si Striatal Nurr1 Facilitates the Dyskinetic State and Exacerbates Levodopa-Induced Dyskinesia in a Rat Model of Parkinson's Disease By www.jneurosci.org Published On :: 2020-04-29T09:30:19-07:00 The transcription factor Nurr1 has been identified to be ectopically induced in the striatum of rodents expressing l-DOPA-induced dyskinesia (LID). In the present study, we sought to characterize Nurr1 as a causative factor in LID expression. We used rAAV2/5 to overexpress Nurr1 or GFP in the parkinsonian striatum of LID-resistant Lewis or LID-prone Fischer-344 (F344) male rats. In a second cohort, rats received the Nurr1 agonist amodiaquine (AQ) together with l-DOPA or ropinirole. All rats received a chronic DA agonist and were evaluated for LID severity. Finally, we performed single-unit recordings and dendritic spine analyses on striatal medium spiny neurons (MSNs) in drug-naïve rAAV-injected male parkinsonian rats. rAAV-GFP injected LID-resistant hemi-parkinsonian Lewis rats displayed mild LID and no induction of striatal Nurr1 despite receiving a high dose of l-DOPA. However, Lewis rats overexpressing Nurr1 developed severe LID. Nurr1 agonism with AQ exacerbated LID in F344 rats. We additionally determined that in l-DOPA-naïve rats striatal rAAV-Nurr1 overexpression (1) increased cortically-evoked firing in a subpopulation of identified striatonigral MSNs, and (2) altered spine density and thin-spine morphology on striatal MSNs; both phenomena mimicking changes seen in dyskinetic rats. Finally, we provide postmortem evidence of Nurr1 expression in striatal neurons of l-DOPA-treated PD patients. Our data demonstrate that ectopic induction of striatal Nurr1 is capable of inducing LID behavior and associated neuropathology, even in resistant subjects. These data support a direct role of Nurr1 in aberrant neuronal plasticity and LID induction, providing a potential novel target for therapeutic development. SIGNIFICANCE STATEMENT The transcription factor Nurr1 is ectopically induced in striatal neurons of rats exhibiting levodopa-induced dyskinesia [LID; a side-effect to dopamine replacement strategies in Parkinson's disease (PD)]. Here we asked whether Nurr1 is causing LID. Indeed, rAAV-mediated expression of Nurr1 in striatal neurons was sufficient to overcome LID-resistance, and Nurr1 agonism exacerbated LID severity in dyskinetic rats. Moreover, we found that expression of Nurr1 in l-DOPA naïve hemi-parkinsonian rats resulted in the formation of morphologic and electrophysiological signatures of maladaptive neuronal plasticity; a phenomenon associated with LID. Finally, we determined that ectopic Nurr1 expression can be found in the putamen of l-DOPA-treated PD patients. These data suggest that striatal Nurr1 is an important mediator of the formation of LID. Full Article
si Impairment of Pattern Separation of Ambiguous Scenes by Single Units in the CA3 in the Absence of the Dentate Gyrus By www.jneurosci.org Published On :: 2020-04-29T09:30:19-07:00 Theoretical models and experimental evidence have suggested that connections from the dentate gyrus (DG) to CA3 play important roles in representing orthogonal information (i.e., pattern separation) in the hippocampus. However, the effects of eliminating the DG on neural firing patterns in the CA3 have rarely been tested in a goal-directed memory task that requires both the DG and CA3. In this study, selective lesions in the DG were made using colchicine in male Long–Evans rats, and single units from the CA3 were recorded as the rats performed visual scene memory tasks. The original scenes used in training were altered during testing by blurring to varying degrees or by using visual masks, resulting in maximal recruitment of the DG–CA3 circuits. Compared with controls, the performance of rats with DG lesions was particularly impaired when blurred scenes were used in the task. In addition, the firing rate modulation associated with visual scenes in these rats was significantly reduced in the single units recorded from the CA3 when ambiguous scenes were presented, largely because DG-deprived CA3 cells did not show stepwise, categorical rate changes across varying degrees of scene ambiguity compared with controls. These findings suggest that the DG plays key roles not only during the acquisition of scene memories but also during retrieval when modified visual scenes are processed in conjunction with the CA3 by making the CA3 