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Fernández Santoro EM, Karim A, Warnaar P, De Zeeuw CI, Badura A, Negrello M. Purkinje cell models: past, present and future. Front Comput Neurosci 2024; 18:1426653. [PMID: 39049990 PMCID: PMC11266113 DOI: 10.3389/fncom.2024.1426653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Accepted: 06/24/2024] [Indexed: 07/27/2024] Open
Abstract
The investigation of the dynamics of Purkinje cell (PC) activity is crucial to unravel the role of the cerebellum in motor control, learning and cognitive processes. Within the cerebellar cortex (CC), these neurons receive all the incoming sensory and motor information, transform it and generate the entire cerebellar output. The relatively homogenous and repetitive structure of the CC, common to all vertebrate species, suggests a single computation mechanism shared across all PCs. While PC models have been developed since the 70's, a comprehensive review of contemporary models is currently lacking. Here, we provide an overview of PC models, ranging from the ones focused on single cell intracellular PC dynamics, through complex models which include synaptic and extrasynaptic inputs. We review how PC models can reproduce physiological activity of the neuron, including firing patterns, current and multistable dynamics, plateau potentials, calcium signaling, intrinsic and synaptic plasticity and input/output computations. We consider models focusing both on somatic and on dendritic computations. Our review provides a critical performance analysis of PC models with respect to known physiological data. We expect our synthesis to be useful in guiding future development of computational models that capture real-life PC dynamics in the context of cerebellar computations.
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Affiliation(s)
| | - Arun Karim
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands
| | - Pascal Warnaar
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands
- Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences, Amsterdam, Netherlands
| | - Chris I. De Zeeuw
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands
- Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences, Amsterdam, Netherlands
| | | | - Mario Negrello
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands
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Peace ST, Johnson BC, Werth JC, Li G, Kaiser ME, Fukunaga I, Schaefer AT, Molnar AC, Cleland TA. Coherent olfactory bulb gamma oscillations arise from coupling independent columnar oscillators. J Neurophysiol 2024; 131:492-508. [PMID: 38264784 PMCID: PMC7615692 DOI: 10.1152/jn.00361.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 01/19/2024] [Accepted: 01/20/2024] [Indexed: 01/25/2024] Open
Abstract
Spike timing-based representations of sensory information depend on embedded dynamical frameworks within neuronal networks that establish the rules of local computation and interareal communication. Here, we investigated the dynamical properties of olfactory bulb circuitry in mice of both sexes using microelectrode array recordings from slice and in vivo preparations. Neurochemical activation or optogenetic stimulation of sensory afferents evoked persistent gamma oscillations in the local field potential. These oscillations arose from slower, GABA(A) receptor-independent intracolumnar oscillators coupled by GABA(A)-ergic synapses into a faster, broadly coherent network oscillation. Consistent with the theoretical properties of coupled-oscillator networks, the spatial extent of zero-phase coherence was bounded in slices by the reduced density of lateral interactions. The intact in vivo network, however, exhibited long-range lateral interactions that suffice in simulation to enable zero-phase gamma coherence across the olfactory bulb. The timing of action potentials in a subset of principal neurons was phase-constrained with respect to evoked gamma oscillations. Coupled-oscillator dynamics in olfactory bulb thereby enable a common clock, robust to biological heterogeneities, that is capable of supporting gamma-band spike synchronization and phase coding across the ensemble of activated principal neurons.NEW & NOTEWORTHY Odor stimulation evokes rhythmic gamma oscillations in the field potential of the olfactory bulb, but the dynamical mechanisms governing these oscillations have remained unclear. Establishing these mechanisms is important as they determine the biophysical capacities of the bulbar circuit to, for example, maintain zero-phase coherence across a spatially extended network, or coordinate the timing of action potentials in principal neurons. These properties in turn constrain and suggest hypotheses of sensory coding.
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Affiliation(s)
- Shane T Peace
- Department of Neurobiology & Behavior, Cornell University, Ithaca, New York, United States
| | - Benjamin C Johnson
- Department of Electrical and Computer Engineering, Cornell University, Ithaca, New York, United States
| | - Jesse C Werth
- Department of Psychology, Cornell University, Ithaca, New York, United States
| | - Guoshi Li
- Department of Psychology, Cornell University, Ithaca, New York, United States
| | - Martin E Kaiser
- Behavioural Neurophysiology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Izumi Fukunaga
- Behavioural Neurophysiology, Max Planck Institute for Medical Research, Heidelberg, Germany
- Neurophysiology of Behaviour Laboratory, The Francis Crick Institute, London, United Kingdom
- Sensory and Behavioural Neuroscience Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Japan
| | - Andreas T Schaefer
- Behavioural Neurophysiology, Max Planck Institute for Medical Research, Heidelberg, Germany
- Neurophysiology of Behaviour Laboratory, The Francis Crick Institute, London, United Kingdom
- Department of Neuroscience, Physiology & Pharmacology, University College London, London, United Kingdom
- Department of Anatomy and Cell Biology, Faculty of Medicine, University of Heidelberg, Heidelberg, Germany
| | - Alyosha C Molnar
- Department of Electrical and Computer Engineering, Cornell University, Ithaca, New York, United States
| | - Thomas A Cleland
- Department of Psychology, Cornell University, Ithaca, New York, United States
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Afterhyperpolarization Promotes the Firing of Mitral Cells through a Voltage-Dependent Modification of Action Potential Threshold. eNeuro 2022; 9:ENEURO.0401-21.2021. [PMID: 35277450 PMCID: PMC8982644 DOI: 10.1523/eneuro.0401-21.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 11/22/2021] [Accepted: 12/13/2021] [Indexed: 11/21/2022] Open
Abstract
In the olfactory bulb, mitral cells (MCs) display a spontaneous firing that is characterized by bursts of action potentials (APs) intermixed with silent periods. Intraburst firing frequency and duration are heterogeneous among MCs and increase with membrane depolarization. By using patch-clamp recording on rat slices, we dissected out the intrinsic properties responsible for this bursting activity. We showed that the threshold of AP generation dynamically changes as a function of the preceding trajectory of the membrane potential. In fact, the AP threshold became more negative when the membrane was hyperpolarized and had a recovery rate inversely proportional to the membrane repolarization rate. Such variations appeared to be produced by changes in the inactivation state of voltage-dependent Na+ channels. Thus, AP initiation was favored by hyperpolarizing events, such as negative membrane oscillations or inhibitory synaptic input. After the first AP, the following fast afterhyperpolarization (AHP) brought the threshold to more negative values and then promoted the emission of the following AP. This phenomenon was repeated for each AP of the burst making the fast AHP a regenerative mechanism that sustained the firing, AHP with larger amplitudes and faster repolarizations being associated with larger and higher-frequency bursts. Burst termination was found to be because of the development of a slow repolarization component of the AHP (slow AHP). Overall, the AHP characteristics appeared as a major determinant of the bursting properties.
