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16 Publications

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    09/03/18 | Topographic precision in sensory and motor corticostriatal projections varies across cell type and cortical area.
    Hooks BM, Papale AE, Paletzki RF, Feroze MW, Eastwood BS, Couey JJ, Winnubst J, Chandrashekar J, Gerfen CR
    Nature Communications. 2018 Sep 03;9(1):3549. doi: 10.1038/s41467-018-05780-7

    The striatum shows general topographic organization and regional differences in behavioral functions. How corticostriatal topography differs across cortical areas and cell types to support these distinct functions is unclear. This study contrasted corticostriatal projections from two layer 5 cell types, intratelencephalic (IT-type) and pyramidal tract (PT-type) neurons, using viral vectors expressing fluorescent reporters in Cre-driver mice. Corticostriatal projections from sensory and motor cortex are somatotopic, with a decreasing topographic specificity as injection sites move from sensory to motor and frontal areas. Topographic organization differs between IT-type and PT-type neurons, including injections in the same site, with IT-type neurons having higher topographic stereotypy than PT-type neurons. Furthermore, IT-type projections from interconnected cortical areas have stronger correlations in corticostriatal targeting than PT-type projections do. As predicted by a longstanding model, corticostriatal projections of interconnected cortical areas form parallel circuits in the basal ganglia.

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    04/10/18 | Dissociable structural and functional hippocampal outputs via distinct subiculum cell classes.
    Cembrowski MS, Phillips MG, DiLisio SF, Shields BC, Winnubst J, Chandrashekar J, Bas E, Spruston N
    Cell. 2018 Apr 10;173(5):1280-92. doi: 10.1016/j.cell.2018.03.031

    The mammalian hippocampus, comprised of serially connected subfields, participates in diverse behavioral and cognitive functions. It has been postulated that parallel circuitry embedded within hippocampal subfields may underlie such functional diversity. We sought to identify, delineate, and manipulate this putatively parallel architecture in the dorsal subiculum, the primary output subfield of the dorsal hippocampus. Population and single-cell RNA-seq revealed that the subiculum can be divided into two spatially adjacent subregions associated with prominent differences in pyramidal cell gene expression. Pyramidal cells occupying these two regions differed in their long-range inputs, local wiring, projection targets, and electrophysiological properties. Leveraging gene-expression differences across these regions, we use genetically restricted neuronal silencing to show that these regions differentially contribute to spatial working memory. This work provides a coherent molecular-, cellular-, circuit-, and behavioral-level demonstration that the hippocampus embeds structurally and functionally dissociable streams within its serial architecture.

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    02/07/18 | Cell type-specific variation of somatotopic precision across corticostriatal projections.
    Hooks BM, Papale AE, Paletzki R, Feroze M, Eastwood BS, Couey JJ, Winnubst J, Chandrashekar J, Gerfen CR
    bioRxiv. 2018 Feb 7:. doi: 10.1101/261446

    The striatum shows general topographic organization and regional differences in behavioral functions. How corticostriatal topography differs across cortical areas and cell types to support these distinct functions is unclear. This study contrasted corticostriatal projections from two layer 5 cell types, intratelencephalic (IT-type) and pyramidal tract (PT-type) neurons, using viral vectors expressing fluorescent reporters in Cre-driver mice. Long-range corticostriatal projections from sensory and motor cortex are somatotopic, with a decreasing somatotopic specificity as injections move from sensory to motor and frontal areas. Somatotopic organization differs between IT-type and PT-type neurons, including injections in the same site, with IT-type neurons having higher somatotopic stereotypy than PT-type neurons. Furthermore, IT-type projections from interconnected cortical areas have stronger correlations in corticostriatal targeting than PT-type projections do. Thus, as predicted by a long-standing basal ganglia model, corticostriatal projections of interconnected cortical areas form parallel circuits in basal ganglia-thalamus-cortex loops.

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    Svoboda LabMouseLight
    11/12/16 | Long distance projections of cortical pyramidal neurons.
    Gerfen CR, Economo MN, Chandrashekar J
    Journal of Neuroscience Research. 2016 Nov 12:. doi: 10.1002/jnr.23978

    The neuronal circuits defined by the axonal projections of pyramidal neurons in the cerebral cortex are responsible for processing sensory and other information to plan and execute behavior. Subtypes of cortical pyramidal neurons are organized across layers, with those in different layers distinguished by their patterns of axonal projections and connectivity. For example, those in layers 2 and 3 project between cortical areas to integrate sensory and other information with motor areas; while those in layers 5 and 6 also integrate information between cortical areas, but also project to subcortical structures involved in the generation of behavior. Recent advances in neuroanatomical techniques allow one to target specific subtypes of cortical pyramidal neurons and label both their inputs and projections. Combining these methods with neurophysiological recording techniques and newly introduced atlases of the mouse brain provide the opportunity to achieve a detailed view of the organization of cerebral cortical circuits.

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    01/20/16 | A platform for brain-wide imaging and reconstruction of individual neurons.
    Economo MN, Clack NG, Lavis LD, Gerfen CR, Svoboda K, Myers EW, Chandrashekar J
    eLife. 2016 Jan 20;5:. doi: 10.7554/eLife.10566

    The structure of axonal arbors controls how signals from individual neurons are routed within the mammalian brain. However, the arbors of very few long-range projection neurons have been reconstructed in their entirety, as axons with diameters as small as 100 nm arborize in target regions dispersed over many millimeters of tissue. We introduce a platform for high-resolution, three-dimensional fluorescence imaging of complete tissue volumes that enables the visualization and reconstruction of long-range axonal arbors. This platform relies on a high-speed two-photon microscope integrated with a tissue vibratome and a suite of computational tools for large-scale image data. We demonstrate the power of this approach by reconstructing the axonal arbors of multiple neurons in the motor cortex across a single mouse brain.

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    Zuker LabMouseLight
    01/15/15 | The neural representation of taste quality at the periphery.
    Barretto RP, Gillis-Smith S, Chandrashekar J, Yarmolinsky DA, Schnitzer MJ, Ryba NJ, Zuker CS
    Nature. 2015 Jan 15;517(7534):373-6. doi: 10.1038/nature13873

    The mammalian taste system is responsible for sensing and responding to the five basic taste qualities: sweet, sour, bitter, salty and umami. Previously, we showed that each taste is detected by dedicated taste receptor cells (TRCs) on the tongue and palate epithelium. To understand how TRCs transmit information to higher neural centres, we examined the tuning properties of large ensembles of neurons in the first neural station of the gustatory system. Here, we generated and characterized a collection of transgenic mice expressing a genetically encoded calcium indicator in central and peripheral neurons, and used a gradient refractive index microendoscope combined with high-resolution two-photon microscopy to image taste responses from ganglion neurons buried deep at the base of the brain. Our results reveal fine selectivity in the taste preference of ganglion neurons; demonstrate a strong match between TRCs in the tongue and the principal neural afferents relaying taste information to the brain; and expose the highly specific transfer of taste information between taste cells and the central nervous system.

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