network respond orthogonally to ambiguous scenes. SIGNIFICANCE STATEMENT Despite the behavioral evidence supporting the role of the dentate gyrus in pattern separation in the hippocampus, the underlying neural mechanisms are largely unknown. By recording single units from the CA3 in DG-lesioned rats performing a visual scene memory task, we report that the scene-related modulation of neural firing was significantly reduced in the DG-lesion rats compared with controls, especially when the original scene stimuli were ambiguously altered. Our findings suggest that the dentate gyrus plays an essential role during memory retrieval and performs a critical computation to make categorical rate modulation occur in the CA3 between different scenes, especially when ambiguity is present in the environment. Full Article
si Somatostatin-Expressing Interneurons in the Auditory Cortex Mediate Sustained Suppression by Spectral Surround By www.jneurosci.org Published On :: 2020-04-29T09:30:19-07:00 Sensory systems integrate multiple stimulus features to generate coherent percepts. Spectral surround suppression, the phenomenon by which sound-evoked responses of auditory neurons are suppressed by stimuli outside their receptive field, is an example of this integration taking place in the auditory system. While this form of global integration is commonly observed in auditory cortical neurons, and potentially used by the nervous system to separate signals from noise, the mechanisms that underlie this suppression of activity are not well understood. We evaluated the contributions to spectral surround suppression of the two most common inhibitory cell types in the cortex, parvalbumin-expressing (PV+) and somatostatin-expressing (SOM+) interneurons, in mice of both sexes. We found that inactivating SOM+ cells, but not PV+ cells, significantly reduces sustained spectral surround suppression in excitatory cells, indicating a dominant causal role for SOM+ cells in the integration of information across multiple frequencies. The similarity of these results to those from other sensory cortices provides evidence of common mechanisms across the cerebral cortex for generating global percepts from separate features. SIGNIFICANCE STATEMENT To generate coherent percepts, sensory systems integrate simultaneously occurring features of a stimulus, yet the mechanisms by which this integration occurs are not fully understood. Our results show that neurochemically distinct neuronal subtypes in the primary auditory cortex have different contributions to the integration of different frequency components of an acoustic stimulus. Together with findings from other sensory cortices, our results provide evidence of a common mechanism for cortical computations used for global integration of stimulus features. Full Article
si Neurog2 Acts as a Classical Proneural Gene in the Ventromedial Hypothalamus and Is Required for the Early Phase of Neurogenesis By www.jneurosci.org Published On :: 2020-04-29T09:30:19-07:00 The tuberal hypothalamus is comprised of the dorsomedial, ventromedial, and arcuate nuclei, as well as parts of the lateral hypothalamic area, and it governs a wide range of physiologies. During neurogenesis, tuberal hypothalamic neurons are thought to be born in a dorsal-to-ventral and outside-in pattern, although the accuracy of this description has been questioned over the years. Moreover, the intrinsic factors that control the timing of neurogenesis in this region are poorly characterized. Proneural genes, including Achate-scute-like 1 (Ascl1) and Neurogenin 3 (Neurog3) are widely expressed in hypothalamic progenitors and contribute to lineage commitment and subtype-specific neuronal identifies, but the potential role of Neurogenin 2 (Neurog2) remains unexplored. Birthdating in male and female mice showed that tuberal hypothalamic neurogenesis begins as early as E9.5 in the lateral hypothalamic and arcuate and rapidly expands to dorsomedial and ventromedial neurons by E10.5, peaking throughout the region by E11.5. We confirmed an outside-in trend, except for neurons born at E9.5, and uncovered a rostrocaudal progression but did not confirm a dorsal-ventral patterning to tuberal hypothalamic neuronal birth. In the absence of Neurog2, neurogenesis stalls, with a significant reduction in early-born BrdU+ cells but no change at later time points. Further, the loss of Ascl1 yielded a similar delay in neuronal