1
|
Joshi S, Haney S, Wang Z, Locatelli F, Smith B, Cao Y, Bazhenov M. Plasticity in inhibitory networks improves pattern separation in early olfactory processing. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.24.576675. [PMID: 38328149 PMCID: PMC10849730 DOI: 10.1101/2024.01.24.576675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Distinguishing between nectar and non-nectar odors presents a challenge for animals due to shared compounds in complex mixtures, where changing ratios often signify differences in reward. Changes in nectar production throughout the day and potentially many times within a forager's lifetime add to the complexity. The honeybee olfactory system, containing less than a 1000 of principal neurons in the early olfactory relay, the antennal lobe (AL), must learn to associate diverse volatile blends with rewards. We used a computational network model and live imaging of the honeybee's AL to explore the neural mechanisms and functions of the AL plasticity. Our findings revealed that when trained with a set of rewarded and unrewarded odors, the AL inhibitory network suppresses shared chemical compounds while enhancing responses to distinct compounds. This results in improved pattern separation and a more concise and efficient neural code. Our Ca2+ imaging data support our model's predictions. Furthermore, we applied these contrast enhancement principles to a Graph Convolutional Network (GCN) and found that similar mechanisms could enhance the performance of artificial neural networks. Our model provides insights into how plasticity at the inhibitory network level reshapes coding for efficient learning of complex odors.
Collapse
Affiliation(s)
- Shruti Joshi
- Department of Electrical and Computer Engineering, University of California San Diego, USA
- Department of Medicine, University of California San Diego, USA
| | - Seth Haney
- Department of Medicine, University of California San Diego, USA
| | - Zhenyu Wang
- Department of Electrical, Computer and Energy Engineering, Arizona State University, USA
| | - Fernando Locatelli
- Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Instituto de Fisiología, Biología Molecular y Neurociencias, CONICET, Buenos Aires, Argentina
| | - Brian Smith
- School of Life Science, Arizona State University, USA
| | - Yu Cao
- Department of Electrical and Computer Engineering, University of Minnesota, USA
| | - Maxim Bazhenov
- Department of Medicine, University of California San Diego, USA
| |
Collapse
|
2
|
Marachlian E, Huerta R, Locatelli FF. Gain modulation and odor concentration invariance in early olfactory networks. PLoS Comput Biol 2023; 19:e1011176. [PMID: 37343029 DOI: 10.1371/journal.pcbi.1011176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 05/11/2023] [Indexed: 06/23/2023] Open
Abstract
The broad receptive field of the olfactory receptors constitutes the basis of a combinatorial code that allows animals to detect and discriminate many more odorants than the actual number of receptor types that they express. One drawback is that high odor concentrations recruit lower affinity receptors which can lead to the perception of qualitatively different odors. Here we addressed the contribution that signal-processing in the antennal lobe makes to reduce concentration dependence in odor representation. By means of calcium imaging and pharmacological approach we describe the contribution that GABA receptors play in terms of the amplitude and temporal profiles of the signals that convey odor information from the antennal lobes to higher brain centers. We found that GABA reduces the amplitude of odor elicited signals and the number of glomeruli that are recruited in an odor-concentration-dependent manner. Blocking GABA receptors decreases the correlation among glomerular activity patterns elicited by different concentrations of the same odor. In addition, we built a realistic mathematical model of the antennal lobe that was used to test the viability of the proposed mechanisms and to evaluate the processing properties of the AL network under conditions that cannot be achieved in physiology experiments. Interestingly, even though based on a rather simple topology and cell interactions solely mediated by GABAergic lateral inhibitions, the AL model reproduced key features of the AL response upon different odor concentrations and provides plausible solutions for concentration invariant recognition of odors by artificial sensors.