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Racz RR, Kollo M, Racz G, Bulz C, Ackels T, Warner T, Wray W, Kiskin N, Chen C, Ye Z, de Hoz L, Rancz E, Schaefer AT. jULIEs: nanostructured polytrodes for low traumatic extracellular recordings and stimulation in the mammalian brain. J Neural Eng 2022; 19. [PMID: 35108701 DOI: 10.1088/1741-2552/ac514f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 02/02/2022] [Indexed: 11/11/2022]
Abstract
Objective Extracellular microelectrode techniques are the most widely used approach to interrogate neuronal populations. Regardless of the manufacturing method, damage to the vasculature and circuit function during probe insertion remains a concern. Reducing the footprint of the penetrating probes is a potential solution to this issue. However, coupling to the extracellular signals requires careful surface engineering. Approach Here, we show that continuously drawn SiO2-insulated ultra-microelectrode fibres offer an attractive substrate to address these challenges. Individual fibres can be fabricated to >10m continuous stretches and a selection of diameters below 30 µm with a low resistance (<100 Ω/m), continuous metal core of <10 µm and atomically flat smooth shank surfaces. To optimize the properties of the miniaturised electrode-tissue interface, we electrodeposit rough Au structures followed by ~20nm IrOx film by electrodeposition resulting in reduction of the interfacial impedance to <500kΩ at 1 kHz. Main results We demonstrate that these ultra-low impedance electrodes (jULIEs) can record and stimulate single and multi-unit activity with minimal tissue disturbance and exceptional signal-to-noise ratio in both superficial (~40µm) and deep (~6mm) structures of the mouse brain. We further show that sensor modifications are stable and probe manufacturing is reproducible. Significance Minimally perturbing bidirectional neural interfacing can reveal circuit function in the mammalian brain in vivo.
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Affiliation(s)
- Romeo Robert Racz
- Neurophysiology, The Francis Crick Institute, 1 MIdland Road, London, London, NW1 1AT, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Mihaly Kollo
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Gabriella Racz
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Ciprian Bulz
- University of Southampton, University Road, Southampton, Hampshire, SO17 1BJ, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Tobias Ackels
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Tom Warner
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - William Wray
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Nikolai Kiskin
- Department of Bioengineering, Imperial College London, Exhibition Road, London, London, SW7 2AZ, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Chi Chen
- Department of Neurogenetics, Charité Universitätsmedizin Berlin, Hermann-Rein-Straße 3, Berlin, Berlin, 10117, GERMANY
| | - Zhiwen Ye
- University of Washington, 1959 NE Pacific St., Seattle, Washington, 98195-7420, UNITED STATES
| | - Livia de Hoz
- Neuroscience Research Center, Charité Universitätsmedizin Berlin, Virchowweg 6, Berlin, Berlin, 10117, GERMANY
| | - Ede Rancz
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Andreas T Schaefer
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
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Burton SD, Urban NN. Cell and circuit origins of fast network oscillations in the mammalian main olfactory bulb. eLife 2021; 10:74213. [PMID: 34658333 PMCID: PMC8553344 DOI: 10.7554/elife.74213] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Accepted: 10/09/2021] [Indexed: 11/13/2022] Open
Abstract
Neural synchrony generates fast network oscillations throughout the brain, including the main olfactory bulb (MOB), the first processing station of the olfactory system. Identifying the mechanisms synchronizing neurons in the MOB will be key to understanding how network oscillations support the coding of a high-dimensional sensory space. Here, using paired recordings and optogenetic activation of glomerular sensory inputs in MOB slices, we uncovered profound differences in principal mitral cell (MC) vs. tufted cell (TC) spike-time synchrony: TCs robustly synchronized across fast- and slow-gamma frequencies, while MC synchrony was weaker and concentrated in slow-gamma frequencies. Synchrony among both cell types was enhanced by shared glomerular input but was independent of intraglomerular lateral excitation. Cell-type differences in synchrony could also not be traced to any difference in the synchronization of synaptic inhibition. Instead, greater TC than MC synchrony paralleled the more periodic firing among resonant TCs than MCs and emerged in patterns consistent with densely synchronous network oscillations. Collectively, our results thus reveal a mechanism for parallel processing of sensory information in the MOB via differential TC vs. MC synchrony, and further contrast mechanisms driving fast network oscillations in the MOB from those driving the sparse synchronization of irregularly firing principal cells throughout cortex.
