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https://www.readbyqxmd.com/read/28821663/agrp-neurons-can-increase-food-intake-during-conditions-of-appetite-suppression-and-inhibit-anorexigenic-parabrachial-neurons
#1
Rachel A Essner, Alison G Smith, Adam A Jamnik, Anna R Ryba, Zoe D Trutner, Matthew E Carter
To maintain energy homeostasis, orexigenic (appetite-inducing) and anorexigenic (appetite suppressing) brain systems functionally interact to regulate food intake. Within the hypothalamus, neurons that express agouti-related protein (AgRP) sense orexigenic factors and orchestrate an increase in food-seeking behavior. In contrast, calcitonin gene-related peptide (CGRP)-expressing neurons in the parabrachial nucleus (PBN) suppress feeding. PBN CGRP neurons become active in response to anorexigenic hormones released following a meal, including amylin, secreted by the pancreas, and cholecystokinin (CCK), secreted by the small intestine...
August 7, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28821651/role-of-somatostatin-positive-cortical-interneurons-in-the-generation-of-sleep-slow-waves
#2
Chadd M Funk, Kayla Peelman, Michele Bellesi, William Marshall, Chiara Cirelli, Giulio Tononi
During non-rapid eye movement (NREM) sleep cortical and thalamic neurons oscillate every second or so between ON periods characterized by membrane depolarization and wake-like tonic firing, and OFF periods characterized by membrane hyperpolarization and neuronal silence. Cortical slow waves - the hallmark of NREM sleep - reflect near-synchronous OFF periods in cortical neurons. However, the mechanisms triggering such OFF periods are unclear, as there is little evidence for somatic inhibition. We studied cortical inhibitory interneurons that express somatostatin (SOM), because ∼70% of them are Martinotti cells that target diffusely layer I and can block excitatory transmission presynaptically, at glutamatergic terminals, and postsynaptically, at apical dendrites, without inhibiting the soma...
August 16, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28819259/dendritic-calcium-spikes-are-clearly-detectable-at-the-cortical-surface
#3
Mototaka Suzuki, Matthew E Larkum
Cortical surface recording techniques such as EEG and ECoG are widely used for measuring brain activity. The prevailing assumption is that surface potentials primarily reflect synaptic activity, although non-synaptic events may also contribute. Here we show that dendritic calcium spikes occurring in pyramidal neurons (that we showed previously are cognitively relevant) are clearly detectable in cortical surface potentials. To show this we developed an optogenetic, non-synaptic approach to evoke dendritic calcium spikes in vivo...
August 17, 2017: Nature Communications
https://www.readbyqxmd.com/read/28818946/a-central-neural-circuit-for-itch-sensation
#4
Di Mu, Juan Deng, Ke-Fei Liu, Zhen-Yu Wu, Yu-Feng Shi, Wei-Min Guo, Qun-Quan Mao, Xing-Jun Liu, Hui Li, Yan-Gang Sun
Although itch sensation is an important protective mechanism for animals, chronic itch remains a challenging clinical problem. Itch processing has been studied extensively at the spinal level. However, how itch information is transmitted to the brain and what central circuits underlie the itch-induced scratching behavior remain largely unknown. We found that the spinoparabrachial pathway was activated during itch processing and that optogenetic suppression of this pathway impaired itch-induced scratching behaviors...
August 18, 2017: Science
https://www.readbyqxmd.com/read/28818944/conversion-of-object-identity-to-object-general-semantic-value-in-the-primate-temporal-cortex
#5
Keita Tamura, Masaki Takeda, Rieko Setsuie, Tadashi Tsubota, Toshiyuki Hirabayashi, Kentaro Miyamoto, Yasushi Miyashita
At the final stage of the ventral visual stream, perirhinal neurons encode the identity of memorized objects through learning. However, it remains elusive whether and how object percepts alone, or concomitantly a nonphysical attribute of the objects ("learned"), are decoded from perirhinal activities. By combining monkey psychophysics with optogenetic and electrical stimulations, we found a focal spot of memory neurons where both stimulations led monkeys to preferentially judge presented objects as "already seen...