Collapse
Affiliation(s)
- Emiliano Marachlian
- Instituto de Fisiología Biología Molecular y Neurociencias (IFIByNE-UBA-CONICET) and Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Ramón Huerta
- BioCircuits Institute, University of California San Diego, La Jolla, California, United States of America
| | - Fernando F Locatelli
- Instituto de Fisiología Biología Molecular y Neurociencias (IFIByNE-UBA-CONICET) and Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| |
Collapse
|
3
|
Lazar AA, Liu T, Yeh CH. The functional logic of odor information processing in the Drosophila antennal lobe. PLoS Comput Biol 2023; 19:e1011043. [PMID: 37083547 PMCID: PMC10156017 DOI: 10.1371/journal.pcbi.1011043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 05/03/2023] [Accepted: 03/22/2023] [Indexed: 04/22/2023] Open
Abstract
Recent advances in molecular transduction of odorants in the Olfactory Sensory Neurons (OSNs) of the Drosophila Antenna have shown that the odorant object identity is multiplicatively coupled with the odorant concentration waveform. The resulting combinatorial neural code is a confounding representation of odorant semantic information (identity) and syntactic information (concentration). To distill the functional logic of odor information processing in the Antennal Lobe (AL) a number of challenges need to be addressed including 1) how is the odorant semantic information decoupled from the syntactic information at the level of the AL, 2) how are these two information streams processed by the diverse AL Local Neurons (LNs) and 3) what is the end-to-end functional logic of the AL? By analyzing single-channel physiology recordings at the output of the AL, we found that the Projection Neuron responses can be decomposed into a concentration-invariant component, and two transient components boosting the positive/negative concentration contrast that indicate onset/offset timing information of the odorant object. We hypothesized that the concentration-invariant component, in the multi-channel context, is the recovered odorant identity vector presented between onset/offset timing events. We developed a model of LN pathways in the Antennal Lobe termed the differential Divisive Normalization Processors (DNPs), which robustly extract the semantics (the identity of the odorant object) and the ON/OFF semantic timing events indicating the presence/absence of an odorant object. For real-time processing with spiking PN models, we showed that the phase-space of the biological spike generator of the PN offers an intuit perspective for the representation of recovered odorant semantics and examined the dynamics induced by the odorant semantic timing events. Finally, we provided theoretical and computational evidence for the functional logic of the AL as a robust ON-OFF odorant object identity recovery processor across odorant identities, concentration amplitudes and waveform profiles.
Collapse
Affiliation(s)
- Aurel A Lazar
- Department of Electrical Engineering, Columbia University, New York, NY, United States of America
| | - Tingkai Liu
- Department of Electrical Engineering, Columbia University, New York, NY, United States of America
| | - Chung-Heng Yeh
- Department of Electrical Engineering, Columbia University, New York, NY, United States of America
| |
Collapse
|
4
|
Kim B, Haney S, Milan AP, Joshi S, Aldworth Z, Rulkov N, Kim AT, Bazhenov M, Stopfer MA. Olfactory receptor neurons generate multiple response motifs, increasing coding space dimensionality. eLife 2023; 12:79152. [PMID: 36719272 PMCID: PMC9925048 DOI: 10.7554/elife.79152] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 01/31/2023] [Indexed: 02/01/2023] Open
Abstract
Odorants binding to olfactory receptor neurons (ORNs) trigger bursts of action potentials, providing the brain with its only experience of the olfactory environment. Our recordings made in vivo from locust ORNs showed that odor-elicited firing patterns comprise four distinct response motifs, each defined by a reliable temporal profile. Different odorants could elicit different response motifs from a given ORN, a property we term motif switching. Further, each motif undergoes its own form of sensory adaptation when activated by repeated plume-like odor pulses. A computational model constrained by our recordings revealed that organizing responses into multiple motifs provides substantial benefits for classifying odors and processing complex odor plumes: each motif contributes uniquely to encode the plume's composition and structure. Multiple motifs and motif switching further improve odor classification by expanding coding dimensionality. Our model demonstrated that these response features could provide benefits for olfactory navigation, including determining the distance to an odor source.