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Affiliation(s)
- Shawn D Burton
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, United States.,Center for the Neural Basis of Cognition, Pittsburgh, United States
| | - Nathaniel N Urban
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, United States.,Center for the Neural Basis of Cognition, Pittsburgh, United States
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6
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Masoli S, Ottaviani A, Casali S, D’Angelo E. Cerebellar Golgi cell models predict dendritic processing and mechanisms of synaptic plasticity. PLoS Comput Biol 2020; 16:e1007937. [PMID: 33378395 PMCID: PMC7837495 DOI: 10.1371/journal.pcbi.1007937] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 01/26/2021] [Accepted: 11/13/2020] [Indexed: 02/06/2023] Open
Abstract
The Golgi cells are the main inhibitory interneurons of the cerebellar granular layer. Although recent works have highlighted the complexity of their dendritic organization and synaptic inputs, the mechanisms through which these neurons integrate complex input patterns remained unknown. Here we have used 8 detailed morphological reconstructions to develop multicompartmental models of Golgi cells, in which Na, Ca, and K channels were distributed along dendrites, soma, axonal initial segment and axon. The models faithfully reproduced a rich pattern of electrophysiological and pharmacological properties and predicted the operating mechanisms of these neurons. Basal dendrites turned out to be more tightly electrically coupled to the axon initial segment than apical dendrites. During synaptic transmission, parallel fibers caused slow Ca-dependent depolarizations in apical dendrites that boosted the axon initial segment encoder and Na-spike backpropagation into basal dendrites, while inhibitory synapses effectively shunted backpropagating currents. This oriented dendritic processing set up a coincidence detector controlling voltage-dependent NMDA receptor unblock in basal dendrites, which, by regulating local calcium influx, may provide the basis for spike-timing dependent plasticity anticipated by theory.
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Affiliation(s)
- Stefano Masoli
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | | | - Stefano Casali
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Egidio D’Angelo
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
- Brain Connectivity Center, IRCCS Mondino Foundation, Pavia, Italy
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7
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Cleland TA, Borthakur A. A Systematic Framework for Olfactory Bulb Signal Transformations. Front Comput Neurosci 2020; 14:579143. [PMID: 33071767 PMCID: PMC7538604 DOI: 10.3389/fncom.2020.579143] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 08/17/2020] [Indexed: 11/13/2022] Open
Abstract
We describe an integrated theory of olfactory systems operation that incorporates experimental findings across scales, stages, and methods of analysis into a common framework. In particular, we consider the multiple stages of olfactory signal processing as a collective system, in which each stage samples selectively from its antecedents. We propose that, following the signal conditioning operations of the nasal epithelium and glomerular-layer circuitry, the plastic external plexiform layer of the olfactory bulb effects a process of category learning-the basis for extracting meaningful, quasi-discrete odor representations from the metric space of undifferentiated olfactory quality. Moreover, this early categorization process also resolves the foundational problem of how odors of interest can be recognized in the presence of strong competitive interference from simultaneously encountered background odorants. This problem is fundamentally constraining on early-stage olfactory encoding strategies and must be resolved if these strategies and their underlying mechanisms are to be understood. Multiscale general theories of olfactory systems operation are essential in order to leverage the analytical advantages of engineered approaches together with our expanding capacity to interrogate biological systems.
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Affiliation(s)
- Thomas A. Cleland
- Computational Physiology Laboratory, Department of Psychology, Cornell University, Ithaca, NY, United States
| | - Ayon Borthakur
- Computational Physiology Laboratory, Field of Computational Biology, Cornell University, Ithaca, NY, United States
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8
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Abstract
Generative models are computational models designed to generate appropriate values for all of their embedded variables, thereby simulating the response properties of a complex system based on the coordinated interactions of a multitude of physical mechanisms. In systems neuroscience, generative models are generally biophysically based compartmental models of neurons and networks that are explicitly multiscale, being constrained by experimental data at multiple levels of organization from cellular membrane properties to large-scale network dynamics. As such, they are able to explain the origins of emergent properties in complex systems, and serve as tests of sufficiency and as quantitative instantiations of working hypotheses that may be too complex to simply intuit. Moreover, when adequately constrained, generative biophysical models are able to predict novel experimental outcomes, and consequently are powerful tools for experimental design. We here outline a general strategy for the iterative design and implementation of generative, multiscale biophysical models of neural systems. We illustrate this process using our ongoing, iteratively developing model of the mammalian olfactory bulb. Because the olfactory bulb exhibits diverse and interesting properties at multiple scales of organization, it is an attractive system in which to illustrate the value of generative modeling across scales.
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Affiliation(s)
- Guoshi Li
- Department of Psychology, Cornell University, Ithaca, NY, USA
- Department of Psychiatry, University of North Carolina, Chapel Hill, NC, USA
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9
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Li G, Cleland TA. A coupled-oscillator model of olfactory bulb gamma oscillations. PLoS Comput Biol 2017; 13:e1005760. [PMID: 29140973 PMCID: PMC5706731 DOI: 10.1371/journal.pcbi.1005760] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 11/29/2017] [Accepted: 09/01/2017] [Indexed: 11/19/2022] Open
Abstract
The olfactory bulb transforms not only the information content of the primary sensory representation, but also its underlying coding metric. High-variance, slow-timescale primary odor representations are transformed by bulbar circuitry into secondary representations based on principal neuron spike patterns that are tightly regulated in time. This emergent fast timescale for signaling is reflected in gamma-band local field potentials, presumably serving to efficiently integrate olfactory sensory information into the temporally regulated information networks of the central nervous system. To understand this transformation and its integration with interareal coordination mechanisms requires that we understand its fundamental dynamical principles. Using a biophysically explicit, multiscale model of olfactory bulb circuitry, we here demonstrate that an inhibition-coupled intrinsic oscillator framework, pyramidal resonance interneuron network gamma (PRING), best captures the diversity of physiological properties exhibited by the olfactory bulb. Most importantly, these properties include global zero-phase synchronization in the gamma band, the phase-restriction of informative spikes in principal neurons with respect to this common clock, and the robustness of this synchronous oscillatory regime to multiple challenging conditions observed in the biological system. These conditions include substantial heterogeneities in afferent activation levels and excitatory synaptic weights, high levels of uncorrelated background activity among principal neurons, and spike frequencies in both principal neurons and interneurons that are irregular in time and much lower than the gamma frequency. This coupled cellular oscillator architecture permits stable and replicable ensemble responses to diverse sensory stimuli under various external conditions as well as to changes in network parameters arising from learning-dependent synaptic plasticity.