August 18, 2017: Science
https://www.readbyqxmd.com/read/28817806/specialized-mechanosensory-nociceptors-mediating-rapid-responses-to-hair-pull
#6
Nima Ghitani, Arnab Barik, Marcin Szczot, James H Thompson, Chia Li, Claire E Le Pichon, Michael J Krashes, Alexander T Chesler
The somatosensory system provides animals with the ability to detect, distinguish, and respond to diverse thermal, mechanical, and irritating stimuli. While there has been progress in defining classes of neurons underlying temperature sensation and gentle touch, less is known about the neurons specific for mechanical pain. Here, we use in vivo functional imaging to identify a class of cutaneous sensory neurons that are selectively activated by high-threshold mechanical stimulation (HTMRs). We show that their optogenetic excitation evokes rapid protective and avoidance behaviors...
August 16, 2017: Neuron
https://www.readbyqxmd.com/read/28809843/tuning-in-the-hippocampal-theta-band-in-vitro-methodologies-for-recording-from-the-isolated-rodent-septohippocampal-circuit
#7
Frédéric Manseau, Sylvain Williams
This protocol outlines the procedures for preparing and recording from the isolated whole hippocampus, of WT and transgenic mice, along with recent improvements in methodologies and applications for the study of theta oscillations. A simple characterization of the isolated hippocampal preparation is presented whereby the relationship between internal hippocampal theta oscillators is examined together with the activity of pyramidal cells, and GABAergic interneurons, of the cornu ammonis-1 (CA1) and subiculum (SUB) areas...
August 2, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28809797/optogenetic-investigation-of-arousal-circuits
#8
REVIEW
Susan M Tyree, Luis de Lecea
Modulation between sleep and wake states is controlled by a number of heterogeneous neuron populations. Due to the topological proximity and genetic co-localization of the neurons underlying sleep-wake state modulation optogenetic methods offer a significant improvement in the ability to benefit from both the precision of genetic targeting and millisecond temporal control. Beginning with an overview of the neuron populations mediating arousal, this review outlines the progress that has been made in the investigation of arousal circuits since the incorporation of optogenetic techniques and the first in vivo application of optogenetic stimulation in hypocretin neurons in the lateral hypothalamus...
August 15, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28807859/widespread-functional-opsin-transduction-in-the-rat-cortex-via-convection-enhanced-delivery-optimized-for-horizontal-spread
#9
Zeyang Yu, Arto Nurmikko, Ilker Ozden
BACKGROUND: Widespread opsin expression in the cortex of rats, where transgenic models have not been established, is not practical to achieve with the traditional diffusion-based virus transduction methods (DBD). NEW METHOD: We developed protocols for convection-enhanced delivery (CED) of virus for optogenetic transduction of the rat cortex. Targeting the motor forelimb area as an example, we performed dual-site CED (6 μL of virus per site, 3 mm pitch between sites) in the rat motor cortex...
August 11, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/28807567/a-new-promoter-allows-optogenetic-vision-restoration-with-enhanced-sensitivity-in-macaque-retina
#10
Antoine Chaffiol, Romain Caplette, Céline Jaillard, Elena Brazhnikova, Mélissa Desrosiers, Elisabeth Dubus, Laëtitia Duhamel, Emilie Macé, Olivier Marre, Patrick Benoit, Philippe Hantraye, Alexis-Pierre Bemelmans, Ernst Bamberg, Jens Duebel, José-Alain Sahel, Serge Picaud, Deniz Dalkara
The majority of inherited retinal degenerations converge on the phenotype of photoreceptor cell death. Second- and third-order neurons are spared in these diseases, making it possible to restore retinal light responses using optogenetics. Viral expression of channelrhodopsin in the third-order neurons under ubiquitous promoters was previously shown to restore visual function, albeit at light intensities above illumination safety thresholds. Here, we report (to our knowledge, for the first time) activation of macaque retinas, up to 6 months post-injection, using channelrhodopsin-Ca(2+)-permeable channelrhodopsin (CatCh) at safe light intensities...
