em {beta}4-Nicotinic Receptors Are Critically Involved in Reward-Related Behaviors and Self-Regulation of Nicotine Reinforcement By www.jneurosci.org Published On :: 2020-04-22T09:29:41-07:00 Nicotine addiction, through smoking, is the principal cause of preventable mortality worldwide. Human genome-wide association studies have linked polymorphisms in the CHRNA5-CHRNA3-CHRNB4 gene cluster, coding for the α5, α3, and β4 nicotinic acetylcholine receptor (nAChR) subunits, to nicotine addiction. β4*nAChRs have been implicated in nicotine withdrawal, aversion, and reinforcement. Here we show that β4*nAChRs also are involved in non-nicotine-mediated responses that may predispose to addiction-related behaviors. β4 knock-out (KO) male mice show increased novelty-induced locomotor activity, lower baseline anxiety, and motivational deficits in operant conditioning for palatable food rewards and in reward-based Go/No-go tasks. To further explore reward deficits we used intracranial self-administration (ICSA) by directly injecting nicotine into the ventral tegmental area (VTA) in mice. We found that, at low nicotine doses, β4KO self-administer less than wild-type (WT) mice. Conversely, at high nicotine doses, this was reversed and β4KO self-administered more than WT mice, whereas β4-overexpressing mice avoided nicotine injections. Viral expression of β4 subunits in medial habenula (MHb), interpeduncular nucleus (IPN), and VTA of β4KO mice revealed dose- and region-dependent differences: β4*nAChRs in the VTA potentiated nicotine-mediated rewarding effects at all doses, whereas β4*nAChRs in the MHb-IPN pathway, limited VTA-ICSA at high nicotine doses. Together, our findings indicate that the lack of functional β4*nAChRs result in deficits in reward sensitivity including increased ICSA at high doses of nicotine that is restored by re-expression of β4*nAChRs in the MHb-IPN. These data indicate that β4 is a critical modulator of reward-related behaviors. SIGNIFICANCE STATEMENT Human genetic studies have provided strong evidence for a relationship between variants in the CHRNA5-CHRNA3-CHRNB4 gene cluster and nicotine addiction. Yet, little is known about the role of β4 nicotinic acetylcholine receptor (nAChR) subunit encoded by this cluster. We investigated the implication of β4*nAChRs in anxiety-, food reward- and nicotine reward-related behaviors. Deletion of the β4 subunit gene resulted in an addiction-related phenotype characterized by low anxiety, high novelty-induced response, lack of sensitivity to palatable food rewards and increased intracranial nicotine self-administration at high doses. Lentiviral vector-induced re-expression of the β4 subunit into either the MHb or IPN restored a "stop" signal on nicotine self-administration. These results suggest that β4*nAChRs provide a promising novel drug target for smoking cessation. Full Article
em Pattern Separation Underpins Expectation-Modulated Memory By www.jneurosci.org Published On :: 2020-04-22T09:29:41-07:00 Pattern separation and completion are fundamental hippocampal computations supporting memory encoding and retrieval. However, despite extensive exploration of these processes, it remains unclear whether and how top-down processes adaptively modulate the dynamics between these computations. Here we examine the role of expectation in shifting the hippocampus to perform pattern separation. In a behavioral task, 29 participants (7 males) learned a cue-object category contingency. Then, at encoding, one-third of the cues preceding the to-be-memorized objects, violated the studied rule. At test, participants performed a recognition task with old objects (targets) and a set of parametrically manipulated (very similar to dissimilar) foils for each object. Accuracy was found to be better for foils of high similarity to targets that were contextually unexpected at encoding compared with expected ones. Critically, there were no expectation-driven differences for targets and low similarity foils. To further explore these effects, we implemented a computational model of the hippocampus, performing the same task as the human participants. We used representational similarity analysis to examine how top-down expectation interacts with bottom-up perceptual input, in each layer. All subfields showed more dissimilar representations for unexpected items, with dentate gyrus (DG) and CA3 being more sensitive to expectation violation than CA1. Again, representational differences between expected and unexpected inputs were prominent for moderate to high levels of input similarity. This effect diminished when inputs from DG and CA3 into CA1 were lesioned. Overall, these novel findings strongly suggest that pattern separation in DG/CA3 underlies the effect that violation of expectation exerts on memory. SIGNIFICANCE STATEMENT What makes some events more memorable than others is a key question in cognitive neuroscience. Violation of expectation often leads to better memory performance, but the neural mechanism underlying this benefit remains elusive. In a behavioral study, we found that memory accuracy is enhanced selectively for unexpected highly similar foils, suggesting expectation violation does not enhance memory indiscriminately, but specifically aids the disambiguation of overlapping inputs. This is further supported by our subsequent investigation using a hippocampal computational model, revealing increased representational dissimilarity for unexpected highly similar foils in DG and CA3. These convergent results provide the first evidence that pattern separation plays an explicit role in supporting memory for unexpected information. Full Article
