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neuronal circuits

Alexandre Caron, Denis Richard
With the still-growing prevalence of obesity worldwide, major efforts are made to understand the various behavioral, environmental, and genetic factors that promote excess fat gain. Obesity results from an imbalance between energy intake and energy expenditure, which emphasizes the importance of deciphering the mechanisms behind energy balance regulation to understand its physiopathology. The control of energy balance is assured by brain systems/circuits capable of generating adequate ingestive and thermogenic responses to maintain the stability of energy reserves, which implies a proper integration of the homeostatic signals that inform about the status of the energy stores...
October 21, 2016: Annals of the New York Academy of Sciences
Annekathrin Widmann, Marc Artinger, Lukas Biesinger, Kathrin Boepple, Christina Peters, Jana Schlechter, Mareike Selcho, Andreas S Thum
Memory formation is a highly complex and dynamic process. It consists of different phases, which depend on various neuronal and molecular mechanisms. In adult Drosophila it was shown that memory formation after aversive Pavlovian conditioning includes-besides other forms-a labile short-term component that consolidates within hours to a longer-lasting memory. Accordingly, memory formation requires the timely controlled action of different neuronal circuits, neurotransmitters, neuromodulators and molecules that were initially identified by classical forward genetic approaches...
October 2016: PLoS Genetics
Hung-Ya Tu, Chih-Chun Hsu, Yu-Jiun Chen, Ching-Kang Chen
The mammalian retina is a layered tissue composed of multiple neuronal types. To understand how visual signals are processed within its intricate synaptic network, electrophysiological recordings are frequently used to study connections among individual neurons. We have optimized a flat-mount preparation for patch clamp recording of genetically marked neurons in both GCL (ganglion cell layer) and INL (inner nuclear layer) of mouse retinas. Recording INL neurons in flat-mounts is favored over slices because both vertical and lateral connections are preserved in the former configuration, allowing retinal circuits with large lateral components to be studied...
October 13, 2016: Journal of Visualized Experiments: JoVE
Marijn Bart Martens, Monica Frega, Jessica Classen, Lisa Epping, Elske Bijvank, Marco Benevento, Hans van Bokhoven, Paul Tiesinga, Dirk Schubert, Nael Nadif Kasri
Heterozygous mutations or deletions in the human Euchromatin histone methyltransferase 1 (EHMT1) gene cause Kleefstra syndrome, a neurodevelopmental disorder that is characterized by autistic-like features and severe intellectual disability (ID). Neurodevelopmental disorders including ID and autism may be related to deficits in activity-dependent wiring of brain circuits during development. Although Kleefstra syndrome has been associated with dendritic and synaptic defects in mice and Drosophila, little is known about the role of EHMT1 in the development of cortical neuronal networks...
October 21, 2016: Scientific Reports
Li-Wa Shao, Rong Niu, Ying Liu
Neurons have a central role in the systemic coordination of mitochondrial unfolded protein response (UPR(mt)) and the cell non-autonomous modulation of longevity. However, the mechanism by which the nervous system senses mitochondrial stress and communicates to the distal tissues to induce UPR(mt) remains unclear. Here we employ the tissue-specific CRISPR-Cas9 approach to disrupt mitochondrial function only in the nervous system of Caenorhabditis elegans, and reveal a cell non-autonomous induction of UPR(mt) in peripheral cells...
October 21, 2016: Cell Research
Gustavo Rios, Evgueniy V Lubenov, Derrick Chi, Michael L Roukes, Athanassios G Siapas
Computations in brain circuits involve the coordinated activation of large populations of neurons distributed across brain areas. However, monitoring neuronal activity in the brain of intact animals with high temporal and spatial resolution has remained a technological challenge. Here we address this challenge by developing dense, three-dimensional (3-D) electrode arrays for electrophysiology. The 3-D arrays constitute the front-end of a modular and configurable system architecture that enables monitoring neuronal activity with unprecedented scale and resolution...
October 21, 2016: Nano Letters
Sergio Valbuena, Juan Lerma
Neurotransmitter receptors are responsible for the transfer of information across the synapse. While ionotropic receptors form ion channels and mediate rapid membrane depolarization, so-called metabotropic receptors exert their action though slower, less direct intracellular signaling pathways. Glutamate, GABA, and acetylcholine can activate both ionotropic and metabotropic receptors, yet the distinction between these "canonical" signaling systems has become less clear since ionotropic receptors were proposed to also activate second messenger systems, defining a "non-canonical" signaling pathway...
