Main Menu (Mobile)- Block

Main Menu - Block

janelia7_blocks-janelia7_fake_breadcrumb | block
Koyama Lab / Publications
custom | custom


facetapi-Q2b17qCsTdECvJIqZJgYMaGsr8vANl1n | block

Associated Lab

facetapi-W9JlIB1X0bjs93n1Alu3wHJQTTgDCBGe | block
facetapi-PV5lg7xuz68EAY8eakJzrcmwtdGEnxR0 | block
facetapi-021SKYQnqXW6ODq5W5dPAFEDBaEJubhN | block
general_search_page-panel_pane_1 | views_panes

192 Publications

Showing 101-110 of 192 results
Your Criteria:
    06/14/13 | Parallel neural pathways mediate CO2 avoidance responses in Drosophila.
    Lin H, Chu L, Fu T, Dickson BJ, Chiang A
    Science. 2013 Jun 14;340(6138):1338-41. doi: 10.1126/science.1236693

    Different stimulus intensities elicit distinct perceptions, implying that input signals are either conveyed through an overlapping but distinct subpopulation of sensory neurons or channeled into divergent brain circuits according to intensity. In Drosophila, carbon dioxide (CO2) is detected by a single type of olfactory sensory neuron, but information is conveyed to higher brain centers through second-order projection neurons (PNs). Two distinct pathways, PN(v)-1 and PN(v)-2, are necessary and sufficient for avoidance responses to low and high CO2 concentrations, respectively. Whereas low concentrations activate PN(v)-1, high concentrations activate both PN(v)s and GABAergic PN(v)-3, which may inhibit PN(v)-1 pathway-mediated avoidance behavior. Channeling a sensory input into distinct neural pathways allows the perception of an odor to be further modulated by both stimulus intensity and context.

    View Publication Page
    Riddiford Lab
    06/11/13 | Microarrays reveal discrete phases in juvenile hormone regulation of mosquito reproduction.
    Riddiford LM
    Proceedings of the National Academy of Sciences of the United States of America. 2013 Jun 11;110(24):9623-4. doi: 10.1073/pnas.1307487110
    06/08/13 | Essential role of the mushroom body in context-dependent CO2 avoidance in Drosophila.
    Bräcker LB, Siju KP, Varela N, Aso Y, Zhang M, Hein I, Vasconcelos ML, Grunwald Kadow IC
    Current Biology. 2013 Jul 8;23(13):1228-34. doi: 10.1016/j.cub.2013.05.029

    Internal state as well as environmental conditions influence choice behavior. The neural circuits underpinning state-dependent behavior remain largely unknown. Carbon dioxide (CO2) is an important olfactory cue for many insects, including mosquitoes, flies, moths, and honeybees [1]. Concentrations of CO2 higher than 0.02% above atmospheric level trigger a strong innate avoidance in the fly Drosophila melanogaster [2, 3]. Here, we show that the mushroom body (MB), a brain center essential for olfactory associative memories [4-6] but thought to be dispensable for innate odor processing [7], is essential for CO2 avoidance behavior only in the context of starvation or in the context of a food-related odor. Consistent with this, CO2 stimulation elicits Ca(2+) influx into the MB intrinsic cells (Kenyon cells: KCs) in vivo. We identify an atypical projection neuron (bilateral ventral projection neuron, biVPN) that connects CO2 sensory input bilaterally to the MB calyx. Blocking synaptic output of the biVPN completely abolishes CO2 avoidance in food-deprived flies, but not in fed flies. These findings show that two alternative neural pathways control innate choice behavior, and they are dependent on the animal’s internal state. In addition, they suggest that, during innate choice behavior, the MB serves as an integration site for internal state and olfactory input.

