Marrs et al. show that the serine hydrolase ?/?-hydrolase domain 6 (ABHD6) controls the accumulation and efficacy of the endocannabinoid 2-arachidonoylglycerol at cannabinoid receptors. ABHD6 is located post-synaptically and its selective inhibition permits the induction of cannabinoid receptor–dependent long-term depression by otherwise subthreshold stimulations. . . . → Read More: The serine hydrolase ABHD6 controls the accumulation and efficacy of 2-AG at cannabinoid receptors
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The parahippocampal region of dorsal presubinculum has neurons that preferentially fire based on the direction of the rat’s head. The medial entorhinal cortex has neurons that are preferentially active according to grid-like regularity in space. Here, the authors find that pre- and parasubiculum also have these grid cells, which are intermingled with head-direction cells. . . . → Read More: Grid cells in pre- and parasubiculum Down syndrome is caused by the triplication of chromosome 21, which results in extra copies of hundreds of genes. Chakrabarti et al. used the Ts65Dn mouse model of Down syndrome to show that Olig1 and Olig2, two transcription factor genes that are triplicated in Down syndrome and in the Ts65Dn mouse, are involved in the manifestation of the inhibition/excitation imbalance phenotype. . . . → Read More: Olig1 and Olig2 triplication causes developmental brain defects in Down syndrome The authors studied hippocampal networks in mouse slices in vitro and found that theta-related place-cell activity in the hippocampus is generated through an interaction between a phasic dendritic excitation and a phasic perisomatic shunting inhibition mediated by interneurons. . . . → Read More: Network mechanisms of theta related neuronal activity in hippocampal CA1 pyramidal neurons The hippocampus has place cells that preferentially fire at a particular location of spatial arena. Dupret et al. report that place fields remapped as a result of goal-directed spatial learning and that sharp wave/ripple reactivation events seen during memory consolidation predicted the strength of subsequent spatial memory. Jeffery and Cacucci highlight this work in their News and View. . . . → Read More: The reorganization and reactivation of hippocampal maps predict spatial memory performance The authors find that disruption of primary motor cortex or dorsolateral prefrontal cortex with transcranial magnetic stimulation has differential effects on motor memory retention depending on whether training was done in blocks of trials or with different tasks interleaved. This suggests that the neural substrate for motor-memory consolidation depends on the practice structure used for training. . . . → Read More: Neural substrates of motor memory consolidation depend on practice structure Understanding of the fly visual circuitry has been hampered by the difficulty of recording from the small neurons involved. Reiff and colleagues present a technique to record visually evoked responses and find that the L2 interneurons in the medulla encode brightness decrements rather than motion. . . . → Read More: Visualizing retinotopic half-wave rectified input to the motion detection circuitry of Drosophila Fritz et al. compared activity in ferret frontal cortex and primary auditory cortex (A1) during auditory and visual tasks requiring discrimination and found that A1 and frontal cortex establish a dynamic, functional connection during auditory behavior that shapes sensory information flow and maintains a persistent trace of recent task-relevant stimulus features. . . . → Read More: Adaptive, behaviorally gated, persistent encoding of task-relevant auditory information in ferret frontal cortex In Drosophila, activation by Wingless results in cleavage of its Frizzled2 receptor and translocation of the C terminus (Fz2-C) from the postsynaptic density to the nuclei. Mosca and Schwarz find that nuclear Fz2-C entry requires the nuclear import factors Importin-?11 and Importin-?2. This pathway promotes postsynaptic development of the subsynaptic reticulum. . . . → Read More: The nuclear import of Frizzled2-C by Importins-?11 and ?2 promotes postsynaptic development The authors combine optogenetics, two-photon microscopy and glutamate uncaging to study D2-type dopamine receptor modulation of glutamatergic transmission in mouse striatopallidal neurons. They find that dopamine regulates spine calcium via multiple pathways. . . . → Read More: Competitive