July 20, 2017: Molecular Therapy: the Journal of the American Society of Gene Therapy
https://www.readbyqxmd.com/read/28806219/selective-activation-of-basal-forebrain-cholinergic-neurons-attenuates-polymicrobial-sepsis-induced-inflammation-via-the-cholinergic-anti-inflammatory-pathway
#11
Qian Zhai, Dengming Lai, Ping Cui, Rui Zhou, Qixing Chen, Jinchao Hou, Yunting Su, Libiao Pan, Hui Ye, Jing-Wei Zhao, Xiangming Fang
OBJECTIVES: Basal forebrain cholinergic neurons are proposed as a major neuromodulatory system in inflammatory modulation. However, the function of basal forebrain cholinergic neurons in sepsis is unknown, and the neural pathways underlying cholinergic anti-inflammation remain unexplored. DESIGN: Animal research. SETTING: University research laboratory. SUBJECTS: Male wild-type C57BL/6 mice and ChAT-ChR2-EYFP (ChAT) transgenic mice...
August 10, 2017: Critical Care Medicine
https://www.readbyqxmd.com/read/28806053/de-blurring-signal-network-dynamics
#12
Dominic Kamps, Leif Dehmelt
To orchestrate the function and development of multicellular organisms, cells integrate intra- and extracellular information. This information is processed via signal networks in space and time, steering dynamic changes in cellular structure and function. Defects in those signal networks can lead to developmental disorders or cancer. However, experimental analysis of signal networks is challenging as their state changes dynamically and differs between individual cells. Thus, causal relationships between network components are blurred if lysates from large cell populations are analyzed...
August 14, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28805800/optogenetic-control-of-kinetochore-function
#13
Huaiying Zhang, Chanat Aonbangkhen, Ekaterina V Tarasovetc, Edward R Ballister, David M Chenoweth, Michael A Lampson
Kinetochores act as hubs for multiple activities during cell division, including microtubule interactions and spindle checkpoint signaling. Each kinetochore can act autonomously, and activities change rapidly as proteins are recruited to, or removed from, kinetochores. Understanding this dynamic system requires tools that can manipulate kinetochores on biologically relevant temporal and spatial scales. Optogenetic approaches have the potential to provide temporal and spatial control with molecular specificity...
August 14, 2017: Nature Chemical Biology
https://www.readbyqxmd.com/read/28803873/neural-circuitry-that-evokes-escape-behavior-upon-activation-of-nociceptive-sensory-neurons-in-drosophila-larvae
#14
Jiro Yoshino, Rei K Morikawa, Eri Hasegawa, Kazuo Emoto
Noxious stimuli trigger a stereotyped escape response in animals. In Drosophila larvae, class IV dendrite arborization (C4 da) sensory neurons in the peripheral nervous system are responsible for perception of multiple nociceptive modalities, including noxious heat and harsh mechanical stimulation, through distinct receptors [1-9]. Silencing or ablation of C4 da neurons largely eliminates larval responses to noxious stimuli [10-12], whereas optogenetic activation of C4 da neurons is sufficient to provoke corkscrew-like rolling behavior similar to what is observed when larvae receive noxious stimuli, such as high temperature or harsh mechanical stimulation [10-12]...
August 4, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28802101/flexible-biodegradable-citrate-based-polymeric-step-index-optical-fiber
#15
Dingying Shan, Chenji Zhang, Surge Kalaba, Nikhil Mehta, Gloria B Kim, Zhiwen Liu, Jian Yang
Implanting fiber optical waveguides into tissue or organs for light delivery and collection is among the most effective ways to overcome the issue of tissue turbidity, a long-standing obstacle for biomedical optical technologies. Here, we report a citrate-based material platform with engineerable opto-mechano-biological properties and demonstrate a new type of biodegradable, biocompatible, and low-loss step-index optical fiber for organ-scale light delivery and collection. By leveraging the rich designability and processibility of citrate-based biodegradable polymers, two exemplary biodegradable elastomers with a fine refractive index difference and yet matched mechanical properties and biodegradation profiles were developed...