birth, suggesting that Ascl1 cannot rescue the loss of Neurog2 and that these proneural genes act independently in the tuberal hypothalamus. Together, our findings show that Neurog2 functions as a classical proneural gene to regulate the temporal progression of tuberal hypothalamic neurogenesis. SIGNIFICANCE STATEMENT Here, we investigated the general timing and pattern of neurogenesis within the tuberal hypothalamus. Our results confirmed an outside-in trend of neurogenesis and uncovered a rostrocaudal progression. We also showed that Neurog2 acts as a classical proneural gene and is responsible for regulating the birth of early-born neurons within the ventromedial hypothalamus, acting independently of Ascl1. In addition, we revealed a role for Neurog2 in cell fate specification and differentiation of ventromedial -specific neurons. Last, Neurog2 does not have cross-inhibitory effects on Neurog1, Neurog3, and Ascl1. These findings are the first to reveal a role for Neurog2 in hypothalamic development. Full Article
si Type I Interferons Act Directly on Nociceptors to Produce Pain Sensitization: Implications for Viral Infection-Induced Pain By www.jneurosci.org Published On :: 2020-04-29T09:30:19-07:00 One of the first signs of viral infection is body-wide aches and pain. Although this type of pain usually subsides, at the extreme, viral infections can induce painful neuropathies that can last for decades. Neither of these types of pain sensitization is well understood. A key part of the response to viral infection is production of interferons (IFNs), which then activate their specific receptors (IFNRs) resulting in downstream activation of cellular signaling and a variety of physiological responses. We sought to understand how type I IFNs (IFN-α and IFN-β) might act directly on nociceptors in the dorsal root ganglion (DRG) to cause pain sensitization. We demonstrate that type I IFNRs are expressed in small/medium DRG neurons and that their activation produces neuronal hyper-excitability and mechanical pain in mice. Type I IFNs stimulate JAK/STAT signaling in DRG neurons but this does not apparently result in PKR-eIF2α activation that normally induces an anti-viral response by limiting mRNA translation. Rather, type I IFNs stimulate MNK-mediated eIF4E phosphorylation in DRG neurons to promote pain hypersensitivity. Endogenous release of type I IFNs with the double-stranded RNA mimetic poly(I:C) likewise produces pain hypersensitivity that is blunted in mice lacking MNK-eIF4E signaling. Our findings reveal mechanisms through which type I IFNs cause nociceptor sensitization with implications for understanding how viral infections promote pain and can lead to neuropathies. SIGNIFICANCE STATEMENT It is increasingly understood that pathogens interact with nociceptors to alert organisms to infection as well as to mount early host defenses. Although specific mechanisms have been discovered for diverse bacterial and fungal pathogens, mechanisms engaged by viruses have remained elusive. Here we show that type I interferons, one of the first mediators produced by viral infection, act directly on nociceptors to produce pain sensitization. Type I interferons act via a specific signaling pathway (MNK-eIF4E signaling), which is known to produce nociceptor sensitization in inflammatory and neuropathic pain conditions. Our work reveals a mechanism through which viral infections cause heightened pain sensitivity Full Article
si Modulations of Insular Projections by Prior Belief Mediate the Precision of Prediction Error during Tactile Learning By www.jneurosci.org Published On :: 2020-05-06T09:30:22-07:00 Awareness for surprising sensory events is shaped by prior belief inferred from past experience. Here, we combined hierarchical Bayesian modeling with fMRI on an associative learning task in 28 male human participants to characterize the effect of the prior belief of tactile events on connections mediating the outcome of perceptual decisions. Activity in anterior insular cortex (AIC), premotor cortex (PMd), and inferior parietal lobule (IPL) were modulated by prior belief on unexpected targets compared with expected targets. On expected targets, prior belief decreased the connection strength from AIC to IPL, whereas it increased the connection strength from AIC to PMd when targets were unexpected. Individual differences in the modulatory strength of prior belief on insular projections