Collapse
Affiliation(s)
- Brian Kim
- Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH)BethesdaUnited States
- Brown University - National Institutes of Health Graduate Partnership ProgramProvidenceUnited States
| | - Seth Haney
- Department of Medicine, University of California, San DiegoSan DiegoUnited States
| | - Ana P Milan
- Department of Clinical Neurophysiology and MEG Center, Amsterdam Neuroscience, Vrije Universiteit AmsterdamAmsterdamNetherlands
| | - Shruti Joshi
- Department of Medicine, University of California, San DiegoSan DiegoUnited States
| | - Zane Aldworth
- Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH)BethesdaUnited States
| | - Nikolai Rulkov
- Biocircuits Institute, University of California, San DiegoLa JollaUnited States
| | - Alexander T Kim
- Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH)BethesdaUnited States
| | - Maxim Bazhenov
- Department of Medicine, University of California, San DiegoSan DiegoUnited States
| | - Mark A Stopfer
- Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH)BethesdaUnited States
| |
Collapse
|
5
|
Krishnamurthy K, Hermundstad AM, Mora T, Walczak AM, Balasubramanian V. Disorder and the Neural Representation of Complex Odors. Front Comput Neurosci 2022; 16:917786. [PMID: 36003684 PMCID: PMC9393645 DOI: 10.3389/fncom.2022.917786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 05/17/2022] [Indexed: 11/25/2022] Open
Abstract
Animals smelling in the real world use a small number of receptors to sense a vast number of natural molecular mixtures, and proceed to learn arbitrary associations between odors and valences. Here, we propose how the architecture of olfactory circuits leverages disorder, diffuse sensing and redundancy in representation to meet these immense complementary challenges. First, the diffuse and disordered binding of receptors to many molecules compresses a vast but sparsely-structured odor space into a small receptor space, yielding an odor code that preserves similarity in a precise sense. Introducing any order/structure in the sensing degrades similarity preservation. Next, lateral interactions further reduce the correlation present in the low-dimensional receptor code. Finally, expansive disordered projections from the periphery to the central brain reconfigure the densely packed information into a high-dimensional representation, which contains multiple redundant subsets from which downstream neurons can learn flexible associations and valences. Moreover, introducing any order in the expansive projections degrades the ability to recall the learned associations in the presence of noise. We test our theory empirically using data from Drosophila. Our theory suggests that the neural processing of sparse but high-dimensional olfactory information differs from the other senses in its fundamental use of disorder.
Collapse
Affiliation(s)
- Kamesh Krishnamurthy
- Joseph Henry Laboratories of Physics and Princeton Neuroscience Institute, Princeton University, Princeton, NJ, United States
| | - Ann M. Hermundstad
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, United States
| | - Thierry Mora
- Laboratoire de Physique Statistique, UMR8550, CNRS, UPMC and École Normale Supérieure, Paris, France
| | - Aleksandra M. Walczak
- Laboratoire de Physique Théorique, UMR8549m CNRS, UPMC and École Normale Supérieure, Paris, France
| | - Vijay Balasubramanian
- David Rittenhouse and Richards Laboratories, University of Pennsylvania, Philadelphia, PA, United States
- *Correspondence: Vijay Balasubramanian
| |
Collapse
|
6
|
Lopez-Hazas J, Montero A, Rodriguez FB. Influence of bio-inspired activity regulation through neural thresholds learning in the performance of neural networks. Neurocomputing 2021. [DOI: 10.1016/j.neucom.2021.08.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
7
|
Singh V, Tchernookov M, Balasubramanian V. What the odor is not: Estimation by elimination. Phys Rev E 2021; 104:024415. [PMID: 34525542 PMCID: PMC8892575 DOI: 10.1103/physreve.104.024415] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 08/02/2021] [Indexed: 11/07/2022]
Abstract
Olfactory systems use a small number of broadly sensitive receptors to combinatorially encode a vast number of odors. We propose a method of decoding such distributed representations by exploiting a statistical fact: Receptors that do not respond to an odor carry more information than receptors that do because they signal the absence of all odorants that bind to them. Thus, it is easier to identify what the odor is not rather than what the odor is. For realistic numbers of receptors, response functions, and odor complexity, this method of elimination turns an underconstrained decoding problem into a solvable one, allowing accurate determination of odorants in a mixture and their concentrations. We construct a neural network realization of our algorithm based on the structure of the olfactory pathway.
Collapse
Affiliation(s)
- Vijay Singh
- Department of Physics, North Carolina A&T State University, Greensboro, NC, 27410, USA
- Department of Physics, & Computational Neuroscience Initiative, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Martin Tchernookov
- Department of Physics, University of Wisconsin, Whitewater, WI, 53190, USA
| | - Vijay Balasubramanian
- Department of Physics, & Computational Neuroscience Initiative, University of Pennsylvania, Philadelphia, PA 19104, USA
| |
Collapse
|
8
|
Olfactory encoding within the insect antennal lobe: The emergence and role of higher order temporal correlations in the dynamics of antennal lobe spiking activity. J Theor Biol 2021; 522:110700. [PMID: 33819477 DOI: 10.1016/j.jtbi.2021.110700] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 03/20/2021] [Accepted: 03/23/2021] [Indexed: 11/22/2022]
Abstract
In this review, we focus on the antennal lobe (AL) of three insect species - the fruit fly, sphinx moth, and locust. We first review the experimentally elucidated anatomy and physiology of the early olfactory system of each species; empirical studies of AL activity, however, often focus on assessing firing rates (averaged over time scales of about 100 ms), and hence the AL odor code is often analyzed in terms of a temporally evolving vector of firing rates. However, such a perspective necessarily misses the possibility of higher order temporal correlations in spiking activity within a single cell and across multiple cells over shorter time scales (of about 10 ms). Hence, we then review our prior theoretical work, where we constructed biophysically detailed, species-specific AL models within the fly, moth, and locust, finding that in each case higher order temporal correlations in spiking naturally emerge from model dynamics (i.e., without a prioriincorporation of elements designed to produce correlated activity). We therefore use our theoretical work to argue the perspective that temporal correlations in spiking over short time scales, which have received little experimental attention to-date, may provide valuable coding dimensions (complementing the coding dimensions provided by the vector of firing rates) that nature has exploited in the encoding of odors within the AL. We further argue that, if the AL does indeed utilize temporally correlated activity to represent odor information, such an odor code could be naturally and easily deciphered within the Mushroom Body.