em Treatment with Mesenchymal-Derived Extracellular Vesicles Reduces Injury-Related Pathology in Pyramidal Neurons of Monkey Perilesional Ventral Premotor Cortex By www.jneurosci.org Published On :: 2020-04-22T09:29:41-07:00 Functional recovery after cortical injury, such as stroke, is associated with neural circuit reorganization, but the underlying mechanisms and efficacy of therapeutic interventions promoting neural plasticity in primates are not well understood. Bone marrow mesenchymal stem cell-derived extracellular vesicles (MSC-EVs), which mediate cell-to-cell inflammatory and trophic signaling, are thought be viable therapeutic targets. We recently showed, in aged female rhesus monkeys, that systemic administration of MSC-EVs enhances recovery of function after injury of the primary motor cortex, likely through enhancing plasticity in perilesional motor and premotor cortices. Here, using in vitro whole-cell patch-clamp recording and intracellular filling in acute slices of ventral premotor cortex (vPMC) from rhesus monkeys (Macaca mulatta) of either sex, we demonstrate that MSC-EVs reduce injury-related physiological and morphologic changes in perilesional layer 3 pyramidal neurons. At 14-16 weeks after injury, vPMC neurons from both vehicle- and EV-treated lesioned monkeys exhibited significant hyperexcitability and predominance of inhibitory synaptic currents, compared with neurons from nonlesioned control brains. However, compared with vehicle-treated monkeys, neurons from EV-treated monkeys showed lower firing rates, greater spike frequency adaptation, and excitatory:inhibitory ratio. Further, EV treatment was associated with greater apical dendritic branching complexity, spine density, and inhibition, indicative of enhanced dendritic plasticity and filtering of signals integrated at the soma. Importantly, the degree of EV-mediated reduction of injury-related pathology in vPMC was significantly correlated with measures of behavioral recovery. These data show that EV treatment dampens injury-related hyperexcitability and restores excitatory:inhibitory balance in vPMC, thereby normalizing activity within cortical networks for motor function. SIGNIFICANCE STATEMENT Neuronal plasticity can facilitate recovery of function after cortical injury, but the underlying mechanisms and efficacy of therapeutic interventions promoting this plasticity in primates are not well understood. Our recent work has shown that intravenous infusions of mesenchymal-derived extracellular vesicles (EVs) that are involved in cell-to-cell inflammatory and trophic signaling can enhance recovery of motor function after injury in monkey primary motor cortex. This study shows that this EV-mediated enhancement of recovery is associated with amelioration of injury-related hyperexcitability and restoration of excitatory-inhibitory balance in perilesional ventral premotor cortex. These findings demonstrate the efficacy of mesenchymal EVs as a therapeutic to reduce injury-related pathologic changes in the physiology and structure of premotor pyramidal neurons and support recovery of function. Full Article
em Emotional Stress Induces Structural Plasticity in Bergmann Glial Cells via an AC5-CPEB3-GluA1 Pathway By www.jneurosci.org Published On :: 2020-04-22T09:29:41-07:00 Stress alters brain function by modifying the structure and function of neurons and astrocytes. The fine processes of astrocytes are critical for the clearance of neurotransmitters during synaptic transmission. Thus, experience-dependent remodeling of glial processes is anticipated to alter the output of neural circuits. However, the molecular mechanisms that underlie glial structural plasticity are not known. Here we show that a single exposure of male and female mice to an acute stress produced a long-lasting retraction of the lateral processes of cerebellar Bergmann glial cells. These cells express the GluA1 subunit of AMPA-type glutamate receptors, and GluA1 knockdown is known to shorten the length of glial processes. We found that stress reduced the level of GluA1 protein and AMPA receptor-mediated currents in Bergmann glial cells, and these effects were absent in mice devoid of CPEB3, a protein that binds to GluA1 mRNA and regulates GluA1 protein synthesis. Administration of a β-adrenergic receptor blocker attenuated the reduction in GluA1, and deletion of adenylate cyclase 5 prevented GluA1 suppression. Therefore, stress suppresses GluA1 protein synthesis via an adrenergic/adenylyl cyclase/CPEB3 pathway, and reduces the length of astrocyte lateral processes. Our results identify a novel mechanism for GluA1 subunit plasticity in non-neuronal cells and suggest a previously unappreciated role for AMPA receptors in stress-induced astrocytic remodeling. SIGNIFICANCE STATEMENT Astrocytes play important roles in synaptic transmission by extending fine processes around synapses. In this study, we showed that a single exposure to an acute stress triggered a retraction of lateral/fine processes in mouse cerebellar astrocytes. These astrocytes express GluA1, a glutamate receptor subunit known to lengthen astrocyte processes. We showed that astrocytic structural changes are associated with a reduction of GluA1 protein levels. This requires activation of β-adrenergic receptors and is triggered by noradrenaline released during stress. We identified adenylyl cyclase 5, an enzyme that elevates cAMP levels, as a downstream effector and found that lowering GluA1 levels depends on CPEB3 proteins that bind to GluA1 mRNA. Therefore, stress regulates GluA1 protein synthesis via an adrenergic/adenylyl cyclase/CPEB3 pathway in astrocytes and remodels their fine processes. Full Article
