Simultaneous Encoding of Odors by Channels with Diverse Sensitivity to Inhibition

Hong, Elizabeth J.; Wilson, Rachel I.

doi:10.1016/j.neuron.2014.12.040

Cited by 81 publications

(115 citation statements)

References 76 publications

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“…Alternatively, variations in the receptor sensitivities could be balanced by more complex inhibition mechanism. For instance, experiments show that different projection neurons have different susceptibilities to inhibition [43]. Here, the experimentally observed turnover of mitral/granule cells and interneurons [71] could adjust the inhibition mechanism locally, which could optimize the olfactory system for a given environment [54].…”

Section: Discussionmentioning

confidence: 99%

Normalized Neural Representations of Complex Odors

Zwicker

2016

PLoS ONE

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The olfactory system removes correlations in natural odors using a network of inhibitory neurons in the olfactory bulb. It has been proposed that this network integrates the response from all olfactory receptors and inhibits them equally. However, how such global inhibition influences the neural representations of odors is unclear. Here, we study a simple statistical model of the processing in the olfactory bulb, which leads to concentration-invariant, sparse representations of the odor composition. We show that the inhibition strength can be tuned to obtain sparse representations that are still useful to discriminate odors that vary in relative concentration, size, and composition. The model reveals two generic consequences of global inhibition: (i) odors with many molecular species are more difficult to discriminate and (ii) receptor arrays with heterogeneous sensitivities perform badly. Comparing these predictions to experiments will help us to understand the role of global inhibition in shaping normalized odor representations in the olfactory bulb.

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Section: Discussionmentioning

confidence: 99%

Normalized Neural Representations of Complex Odors

Zwicker

2016

PLoS ONE

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“…These modifications include lateral inhibition from other glomeruli onto ORN axon terminals to adjust the firing rate of projection neurons so they are mostly independent of odor concentration (a gain control mechanism; refs. 5-7, 9, 10), and other mechanisms to spread information about the odor environment more evenly over all of the glomeruli (3,6,7,9,10). Projection neurons have a background firing rate of about 5 Hz.…”

Section: Will Consider (Seementioning

confidence: 99%

What the fly’s nose tells the fly’s brain

Stevens

2015

Proc. Natl. Acad. Sci. U.S.A.

102

134

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The fly olfactory system has a three-layer architecture: The fly’s olfactory receptor neurons send odor information to the first layer (the encoder) where this information is formatted as combinatorial odor code, one which is maximally informative, with the most informative neurons firing fastest. This first layer then sends the encoded odor information to the second layer (decoder), which consists of about 2,000 neurons that receive the odor information and “break” the code. For each odor, the amplitude of the synaptic odor input to the 2,000 second-layer neurons is approximately normally distributed across the population, which means that only a very small fraction of neurons receive a large input. Each odor, however, activates its own population of large-input neurons and so a small subset of the 2,000 neurons serves as a unique tag for the odor. Strong inhibition prevents most of the second-stage neurons from firing spikes, and therefore spikes from only the small population of large-input neurons is relayed to the third stage. This selected population provides the third stage (the user) with an odor label that can be used to direct behavior based on what odor is present.

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“…Inhibition in the AL scales with increasing odor intensity and the spatial pattern of activation of GABAergic LNs is odor invariant (33). Inhibition of the CSDn also scales with odor intensity (30) but it is unknown if unique odors can recruit distinct spatial patterns of CSDn activity.…”

Section: Resultsmentioning

confidence: 99%

Regulation of modulatory cell activity across olfactory structures in Drosophila melanogaster

Zhang

Coates

Dacks

et al. 2019

Preprint

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SignificanceThe centrifugal innervation of neuronal circuits is ubiquitous across centralized nervous systems. Such inputs often arise from modulatory neurons that arborize broadly throughout the brain. How information is integrated in such cells and how release from their distant terminals is regulated remains largely unknown. We show that a serotonergic neuron that innervates multiple stages of odor processing in Drosophila has distinct activity throughout its neurites, including opposite polarity responses in first and second order olfactory neuropils. Disparate activity arises from local interactions within each target region. Our results show that such neurons exhibit dendritic computation rather than somatic integration alone, and that examining local interactions at release sites is critical for understanding centrifugal innervation. AbstractAll centralized nervous systems possess modulatory neurons that arborize broadly across multiple brain regions. Such modulatory systems are critical for proper sensory, motor, and cognitive processing. How single modulatory neurons integrate into circuits within their target destination remains largely unexplored due to difficulties in both labeling individual cells and imaging across distal parts of the CNS. Here, we take advantage of an identified modulatory neuron in Drosophila that arborizes in multiple olfactory neuropils. We demonstrate that this serotonergic neuron has opposing odor responses in its neurites of the antennal lobe and lateral horn, first and second order olfactory neuropils respectively. Specifically, processes of this neuron in the antennal lobe have responses that are inhibitory and odor-independent, while lateral horn responses are excitatory and odor-specific. The results show that widespread modulatory neurons may not function purely as integrate-and-fire cells, but rather their transmitter release is locally regulated based on neuropil. As nearly all vertebrate and invertebrate neurons are subject to synaptic inputs along their dendro-axonic axis, it is likely that our findings generalize across phylogeny and other broadly-projecting modulatory systems.

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Simultaneous Encoding of Odors by Channels with Diverse Sensitivity to Inhibition

Cited by 81 publications

References 76 publications

Normalized Neural Representations of Complex Odors

Normalized Neural Representations of Complex Odors

What the fly’s nose tells the fly’s brain

Regulation of modulatory cell activity across olfactory structures in Drosophila melanogaster

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