correlated with the precision that increases the influence of prediction errors on belief updating. These results suggest complementary effects of prior belief on insular-frontoparietal projections mediating the precision of prediction during probabilistic tactile learning. SIGNIFICANCE STATEMENT In a probabilistic environment, the prior belief of sensory events can be inferred from past experiences. How this prior belief modulates effective brain connectivity for updating expectations for future decision-making remains unexplored. Combining hierarchical Bayesian modeling with fMRI, we show that during tactile associative learning, prior expectations modulate connections originating in the anterior insula cortex and targeting salience-related and attention-related frontoparietal areas (i.e., parietal and premotor cortex). These connections seem to be involved in updating evidence based on the precision of ascending inputs to guide future decision-making. Full Article
si A Causal Role for Mouse Superior Colliculus in Visual Perceptual Decision-Making By www.jneurosci.org Published On :: 2020-05-06T09:30:22-07:00 The superior colliculus (SC) is arguably the most important visual structure in the mouse brain and is well known for its involvement in innate responses to visual threats and prey items. In other species, the SC plays a central role in voluntary as well as innate visual functions, including crucial contributions to selective attention and perceptual decision-making. In the mouse, the possible role of the SC in voluntary visual choice behaviors has not been established. Here, we demonstrate that the mouse SC of both sexes plays a causal role in visual perceptual decision-making by transiently inhibiting SC activity during an orientation change detection task. First, unilateral SC inhibition-induced spatially specific deficits in detection. Hit rates were reduced, and reaction times increased for orientation changes in the contralateral but not ipsilateral visual field. Second, the deficits caused by SC inhibition were specific to a temporal epoch coincident with early visual burst responses in the SC. Inhibiting SC during this 100-ms period caused a contralateral detection deficit, whereas inhibition immediately before or after did not. Third, SC inhibition reduced visual detection sensitivity. Psychometric analysis revealed that inhibiting SC visual activity significantly increased detection thresholds for contralateral orientation changes. In addition, effects on detection thresholds and lapse rates caused by SC inhibition were larger in the presence of a competing visual stimulus, indicating a role for the mouse SC in visual target selection. Together, our results demonstrate that the mouse SC is necessary for the normal performance of voluntary visual choice behaviors. SIGNIFICANCE STATEMENT The mouse superior colliculus (SC) has become a popular model for studying the circuit organization and development of the visual system. Although the SC is a fundamental component of the visual pathways in mice, its role in visual perceptual decision-making is not clear. By investigating how temporally precise SC inhibition influenced behavioral performance during a visually guided orientation change detection task, we identified a 100-ms temporal epoch of SC visual activity that is crucial for the ability of mice to detect behaviorally relevant visual changes. In addition, we found that SC inhibition also caused deficits in visual target selection. Thus, our findings highlight the importance of the SC for visual perceptual choice behavior in the mouse. Full Article
si The Correlation of Neuronal Signals with Behavior at Different Levels of Visual Cortex and Their Relative Reliability for Behavioral Decisions By www.jneurosci.org Published On :: 2020-05-06T09:30:22-07:00 Behavior can be guided by neuronal activity in visual, auditory, or somatosensory cerebral cortex, depending on task requirements. In contrast to this flexible access of cortical signals, several observations suggest that behaviors depend more on neurons in later areas of visual cortex than those in earlier areas, although neurons in earlier areas would provide more reliable signals for many tasks. We recorded from neurons in different levels of visual cortex of 2 male rhesus monkeys while the animals did a visual discrimination task and examined trial-to-trial correlations between neuronal and behavioral