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Affiliation(s)
- Guoshi Li
- Dept. Psychology, Cornell University, Ithaca, NY United States of America
| | - Thomas A. Cleland
- Dept. Psychology, Cornell University, Ithaca, NY United States of America
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10
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Alturki A, Feng F, Nair A, Guntu V, Nair SS. Distinct current modules shape cellular dynamics in model neurons. Neuroscience 2016; 334:309-331. [PMID: 27530698 DOI: 10.1016/j.neuroscience.2016.08.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 08/06/2016] [Accepted: 08/08/2016] [Indexed: 10/21/2022]
Abstract
Numerous intrinsic currents are known to collectively shape neuronal membrane potential dynamics, or neuronal signatures. Although how sets of currents shape specific signatures such as spiking characteristics or oscillations has been studied individually, it is less clear how a neuron's suite of currents jointly shape its entire set of signatures. Biophysical conductance-based models of neurons represent a viable tool to address this important question. We hypothesized that currents are grouped into distinct modules that shape specific neuronal characteristics or signatures, such as resting potential, sub-threshold oscillations, and spiking waveforms, for several classes of neurons. For such a grouping to occur, the currents within one module should have minimal functional interference with currents belonging to other modules. This condition is satisfied if the gating functions of currents in the same module are grouped together on the voltage axis; in contrast, such functions are segregated along the voltage axis for currents belonging to different modules. We tested this hypothesis using four published example case models and found it to be valid for these classes of neurons. This insight into the neurobiological organization of currents also suggests an intuitive, systematic, and robust methodology to develop biophysical single-cell models with multiple biological characteristics applicable for both hand- and automated-tuning approaches. We illustrate the methodology using two example case rodent pyramidal neurons, from the lateral amygdala and the hippocampus. The methodology also helped reveal that a single-core compartment model could capture multiple neuronal properties. Such biophysical single-compartment models have potential to improve the fidelity of large network models.
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Affiliation(s)
- Adel Alturki
- Department of Electrical and Computer Engineering, University of Missouri, Columbia, MO, United States
| | - Feng Feng
- Department of Electrical and Computer Engineering, University of Missouri, Columbia, MO, United States
| | - Ajay Nair
- Veteran's Hospital, University of Missouri, Columbia, MO, United States
| | - Vinay Guntu
- Department of Electrical and Computer Engineering, University of Missouri, Columbia, MO, United States
| | - Satish S Nair
- Department of Electrical and Computer Engineering, University of Missouri, Columbia, MO, United States.
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11
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McIntyre ABR, Cleland TA. Biophysical constraints on lateral inhibition in the olfactory bulb. J Neurophysiol 2016; 115:2937-49. [PMID: 27009162 DOI: 10.1152/jn.00671.2015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 03/16/2016] [Indexed: 12/26/2022] Open
Abstract
The mitral cells (MCs) of the mammalian olfactory bulb (OB) constitute one of two populations of principal neurons (along with middle/deep tufted cells) that integrate afferent olfactory information with top-down inputs and intrinsic learning and deliver output to downstream olfactory areas. MC activity is regulated in part by inhibition from granule cells, which form reciprocal synapses with MCs along the extents of their lateral dendrites. However, with MC lateral dendrites reaching over 1.5 mm in length in rats, the roles of distal inhibitory synapses pose a quandary. Here, we systematically vary the properties of a MC model to assess the capacity of inhibitory synaptic inputs on lateral dendrites to influence afferent information flow through MCs. Simulations using passivized models with varying dendritic morphologies and synaptic properties demonstrated that, even with unrealistically favorable parameters, passive propagation fails to convey effective inhibitory signals to the soma from distal sources. Additional simulations using an active model exhibiting action potentials, subthreshold oscillations, and a dendritic morphology closely matched to experimental values further confirmed that distal synaptic inputs along the lateral dendrite could not exert physiologically relevant effects on MC spike timing at the soma. Larger synaptic conductances representative of multiple simultaneous inputs were not sufficient to compensate for the decline in signal with distance. Reciprocal synapses on distal MC lateral dendrites may instead serve to maintain a common fast oscillatory clock across the OB by delaying spike propagation within the lateral dendrites themselves.
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Affiliation(s)
- Alexa B R McIntyre
- Tri-Institutional Program in Computational Biology and Medicine, Cornell University, Ithaca, New York; and
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12
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Carey RM, Sherwood WE, Shipley MT, Borisyuk A, Wachowiak M. Role of intraglomerular circuits in shaping temporally structured responses to naturalistic inhalation-driven sensory input to the olfactory bulb. J Neurophysiol 2015; 113:3112-29. [PMID: 25717156 DOI: 10.1152/jn.00394.2014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 02/20/2015] [Indexed: 11/22/2022] Open
Abstract
Olfaction in mammals is a dynamic process driven by the inhalation of air through the nasal cavity. Inhalation determines the temporal structure of sensory neuron responses and shapes the neural dynamics underlying central olfactory processing. Inhalation-linked bursts of activity among olfactory bulb (OB) output neurons [mitral/tufted cells (MCs)] are temporally transformed relative to those of sensory neurons. We investigated how OB circuits shape inhalation-driven dynamics in MCs using a modeling approach that was highly constrained by experimental results. First, we constructed models of canonical OB circuits that included mono- and disynaptic feedforward excitation, recurrent inhibition and feedforward inhibition of the MC. We then used experimental data to drive inputs to the models and to tune parameters; inputs were derived from sensory neuron responses during natural odorant sampling (sniffing) in awake rats, and model output was compared with recordings of MC responses to odorants sampled with the same sniff waveforms. This approach allowed us to identify OB circuit features underlying the temporal transformation of sensory inputs into inhalation-linked patterns of MC spike output. We found that realistic input-output transformations can be achieved independently by multiple circuits, including feedforward inhibition with slow onset and decay kinetics and parallel feedforward MC excitation mediated by external tufted cells. We also found that recurrent and feedforward inhibition had differential impacts on MC firing rates and on inhalation-linked response dynamics. These results highlight the importance of investigating neural circuits in a naturalistic context and provide a framework for further explorations of signal processing by OB networks.
