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Wienisch, Martin

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Wienisch

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Martin

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Wienisch, Martin
Author's Publications: search.filters.isAuthorOfPublication.cccc93d7-b807-455f-a460-5efae1af25c6

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Now showing 1 - 4 of 4
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    Population imaging at subcellular resolution supports specific and local inhibition by granule cells in the olfactory bulb
    (Nature Publishing Group, 2016) Wienisch, Martin; Murthy, Venkatesh
    Information processing in early sensory regions is modulated by a diverse range of inhibitory interneurons. We sought to elucidate the role of olfactory bulb interneurons called granule cells (GCs) in odor processing by imaging the activity of hundreds of these cells simultaneously in mice. Odor responses in GCs were temporally diverse and spatially disperse, with some degree of non-random, modular organization. The overall sparseness of activation of GCs was highly correlated with the extent of glomerular activation by odor stimuli. Increasing concentrations of single odorants led to proportionately larger population activity, but some individual GCs had non-monotonic relations to concentration due to local inhibitory interactions. Individual dendritic segments could sometimes respond independently to odors, revealing their capacity for compartmentalized signaling in vivo. Collectively, the response properties of GCs point to their role in specific and local processing, rather than global operations such as response normalization proposed for other interneurons.
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    Erratum: Distinct spatiotemporal activity in principal neurons of the mouse olfactory bulb in anesthetized and awake states
    (Frontiers Media S.A., 2013) Blauvelt, David Gregory; Sato, Tomokazu F.; Wienisch, Martin; Knöpfel, Thomas; Murthy, Venkatesh
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    Optophysiological Analysis of Associational Circuits in the Olfactory Cortex
    (Frontiers Research Foundation, 2012) Hagiwara, Akari; Pal, Sumon K.; Sato, Tomokazu F.; Wienisch, Martin; Murthy, Venkatesh
    Primary olfactory cortical areas receive direct input from the olfactory bulb, but also have extensive associational connections that have been mainly studied with classical anatomical methods. Here, we shed light on the functional properties of associational connections in the anterior and posterior piriform cortices (aPC and pPC) using optophysiological methods. We found that the aPC receives dense functional connections from the anterior olfactory nucleus (AON), a major hub in olfactory cortical circuits. The local recurrent connectivity within the aPC, long invoked in cortical autoassociative models, is sparse and weak. By contrast, the pPC receives negligible input from the AON, but has dense connections from the aPC as well as more local recurrent connections than the aPC. Finally, there are negligible functional connections from the pPC to aPC. Our study provides a circuit basis for a more sensory role for the aPC in odor processing and an associative role for the pPC.
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    Distinct Spatiotemporal Activity in Principal Neurons of the Mouse Olfactory Bulb in Anesthetized and Awake States
    (Frontiers Media S.A., 2013) Blauvelt, David Gregory; Sato, Tomokazu F.; Wienisch, Martin; Murthy, Venkatesh
    The acquisition of olfactory information and its early processing in mammals are modulated by brain states through sniffing behavior and neural feedback. We imaged the spatiotemporal pattern of odor-evoked activity in a population of output neurons (mitral/tufted cells, MTCs) in the olfactory bulb (OB) of head-restrained mice expressing a genetically-encoded calcium indicator. The temporal dynamics of MTC population activity were relatively simple in anesthetized animals, but were highly variable in awake animals. However, the apparently irregular activity in awake animals could be predicted well using sniff timing measured externally, or inferred through fluctuations in the global responses of MTC population even without explicit knowledge of sniff times. The overall spatial pattern of activity was conserved across states, but odor responses had a diffuse spatial component in anesthetized mice that was less prominent during wakefulness. Multi-photon microscopy indicated that MTC lateral dendrites were the likely source of spatially disperse responses in the anesthetized animal. Our data demonstrate that the temporal and spatial dynamics of MTCs can be significantly modulated by behavioral state, and that the ensemble activity of MTCs can provide information about sniff timing to downstream circuits to help decode odor responses.