em Basigin Associates with Integrin in Order to Regulate Perineurial Glia and Drosophila Nervous System Morphology By www.jneurosci.org Published On :: 2020-04-22T09:29:41-07:00 The Drosophila nervous system is ensheathed by a layer of outer glial cells, the perineurial glia, and a specialized extracellular matrix, the neural lamella. The function of perineurial glial cells and how they interact with the extracellular matrix are just beginning to be elucidated. Integrin-based focal adhesion complexes link the glial membrane to the extracellular matrix, but little is known about integrin's regulators in the glia. The transmembrane Ig domain protein Basigin/CD147/EMMPRIN is highly expressed in the perineurial glia surrounding the Drosophila larval nervous system. Here we show that Basigin associates with integrin at the focal adhesions to uphold the structure of the glia-extracellular matrix sheath. Knockdown of Basigin in perineurial glia using RNAi results in significant shortening of the ventral nerve cord, compression of the glia and extracellular matrix in the peripheral nerves, and reduction in larval locomotion. We determined that Basigin is expressed in close proximity to integrin at the glial membrane, and that expression of the extracellular integrin-binding domain of Basigin is sufficient to rescue peripheral glial compression. We also found that a reduction in expression of integrin at the membrane rescues the ventral nerve cord shortening, peripheral glial compression, and locomotor phenotypes, and that reduction in the integrin-binding protein Talin can partially rescue glial compression. These results identify Basigin as a potential negative regulator of integrin in the glia, supporting proper glial and extracellular matrix ensheathment of the nervous system. SIGNIFICANCE STATEMENT The glial cells and extracellular matrix play important roles in supporting and protecting the nervous system, but the interactions between these components have not been well characterized. Our study identified expression of a conserved Ig superfamily protein, Basigin, at the glial membrane of Drosophila where it associates with the integrin-based focal adhesion complexes to ensure proper ensheathment of the CNS and PNS. Loss of Basigin in the glia results in an overall compression of the nervous system due to integrin dysregulation, which causes locomotor defects in the animals. This underlies the importance of glia-matrix communication for structural and functional support of the nervous system. Full Article
em Deletion of Voltage-Gated Calcium Channels in Astrocytes during Demyelination Reduces Brain Inflammation and Promotes Myelin Regeneration in Mice By www.jneurosci.org Published On :: 2020-04-22T09:29:41-07:00 To determine whether Cav1.2 voltage-gated Ca2+ channels contribute to astrocyte activation, we generated an inducible conditional knock-out mouse in which the Cav1.2 α subunit was deleted in GFAP-positive astrocytes. This astrocytic Cav1.2 knock-out mouse was tested in the cuprizone model of myelin injury and repair which causes astrocyte and microglia activation in the absence of a lymphocytic response. Deletion of Cav1.2 channels in GFAP-positive astrocytes during cuprizone-induced demyelination leads to a significant reduction in the degree of astrocyte and microglia activation and proliferation in mice of either sex. Concomitantly, the production of proinflammatory factors such as TNFα, IL1β and TGFβ1 was significantly decreased in the corpus callosum and cortex of Cav1.2 knock-out mice through demyelination. Furthermore, this mild inflammatory environment promotes oligodendrocyte progenitor cells maturation and myelin regeneration across the remyelination phase of the cuprizone model. Similar results were found in animals treated with nimodipine, a Cav1.2 Ca2+ channel inhibitor with high affinity to the CNS. Mice of either sex injected with nimodipine during the demyelination stage of the cuprizone treatment displayed a reduced number of reactive astrocytes and showed a faster and more efficient brain remyelination. Together, these results indicate that Cav1.2 Ca2+ channels play a crucial role in the induction and proliferation of reactive astrocytes during demyelination; and that attenuation of astrocytic voltage-gated Ca2+ influx may be an effective therapy to reduce brain inflammation and promote myelin recovery in demyelinating diseases. SIGNIFICANCE STATEMENT Reducing voltage-gated Ca2+ influx in astrocytes during brain demyelination significantly attenuates brain inflammation and astrocyte reactivity. Furthermore, these changes promote myelin restoration and oligodendrocyte maturation throughout remyelination. Full Article