August 4, 2017: Biomaterials
https://www.readbyqxmd.com/read/28800085/recent-progress-of-development-of-optogenetic-implantable-neural-probes
#16
REVIEW
Hubin Zhao
As a cell type-specific neuromodulation method, optogenetic technique holds remarkable potential for the realisation of advanced neuroprostheses. By genetically expressing light-sensitive proteins such as channelrhodopsin-2 (ChR2) in cell membranes, targeted neurons could be controlled by light. This new neuromodulation technique could then be applied into extensive brain networks and be utilised to provide effective therapies for neurological disorders. However, the development of novel optogenetic implants is still a key challenge in the field...
August 11, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28798945/optogenetic-stimulation-and-recording-of-primary-cultured-neurons-with-spatiotemporal-control
#17
Jérémie Barral, Alex D Reyes
We studied a network of cortical neurons in culture and developed an innovative optical device to stimulate optogenetically a large neuronal population with both spatial and temporal precision. We first describe how to culture primary neurons expressing channelrhodopsin. We then detail the optogenetic setup based on the workings of a fast Digital Light Processing (DLP) projector. The setup is able to stimulate tens to hundreds neurons with independent trains of light pulses that evoked action potentials with high temporal resolution...
June 20, 2017: Bio-protocol
https://www.readbyqxmd.com/read/28795515/multiplexed-optogenetic-stimulation-of-neurons-with-spectrum-selective-upconversion-nanoparticles
#18
Xudong Lin, Ying Wang, Xian Chen, Runhuai Yang, Zixun Wang, Jingyu Feng, Haitao Wang, King W C Lai, Jufang He, Feng Wang, Peng Shi
Optical modulation of nervous system becomes increasingly popular as the wide adoption of optogenetics. For these applications, upconversion materials hold great promise as novel photonic elements. This study describes an upconversion based strategy for combinatorial neural stimulation both in vitro and in vivo by using spectrum-selective upconversion nanoparticles (UCNPs). NaYF4 based UCNPs are used to absorb near-infrared (NIR) energy and to emit visible light for stimulating neurons expressing different channelrhodopsin (ChR) proteins...
August 10, 2017: Advanced Healthcare Materials
https://www.readbyqxmd.com/read/28794102/optogenetics-and-pharmacogenetics-principles-and-applications
#19
Jingwei Jiang, Huxing Cui, Kamal Rahmouni
Remote and selective spatiotemporal control of the activity of neurons to regulate behavior and physiological functions has been a long-sought goal in system neuroscience. Identification and subsequent bioengineering of light-sensitive ion channels (e.g., channelrhodopsins, halorhodopsin and archaerhodopsins) from the bacteria has made it possible to utilize light to artificially modulate neuronal activity, namely optogenetics. Recent advance in genetics has also allowed development of novel pharmacological tools to selectively and remotely control neuronal activity using engineered G-protein coupled receptors which can be activated by otherwise inert drug-like small molecules such as the Designer Receptors Exclusively Activated by Designer Drug (DREADD) - a form of chemogenetics...
August 9, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28793264/vesicle-docking-is-a-key-target-of-local-pi-4-5-p2-metabolism-in-the-secretory-pathway-of-ins-1-cells
#20
Chen Ji, Fan Fan, Xuelin Lou
Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) signaling is transient and spatially confined in live cells. How this pattern of signaling regulates transmitter release and hormone secretion has not been addressed. We devised an optogenetic approach to control PI(4,5)P2 levels in time and space in insulin-secreting cells. Combining this approach with total internal reflection fluorescence microscopy, we examined individual vesicle-trafficking steps. Unlike long-term PI(4,5)P2 perturbations, rapid and cell-wide PI(4,5)P2 reduction in the plasma membrane (PM) strongly inhibits secretion and intracellular Ca(2+) concentration ([Ca(2+)]i) responses, but not sytaxin1a clustering...
August 8, 2017: Cell Reports
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