    View Publication Page
    06/07/13 | Imaging morphogenesis: technological advances and biological insights.
    Keller PJ
    Science. 2013 Jun 7;340(6137):1234168. doi: 10.1126/science.1234168

    Morphogenesis, the development of the shape of an organism, is a dynamic process on a multitude of scales, from fast subcellular rearrangements and cell movements to slow structural changes at the whole-organism level. Live-imaging approaches based on light microscopy reveal the intricate dynamics of this process and are thus indispensable for investigating the underlying mechanisms. This Review discusses emerging imaging techniques that can record morphogenesis at temporal scales from seconds to days and at spatial scales from hundreds of nanometers to several millimeters. To unlock their full potential, these methods need to be matched with new computational approaches and physical models that help convert highly complex image data sets into biological insights.

    Science Profile: A Research Career in Focus

    View Publication Page
    06/06/13 | Two-photon calcium imaging during fictive navigation in virtual environments.
    Ahrens MB, Huang KH, Narayan S, Mensh BD, Engert F
    Frontiers in Neural Circuits. 2013 Jun 6;7:104. doi: 10.3389/fncir.2013.00104 *equal contribution

    A full understanding of nervous system function requires recording from large populations of neurons during naturalistic behaviors. Here we enable paralyzed larval zebrafish to fictively navigate two-dimensional virtual environments while we record optically from many neurons with two-photon imaging. Electrical recordings from motor nerves in the tail are decoded into intended forward swims and turns, which are used to update a virtual environment displayed underneath the fish. Several behavioral features-such as turning responses to whole-field motion and dark avoidance-are well-replicated in this virtual setting. We readily observed neuronal populations in the hindbrain with laterally selective responses that correlated with right or left optomotor behavior. We also observed neurons in the habenula, pallium, and midbrain with response properties specific to environmental features. Beyond single-cell correlations, the classification of network activity in such virtual settings promises to reveal principles of brainwide neural dynamics during behavior.

    View Publication Page
    06/05/13 | ASI regulates satiety quiescence in C. elegans.
    Gallagher T, Kim J, Oldenbroek M, Kerr R, You Y
    The Journal of Neuroscience : The Official Journal of the Society for Neuroscience. 2013 Jun 5;33(23):9716-24. doi: 10.1523/JNEUROSCI.4493-12.2013

    In Caenorhabditis elegans, satiety quiescence mimics behavioral aspects of satiety and postprandial sleep in mammals. On the basis of calcium-imaging, genetics, and behavioral studies, here we report that a pair of amphid neurons, ASI, is activated by nutrition and regulates worms’ behavioral states specifically promoting satiety quiescence; ASI inhibits the switch from quiescence to dwelling (a browsing state) and accelerates the switch from dwelling to quiescence. The canonical TGFβ pathway, whose ligand is released from ASI, regulates satiety quiescence. The mutants of a ligand, a receptor and SMADs in the TGFβ pathway all eat more and show less quiescence than wild-type. The TGFβ receptor in downstream neurons RIM and RIC is sufficient for worms to exhibit satiety quiescence, suggesting neuronal connection from ASI to RIM and RIC is essential for feeding regulation through the TGFβ pathway. ASI also regulates satiety quiescence partly through cGMP signaling; restoring cGMP signaling in ASI rescues the satiety quiescence defect of cGMP signaling mutants. From these results, we propose that TGFβ and cGMP pathways in ASI connect nutritional status to promotion of satiety quiescence, a sleep-like behavioral state.

    View Publication Page
    Svoboda Lab
    06/02/13 | Neural coding during active somatosensation revealed using illusory touch.
    O’Connor DH, Hires SA, Guo ZV, Li N, Yu J, Sun Q, Huber D, Svoboda K
    Nature Neuroscience. 2013 Jun 2;16(7):958-65. doi: 10.1038/nn.3419

    Active sensation requires the convergence of external stimuli with representations of body movements. We used mouse behavior, electrophysiology and optogenetics to dissect the temporal interactions among whisker movement, neural activity and sensation of touch. We photostimulated layer 4 activity in single barrels in a closed loop with whisking. Mimicking touch-related neural activity caused illusory perception of an object at a particular location, but scrambling the timing of the spikes over one whisking cycle (tens of milliseconds) did not abolish the illusion, indicating that knowledge of instantaneous whisker position is unnecessary for discriminating object locations. The illusions were induced only during bouts of directed whisking, when mice expected touch, and in the relevant barrel. Reducing activity biased behavior, consistent with a spike count code for object detection at a particular location. Our results show that mice integrate coding of touch with movement over timescales of a whisking bout to produce perception of active touch.

