@article {48979, title = {Chemogenetic tools for causal cellular and neuronal biology.}, journal = {Physiological Reviews}, year = {2017}, month = {2017 Dec 12}, abstract = {

Chemogenetic technologies enable selective pharmacological control of specific cell populations. An increasing number of approaches have been developed that modulate different signaling pathways. Selective pharmacological control over G protein-coupled receptor signaling, ion channel conductances, protein association, protein stability, and small molecule targeting allows modulation of cellular processes in distinct cell types. Here, we review these chemogenetic technologies and instances of their applications in complex tissues in vivo and ex vivo.

}, doi = {10.1152/physrev.00009.2017}, author = {Atasoy, Deniz and Sternson, Scott M} } @inbook {48432, title = {Functional and anatomical dissection of feeding circuits.}, booktitle = {Neuroendocrinology of Appetite}, year = {2016}, pages = {112-133}, abstract = {

This chapter reviews the application of new genetically encoded tools in feeding circuits that regulate appetite. Rapid activation and inhibition of agouti related peptide (AgRP) neurons conclusively established a causal role for rapid control of food intake. Chemogenetic activation of AgRP neurons using hM3Dq avoids the invasive protocols required for ChR2 activation. ChR2 distributes into axons, and selective optogenetic activation of AgRP neuron axon projection fields in distinct brain areas was used to examine their individual contribution to feeding behavior. Some of the brain areas targeted by AgRP neuron axon projections have been examined further for cell type specific control of appetite. Rodents with bed nucleus of stria terminalis (BNST) lesions show hyperphagia and obesity, indicating that reduced BNST output promotes feeding. pro-opiomelanocortin (POMC) neurons regulate feeding over longer timescales. parabrachial nucleus (PBN) neurons have a powerful inhibitory role on food intake, but their inhibition does not strongly elevate food intake.

}, doi = {10.1002/9781118839317.ch6}, author = {Atasoy, Deniz and Sternson, Scott M} } @article {47263, title = {An emerging technology framework for the neurobiology of appetite.}, journal = {Cell Metabolism}, volume = {23}, year = {2015}, month = {2015 Dec 24}, pages = {234-53}, abstract = {

Advances in neuro-technology for mapping, manipulating, and monitoring molecularly defined cell types are rapidly advancing insight into neural circuits that regulate appetite. Here, we review these important tools and their applications in circuits that control food seeking and consumption. Technical capabilities provided by these tools establish a rigorous experimental framework for research into the neurobiology of hunger.

}, doi = {10.1016/j.cmet.2015.12.002}, author = {Sternson, Scott M and Atasoy, Deniz and Betley, J Nicholas and Henry, Fredrick E and Xu, Sheng-jin} } @article {45717, title = {Agouti-related protein neuron circuits that regulate appetite.}, journal = {Neuroendocrinology}, volume = {507}, year = {2014}, month = {2014 Nov 6}, pages = {238-42}, abstract = {

New tools for mapping and manipulating molecularly defined neural circuits have improved understanding of how the central nervous system regulates appetite. Studies focused on AGRP neurons, a starvation-sensitive hypothalamic population, have identified multiple circuit elements that can elicit or suppress feeding behavior. Distinct axon projections of this neuron population point to different circuits that regulate long-term appetite, short-term feeding, or visceral malaise-mediated anorexia. Here, we review recent studies examining these neural circuits that control food intake. {\textcopyright} 2014 S. Karger AG, Basel.

}, issn = {1423-0194}, doi = {10.1159/000369072}, author = {Sternson, Scott M and Atasoy, Deniz} } @article {45696, title = {A genetically specified connectomics approach applied to long-range feeding regulatory circuits.}, journal = {Nature Neuroscience}, volume = {17}, year = {2014}, month = {2014 Dec}, pages = {1830-9}, abstract = {

Synaptic connectivity and molecular composition provide a blueprint for information processing in neural circuits. Detailed structural analysis of neural circuits requires nanometer resolution, which can be obtained with serial-section electron microscopy. However, this technique remains challenging for reconstructing molecularly defined synapses. We used a genetically encoded synaptic marker for electron microscopy (GESEM) based on intra-vesicular generation of electron-dense labeling in axonal boutons. This approach allowed the identification of synapses from Cre recombinase-expressing or GAL4-expressing neurons in the mouse and fly with excellent preservation of ultrastructure. We applied this tool to visualize long-range connectivity of AGRP and POMC neurons in the mouse, two molecularly defined hypothalamic populations that are important for feeding behavior. Combining selective ultrastructural reconstruction of neuropil with functional and viral circuit mapping, we characterized some basic features of circuit organization for axon projections of these cell types. Our findings demonstrate that GESEM labeling enables long-range connectomics with molecularly defined cell types.

