Clic1), whose expression was associated with drug-induced weight gain, and in these studies, we assess the effect of Clic1 inhibition on food intake and body weight in mice. METHODS: We studied the impact of Clic1 inhibition in mouse models of binge-eating, diet-induced obese mice and genetic models of obesity (Magel2 KO mice). RESULTS: Clic1 knockout (KO) mice ate significantly less and had a lower body weight than WT littermates when either fed chow or high fat diet. Furthermore, pharmacological inhibition of Clic1 in diet-induced obese mice resulted in suppression of food intake and promoted highly efficacious weight loss. Clic1 inhibition also reduced food intake in binge-eating models and hyperphagic Magel2 KO mice. We observed that chronic obesity resulted in a significant change in subcellular localization of Clic1 with an increased ratio of Clic1 in the membrane in the obese state. These observations provide a novel therapeutic strategy to block Clic1 translocation as a potential mechanism to reduce food intake and lower body weight. CONCLUSIONS: These studies attribute a novel role of Clic1 as a driver of food intake and overconsumption. In summary, we have identified hypothalamic expression of Clic1 plays a key role in food intake, providing a novel therapeutic target to treat overconsumption that is the root cause of modern obesity.

Gut lumen-leaked microbial DNA causes myocardial inflammation and impairs cardiac contractility in ageing mouse heart.

Emerging evidence indicates the critical roles of microbiota in mediating host cardiac functions in ageing, however, the mechanisms underlying the communications between microbiota and cardiac cells during the ageing process have not been fully elucidated. Bacterial DNA was enriched in the cardiomyocytes of both ageing humans and mice. Antibiotic treatment remarkably reduced bacterial DNA abundance in ageing mice. Gut microbial DNA containing extracellular vesicles (mEVs) were readily leaked into the bloodstream and infiltrated into cardiomyocytes in ageing mice, causing cardiac microbial DNA enrichment. Vsig4+ macrophages efficiently block the spread of gut mEVs whereas Vsig4+ cell population was greatly decreased in ageing mice. Gut mEV treatment resulted in cardiac inflammation and a reduction in cardiac contractility in young Vsig4-/- mice. Microbial DNA depletion attenuated the pathogenic effects of gut mEVs. cGAS/STING signaling is critical for the effects of microbial DNA. Restoring Vsig4+ macrophage population in ageing WT mice reduced cardiac microbial DNA abundance and inflammation and improved heart contractility.

Hyperleptinemia contributes to antipsychotic drug-associated obesity and metabolic disorders.

Despite their high degree of effectiveness in the management of psychiatric conditions, exposure to antipsychotic drugs, including olanzapine and risperidone, is frequently associated with substantial weight gain and the development of diabetes. Even before weight gain, a rapid rise in circulating leptin concentrations can be observed in most patients taking antipsychotic drugs. To date, the contribution of this hyperleptinemia to weight gain and metabolic deterioration has not been defined. Here, with an established mouse model that recapitulates antipsychotic drug-induced obesity and insulin resistance, we not only confirm that hyperleptinemia occurs before weight gain but also demonstrate that hyperleptinemia contributes directly to the development of obesity and associated metabolic disorders. By suppressing the rise in leptin through the use of a monoclonal leptin-neutralizing antibody, we effectively prevented weight gain, restored glucose tolerance, and preserved adipose tissue and liver function in antipsychotic drug-treated mice. Mechanistically, suppressing excess leptin resolved local tissue and systemic inflammation typically associated with antipsychotic drug treatment. We conclude that hyperleptinemia is a key contributor to antipsychotic drug-associated weight gain and metabolic deterioration. Leptin suppression may be an effective approach to reducing the undesirable side effects of antipsychotic drugs.

Microbial DNA enrichment promotes liver steatosis and fibrosis in the course of non-alcoholic steatohepatitis.