regulation of synaptic Ca2+ influx by D2 dopamine and A2A adenosine receptors Fear conditioning results from the association that develops between a neutral conditioned stimulus and an aversive unconditioned stimulus (UCS), which is thought to be supported by plasticity in the amygdala. Here, the authors find that information about the UCS is conveyed to the amygdala by neurons in the periaqueductal gray. . . . → Read More: Neural substrates for expectation-modulated fear learning in the amygdala and periaqueductal gray Building on their previous observation that neuronal calcium spike activity can drive neurotransmitter specification during development, these authors report that cJun phosphorylation integrates activity-dependent and intrinsic transmitter specification through the regulation of tlx3 transcription in Xenopus sensory neurons. . . . → Read More: cJun integrates calcium activity and tlx3 expression to regulate neurotransmitter specification Some brain areas, such as the olfactory bulb, can decorrelate (that is, separate out) very general inputs. However, the mechanisms enabling such decorrelation are unclear. This study presents a computational model that shows that efficient pattern decorrelation can emerge from a combination of nonlinear input-output functions and recurrent, sparse and strong inter-neuronal connectivity. . . . → Read More: Mechanisms of pattern decorrelation by recurrent neuronal circuits The authors find that a person’s estimate of a time interval exhibits biases that depend on both its duration and the distribution from which it is drawn. This behavioral pattern could be described using a Bayesian model. These findings suggest that internal timing mechanisms can adapt to the temporal statistics of the environment to minimize uncertainty. . . . → Read More: Temporal context calibrates interval timing This paper reports the development of a K+-selective glutamate receptor, HyLighter, that reversibly inhibits neuronal activity in response to light. The low light requirement and bi-stability of HyLighter could be useful for studying neural circuitry. . . . → Read More: A light-gated, potassium-selective glutamate receptor for the optical inhibition of neuronal firing This review article highlights the recent advances on how amyloid-? (A?) peptides can affect synaptic and neuronal circuit function—both in the context of normal brain function and in Alzheimer’s disease—and discusses the consequence of aberrant A? at neural network level. . . . → Read More: Amyloid-?–induced neuronal dysfunction in Alzheimer’s disease: from synapses toward neural networks The authors show that a mutation in the synaptic vesicle protein otoferlin impairs hearing by reducing the rate of vesicle replenishment at the inner hair cell ribbon synapse. They propose that the function of otoferlin is to replenish synaptic vesicles. . . . → Read More: Hearing requires otoferlin-dependent efficient replenishment of synaptic vesicles in hair cells The authors show that a developmental shift occurs in the dimensions of the calcium domain required for vesicle endocytosis at calyx of Held terminals. After hearing onset, endocytosis at mature synapses is largely driven by calcium nanodomains. Endocytosis becomes independent of calmodulin and calcineurin and completely dependent on GTP hydrolysis. . . . → Read More: Developmental shift to a mechanism of synaptic vesicle endocytosis requiring nanodomain Ca2+ Dieterich et al. describe a methodology to label all newly synthesized neuronal proteins in situ. This method, which they name FUNCAT, relies on the inclusion of noncanonical amino acids and selective fluorescent labeling via click chemistry. The authors show that this system is amenable to dual pulse-chase experiments and dynamic tracking of newly synthesized proteins. . . . → Read More: In situ visualization and dynamics of newly synthesized proteins in rat hippocampal neurons The low threshold for action potential generation in the axon initial segment (AIS) is thought to reflect a high sodium channel density. Using high-speed sodium imaging, Fleidervish et al. estimate that sodium channel density in the AIS is only threefold higher than in the soma, a smaller difference than previously estimated. . . . → Read More: Na+ imaging reveals little difference in action potential–evoked Na+ influx between axon and soma The authors chronically stimulated cultured cortical cell networks. They observed changes in the timing of neural activity that