em The VGF-derived Peptide TLQP21 Impairs Purinergic Control of Chemotaxis and Phagocytosis in Mouse Microglia By www.jneurosci.org Published On :: 2020-04-22T09:29:41-07:00 Microglial cells are considered as sensors of brain pathology by detecting any sign of brain lesions, infections, or dysfunction and can influence the onset and progression of neurological diseases. They are capable of sensing their neuronal environment via many different signaling molecules, such as neurotransmitters, neurohormones and neuropeptides. The neuropeptide VGF has been associated with many metabolic and neurological disorders. TLQP21 is a VGF-derived peptide and has been shown to signal via C3aR1 and C1qBP receptors. The effect of TLQP21 on microglial functions in health or disease is not known. Studying microglial cells in acute brain slices, we found that TLQP21 impaired metabotropic purinergic signaling. Specifically, it attenuated the ATP-induced activation of a K+ conductance, the UDP-stimulated phagocytic activity, and the ATP-dependent laser lesion-induced process outgrowth. These impairments were reversed by blocking C1qBP, but not C3aR1 receptors. While microglia in brain slices from male mice lack C3aR1 receptors, both receptors are expressed in primary cultured microglia. In addition to the negative impact on purinergic signaling, we found stimulating effects of TLQP21 in cultured microglia, which were mediated by C3aR1 receptors: it directly evoked membrane currents, stimulated basal phagocytic activity, evoked intracellular Ca2+ transient elevations, and served as a chemotactic signal. We conclude that TLQP21 has differential effects on microglia depending on C3aR1 activation or C1qBP-dependent attenuation of purinergic signaling. Thus, TLQP21 can modulate the functional phenotype of microglia, which may have an impact on their function in health and disease. SIGNIFICANCE STATEMENT The neuropeptide VGF and its peptides have been associated with many metabolic and neurological disorders. TLQP21 is a VGF-derived peptide that activates C1qBP receptors, which are expressed by microglia. We show here, for the first time, that TLQP21 impairs P2Y-mediated purinergic signaling and related functions. These include modulation of phagocytic activity and responses to injury. As purinergic signaling is central for microglial actions in the brain, this TLQP21-mediated mechanism might regulate microglial activity in health and disease. We furthermore show that, in addition to C1qBP, functional C3aR1 responses contribute to TLQP21 action on microglia. However, C3aR1 responses were only present in primary cultures but not in situ, suggesting that the expression of these receptors might vary between different microglial activation states. Full Article
em Sustained Visual Priming Effects Can Emerge from Attentional Oscillation and Temporal Expectation By www.jneurosci.org Published On :: 2020-04-29T09:30:19-07:00 Priming refers to the influence that a previously encountered object exerts on future responses to similar objects. For many years, visual priming has been known as a facilitation and sometimes an inhibition effect that lasts for an extended period of time. It contrasts with the recent finding of an oscillated priming effect where facilitation and inhibition alternate over time periodically. Here we developed a computational model of visual priming that combines rhythmic sampling of the environment (attentional oscillation) with active preparation for future events (temporal expectation). Counterintuitively, it shows that both the sustained and oscillated priming effects can emerge from an interaction between attentional oscillation and temporal expectation. The interaction also leads to novel predictions, such as the change of visual priming effects with temporal expectation and attentional oscillation. Reanalysis of two published datasets and the results of two new experiments of visual priming tasks with male and female human participants provide support for the model's relevance to human behavior. More generally, our model offers a new perspective that may unify the increasing findings of behavioral and neural oscillations with the classic findings in visual perception and attention. SIGNIFICANCE STATEMENT There is increasing behavioral and neural evidence that visual attention is a periodic process that sequentially samples different alternatives in the theta frequency range. It contrasts with the classic findings of sustained facilitatory or inhibitory attention effects. How can an oscillatory perceptual process give rise to sustained attention effects? Here we make this connection by proposing a computational model for a "fruit fly" visual priming task and showing both the sustained and oscillated priming effects can have the same origin: an interaction between rhythmic sampling of the environment and active preparation for future events. One unique contribution of our model is to predict how temporal contexts affects priming. It also opens up the possibility of reinterpreting other attention-related classic phenomena. Full Article
em A Model to Study NMDA Receptors in Early Nervous System Development By www.jneurosci.org Published On :: 2020-04-29T09:30:19-07:00 N-methyl-D-aspartate receptors (NMDARs) are glutamate-gated ion channels that play critical roles in neuronal development and nervous system function. Here, we developed a model to study NMDARs in early development in zebrafish, by generating CRISPR-mediated lesions in the NMDAR genes, grin1a and grin1b, which encode the obligatory GluN1 subunits. While receptors containing grin1a or grin1b show high Ca2+ permeability, like their mammalian counterpart, grin1a is expressed earlier and more broadly in development than grin1b. Both grin1a–/– and grin1b–/– zebrafish are viable. Unlike in rodents, where the grin1 knockout is embryonic lethal, grin1 double-mutant fish (grin1a–/–; grin1b–/–), which lack all NMDAR-mediated synaptic transmission, survive until ~10 d dpf (days post fertilization), providing a unique opportunity to explore NMDAR function during development and in generating behaviors. Many behavioral defects in the grin1 double-mutant larvae, including abnormal evoked responses to light and acoustic