responses. These correlations became stronger in primary visual cortex as neuronal signals in that area became more reliable relative to the other areas. The results suggest that the mechanisms that read signals from cortex might access any cortical area depending on the relative value of those signals for the task at hand. SIGNIFICANCE STATEMENT Information is encoded by the action potentials of neurons in various cortical areas in a hierarchical manner such that increasingly complex stimulus features are encoded in successive stages. The brain must extract information from the response of appropriate neurons to drive optimal behavior. A widely held view of this decoding process is that the brain relies on the output of later cortical areas to make decisions, although neurons in earlier areas can provide more reliable signals. We examined correlations between perceptual decisions and the responses of neurons in different levels of monkey visual cortex. The results suggest that the brain may access signals in any cortical area depending on the relative value of those signals for the task at hand. Full Article
si Molecular Mechanisms of Non-ionotropic NMDA Receptor Signaling in Dendritic Spine Shrinkage By www.jneurosci.org Published On :: 2020-05-06T09:30:22-07:00 Structural plasticity of dendritic spines is a key component of the refinement of synaptic connections during learning. Recent studies highlight a novel role for the NMDA receptor (NMDAR), independent of ion flow, in driving spine shrinkage and LTD. Yet little is known about the molecular mechanisms that link conformational changes in the NMDAR to changes in spine size and synaptic strength. Here, using two-photon glutamate uncaging to induce plasticity at individual dendritic spines on hippocampal CA1 neurons from mice and rats of both sexes, we demonstrate that p38 MAPK is generally required downstream of non-ionotropic NMDAR signaling to drive both spine shrinkage and LTD. In a series of pharmacological and molecular genetic experiments, we identify key components of the non-ionotropic NMDAR signaling pathway driving dendritic spine shrinkage, including the interaction between NOS1AP (nitric oxide synthase 1 adaptor protein) and neuronal nitric oxide synthase (nNOS), nNOS enzymatic activity, activation of MK2 (MAPK-activated protein kinase 2) and cofilin, and signaling through CaMKII. Our results represent a large step forward in delineating the molecular mechanisms of non-ionotropic NMDAR signaling that can drive shrinkage and elimination of dendritic spines during synaptic plasticity. SIGNIFICANCE STATEMENT Signaling through the NMDA receptor (NMDAR) is vitally important for the synaptic plasticity that underlies learning. Recent studies highlight a novel role for the NMDAR, independent of ion flow, in driving synaptic weakening and dendritic spine shrinkage during synaptic plasticity. Here, we delineate several key components of the molecular pathway that links conformational signaling through the NMDAR to dendritic spine shrinkage during synaptic plasticity. Full Article
si 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
si Calcineurin Inhibition Causes {alpha}2{delta}-1-Mediated Tonic Activation of Synaptic NMDA Receptors and Pain Hypersensitivity By www.jneurosci.org Published On :: 2020-05-06T09:30:22-07:00 Calcineurin inhibitors, such as tacrolimus (FK506) and cyclosporine, are widely used as standard immunosuppressants in organ transplantation recipients. However, these drugs can cause severe pain in patients, commonly referred to as calcineurin inhibitor-induced pain syndrome (CIPS). Although calcineurin inhibition increases NMDAR activity in the spinal cord, the underlying mechanism remains enigmatic. Using an animal model of CIPS, we found that systemic administration of FK506 in male and female mice significantly increased the amount of α2-1–GluN1 complexes in the spinal cord and the level of α2-1–bound GluN1 proteins in spinal synaptosomes. Treatment with FK506 significantly increased the frequency of mEPSCs and the amplitudes of monosynaptic EPSCs evoked from the dorsal root and puff NMDAR currents in spinal dorsal horn neurons. Inhibiting α2-1 with gabapentin or disrupting the α2-1–NMDAR interaction with α2-1Tat peptide completely reversed the effects of FK506. In α2-1 gene KO mice, treatment with FK506 failed to increase the frequency of NMDAR-mediated mEPSCs and the amplitudes of