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Affiliation(s)
- Ryan M Carey
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts
| | | | - Michael T Shipley
- Department of Anatomy and Neurobiology, Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland; and
| | - Alla Borisyuk
- Department of Mathematics, University of Utah, Salt Lake City, Utah
| | - Matt Wachowiak
- Department of Neurobiology and Anatomy and Brain Institute, University of Utah, Salt Lake City, Utah
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13
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Masoli S, Solinas S, D'Angelo E. Action potential processing in a detailed Purkinje cell model reveals a critical role for axonal compartmentalization. Front Cell Neurosci 2015; 9:47. [PMID: 25759640 PMCID: PMC4338753 DOI: 10.3389/fncel.2015.00047] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 01/30/2015] [Indexed: 12/02/2022] Open
Abstract
The Purkinje cell (PC) is among the most complex neurons in the brain and plays a critical role for cerebellar functioning. PCs operate as fast pacemakers modulated by synaptic inputs but can switch from simple spikes to complex bursts and, in some conditions, show bistability. In contrast to original works emphasizing dendritic Ca-dependent mechanisms, recent experiments have supported a primary role for axonal Na-dependent processing, which could effectively regulate spike generation and transmission to deep cerebellar nuclei (DCN). In order to account for the numerous ionic mechanisms involved (at present including Nav1.6, Cav2.1, Cav3.1, Cav3.2, Cav3.3, Kv1.1, Kv1.5, Kv3.3, Kv3.4, Kv4.3, KCa1.1, KCa2.2, KCa3.1, Kir2.x, HCN1), we have elaborated a multicompartmental model incorporating available knowledge on localization and gating of PC ionic channels. The axon, including initial segment (AIS) and Ranvier nodes (RNs), proved critical to obtain appropriate pacemaking and firing frequency modulation. Simple spikes initiated in the AIS and protracted discharges were stabilized in the soma through Na-dependent mechanisms, while somato-dendritic Ca channels contributed to sustain pacemaking and to generate complex bursting at high discharge regimes. Bistability occurred only following Na and Ca channel down-regulation. In addition, specific properties in RNs K currents were required to limit spike transmission frequency along the axon. The model showed how organized electroresponsive functions could emerge from the molecular complexity of PCs and showed that the axon is fundamental to complement ionic channel compartmentalization enabling action potential processing and transmission of specific spike patterns to DCN.
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Affiliation(s)
- Stefano Masoli
- Department of Brain and Behavioral Science, University of Pavia Pavia, Italy
| | - Sergio Solinas
- Brain Connectivity Center, Istituto Neurologico IRCCS C. Mondino Pavia, Italy
| | - Egidio D'Angelo
- Department of Brain and Behavioral Science, University of Pavia Pavia, Italy ; Brain Connectivity Center, Istituto Neurologico IRCCS C. Mondino Pavia, Italy
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Leng G, Hashimoto H, Tsuji C, Sabatier N, Ludwig M. Discharge patterning in rat olfactory bulb mitral cells in vivo. Physiol Rep 2014; 2:e12021. [PMID: 25281614 PMCID: PMC4254087 DOI: 10.14814/phy2.12021] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 04/18/2014] [Accepted: 04/18/2014] [Indexed: 11/24/2022] Open
Abstract
Here we present a detailed statistical analysis of the discharge characteristics of mitral cells of the main olfactory bulb of urethane-anesthetized rats. Neurons were recorded from the mitral cell layer, and antidromically identified by stimuli applied to the lateral olfactory tract. All mitral cells displayed repeated, prolonged bursts of action potentials typically lasting >100 sec and separated by similarly long intervals; about half were completely silent between bursts. No such bursting was observed in nonmitral cells recorded in close proximity to mitral cells. Bursts were asynchronous among even adjacent mitral cells. The intraburst activity of most mitral cells showed strong entrainment to the spontaneous respiratory rhythm; similar entrainment was seen in some, but not all nonmitral cells. All mitral cells displayed a peak of excitability at ~25 msec after spikes, as reflected by a peak in the interspike interval distribution and in the corresponding hazard function. About half also showed a peak at about 6 msec, reflecting the common occurrence of doublet spikes. Nonmitral cells showed no such doublet spikes. Bursts typically increased in intensity over the first 20-30 sec of a burst, during which time doublets were rare or absent. After 20-30 sec (in cells that exhibited doublets), doublets occurred frequently for as long as the burst persisted, in trains of up to 10 doublets. The last doublet was followed by an extended relative refractory period the duration of which was independent of train length. In cells that were excited by application of a particular odor, responsiveness was apparently greater during silent periods between bursts than during bursts. Conversely in cells that were inhibited by a particular odor, responsiveness was only apparent when cells were active. Extensive raw (event timing) data from the cells, together with details of those analyses, are provided as supplementary material, freely available for secondary use by others.