depended on the intervals used during training. . . . → Read More: Neural dynamics of in vitro cortical networks reflects experienced temporal patterns The mechanisms by which the brain selects a particular stimulus as the next target for gaze are only partially understood. A cholinergic nucleus in the owl’s midbrain exhibits functional properties that suggest a role for it as a ‘salience map’ in facilitating bottom-up stimulus selection. . . . → Read More: Stimulus-driven competition in a cholinergic midbrain nucleus This study finds that inhibition of the hypothalamic melanocortin receptors increases the level of high-density lipoprotein HDL-C, a form of cholesterol, circulating in the blood stream. Uptake of HDL-C into the liver was slowed, as expression of one of the hepatic cholesterol receptors was downregulated. . . . → Read More: Melanocortin signaling in the CNS directly regulates circulating cholesterol After neurotransmitter release evoked by intense stimulation, synaptic vesicles are retrieved either by clathrin-mediated endocytosis or by activity-dependent bulk endocytosis (ADBE), both of which require the GTPase dynamin I. Here the authors show that presynaptic glycogen synthase kinase-3 specifically regulates synaptic vesicle retrieval during ADBE via phosphorylation of dynamin I. . . . → Read More: Dynamin I phosphorylation by GSK3 controls activity-dependent bulk endocytosis of synaptic vesicles Dopamine D2 receptor antagonists increase the risk of extrapyramidal symptoms (EPS) within minutes. This study reports significant reductions in the striatal volume of healthy human subjects within hours of D2R antagonist treatment; the volume changes predict structural-functional decoupling in motor circuits and acute EPS with high precision. . . . → Read More: Acute D2 receptor blockade induces rapid, reversible remodeling in human cortical-striatal circuits People vary markedly in how quickly they can resolve competitive action decisions. Using magnetic resonance spectroscopy, the authors find that the speed with which an individual resolves such competition can be predicted by the concentration of GABA in a region of frontal cortex. . . . → Read More: More GABA, less distraction: a neurochemical predictor of motor decision speed This study shows that cannabinoid-1 receptor (CB1)-positive inhibitory interneurons in the entorhinal cortex selectively innervate those principal neurons that project to the hippocampal commissure. Principal neurons that form the perforant path from entorhinal cortex to hippocampal dentate gyrus were devoid of CB1-positive synapses. . . . → Read More: Target-selective GABAergic control of entorhinal cortex output Fragile X mental retardation protein controls gating of the sodium-activated potassium channel SlackFragile X mental retardation protein (FMRP) binds to RNA and interacts with other ribonucleoproteins. Here, the authors describe both an interaction between FMRP and the sodium-activated potassium channel Slack-B and the FMRP regulation of Slack channel kinetics. . . . → Read More: Fragile X mental retardation protein controls gating of the sodium-activated potassium channel Slack Acupuncture can locally reduce pain, but it has remained unclear how it might work. Goldman et al. find that acupuncture elevates local tissue adenosine levels in a mouse model. The anti-nociceptive effect of acupuncture was absent in mice lacking the adenosine receptor A1. . . . → Read More: Adenosine A1 receptors mediate local anti-nociceptive effects of acupuncture This study shows that a polymodal nociceptive sensory neuron in C. elegans detects both harsh body touch and noxious cold. Using calcium imaging and genetic tools, the researchers report that the same sensory neuron uses Degerin/Epithelial Na+ channel proteins MEC-10 and DEGT-1 for harsh touch detection and TRPA-1 channel for cold sensing. . . . → Read More: Specific roles for DEG/ENaC and TRP channels in touch and thermosensation in C. elegans nociceptors In growth cones of Xenopus spinal neurons, Hines et al. show that the chemorepellant myelin-associated glycoprotein (MAG) induces asymmetric endocytosis of ?1-integrin, via a calcium- and PI3K-dependent mechanism. Further, they show that polarized ?1-integrin function is necessary and sufficient for growth cone repulsion. . . . → Read More: Asymmetric endocytosis and remodeling of ?1-integrin adhesions during growth cone chemorepulsion by MAG |
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