AIM: Low-grade inflammation is the hallmark of non-alcoholic fatty liver diseases (NAFLD) and non-alcoholic steatohepatitis (NASH). The leakage of microbiota-derived products can contribute to liver inflammation during NAFLD/NASH development. Here, we assessed the roles of gut microbial DNA-containing extracellular vesicles (mEVs) in regulating liver cellular abnormalities in the course of NAFLD/NASH. METHODS: We performed studies with Vsig4-/- , C3-/- , cGAS-/- , and their wild-type littermate mice. Vsig4+ macrophage population and bacterial DNA abundance were examined in both mouse and human liver by either flow cytometric or immunohistochemistry analysis. Gut mEVs were adoptively transferred into Vsig4-/- , C3-/- , cGAS-/- , or littermate WT mice, and hepatocyte inflammation and HSC fibrogenic activation were measured in these mice. RESULTS: Non-alcoholic fatty liver diseases and non-alcoholic steatohepatitis development was concomitant with a diminished liver Vsig4+ macrophage population and a marked bacterial DNA enrichment in both hepatocytes and HSCs. In the absence of Vsig4+ macrophages, gut mEVs translocation led to microbial DNA accumulation in hepatocytes and HSCs, resulting elevated hepatocyte inflammation and HSC fibrogenic activation. In contrast, in lean WT mice, Vsig4+ macrophages remove gut mEVs from bloodstream through a C3-dependent opsonization mechanism and prevent the infiltration of gut mEVs into hepatic cells. Additionally, Vsig4-/- mice more quickly developed significant liver steatosis and fibrosis than WT mice after Western diet feeding. In vitro treatment with NASH mEVs triggered hepatocyte inflammation and HSC fibrogenic activation. Microbial DNAs are key cargo for the effects of gut mEVs by activating cGAS/STING. CONCLUSION: Accumulation of microbial DNAs fuels the development of NAFLD/NASH-associated liver abnormalities.

MiR-690 treatment causes decreased fibrosis and steatosis and restores specific Kupffer cell functions in NASH.

Nonalcoholic steatohepatitis (NASH) is a liver disease associated with significant morbidity. Kupffer cells (KCs) produce endogenous miR-690 and, via exosome secretion, shuttle this miRNA to other liver cells, such as hepatocytes, recruited hepatic macrophages (RHMs), and hepatic stellate cells (HSCs). miR-690 directly inhibits fibrogenesis in HSCs, inflammation in RHMs, and de novo lipogenesis in hepatocytes. When an miR-690 mimic is administered to NASH mice in vivo, all the features of the NASH phenotype are robustly inhibited. During the development of NASH, KCs become miR-690 deficient, and miR-690 levels are markedly lower in mouse and human NASH livers than in controls. KC-specific KO of miR-690 promotes NASH pathogenesis. A primary target of miR-690 is NADK mRNA, and NADK levels are inversely proportional to the cellular miR-690 content. These studies show that KCs play a central role in the etiology of NASH and raise the possibility that miR-690 could emerge as a therapeutic for this condition.

Microbial DNA Enrichment Promotes Adrenomedullary Inflammation, Catecholamine Secretion, and Hypertension in Obese Mice.

Background Obesity is an established risk factor for hypertension. Although obesity-induced gut barrier breach leads to the leakage of various microbiota-derived products into host circulation and distal organs, the roles of microbiota in mediating the development of obesity-associated adrenomedullary disorders and hypertension have not been elucidated. We seek to explore the impacts of microbial DNA enrichment on inducing obesity-related adrenomedullary abnormalities and hypertension. Methods and Results Obesity was accompanied by remarkable bacterial DNA accumulation and elevated inflammation in the adrenal glands. Gut microbial DNA containing extracellular vesicles (mEVs) were readily leaked into the bloodstream and infiltrated into the adrenal glands in obese mice, causing microbial DNA enrichment. In lean wild-type mice, adrenal macrophages expressed CRIg (complement receptor of the immunoglobulin superfamily) that efficiently blocks the infiltration of gut mEVs. In contrast, the adrenal CRIg+ cell population was greatly decreased in obese mice. In lean CRIg-/- or C3-/- (complement component 3) mice intravenously injected with gut mEVs, adrenal microbial DNA accumulation elevated adrenal inflammation and norepinephrine secretion, concomitant with hypertension. In addition, microbial DNA promoted inflammatory responses and norepinephrine production in rat pheochromocytoma PC12 cells treated with gut mEVs. Depletion of microbial DNA cargo markedly blunted the effects of gut mEVs. We also validated that activation of cGAS (cyclic GMP-AMP synthase)/STING (cyclic GMP-AMP receptor stimulator of interferon genes) signaling is required for the ability of microbial DNA to trigger adrenomedullary dysfunctions in both in vivo and in vitro experiments. Restoring CRIg+ cells in obese mice decreased microbial DNA abundance, inflammation, and hypertension. Conclusions The leakage of gut mEVs leads to adrenal enrichment of microbial DNA that are pathogenic to induce obesity-associated adrenomedullary abnormalities and hypertension. Recovering the CRIg+ macrophage population attenuates obesity-induced adrenomedullary disorders.