stimuli, prey-capture deficits, and a failure to habituate to acoustic stimuli, are replicated by short-term treatment with the NMDAR antagonist MK-801, suggesting that they arise from acute effects of compromised NMDAR-mediated transmission. Other defects, however, such as periods of hyperactivity and alterations in place preference, are not phenocopied by MK-801, suggesting a developmental origin. Together, we have developed a unique model to study NMDARs in the developing vertebrate nervous system. SIGNIFICANCE STATEMENT Rapid communication between cells in the nervous system depends on ion channels that are directly activated by chemical neurotransmitters. One such ligand-gated ion channel, the NMDAR, impacts nearly all forms of nervous system function. It has been challenging, however, to study the prolonged absence of NMDARs in vertebrates, and hence their role in nervous system development, due to experimental limitations. Here, we demonstrate that zebrafish lacking all NMDAR transmission are viable through early development and are capable of a wide range of stereotypic behaviors. As such, this zebrafish model provides a unique opportunity to study the role of NMDAR in the development of the early vertebrate nervous system. Full Article
em Reward-Based Improvements in Motor Control Are Driven by Multiple Error-Reducing Mechanisms By www.jneurosci.org Published On :: 2020-04-29T09:30:19-07:00 Reward has a remarkable ability to invigorate motor behavior, enabling individuals to select and execute actions with greater precision and speed. However, if reward is to be exploited in applied settings, such as rehabilitation, a thorough understanding of its underlying mechanisms is required. In a series of experiments, we first demonstrate that reward simultaneously improves the selection and execution components of a reaching movement. Specifically, reward promoted the selection of the correct action in the presence of distractors, while also improving execution through increased speed and maintenance of accuracy. These results led to a shift in the speed-accuracy functions for both selection and execution. In addition, punishment had a similar impact on action selection and execution, although it enhanced execution performance across all trials within a block, that is, its impact was noncontingent to trial value. Although the reward-driven enhancement of movement execution has been proposed to occur through enhanced feedback control, an untested possibility is that it is also driven by increased arm stiffness, an energy-consuming process that enhances limb stability. Computational analysis revealed that reward led to both an increase in feedback correction in the middle of the movement and a reduction in motor noise near the target. In line with our hypothesis, we provide novel evidence that this noise reduction is driven by a reward-dependent increase in arm stiffness. Therefore, reward drives multiple error-reduction mechanisms which enable individuals to invigorate motor performance without compromising accuracy. SIGNIFICANCE STATEMENT While reward is well-known for enhancing motor performance, how the nervous system generates these improvements is unclear. Despite recent work indicating that reward leads to enhanced feedback control, an untested possibility is that it also increases arm stiffness. We demonstrate that reward simultaneously improves the selection and execution components of a reaching movement. Furthermore, we show that punishment has a similar positive impact on performance. Importantly, by combining computational and biomechanical approaches, we show that reward leads to both improved feedback correction and an increase in stiffness. Therefore, reward drives multiple error-reduction mechanisms which enable individuals to invigorate performance without compromising accuracy. This work suggests that stiffness control plays a vital, and underappreciated, role in the reward-based imporvemenets in motor control. Full Article
em Nestin Selectively Facilitates the Phosphorylation of the Lissencephaly-Linked Protein Doublecortin (DCX) by cdk5/p35 to Regulate Growth Cone Morphology and Sema3a Sensitivity in Developing Neurons By www.jneurosci.org Published On :: 2020-05-06T09:30:22-07:00 Nestin, an intermediate filament protein widely used as a marker of neural progenitors, was recently found to be expressed transiently in developing cortical neurons in culture and in developing mouse cortex. In young cortical cultures, nestin regulates axonal growth cone morphology. In addition, nestin, which is known to bind the neuronal cdk5/p35 kinase, affects responses to axon guidance cues upstream of cdk5, specifically, to Sema3a. Changes in growth cone morphology require rearrangements of cytoskeletal networks, and changes in microtubules and actin filaments are well studied. In contrast, the roles of intermediate filament proteins in this process are poorly understood, even in cultured neurons. Here, we investigate the molecular mechanism by which nestin affects growth cone morphology and Sema3a sensitivity. We find that nestin selectively facilitates the phosphorylation of the lissencephaly-linked protein doublecortin (DCX) by cdk5/p35, but the phosphorylation of other cdk5 substrates is not affected by nestin. We uncover that this substrate selectivity is based on the ability of nestin to interact with DCX, but not with other cdk5 substrates. Nestin thus creates a selective scaffold for DCX with activated cdk5/p35. Last, we use cortical cultures derived from Dcx KO mice to show that