Collapse
|
9
|
Haney S, Saha D, Raman B, Bazhenov M. Differential effects of adaptation on odor discrimination. J Neurophysiol 2018; 120:171-185. [PMID: 29589811 DOI: 10.1152/jn.00389.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Adaptation of neural responses is ubiquitous in sensory systems and can potentially facilitate many important computational functions. Here we examined this issue with a well-constrained computational model of the early olfactory circuits. In the insect olfactory system, the responses of olfactory receptor neurons (ORNs) on the antennae adapt over time. We found that strong adaptation of sensory input is important for rapidly detecting a fresher stimulus encountered in the presence of other background cues and for faithfully representing its identity. However, when the overlapping odorants were chemically similar, we found that adaptation could alter the representation of these odorants to emphasize only distinguishing features. This work demonstrates novel roles for peripheral neurons during olfactory processing in complex environments. NEW & NOTEWORTHY Olfactory systems face the problem of distinguishing salient information from a complex olfactory environment. The neural representations of specific odor sources should be consistent regardless of the background. How are olfactory representations robust to varying environmental interference? We show that in locusts the extraction of salient information begins in the periphery. Olfactory receptor neurons adapt in response to odorants. Adaptation can provide a computational mechanism allowing novel odorant components to be highlighted during complex stimuli.
Collapse
Affiliation(s)
- Seth Haney
- Department of Medicine, University of California, San Diego, La Jolla, California
| | - Debajit Saha
- Department of Biomedical Engineering, Washington University in St. Louis , St. Louis, Missouri
| | - Baranidharan Raman
- Department of Biomedical Engineering, Washington University in St. Louis , St. Louis, Missouri
| | - Maxim Bazhenov
- Department of Medicine, University of California, San Diego, La Jolla, California
| |
Collapse
|
10
|
Gorur-Shandilya S, Demir M, Long J, Clark DA, Emonet T. Olfactory receptor neurons use gain control and complementary kinetics to encode intermittent odorant stimuli. eLife 2017; 6:e27670. [PMID: 28653907 PMCID: PMC5524537 DOI: 10.7554/elife.27670] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 06/26/2017] [Indexed: 11/13/2022] Open
Abstract
Insects find food and mates by navigating odorant plumes that can be highly intermittent, with intensities and durations that vary rapidly over orders of magnitude. Much is known about olfactory responses to pulses and steps, but it remains unclear how olfactory receptor neurons (ORNs) detect the intensity and timing of natural stimuli, where the absence of scale in the signal makes detection a formidable olfactory task. By stimulating Drosophila ORNs in vivo with naturalistic and Gaussian stimuli, we show that ORNs adapt to stimulus mean and variance, and that adaptation and saturation contribute to naturalistic sensing. Mean-dependent gain control followed the Weber-Fechner relation and occurred primarily at odor transduction, while variance-dependent gain control occurred at both transduction and spiking. Transduction and spike generation possessed complementary kinetic properties, that together preserved the timing of odorant encounters in ORN spiking, regardless of intensity. Such scale-invariance could be critical during odor plume navigation.
Collapse
Affiliation(s)
- Srinivas Gorur-Shandilya
- Interdepartmental Neuroscience Program, Yale University, New Haven, United States
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, United States
| | - Mahmut Demir
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, United States
| | - Junjiajia Long
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, United States
- Department of Physics, Yale University, New Haven, United States
| | - Damon A Clark
- Interdepartmental Neuroscience Program, Yale University, New Haven, United States
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, United States
- Department of Physics, Yale University, New Haven, United States
| | - Thierry Emonet
- Interdepartmental Neuroscience Program, Yale University, New Haven, United States
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, United States
- Department of Physics, Yale University, New Haven, United States
| |
Collapse
|