Adipocytes control food intake and weight regain via Vacuolar-type H+ ATPase.

Energy metabolism becomes dysregulated in individuals with obesity and many of these changes persist after weight loss and likely play a role in weight regain. In these studies, we use a mouse model of diet-induced obesity and weight loss to study the transcriptional memory of obesity. We found that the 'metabolic memory' of obesity is predominantly localized in adipocytes. Utilizing a C. elegans-based food intake assay, we identify 'metabolic memory' genes that play a role in food intake regulation. We show that expression of ATP6v0a1, a subunit of V-ATPase, is significantly induced in both obese mouse and human adipocytes that persists after weight loss. C. elegans mutants deficient in Atp6v0A1/unc32 eat less than WT controls. Adipocyte-specific Atp6v0a1 knockout mice have reduced food intake and gain less weight in response to HFD. Pharmacological disruption of V-ATPase assembly leads to decreased food intake and less weight re-gain. In summary, using a series of genetic tools from invertebrates to vertebrates, we identify ATP6v0a1 as a regulator of peripheral metabolic memory, providing a potential target for regulation of food intake, weight loss maintenance and the treatment of obesity.

Aberrant iron distribution via hepatocyte-stellate cell axis drives liver lipogenesis and fibrosis.

Hepatocytes have important roles in liver iron homeostasis, abnormalities in which are tightly associated with liver steatosis and fibrosis. Here, we show that non-alcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH) are characterized by iron-deficient hepatocytes and iron overload in hepatic stellate cells (HSCs). Iron deficiency enhances hepatocyte lipogenesis and insulin resistance through HIF2α-ATF4 signaling. Elevated secretion of iron-containing hepatocyte extracellular vesicles (EVs), which are normally cleared by Kupffer cells, accounts for hepatocyte iron deficiency and HSC iron overload in NAFLD/NASH livers. Iron accumulation results in overproduction of reactive oxygen species that promote HSC fibrogenic activation. Conversely, blocking hepatocyte EV secretion or depleting EV iron cargo restores liver iron homeostasis, concomitant with mitigation of NAFLD/NASH-associated liver steatosis and fibrosis. Taken together, these studies show that iron distribution disorders contribute to the development of liver metabolic diseases.

Self-Administration of Drugs in Mouse Models of Feeding and Obesity.

Preclinical studies in mice often rely on invasive protocols, such as injections or oral gavage, to deliver drugs. These stressful routes of administration have significant effects on important metabolic parameters including food intake and body weight. Although an attractive option to circumvent this is to compound the drug in rodent food or dissolve it in water, these approaches also have limitations as they are affected by drug stability at room temperature for extended periods of time, the drug's solubility in water, and that the dosing is highly dependent on timing of food or water intake. The constant availability of the drug also limits translational relevance on how drugs are administered to patients. To overcome these limitations, drugs can be mixed with highly palatable food, such as peanut butter, allowing mice to self-administer compounds. Mice reliably and reproducibly consume the drug/peanut butter pellet in a short time frame. This approach facilitates a delivery approach with minimal stress compared with an injection or gavage. This protocol demonstrates the approach of drug preparation, animal acclimatization to placebo delivery, and drug delivery. The implications of this approach are discussed in studies related to timing of drug administration and the circadian rhythm.

Conserved immunomodulatory transcriptional networks underlie antipsychotic-induced weight gain.

Although antipsychotics, such as olanzapine, are effective in the management of psychiatric conditions, some patients experience excessive antipsychotic-induced weight gain (AIWG). To illuminate pathways underlying AIWG, we compared baseline blood gene expression profiles in two cohorts of mice that were either prone (AIWG-P) or resistant (AIWG-R) to weight gain in response to olanzapine treatment for two weeks. We found that transcripts elevated in AIWG-P mice relative to AIWG-R are enriched for high-confidence transcriptional targets of numerous inflammatory and immunomodulatory signaling nodes. Moreover, these nodes are themselves enriched for genes whose disruption in mice is associated with reduced body fat mass and slow postnatal weight gain. In addition, we identified gene expression profiles in common between our mouse AIWG-P gene set and an existing human AIWG-P gene set whose regulation by immunomodulatory transcription factors is highly conserved between species. Finally, we identified striking convergence between mouse AIWG-P transcriptional regulatory networks and those associated with body weight and body mass index in humans. We propose that immunomodulatory transcriptional networks drive AIWG, and that these networks have broader conserved roles in whole body-metabolism.