}, issn = {1546-1726}, doi = {10.1038/nn.3854}, author = {Atasoy, Deniz and Betley, J Nicholas and Li, Wei-Ping and Su, Helen H and Sertel, Sinem M and Scheffer, Louis K and Simpson, Julie H and Fetter, Richard D and Sternson, Scott M} } @article {5136, title = {Deconstruction of a neural circuit for hunger.}, journal = {Nature}, volume = {488}, year = {2012}, month = {2012 Aug 9}, pages = {172-7}, abstract = {

Hunger is a complex behavioural state that elicits intense food seeking and consumption. These behaviours are rapidly recapitulated by activation of starvation-sensitive AGRP neurons, which present an entry point for reverse-engineering neural circuits for hunger. Here we mapped synaptic interactions of AGRP neurons with multiple cell populations in mice and probed the contribution of these distinct circuits to feeding behaviour using optogenetic and pharmacogenetic techniques. An inhibitory circuit with paraventricular hypothalamus (PVH) neurons substantially accounted for acute AGRP neuron-evoked eating, whereas two other prominent circuits were insufficient. Within the PVH, we found that AGRP neurons target and inhibit oxytocin neurons, a small population that is selectively lost in Prader-Willi syndrome, a condition involving insatiable hunger. By developing strategies for evaluating molecularly defined circuits, we show that AGRP neuron suppression of oxytocin neurons is critical for evoked feeding. These experiments reveal a new neural circuit that regulates hunger state and pathways associated with overeating disorders.

}, issn = {1476-4687}, doi = {10.1038/nature11270}, author = {Atasoy, Deniz and Betley, J Nicholas and Su, Helen H and Sternson, Scott M} } @article {3309, title = {AGRP neurons are sufficient to orchestrate feeding behavior rapidly and without training.}, journal = {Nature Neuroscience}, volume = {14}, year = {2011}, month = {2011 Mar}, pages = {351-5}, abstract = {

Two intermingled hypothalamic neuron populations specified by expression of agouti-related peptide (AGRP) or pro-opiomelanocortin (POMC) positively and negatively influence feeding behavior, respectively, possibly by reciprocally regulating downstream melanocortin receptors. However, the sufficiency of these neurons to control behavior and the relationship of their activity to the magnitude and dynamics of feeding are unknown. To measure this, we used channelrhodopsin-2 for cell type-specific photostimulation. Activation of only 800 AGRP neurons in mice evoked voracious feeding within minutes. The behavioral response increased with photoexcitable neuron number, photostimulation frequency and stimulus duration. Conversely, POMC neuron stimulation reduced food intake and body weight, which required melanocortin receptor signaling. However, AGRP neuron-mediated feeding was not dependent on suppressing this melanocortin pathway, indicating that AGRP neurons directly engage feeding circuits. Furthermore, feeding was evoked selectively over drinking without training or prior photostimulus exposure, which suggests that AGRP neurons serve a dedicated role coordinating this complex behavior.

}, keywords = {Agouti-Related Protein, Animal, Animals, Behavior, Classical, Conditioning, Eating, Feeding Behavior, Hypothalamus, Melanocortins, Mice, Neurons, Photic Stimulation, Pro-Opiomelanocortin, Recombinant Fusion Proteins, Rhodopsin}, issn = {1546-1726}, doi = {10.1038/nn.2739}, author = {Aponte, Yexica and Atasoy, Deniz and Sternson, Scott M} } @article {3977, title = {Chemical and genetic engineering of selective ion channel-ligand interactions.}, journal = {Science}, volume = {333}, year = {2011}, month = {2011 Sep 2}, pages = {1292-6}, abstract = {

Ionic flux mediates essential physiological and behavioral functions in defined cell populations. Cell type-specific activators of diverse ionic conductances are needed for probing these effects. We combined chemistry and protein engineering to enable the systematic creation of a toolbox of ligand-gated ion channels (LGICs) with orthogonal pharmacologic selectivity and divergent functional properties. The LGICs and their small-molecule effectors were able to activate a range of ionic conductances in genetically specified cell types. LGICs constructed for neuronal perturbation could be used to selectively manipulate neuron activity in mammalian brains in vivo. The diversity of ion channel tools accessible from this approach will be useful for examining the relationship between neuronal activity and animal behavior, as well as for cell biological and physiological applications requiring chemical control of ion conductance.