October 19, 2016: Neuron
Yongseok Yoo, Woori Kim
Neural systems are inherently noisy. One well-studied example of a noise reduction mechanism in the brain is the population code, where representing a variable with multiple neurons allows the encoded variable to be recovered with fewer errors. Studies have assumed ideal observer models for decoding population codes, and the manner in which information in the neural population can be retrieved remains elusive. This letter addresses a mechanism by which realistic neural circuits can recover encoded variables...
October 20, 2016: Neural Computation
Shelby A Montague, Bruce S Baker
An animal's ability to learn and to form memories is essential for its survival. The fruit fly has proven to be a valuable model system for studies of learning and memory. One learned behavior in fruit flies is courtship conditioning. In Drosophila courtship conditioning, male flies learn not to court females during training with an unreceptive female. He retains a memory of this training and for several hours decreases courtship when subsequently paired with any female. Courtship conditioning is a unique learning paradigm; it uses a positive-valence stimulus, a female fly, to teach a male to decrease an innate behavior, courtship of the female...
2016: PloS One
Laurence D Picton, Keith T Sillar
Dopamine plays important roles in the development and modulation of motor control circuits. Here we show that dopamine exerts potent effects on the central pattern generator circuit controlling locomotory swimming in post-embryonic Xenopus tadpoles. Dopamine (0.5-100 μM) reduced fictive swim bout occurrence and caused both spontaneous and evoked episodes to become shorter, slower and weaker. The D2-like receptor agonist quinpirole mimicked this repertoire of inhibitory effects on swimming, whilst the D4 receptor antagonist, L745,870, had the opposite effects...
October 20, 2016: Scientific Reports
Haitao Yu, Rishi R Dhingra, Thomas E Dick, Roberto Fernandez Galan
Neural activity generally displays irregular firing patterns even in circuits with apparently regular outputs, such as motor pattern generators, in which the output frequency fluctuates randomly around a mean value. This "circuit noise" is inherited from the random firing of single neurons, which emerges from stochastic ion-channel gating (channel noise), spontaneous neurotransmitter release, and its diffusion and binding to synaptic receptors. Here, we demonstrate how to expand conductance-based network models that are originally deterministic to include realistic, physiological noise, focusing on stochastic ion-channel gating...
October 19, 2016: Journal of Neurophysiology
Clarissa J Whitmire, Daniel C Millard, Garrett B Stanley
Sensory stimulation drives complex interactions across neural circuits as information is encoded and then transmitted from one brain region to the next. In the highly interconnected thalamocortical circuit, these complex interactions elicit repeatable neural dynamics in response to temporal patterns of stimuli that provide insight into the circuit properties that generated them. Here, using a combination of in-vivo voltage sensitive dye (VSD) imaging of cortex, single unit recording in thalamus, and optogenetics to manipulate thalamic state in the rodent vibrissa pathway, we probed the thalamocortical circuit with simple temporal patterns of stimuli delivered either to the whiskers on the face (sensory stimulation) or to the thalamus directly via electrical or optogenetic inputs (artificial stimulation)...
October 19, 2016: Journal of Neurophysiology
Yiqin Jiang, Elise Pitmon, Jack Berry, Fred W Wolf, Zach McKenzie, Tim J Lebestky
Sleep is an essential behavioral state of rest that is regulated by homeostatic drives to ensure a balance of sleep and activity, as well as independent arousal mechanisms in the central brain. Dopamine has been identified as a critical regulator of both sleep behavior and arousal. Here we present results of a genetic screen that selectively restored the Dopamine Receptor (DopR/DopR1/dumb) to specific neuroanatomical regions of the adult Drosophila brain to assess requirements for DopR in sleep behavior. We have identified subsets of the mushroom body that utilize DopR in daytime sleep regulation...
October 19, 2016: G3: Genes—Genomes—Genetics
Sara Calafate, William Flavin, Patrik Verstreken, Diederik Moechars
Tau pathology propagates within synaptically connected neuronal circuits, but the underlying mechanisms are unclear. BIN1-amphiphysin2 is the second most prevalent genetic risk factor for late-onset Alzheimer's disease. In diseased brains, the BIN1-amphiphysin2 neuronal isoform is downregulated. Here, we show that lowering BIN1-amphiphysin2 levels in neurons promotes Tau pathology propagation whereas overexpression of neuronal BIN1-amphiphysin2 inhibits the process in two in vitro models. Increased Tau propagation is caused by increased endocytosis, given our finding that BIN1-amphiphysin2 negatively regulates endocytic flux...