the effects of nestin on growth cone morphology and on Sema3a sensitivity are DCX-dependent, thus suggesting a functional role for the DCX-nestin complex in neurons. We propose that nestin changes growth cone behavior by regulating the intracellular kinase signaling environment in developing neurons. The sex of animal subjects is unknown. SIGNIFICANCE STATEMENT Nestin, an intermediate filament protein highly expressed in neural progenitors, was recently identified in developing neurons where it regulates growth cone morphology and responsiveness to the guidance cue Sema3a. Changes in growth cone morphology require rearrangements of cytoskeletal networks, but the roles of intermediate filaments in this process are poorly understood. We now report that nestin selectively facilitates phosphorylation of the lissencephaly-linked doublecortin (DCX) by cdk5/p35, but the phosphorylation of other cdk5 substrates is not affected. This substrate selectivity is based on preferential scaffolding of DCX, cdk5, and p35 by nestin. Additionally, we demonstrate a functional role for the DCX-nestin complex in neurons. We propose that nestin changes growth cone behavior by regulating intracellular kinase signaling in developing neurons. Full Article
em M-Current Inhibition in Hippocampal Excitatory Neurons Triggers Intrinsic and Synaptic Homeostatic Responses at Different Temporal Scales By www.jneurosci.org Published On :: 2020-05-06T09:30:22-07:00 Persistent alterations in neuronal activity elicit homeostatic plastic changes in synaptic transmission and/or intrinsic excitability. However, it is unknown whether these homeostatic processes operate in concert or at different temporal scales to maintain network activity around a set-point value. Here we show that chronic neuronal hyperactivity, induced by M-channel inhibition, triggered intrinsic and synaptic homeostatic plasticity at different timescales in cultured hippocampal pyramidal neurons from mice of either sex. Homeostatic changes of intrinsic excitability occurred at a fast timescale (1–4 h) and depended on ongoing spiking activity. This fast intrinsic adaptation included plastic changes in the threshold current and a distal relocation of FGF14, a protein physically bridging Nav1.6 and Kv7.2 channels along the axon initial segment. In contrast, synaptic adaptations occurred at a slower timescale (~2 d) and involved decreases in miniature EPSC amplitude. To examine how these temporally distinct homeostatic responses influenced hippocampal network activity, we quantified the rate of spontaneous spiking measured by multielectrode arrays at extended timescales. M-Channel blockade triggered slow homeostatic renormalization of the mean firing rate (MFR), concomitantly accompanied by a slow synaptic adaptation. Thus, the fast intrinsic adaptation of excitatory neurons is not sufficient to account for the homeostatic normalization of the MFR. In striking contrast, homeostatic adaptations of intrinsic excitability and spontaneous MFR failed in hippocampal GABAergic inhibitory neurons, which remained hyperexcitable following chronic M-channel blockage. Our results indicate that a single perturbation such as M-channel inhibition triggers multiple homeostatic mechanisms that operate at different timescales to maintain network mean firing rate. SIGNIFICANCE STATEMENT Persistent alterations in synaptic input elicit homeostatic plastic changes in neuronal activity. Here we show that chronic neuronal hyperexcitability, induced by M-type potassium channel inhibition, triggered intrinsic and synaptic homeostatic plasticity at different timescales in hippocampal excitatory neurons. The data indicate that the fast adaptation of intrinsic excitability depends on ongoing spiking activity but is not sufficient to provide homeostasis of the mean firing rate. Our results show that a single perturbation such as M-channel inhibition can trigger multiple homeostatic processes that operate at different timescales to maintain network mean firing rate. Full Article
em World Food Day 2013 to promote healthy food systems By www.fao.org Published On :: Fri, 27 Sep 2013 00:00:00 GMT FAO will use World Food Day this year to promote one of the five pillars of Zero Hunger Challenge. The theme of the campaign will be “Sustainable Food Systems for Food Security and Nutrition.” Events in more than 120 countries – supported by videos, an issues paper, posters, media interviews and more – will communicate the message that our food systems [...] Full Article
em Empowerment is key to eradicating hunger By www.fao.org Published On :: Wed, 05 Mar 2014 00:00:00 GMT Global food security largely depends on smallholder family farms where in many regions of the world women play a crucial role as both producers and providers of food. Studies show that when women and other rural poor have better access to resources, the benefits are far-reaching. Families are healthier, more children attend school, agricultural productivity improves, incomes increase, and rural communities [...] Full Article
em Jackie Chan set to defeat the world's worst enemy - Hunger By www.fao.org Published On :: Tue, 25 Mar 2014 00:00:00 GMT International Kungfu superstar and renowned Hollywood film actor Jackie Chan has joined FAO in the fight against hunger. In a recent visit to Ethiopia, Chan met with beneficiaries of the ‘Purchase from Africans for Africa’ (PAA) project as well as a South-South Cooperation Programme where he discussed with Chinese experts how they exchange technical knowledge with Ethiopian farmers to help them [...] Full Article