}, keywords = {5-HT3, Animals, Benzamides, Bicyclo Compounds, Brain, Feeding Behavior, Female, Glycine, HEK293 Cells, Humans, Inbred C57BL, Ion Channel Gating, Ligand-Gated Ion Channels, Ligands, Membrane Potentials, Mice, Mutagenesis, Neurons, Nicotinic, Patch-Clamp Techniques, Protein Binding, Protein Engineering, Protein Structure, Quinuclidines, Receptors, Recombinant Fusion Proteins, Serotonin, Small Molecule Libraries, Stereoisomerism, Tertiary}, issn = {1095-9203}, doi = {10.1126/science.1206606}, author = {Magnus, Christopher J and Lee, Peter H and Atasoy, Deniz and Su, Helen H and Looger, Loren L and Sternson, Scott M} } @article {3975, title = {Hunger states switch a flip-flop memory circuit via a synaptic AMPK-dependent positive feedback loop.}, journal = {Cell}, volume = {146}, year = {2011}, month = {2011 Sep 16}, pages = {992-1003}, abstract = {

Synaptic plasticity in response to changes in physiologic state is coordinated by hormonal signals across multiple neuronal cell types. Here, we combine cell-type-specific electrophysiological, pharmacological, and optogenetic techniques to dissect neural circuits and molecular pathways controlling synaptic plasticity onto AGRP neurons, a population that regulates feeding. We find that food deprivation elevates excitatory synaptic input, which is mediated by\ a presynaptic positive feedback loop involving AMP-activated protein kinase. Potentiation of glutamate release was triggered by the orexigenic hormone ghrelin and exhibited hysteresis, persisting for hours after ghrelin removal. Persistent activity was reversed by the anorexigenic hormone leptin, and optogenetic photostimulation demonstrated involvement of opioid release from POMC neurons. Based on these experiments, we propose a memory storage device for physiological state constructed from bistable synapses that are flipped between two sustained activity states by transient exposure to hormones signaling energy levels.

}, issn = {1097-4172}, doi = {10.1016/j.cell.2011.07.039}, author = {Yang, Yunlei and Atasoy, Deniz and Su, Helen H and Sternson, Scott M} } @article {2183, title = {Automatic reconstruction of 3D neuron structures using a graph-augmented deformable model.}, journal = {Bioinformatics}, volume = {26}, year = {2010}, month = {2010 Jun 15}, pages = {i38-46}, abstract = {

Digital reconstruction of 3D neuron structures is an important step toward reverse engineering the wiring and functions of a brain. However, despite a number of existing studies, this task is still challenging, especially when a 3D microscopic image has low single-to-noise ratio and discontinued segments of neurite patterns.

}, keywords = {Animals, Caenorhabditis elegans, Computer-Assisted, Drosophila, Image Processing, Imaging, Mice, Neurons, Three-Dimensional}, issn = {1367-4811}, doi = {10.1093/bioinformatics/btq212}, author = {Peng, Hanchuan and Ruan, Zongcai and Atasoy, Deniz and Sternson, Scott} } @article {2186, title = {A FLEX switch targets Channelrhodopsin-2 to multiple cell types for imaging and long-range circuit mapping.}, journal = {The Journal of Neuroscience: The Official Journal of the Society for Neuroscience}, volume = {28}, year = {2008}, month = {2008 Jul 9}, pages = {7025-30}, keywords = {3-dione, 6-Cyano-7-nitroquinoxaline-2, Animals, Arcuate Nucleus, Brain Mapping, Cell Line, Computer-Assisted, Dependovirus, Diagnostic Imaging, Excitatory Amino Acid Antagonists, Gene Expression Regulation, Green Fluorescent Proteins, Humans, Image Processing, Membrane Potentials, Mice, Nerve Net, Patch-Clamp Techniques, Photic Stimulation, Rhodopsin, Transfection, Transformed, Transgenic}, issn = {1529-2401}, doi = {10.1523/JNEUROSCI.1954-08.2008}, author = {Atasoy, Deniz and Aponte, Yexica and Su, Helen Hong and Sternson, Scott M} }