October 18, 2016: Cell Reports
Verónica Pérez-Schuster, Anirudh Kulkarni, Morgane Nouvian, Sebastián A Romano, Konstantinos Lygdas, Adrien Jouary, Mario Dippopa, Thomas Pietri, Mathieu Haudrechy, Virginie Candat, Jonathan Boulanger-Weill, Vincent Hakim, Germán Sumbre
Following moving visual stimuli (conditioning stimuli, CS), many organisms perceive, in the absence of physical stimuli, illusory motion in the opposite direction. This phenomenon is known as the motion aftereffect (MAE). Here, we use MAE as a tool to study the neuronal basis of visual motion perception in zebrafish larvae. Using zebrafish eye movements as an indicator of visual motion perception, we find that larvae perceive MAE. Blocking eye movements using optogenetics during CS presentation did not affect MAE, but tectal ablation significantly weakened it...
October 18, 2016: Cell Reports
David J Anderson
Goal-directed social behaviours such as mating and fighting are associated with scalable and persistent internal states of emotion, motivation, arousal or drive. How those internal states are encoded and coupled to behavioural decision making and action selection is not clear. Recent studies in Drosophila melanogaster and mice have identified circuit nodes that have causal roles in the control of innate social behaviours. Remarkably, in both species, these relatively small groups of neurons can influence both aggression and mating, and also play a part in the encoding of internal states that promote these social behaviours...
October 18, 2016: Nature Reviews. Neuroscience
Neil C Ford, Mark L Baccei
Spinal lamina I projection neurons serve as a major conduit by which noxious stimuli detected in the periphery are transmitted to nociceptive circuits in the brain, including the parabrachial nucleus (PB) and the periaqueductal gray (PAG). While neonatal spino-PB neurons are more than twice as likely to exhibit spontaneous activity compared to spino-PAG neurons, the underlying mechanisms remain unclear since nothing is known about the voltage-independent (i.e. 'leak') ion channels expressed by these distinct populations during early life...
October 14, 2016: Neuroscience
Anthony G Hudetz, Jeannette A Vizuete, Siveshigan Pillay, George A Mashour
Consciousness has been linked to the repertoire of brain states at various spatiotemporal scales. Anesthesia is thought to modify consciousness by altering information integration in cortical and thalamocortical circuits. At a mesoscopic scale, neuronal populations in the cortex form synchronized ensembles whose characteristics are presumably state-dependent but this has not been rigorously tested. In this study, spontaneous neuronal activity was recorded with 64-contact microelectrode arrays in primary visual cortex of chronically instrumented, unrestrained rats under stepwise decreasing levels of desflurane anesthesia (8%, 6%, 4%, and 2% inhaled concentrations) and wakefulness (0% concentration)...
October 14, 2016: Neuroscience
Christopher S Medina, Octavian Biris, Tomas L Falzone, Xiaowei Zhang, Amber J Zimmerman, Elaine L Bearer
Microtubule-based motors carry cargo back and forth between the synaptic region and the cell body. Defects in axonal transport result in peripheral neuropathies, some of which are caused by mutations in KIF5A, a gene encoding one of the heavy chain isoforms of conventional kinesin-1. Some mutations in KIF5A also cause severe central nervous system defects in humans. While transport dynamics in the peripheral nervous system have been well characterized experimentally, transport in the central nervous system is less experimentally accessible and until now not well described...
October 14, 2016: NeuroImage
Virginia Mela, Sara Jimenez, Alejandra Freire-Regatillo, Vicente Barrios, Eva-María Marco, Ana-Belén Lopez-Rodriguez, Jesús Argente, María-Paz Viveros, Julie A Chowen
The neonatal leptin surge, occurring from postnatal day (PND) 5 to 13 and peaking at PND9 in rodents, is important for the development of neuroendocrine circuits involved in metabolic control and reproductive function. We previously demonstrated that treatment with a leptin antagonist from PND 5 to 9, coincident with peak leptin levels in the neonatal surge, modified trophic factors and markers of cell turnover and neuronal maturation in the hypothalamus of peri-pubertal rats. The kisspeptin system and metabolic neuropeptide and hormone levels were also modified...
October 14, 2016: Peptides
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