    View Publication Page
    06/01/13 | A Schnurri/Mad/Medea complex attenuates the dorsal-twist gradient readout at vnd.
    Crocker J, Erives A
    Dev Biol. 2013 Jun 01;378(1):64-72. doi: 10.1016/j.ydbio.2013.03.002

    Morphogen gradients are used in developing embryos, where they subdivide a field of cells into territories characterized by distinct cell fate potentials. Such systems require both a spatially-graded distribution of the morphogen, and an ability to encode different responses at different target genes. However, the potential for different temporal responses is also present because morphogen gradients typically provide temporal cues, which may be a potential source of conflict. Thus, a low threshold response adapted for an early temporal onset may be inappropriate when the desired spatial response is a spatially-limited, high-threshold expression pattern. Here, we identify such a case with the Drosophila vnd locus, which is a target of the dorsal (dl) nuclear concentration gradient that patterns the dorsal/ventral (D/V) axis of the embryo. The vnd gene plays a critical role in the "ventral dominance" hierarchy of vnd, ind, and msh, which individually specify distinct D/V neural columnar fates in increasingly dorsal ectodermal compartments. The role of vnd in this regulatory hierarchy requires early temporal expression, which is characteristic of low-threshold responses, but its specification of ventral neurogenic ectoderm demands a relatively high-threshold response to dl. We show that the Neurogenic Ectoderm Enhancer (NEE) at vnd takes additional input from the complementary Dpp gradient via a conserved Schnurri/Mad/Medea silencer element (SSE) unlike NEEs at brk, sog, rho, and vn. These results show how requirements for conflicting temporal and spatial responses to the same gradient can be solved by additional inputs from complementary gradients.

    View Publication Page
    06/01/13 | APP2: automatic tracing of 3D neuron morphology based on hierarchical pruning of a gray-weighted image distance-tree.
    Xiao H, Peng H
    Bioinformatics (Oxford, England). 2013 Jun 1;29:1448-54. doi: 10.1093/bioinformatics/btt170

    Tracing of neuron morphology is an essential technique in computational neuroscience. However, despite a number of existing methods, few open-source techniques are completely or sufficiently automated and at the same time are able to generate robust results for real 3D microscopy images.

    View Publication Page
    Looger Lab
    06/01/13 | Genetically encoded calcium indicators and astrocyte calcium microdomains.
    Tong X, Shigetomi E, Looger LL, Khakh BS
    The Neuroscientist : A Review Journal Bringing Neurobiology, Neurology and Psychiatry. 2013 Jun;19(3):274-91. doi: 10.1177/1073858412468794

    The discovery of intracellular Ca(2+) signals within astrocytes has changed our view of how these ubiquitous cells contribute to brain function. Classically thought merely to serve supportive functions, astrocytes are increasingly thought to respond to, and regulate, neurons. The use of organic Ca(2+) indicator dyes such as Fluo-4 and Fura-2 has proved instrumental in the study of astrocyte physiology. However, progress has recently been accelerated by the use of cytosolic and membrane targeted genetically encoded calcium indicators (GECIs). Herein, we review these recent findings, discuss why studying astrocyte Ca(2+) signals is important to understand brain function, and summarize work that led to the discovery of TRPA1 channel-mediated near-membrane Ca(2+) signals in astrocytes and their indirect neuromodulatory roles at inhibitory synapses in the CA1 stratum radiatum region of the hippocampus. We suggest that the use of membrane-targeted and cytosolic GECIs holds great promise to explore the diversity of Ca(2+) signals within single astrocytes and also to study diversity of function for astrocytes in different parts of the brain.

    View Publication Page