em Forests and trees – a source of shelter, food, energy and employment for millions By www.fao.org Published On :: Wed, 25 Jun 2014 00:00:00 GMT The challenge is to maintain and develop the socioeconomic benefits from forests while safeguarding the resource. FAO’s State of the World’s Forests (SOFO) 2014 argues that if the focus of data collection and policy is shifted from trees to people, forests can be sustainably managed to meet society’s growing demands. Read the most important findings: The formal forestry sector employs some 13.2 [...] Full Article
em Family farming is part of the solution to the hunger problem By www.fao.org Published On :: Wed, 24 Dec 2014 00:00:00 GMT The United Nations launched the 2014 International Year of Family Farming to stress the vast potential family farmers have to eradicate hunger and preserve natural resources. In both developed and developing countries, more than 500 million, or nine out of ten, farms are managed by families, making family farms the predominant form of agriculture. They not only produce about 80% [...] Full Article
em Farming systems that ‘Save and Grow' – in pictures By www.fao.org Published On :: Wed, 20 Jan 2016 00:00:00 GMT Maize, rice and wheat are fundamental to world food security. We must safeguard production in the world’s grain belts and rice bowls, and increase yields in countries where production has to substantially improve as populations grow. Climate change adds new pressures on cereals, including rising temperatures and a higher incidence of pests, diseases, droughts and floods. FAO’s model of ecosystem-based agriculture, [...] Full Article
em On ecosystems and the services they provide – Let's talk facts By www.fao.org Published On :: Wed, 03 Feb 2016 00:00:00 GMT Ecosystem services make human life possible by, for example, providing nutritious food and clean water, regulating disease and climate, supporting the pollination of crops and soil formation, and providing recreational, cultural and spiritual benefits. In 2014, the value of ecosystem services was estimated at a staggering US$ 125 trillion. Ecosystem services, provided by biodiversity, are fundamental to food production and [...] Full Article
em This is a test do not deleteme By www.fao.org Published On :: Mon, 15 Feb 2016 00:00:00 GMT This is a test do not deleteme Full Article
em Empowering women to end hunger and poverty By www.fao.org Published On :: Wed, 01 Mar 2017 00:00:00 GMT In the varied and vital roles they play – as farmers, farm workers, entrepreneurs, caregivers and community leaders – rural women form the backbone of rural societies. Almost everywhere, they make crucial contributions to food production, food processing and marketing. Indeed, because women produce, process and prepare much of the food available, they are critical to the food security of [...] Full Article
em 5 remarkable landscapes and lifestyles that you didn't know existed By www.fao.org Published On :: Fri, 15 Dec 2017 00:00:00 GMT The terraced hills of the Andes, the rice paddies of southern China, the oasis systems of the Maghreb: agriculture molds landscapes and places. Agriculture also shapes livelihoods, lifestyles, food traditions and cultures. What kind of plants grow or can’t grow, how they are harvested and what people eat define people’s lives. Because our natural resources are under great strain, we need [...] Full Article
em Empowering rural women is key to ensuring food security By www.fao.org Published On :: Mon, 05 Mar 2018 00:00:00 GMT When approaching the small house, Hanen can be seen laughing with her family in the yard. Hanen is a 25-year-old biologist living in Ouled Taleb, Siliana, one of several areas in North West Tunisia that are particularly hard-hit by unemployment, low income and high rates of migration. Hanen comes from a poor rural family, who invested in their children’s education [...] Full Article
em 7 success factors to empowering rural women through ICTs By www.fao.org Published On :: Thu, 08 Mar 2018 00:00:00 GMT The digital revolution has changed the way we work, access information and connect with each other. It offers opportunities to those who can use the new technologies, but also presents new challenges for those who are left behind. Often referred to collectively as Information and Communications Technologies or ICTs, these technologies are any method of electronically sharing or storing data: telephones, [...] Full Article
em Transforming food systems By www.fao.org Published On :: Fri, 22 Jun 2018 00:00:00 GMT We can’t really talk about the planet’s most pressing environmental problems without talking about food systems. And by food systems, we also mean the agriculture that it takes to support them: farming, fisheries, forestry and the value chains that provide food and fiber for our daily lives. Full Article
em No boats needed for a Guatemalan fishing community By www.fao.org Published On :: Fri, 03 Aug 2018 00:00:00 GMT Imagine living in one of the driest areas on the planet. What little rain there is falls over the space of a few months, yielding around 700 mm in total each year. A population of 1.2 million has to survive on 65 percent less water than the rest of their compatriots, on a traditional staple diet of corn and beans. [...] Full Article
em 5 ways FAO helps people in emergencies By www.fao.org Published On :: Fri, 17 Aug 2018 00:00:00 GMT Disasters, like an earthquake or a violent coup d’état, can strike suddenly, or like droughts and floods, develop slowly. Emergencies are devastating for people everywhere, but for those whose livelihoods or food needs depend entirely on agriculture and natural resources, these disasters can often be overwhelming. FAO addresses emergencies in a variety of ways from early warning and preparedness to [...] Full Article