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Affiliation(s)
- Gareth Leng
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | - Hirofumi Hashimoto
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | - Chiharu Tsuji
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | - Nancy Sabatier
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | - Mike Ludwig
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
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15
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Cleland TA. Construction of Odor Representations by Olfactory Bulb Microcircuits. PROGRESS IN BRAIN RESEARCH 2014; 208:177-203. [DOI: 10.1016/b978-0-444-63350-7.00007-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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16
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Cholecystokinin: an excitatory modulator of mitral/tufted cells in the mouse olfactory bulb. PLoS One 2013; 8:e64170. [PMID: 23691163 PMCID: PMC3655022 DOI: 10.1371/journal.pone.0064170] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Accepted: 04/12/2013] [Indexed: 12/02/2022] Open
Abstract
Cholecystokinin (CCK) is widely distributed in the brain as a sulfated octapeptide (CCK-8S). In the olfactory bulb, CCK-8S is concentrated in two laminae: an infraglomerular band in the external plexiform layer, and an inframitral band in the internal plexiform layer (IPL), corresponding to somata and terminals of superficial tufted cells with intrabulbar projections linking duplicate glomerular maps of olfactory receptors. The physiological role of CCK in this circuit is unknown. We made patch clamp recordings of CCK effects on mitral cell spike activity in mouse olfactory bulb slices, and applied immunohistochemistry to localize CCKB receptors. In cell-attached recordings, mitral cells responded to 300 nM –1 µM CCK-8S by spike excitation, suppression, or mixed excitation-suppression. Antagonists of GABAA and ionotropic glutamate receptors blocked suppression, but excitation persisted. Whole-cell recordings revealed that excitation was mediated by a slow inward current, and suppression by spike inactivation or inhibitory synaptic input. Similar responses were elicited by the CCKB receptor-selective agonist CCK-4 (1 µM). Excitation was less frequent but still occurred when CCKB receptors were blocked by LY225910, or disrupted in CCKB knockout mice, and was also observed in CCKA knockouts. CCKB receptor immunoreactivity was detected on mitral and superficial tufted cells, colocalized with Tbx21, and was absent from granule cells and the IPL. Our data indicate that CCK excites mitral cells postsynaptically, via both CCKA and CCKB receptors. We hypothesize that extrasynaptic CCK released from tufted cell terminals in the IPL may diffuse to and directly excite mitral cell bodies, creating a positive feedback loop that can amplify output from pairs of glomeruli receiving sensory inputs encoded by the same olfactory receptor. Dynamic plasticity of intrabulbar projections suggests that this could be an experience-dependent amplification mechanism for tuning and optimizing olfactory bulb signal processing in different odor environments.
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17
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Abstract
Cholinergic inputs from the basal forebrain regulate multiple olfactory bulb (OB) functions, including odor discrimination, perceptual learning, and short-term memory. Previous studies have shown that nicotinic cholinergic receptor activation sharpens mitral cell chemoreceptive fields, likely via intraglomerular circuitry. Muscarinic cholinergic activation is less well understood, though muscarinic receptors are implicated in olfactory learning and in the regulation of synchronized oscillatory dynamics in hippocampus and cortex. To understand the mechanisms underlying cholinergic neuromodulation in OB, we developed a biophysical model of the OB neuronal network including both glomerular layer and external plexiform layer (EPL) computations and incorporating both nicotinic and muscarinic neuromodulatory effects. Our simulations show how nicotinic activation within glomerular circuits sharpens mitral cell chemoreceptive fields, even in the absence of EPL circuitry, but does not facilitate intrinsic oscillations or spike synchronization. In contrast, muscarinic receptor activation increases mitral cell spike synchronization and field oscillatory power by potentiating granule cell excitability and lateral inhibitory interactions within the EPL, but it has little effect on mitral cell firing rates and hence does not sharpen olfactory representations under a rate metric. These results are consistent with the theory that EPL interactions regulate the timing, rather than the existence, of mitral cell action potentials and perform their computations with respect to a spike timing-based metric. This general model suggests that the roles of nicotinic and muscarinic receptors in olfactory bulb are both distinct and complementary to one another, together regulating the effects of ascending cholinergic inputs on olfactory bulb transformations.
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18
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Arruda D, Publio R, Roque AC. The periglomerular cell of the olfactory bulb and its role in controlling mitral cell spiking: a computational model. PLoS One 2013; 8:e56148. [PMID: 23405261 PMCID: PMC3566063 DOI: 10.1371/journal.pone.0056148] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 01/07/2013] [Indexed: 01/14/2023] Open
Abstract
Interneurons in the olfactory bulb are key elements of odor processing but their roles have not yet being fully understood. Two types of inhibitory interneurons, periglomerular and granule cells, act at two different levels within the olfactory bulb and may have different roles in coordinating the spiking of mitral cells, which are the principal output neurons of the olfactory bulb. In this work we introduce a reduced compartmental model of the periglomerular cell and use it to investigate its role on mitral cell spiking in a model of an elementary cell triad composed of these two cell types plus a granule cell. Our simulation results show that the periglomerular cell is more effective in inhibiting the mitral cell than the granule cell. Based on our results we predict that periglomerular and granule cells have different roles in the control of mitral cell spiking. The periglomerular cell would be the only one capable of completely inhibiting the mitral cell, and the activity decrease of the mitral cell through this inhibitory action would occur in a stepwise fashion depending on parameters of the periglomerular and granule cells as well as on the relative times of arrival of external stimuli to the three cells. The major role of the granule cell would be to facilitate the inhibitory action of the periglomerular cell by enlarging the range of parameters of the periglomerular cell which correspond to complete inhibition of the mitral cell. The combined action of the two interneurons would thus provide an efficient way of controling the instantaneous value of the firing rate of the mitral cell.
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Affiliation(s)
- Denise Arruda
- Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil.