Flexible thin-film acoustic wave devices with off-axis bending characteristics for multisensing applications.

Flexible surface acoustic wave (SAW) devices have recently attracted tremendous attention for their widespread application in sensing and microfluidics. However, for these applications, SAW devices often need to be bent into off-axis deformations between the acoustic wave propagation direction and bending direction. Currently, there are few studies on this topic, and the bending mechanisms during off-axis bending deformations have remained unexplored for multisensing applications. Herein, we fabricated aluminum nitride (AlN) flexible SAW devices by using high-quality AlN films deposited on flexible glass substrates and systematically investigated their complex deformation behaviors. A theoretical model was first developed using coupling wave equations and the boundary condition method to analyze the characteristics of the device with bending and off-axis deformation under elastic strains. The relationships between the frequency shifts of the SAW device and the bending strain and off-axis angle were obtained, and the results were identical to those from the theoretical calculations. Finally, we performed proof-of-concept demonstrations of its multisensing potential by monitoring human wrist movements at various off-axis angles and detecting UV light intensities on a curved surface, thus paving the way for the application of versatile flexible electronics.

Short-Term Influence of Recent Trial History on Perceptual Choice Changes with Stimulus Strength.

Perceptual decisions, especially for difficult stimuli, can be influenced by choices and outcomes in previous trials. However, it is not well understood how stimulus strength modulates the temporal characteristics as well as the magnitude of trial history influence. We addressed this question using a contrast detection task in freely moving mice. We found that, at lower as compared to higher stimulus contrast, the current choice of the mice was more influenced by choices and outcomes in the past trials and the influence emerged from a longer history. To examine the neural basis of stimulus strength-dependent history influence, we recorded from the secondary motor cortex (M2), a prefrontal region that plays an important role in cue-guided actions and memory-guided behaviors. We found that more M2 neurons conveyed information about choices on the past two trials at lower than at higher contrast. Furthermore, history-trial activity in M2 was important for decoding upcoming choice at low contrast. Thus, trial history influence of perceptual choice is adaptive to the strength of sensory evidence, which may be important for action selection in a dynamic environment.

Altered visual cortical processing in a mouse model of MECP2 duplication syndrome.

As an epigenetic modulator of gene expression, Methyl-CpG binding protein 2 (MeCP2) is essential for normal neurological function. Dysfunction of MeCP2 is associated with a variety of neurological disorders. MECP2 gene duplication in human causes neuropsychiatric symptoms such as mental retardation and autism. MeCP2 overexpression in mice results in neurobehavioural disorders, dendritic abnormalities, and synaptic defects. However, how gain of MeCP2 function influences cortical processing of sensory information remains unclear. In this study, we examined visual processing in a mouse model of MECP2 duplication syndrome (MECP2 Tg1 mouse) at 8 and 14 weeks, which were before and after the onset of behavioural symptoms, respectively. In vivo extracellular recordings from primary visual cortex (V1) showed that neurons in Tg1 mice at both adult ages preferred higher spatial frequencies (SFs) than those in wild-type (WT) littermate controls, and the semi-saturation contrasts of neurons were lower in Tg1 mice at 8 weeks but not at 14 weeks. Behavioural experiments showed that the performance for visual detection at high SFs and low contrasts was higher in MECP2 Tg1 mice. Thus, MeCP2 gain-of-function in mice leads to higher visual acuity and contrast sensitivity, both at the levels of cortical response and behavioural performance.

Automated, highly reproducible, wide-field, light-based cortical mapping method using a commercial stereo microscope and its applications.

We introduce a more flexible optogenetics-based mapping system attached on a stereo microscope, which offers automatic light stimulation to individual regions of interest in the cortex that expresses light-activated channelrhodopsin-2 in vivo. Combining simultaneous recording of electromyography from specific forelimb muscles, we demonstrate that this system offers much better efficiency and precision in mapping distinct domains for controlling limb muscles in the mouse motor cortex. Furthermore, the compact and modular design of the system also yields a simple and flexible implementation to different commercial stereo microscopes, and thus could be widely used among laboratories.