em Rising popularity of email newsletters across the Organization By www.fao.org Published On :: Mon, 09 Mar 2020 00:00:00 GMT FAO email newsletters have sparked great interest across the Organization in the last few years, with over 2 million emails sent out in 2018 and over 3 million last year. Corporate newsletters cover approximately 100 [...] Full Article
em Americans Think National Parks Are Worth Way More Than We Spend On Them By www.smithsonianmag.com Published On :: Fri, 15 Jul 2016 13:00:00 +0000 An independent survey finds that although NPS's annual budget is around $3 billion, Americans are willing to pay much more Full Article
em You Can Thank Scientists for the National Park System By www.smithsonianmag.com Published On :: Thu, 01 Sep 2016 12:44:35 +0000 Early conservation research and scientific expeditions laid the groundwork and helped to convince the public national parks were a good idea Full Article
em Assembly to finalize list for Washington, D.C. trip By www.ketchikandailynews.com Published On :: Full Article
em Assembly OKs ‘salmon cans’: Set of policy issue statements that Boro representative will take to D.C. approved By www.ketchikandailynews.com Published On :: Full Article
em Council opposes elimination of Ocean Rangers: City sets meeting with linemen, union rep By www.ketchikandailynews.com Published On :: Full Article
em AMHS work group: Members will provide Dunleavy direction on AMHS By www.ketchikandailynews.com Published On :: Full Article
em Ten Myths About the 1918 Flu Pandemic By www.smithsonianmag.com Published On :: Fri, 12 Jan 2018 14:00:00 +0000 The ‘greatest pandemic in history’ was 100 years ago – but many of us still get the basic facts wrong Full Article
em Pinkman Selling Meth to Creed on the Emmys [35s] By www.youtube.com Published On :: Jesse Pinkman (Aaron Paul) from 'Breaking Bad' selling crystal meth to Creed Bratton from 'The Office' in a skit from the 63rd Emmy Awards (2011). [...] Full Article
em Art Is Dead The Dowser Married the Alchemist - Install Shots By www.artisdead.net Published On :: Full Article
em U.K. Storms Unearth Bones From Historic Scottish Cemetery—and Archaeologists Are Worried By www.smithsonianmag.com Published On :: Thu, 12 Mar 2020 17:40:03 +0000 The burial site, which contains remains from both the Picts and the Norse, is at risk of disappearing due to coastal erosion Full Article
em Remnants of 13th-Century Town Walls Unearthed in Wales By www.smithsonianmag.com Published On :: Fri, 20 Mar 2020 14:03:29 +0000 Caernarfon, where the discovery was made, was key to Edward I's conquest of the Welsh Full Article
em Amid a Pandemic, Olympic Committee Postpones Summer Games Until 2021 By www.smithsonianmag.com Published On :: Tue, 24 Mar 2020 14:55:31 +0000 Delaying the Games for a year is considered by many to be the best course of action for public health Full Article
em Females Live Longer Than Males—Among Humans and Other Mammals, Too By www.smithsonianmag.com Published On :: Wed, 25 Mar 2020 12:30:00 +0000 A sweeping new study of 101 mammal species found that females live, on average, 18.6 percent longer than their male counterparts Full Article
em Archaeologists Unearth Remnants of Kitchen Behind Oldest House Still Standing in Maui By www.smithsonianmag.com Published On :: Wed, 25 Mar 2020 18:00:02 +0000 The missionary who lived in the house during the mid-1800s delivered vaccinations to locals during a smallpox epidemic Full Article
em Amid Pandemic, Artists Invoke Japanese Spirit Said to Protect Against Disease By www.smithsonianmag.com Published On :: Fri, 27 Mar 2020 15:44:38 +0000 Illustrators are sharing artwork of Amabie, a spirit first popularized during the Edo period, on social media Full Article
em How—and When—Will the COVID-19 Pandemic End? By www.smithsonianmag.com Published On :: Fri, 27 Mar 2020 21:01:30 +0000 Americans have some time before social distancing measures can let up—and every day counts Full Article
em This Museum Is Asking People to Remake Famous Artworks With Household Items By www.smithsonianmag.com Published On :: Tue, 31 Mar 2020 14:28:28 +0000 The Getty Museum hopes its social media challenge will spark inspiration amid the COVID-19 pandemic Full Article
em Why the National Emergency Library Is So Controversial By www.smithsonianmag.com Published On :: Wed, 01 Apr 2020 15:46:10 +0000 The Internet Archive describes the downloadable collection of more than one million books as a library, but critics call it piracy Full Article
em In Ancient Florida, the Calusa Built an Empire Out of Shells and Fish By www.smithsonianmag.com Published On :: Thu, 02 Apr 2020 15:30:30 +0000 New research suggests the civilization used huge enclosures to trap and stockpile live fish to support its complex society Full Article
em Hollywood's 'Golden Age' Saw Massive Dip in Female Film Representation By www.smithsonianmag.com Published On :: Fri, 03 Apr 2020 11:30:00 +0000 A new study ties the ousting of women directors, actors, producers and screenwriters to the rise of entertainment studios Full Article
em 196-Foot Section of the Berlin Wall Demolished to Make Way for Condos By www.smithsonianmag.com Published On :: Fri, 03 Apr 2020 18:21:03 +0000 Angry historians say the stretch of concrete was one of the largest remaining sections of the inner wall Full Article