evoked EPSCs and puff NMDAR currents in spinal dorsal horn neurons. Furthermore, systemic administration of gabapentin or intrathecal injection of α2-1Tat peptide reversed thermal and mechanical hypersensitivity in FK506-treated mice. In addition, genetically deleting GluN1 in dorsal root ganglion neurons or α2-1 genetic KO similarly attenuated FK506-induced thermal and mechanical hypersensitivity. Together, our findings indicate that α2-1–bound NMDARs mediate calcineurin inhibitor-induced tonic activation of presynaptic and postsynaptic NMDARs at the spinal cord level and that presynaptic NMDARs play a prominent role in the development of CIPS. SIGNIFICANCE STATEMENT Calcineurin inhibitors are immunosuppressants used to prevent rejection of transplanted organs and tissues. However, these drugs can cause severe, unexplained pain. We showed that calcineurin inhibition enhances physical interaction between α2-1 and NMDARs and their synaptic trafficking in the spinal cord. α2-1 is essential for calcineurin inhibitor-induced aberrant activation of presynaptic and postsynaptic NMDARs in the spinal cord. Furthermore, inhibiting α2-1 or disrupting α2-1–NMDAR interaction reduces calcineurin inhibitor-induced pain hypersensitivity. Eliminating NMDARs in primary sensory neurons or α2-1 KO also attenuates calcineurin inhibitor-induced pain hypersensitivity. This new information extends our mechanistic understanding of the role of endogenous calcineurin in regulating synaptic plasticity and nociceptive transmission and suggests new strategies for treating this painful condition. Full Article
si 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
si Asia-Pacific campaign targets reduced food losses By www.fao.org Published On :: Thu, 29 Aug 2013 00:00:00 GMT FAO and its partners have launched an initiative aimed at cutting food waste across the Asia-Pacific region. Save Food Asia-Pacific Campaign targets losses both straight after harvest and between the market and people’s plates. FAO estimates that reducing global food waste by just one quarter would be sufficient to feed the 870 million people suffering from chronic hunger in the world. [...] Full Article
si Zero Hunger is possible ‘within our lifetimes' By www.fao.org Published On :: Tue, 24 Sep 2013 00:00:00 GMT FAO Director-General José Graziano da Silva underlined his firm belief that a hunger-free world is possible "within our lifetimes," during high-level talks in New York. "The Zero Hunger Challenge calls for something new – something bold, but long overdue," he said. It was a "decisive global commitment to end hunger, eliminate childhood stunting, make all food systems sustainable, eradicate rural poverty, [...] Full Article
si Resilience is key in drive to zero hunger By www.fao.org Published On :: Sun, 10 Nov 2013 00:00:00 GMT FAO’s emergency programme to support farmers affected by severe flooding in northern Benin includes creating resilience among communities in order to avert further threats to their livelihoods and food security. Farming families in northern Benin lost crops, livestock and fishing grounds when the Niger River overran its banks in August, just as many villagers were trying to recover from previous floods [...] Full Article
si Asia-Pacific countries take Zero Hunger Challenge by the horns By www.fao.org Published On :: Wed, 16 Apr 2014 00:00:00 GMT The mission for an end to hunger in the world’s most populous region has received a boost, with member countries responding positively to a call by FAO for a “massive effort” to end hunger in Asia and the Pacific. 1. Asia-Pacific is home to nearly two-thirds of the world’s chronically hungry people. |True| Asia-Pacific, with over 4.2 billion people, is home [...] Full Article
si Water – the most basic resource but also the most essential By www.fao.org Published On :: Wed, 07 May 2014 00:00:00 GMT Basic facts The world contains an estimated 1 400 million cubic km of water. Only 0.003% of this vast amount, about 45 000 cubic km, are what is called “fresh water resources” - water that theoretically can be used for drinking, hygiene, agriculture and industry. But not all of this water is accessible. For example, seasonal flooding makes water extremely difficult [...] Full Article