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19
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Masurkar AV, Chen WR. Calcium currents of olfactory bulb juxtaglomerular cells: profile and multiple conductance plateau potential simulation. Neuroscience 2011; 192:231-46. [PMID: 21704681 DOI: 10.1016/j.neuroscience.2011.06.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 05/06/2011] [Accepted: 06/03/2011] [Indexed: 11/25/2022]
Abstract
The olfactory glomerulus is the locus of information transfer between olfactory sensory neurons and output neurons of the olfactory bulb. Juxtaglomerular cells (JGCs) may influence intraglomerular processing by firing plateau potentials that support multiple spikes. It is unclear what inward currents mediate this firing pattern. In previous work, we characterized potassium currents of JGCs. We focus here on the inward currents using whole cell current clamp and voltage recording in a rat in vitro slice preparation, as well as computer simulation. We first showed that sodium current was not required to mediate plateau potentials. Voltage clamp characterization of calcium current (I(Ca)) determined that I(Ca) consisted of a slow activating, rapidly inactivating (τ(10%-90% rise) 6-8 ms, τ(inactivation) 38-77 ms) component I(cat1), similar to T-type currents, and a sustained (τ(inactivation)>>500 ms) component I(cat2), likely composed of L-type and P/Q-type currents. We used computer simulation to test their roles in plateau potential firing. We robustly modeled I(cat1) and I(cat2) to Hodgkin-Huxley schemes (m(3)h and m(2), respectively) and simulated a JGC plateau potential with six conductances: calcium currents as above, potassium currents from our prior study (A-type I(kt1), D-type I(kt2), delayed rectifier I(kt3)), and a fast sodium current (I(Na)). We demonstrated that I(cat1) was required for mediating the plateau potential, unlike I(Na) and I(cat2), and its τ(inactivation) determined plateau duration. We also found that I(kt1) dictated plateau potential shape more than I(kt2) and I(kt3). The influence of these two transient and opposing conductances suggests a unique mechanism of plateau potential physiology.
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Affiliation(s)
- A V Masurkar
- Department of Neurobiology, Yale University School of Medicine, New Haven, CT 06520, USA.
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20
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Zibman S, Shpak G, Wagner S. Distinct intrinsic membrane properties determine differential information processing between main and accessory olfactory bulb mitral cells. Neuroscience 2011; 189:51-67. [PMID: 21627980 DOI: 10.1016/j.neuroscience.2011.05.039] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 05/13/2011] [Accepted: 05/14/2011] [Indexed: 11/19/2022]
Abstract
Most mammals rely on semiochemicals, such as pheromones, to mediate their social interactions. Recent studies found that semiochemicals are perceived by at least two distinct chemosensory systems: the main and accessory olfactory systems, which share many molecular, cellular, and anatomical features. Nevertheless, the division of labor between these systems remained unclear. Previously we suggested that the two olfactory systems differ in the way they process sensory information. In this study we found that mitral cells of the main and accessory olfactory bulbs, the first brain stations of both systems, display markedly different passive and active intrinsic properties which permit distinct types of information processing. Moreover, we found that accessory olfactory bulb mitral cells are divided into three neuronal sub-populations with distinct firing properties. These neuronal sub-populations can be integrated in a simulated neuronal network that neglects episodic stimuli while amplifying reaction to long-lasting signals.
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Affiliation(s)
- S Zibman
- Institute for Life Sciences and Interdisciplinary Center for Neural Computation, Hebrew University, Jerusalem, Israel
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21
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David FO, Hugues E, Cenier T, Fourcaud-Trocmé N, Buonviso N. Specific entrainment of mitral cells during gamma oscillation in the rat olfactory bulb. PLoS Comput Biol 2009; 5:e1000551. [PMID: 19876377 PMCID: PMC2760751 DOI: 10.1371/journal.pcbi.1000551] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Accepted: 09/30/2009] [Indexed: 11/20/2022] Open
Abstract
Local field potential (LFP) oscillations are often accompanied by synchronization of activity within a widespread cerebral area. Thus, the LFP and neuronal coherence appear to be the result of a common mechanism that underlies neuronal assembly formation. We used the olfactory bulb as a model to investigate: (1) the extent to which unitary dynamics and LFP oscillations can be correlated and (2) the precision with which a model of the hypothesized underlying mechanisms can accurately explain the experimental data. For this purpose, we analyzed simultaneous recordings of mitral cell (MC) activity and LFPs in anesthetized and freely breathing rats in response to odorant stimulation. Spike trains were found to be phase-locked to the gamma oscillation at specific firing rates and to form odor-specific temporal patterns. The use of a conductance-based MC model driven by an approximately balanced excitatory-inhibitory input conductance and a relatively small inhibitory conductance that oscillated at the gamma frequency allowed us to provide one explanation of the experimental data via a mode-locking mechanism. This work sheds light on the way network and intrinsic MC properties participate in the locking of MCs to the gamma oscillation in a realistic physiological context and may result in a particular time-locked assembly. Finally, we discuss how a self-synchronization process with such entrainment properties can explain, under experimental conditions: (1) why the gamma bursts emerge transiently with a maximal amplitude position relative to the stimulus time course; (2) why the oscillations are prominent at a specific gamma frequency; and (3) why the oscillation amplitude depends on specific stimulus properties. We also discuss information processing and functional consequences derived from this mechanism. Olfactory function relies on a chain of neural relays that extends from the periphery to the central nervous system and implies neural activity with various timescales. A central question in neuroscience is how information is encoded by the neural activity. In the mammalian olfactory bulb, local neural activity oscillations in the 40–80 Hz range (gamma) may influence the timing of individual neuron activities such that olfactory information may be encoded in this way. In this study, we first characterize in vivo the detailed activity of individual neurons relative to the oscillation and find that, depending on their state, neurons can exhibit periodic activity patterns. We also find, at least qualitatively, a relation between this activity and a particular odor. This is reminiscent of general physical phenomena—the entrainment by an oscillation—and to verify this hypothesis, in a second phase, we build a biologically realistic model mimicking these in vivo conditions. Our model confirms quantitatively this hypothesis and reveals that entrainment is maximal in the gamma range. Taken together, our results suggest that the neuronal activity may be specifically formatted in time during the gamma oscillation in such a way that it could, at this stage, encode the odor.
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Affiliation(s)
- François O David
- Neurosciences Sensorielles, Comportement, Cognition, CNRS-Université Claude Bernard, Lyon, France.