si Genetic diversity is our hidden jewel, we should treasure every bit of it By www.fao.org Published On :: Wed, 29 Oct 2014 00:00:00 GMT Biodiversity for food and agriculture is among the earth’s most important resources. Biodiversity is indispensable: be it the insects that pollinate plants, the microscopic bacteria used for making cheese, the diverse livestock breeds used to make a living in harsh environments, the thousands species of fish, and other aquatic species in our lakes, rivers and oceans, or the thousands of [...] Full Article
si Antimicrobial resistance – What you need to know By www.fao.org Published On :: Tue, 14 Nov 2017 00:00:00 GMT An estimated 700 000 people die each year from antimicrobial resistant (AMR) infections and an untold number of sick animals may not be responding to treatment. AMR is a significant global threat to public health, food safety and security, as well as to livelihoods, animal production and economic and agricultural development. The intensification of agricultural production has led to a rising use of antimicrobials – a use that is expected to more than double by 2030. Antimicrobials are important for the treatment of animal and plant diseases [...] Full Article
si Beauty (and taste!) are on the inside By www.fao.org Published On :: Mon, 12 Mar 2018 00:00:00 GMT It is often said that beauty is in the eye of the beholder. But when it comes to fruit and vegetables, one third of them never even make it to our grocery store shelves because they are rejected on their way from the farm to the store. While supermarkets have a part to play in this, we must also examine [...] Full Article
si Persistence and profits pay off By www.fao.org Published On :: Fri, 23 Mar 2018 00:00:00 GMT Knocking on closed doors is something Renu Bala is very good at. First, it was the doors of her neighbours in Panjor Bhanga, her home village in northern Bangladesh. She had an idea for them: what if they formed a milk cooperative? They didn’t have much to lose. “The women of this village are very poor and raise only local Deshi cattle,” Renu explains. [...] Full Article
si Nature's invisible connections and contributions to us By www.fao.org Published On :: Tue, 22 May 2018 00:00:00 GMT One person has curly hair; one person has straight hair. One person tans, another burns. One person can curl her lip, another can’t. This is all because of our genes and the differences in them. Diversity. It is the spice of life. Full Article
si Biodiversity reveals the treasures all around us By www.fao.org Published On :: Mon, 28 May 2018 00:00:00 GMT Biodiversity may sound complicated, but it’s a fairly simple concept: the existence of many different types of plants and animals makes the world a healthier and more productive place. A mix of genetics, species and habitats allows Earth’s ecosystems to keep up with challenges like population growth and climate change. Biodiversity is important to us because it plays a crucial [...] Full Article
si Common oceans – our shared responsibility By www.fao.org Published On :: Wed, 27 Jun 2018 00:00:00 GMT Oceans cover 70 percent of our planet. But did you know that 40 percent of the earth’s surface is covered by what is known as our common oceans? Full Article
si Sign up to receive FAO's publications newsletters By www.fao.org Published On :: Fri, 20 Dec 2019 00:00:00 GMT To keep up to date on FAO’s most recent publications, sign up to one of the newsletters produced by the Publications team of the Office for Corporate Communication: The weekly update [...] Full Article
si Farmers' Market at FAO Headquarters on the occasion of the Biodiversity for Food Diversity fair By www.fao.org Published On :: Thu, 20 Feb 2020 00:00:00 GMT Buy fresh and seasonal produce at the Farmers’ Market on Wednesday 26 February from 12.00 – 16.00 hours, and be sure to visit the [...] Full Article
si 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
si Visit the Only Village Inside the Grand Canyon By www.smithsonianmag.com Published On :: Thu, 19 Nov 2015 15:13:57 +0000 Supai is so remote, mail is delivered by mule train Full Article
si These Massive Rock Formations Look Just Like Cracked Eggs By www.smithsonianmag.com Published On :: Fri, 25 Mar 2016 15:01:08 +0000 Bisti Badlands’ bizarre eggs bring a bit of Easter to the New Mexico desert Full Article
si Beautiful Photos from America’s Six Least-Visited National Parks By www.smithsonianmag.com Published On :: Wed, 05 Oct 2016 16:26:27 +0000 These parks are less popular, but no less spectacular Full Article
si The Social Network 2010 ☚ ☚ ☚ Something about a web site that gets you laid By www.bigempire.com Published On :: Full Article
si Inside the Alluring Power of Public Opinion Polls From Elections Past By www.smithsonianmag.com Published On :: Mon, 26 Sep 2016 15:55:20 +0000 A digital-savvy historian discusses his popular @HistOpinion Twitter account Full Article
si Council talks grant funding: Requests extension for public comment period on Metlakatla power tie-in By www.ketchikandailynews.com Published On :: Full Article
si This Secret Boat Was Built for a WWII Invasion That Never Happened By www.smithsonianmag.com Published On :: Tue, 28 Aug 2018 12:00:00 +0000 In 2011, declassified CIA documents shed light on a covert government program dating back to WWII Full Article
si How the British Navy Camouflaged Their Ships Using Art By www.smithsonianmag.com Published On :: Wed, 29 Aug 2018 12:00:00 +0000 The British Navy knew it couldn't completely disguise a ship to protect it from attack during WWI. So they turned to 'Dazzle Painting' Full Article
si How Napalm Bombs Intensified U.S. Attacks During WWII By www.smithsonianmag.com Published On :: Thu, 30 Aug 2018 12:00:00 +0000 Bombing ground targets from the air is tricky and not always accurate. But a new type of bomb creates an unimaginable level of destruction Full Article
si Why Shipbuilders Were Forced to Stop Using British Oak By www.smithsonianmag.com Published On :: Mon, 03 Sep 2018 12:00:00 +0000 After the Napoleonic Wars caused a shortage of British Oak, frigate builders looked all over the empire for an alternative. They found one in India Full Article
si 2009-01-20, #1: President Woke Up And The Dinosaur Was Still There. By interglacial.com Published On :: Full Article
si http://digg.com/submit?url=http://www.edge.org/conversation/a-cultural-history-of-physics By digg.com Published On :: Full Article
si http://digg.com/submit?url=http://www.edge.org/conversation/-quotthe-man-who-runs-the-world-39s-smartest-website-quot-in-the-observer By digg.com Published On :: Full Article
si Stolen Collection of Persian Poetry Found With Help of 'Indiana Jones of the Art World' Goes on Auction By www.smithsonianmag.com Published On :: Tue, 10 Mar 2020 19:30:53 +0000 The 15th-century edition of Hafez's "Divan" will be sold at Sotheby's next month Full Article
si Invasive Snails Might Save Coffee Crops From Fungus, but Experts Advise Caution By www.smithsonianmag.com Published On :: Wed, 11 Mar 2020 17:46:34 +0000 The snails are an invasive crop pest that are known to eat more than just coffee rust Full Article
si Prince Edward and Wallis Simpson's Sprawling Bahamas Estate Is Up for Sale By www.smithsonianmag.com Published On :: Fri, 13 Mar 2020 18:14:18 +0000 After abdicating the British throne, Edward was appointed governor of the Bahamas, where he temporarily lived in a lavish home in Nassau Full Article
si Newly Unearthed Mesoamerican Ball Court Offers Insights on Game's Origins By www.smithsonianmag.com Published On :: Mon, 16 Mar 2020 16:11:51 +0000 "This could be the oldest and longest-lived team ball game in the world," says one archaeologist Full Article
si GPS Study Shows Outdoor Cats Have Oversized Effect on Neighborhood Wildlife By www.smithsonianmag.com Published On :: Mon, 16 Mar 2020 20:54:55 +0000 The cats also cross the road an average of 4.5 times in six days, putting themselves in danger Full Article
si Possible Half-Human, Half-Praying-Mantis Carving Found on Ancient Rocks By www.smithsonianmag.com Published On :: Thu, 19 Mar 2020 14:18:09 +0000 The puzzling glyph, which bears some resemblance to the "squatting man" motif, suggests that insects have long held a place in human lore Full Article
si Ten Museums You Can Virtually Visit By www.smithsonianmag.com Published On :: Fri, 20 Mar 2020 11:00:00 +0000 Museums are closing their doors amid the coronavirus crisis, but many offer digital exhibitions visitors can browse from the comfort of home Full Article
si Portable, Pocket-Sized Rock Art Discovered in Ice Age Indonesian Cave By www.smithsonianmag.com Published On :: Fri, 20 Mar 2020 14:38:26 +0000 The findings further refute the outdated notion that humans' capacity for complex artistic expression evolved exclusively in Europe Full Article
si Celebrating the 80th Anniversary of Batman's Sidekick, Robin By www.smithsonianmag.com Published On :: Fri, 20 Mar 2020 17:52:59 +0000 Many teens have taken on the role, but not every Robin was a "boy" wonder Full Article