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22
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Maex R, Steuber V. The first second: models of short-term memory traces in the brain. Neural Netw 2009; 22:1105-12. [PMID: 19635658 DOI: 10.1016/j.neunet.2009.07.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Revised: 05/26/2009] [Accepted: 07/14/2009] [Indexed: 10/20/2022]
Abstract
Many network models in computational neuroscience rise to the challenge of explaining behavioural phenomena ranging from microseconds to tens of seconds using components operating mostly on a time-scale of milliseconds. These models have in common that the underlying system has a memory, which implies that its output depends on its past input history. In this review we compare how such memory traces or delayed responses may be implemented in different brain areas supporting a diversity of functions.
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Affiliation(s)
- Reinoud Maex
- Science and Technology Research Institute, University of Hertfordshire, College Lane, Hatfield, Hertfordshire, United Kingdom.
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23
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Künsting T, Spors H. Dynamics of input patterns modulate the behavior of a model of olfactory bulb function. J Neurophysiol 2009; 102:100-9. [PMID: 19357336 DOI: 10.1152/jn.90699.2008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Input patterns to the olfactory bulb are dynamic and change in an odor-specific manner as measured by selective calcium imaging of olfactory bulb input. To our knowledge, none of the published models of olfactory bulb function uses dynamic input patterns. Therefore we tested how dynamic input alters the behavior of a simple model consisting of two layers. The membrane potential of the first-layer neurons, integrate-and-fire neurons corresponding to mitral cells, was modulated with a subthreshold oscillation at respiration frequency. The membrane potential of the second-layer neurons was used to discriminate input patterns. We implemented oscillating input with amplitudes and latencies different for each mitral cell. Not only varying the input amplitudes but also de-synchronizing the input, and varying the relation between latency and input amplitude, individually changed the model's performance significantly. The discrimination time was affected more easily than the number of second-layer neurons that can differentiate an odor pair. Increasing the de-synchronization, i.e., the spread of latency values, reduced the differences in response time between strong and weak stimulus pairs without reducing the number of reacting cells. Input phase relative to the subthreshold oscillation altered the effect of de-synchronization. Thus dynamic input changes performance parameters of models of olfactory information processing that can be verified experimentally.
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Affiliation(s)
- Thomas Künsting
- Win Group of Olfactory Dynamics, Heidelberger Akademie der Wissenschaften, Heidelberg, Germany
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24
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Matsumoto H, Kashiwadani H, Nagao H, Aiba A, Mori K. Odor-induced persistent discharge of mitral cells in the mouse olfactory bulb. J Neurophysiol 2009; 101:1890-900. [PMID: 19164106 DOI: 10.1152/jn.91019.2008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Short-term retention of sensory information in the form of persistent activity of central neurons plays a key role in transforming a brief sensory stimulation into longer-lasting brain responses. The olfactory system uses this transformation for various functional purposes, but the underlying neuronal mechanisms remain elusive. Here, we recorded odor-evoked, single-unit spike responses of mitral and tufted (M/T) cells in the mouse olfactory bulb (OB) under urethane anesthesia and examined the neuronal mechanisms of the persistent discharge (PD) of M/T cells that outlasts the odor stimulus for tens of seconds. The properties of the persistent afterdischarge that occurred after odor stimulation were distinct from those of odor-induced immediate spike responses in terms of the magnitude, odorant specificity, and odorant concentration-response relationship. This suggests that neuronal mechanisms other than prolonged input from olfactory sensory neurons are involved in generating these afterdischarges. Metabotropic glutamate receptor 1 (mGluR1) is expressed in the dendrites of M/T cells and is thought to participate in intraglomerular interactions among M/T cells. In OBs lacking mGluR1, or treated locally with an mGluR1-selective antagonist, the duration of the odor-induced spike responses was significantly lower than that in control OBs, indicating that mGluR1 within the bulbar neuronal circuits participates in the PD generation. These results suggest that neuronal circuits in the OB can actively prolong the odor-induced spike activity of bulbar output neurons and thus transform a brief odor input into longer-lasting activity in the central olfactory system.
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Affiliation(s)
- Hideyuki Matsumoto
- Department of Physiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Japan
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25
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Carey RM, Verhagen JV, Wesson DW, Pírez N, Wachowiak M. Temporal structure of receptor neuron input to the olfactory bulb imaged in behaving rats. J Neurophysiol 2008; 101:1073-88. [PMID: 19091924 DOI: 10.1152/jn.90902.2008] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The dynamics of sensory input to the nervous system play a critical role in shaping higher-level processing. In the olfactory system, the dynamics of input from olfactory receptor neurons (ORNs) are poorly characterized and depend on multiple factors, including respiration-driven airflow through the nasal cavity, odorant sorption kinetics, receptor-ligand interactions between odorant and receptor, and the electrophysiological properties of ORNs. Here, we provide a detailed characterization of the temporal organization of ORN input to the mammalian olfactory bulb (OB) during natural respiration, using calcium imaging to monitor ORN input to the OB in awake, head-fixed rats expressing odor-guided behaviors. We report several key findings. First, across a population of homotypic ORNs, each inhalation of odorant evokes a burst of action potentials having a rise time of about 80 ms and a duration of about 100 ms. This rise time indicates a relatively slow, progressive increase in ORN activation as odorant flows through the nasal cavity. Second, the dynamics of ORN input differ among glomeruli and for different odorants and concentrations, but remain reliable across successive inhalations. Third, inhalation alone (in the absence of odorant) evokes ORN input to a significant fraction of OB glomeruli. Finally, high-frequency sniffing of odorant strongly reduces the temporal coupling between ORN inputs and the respiratory cycle. These results suggest that the dynamics of sensory input to the olfactory system may play a role in coding odor information and that, in the awake animal, strategies for processing odor information may change as a function of sampling behavior.
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Affiliation(s)
- Ryan M Carey
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
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26
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David F, Linster C, Cleland TA. Lateral dendritic shunt inhibition can regularize mitral cell spike patterning. J Comput Neurosci 2007; 25:25-38. [PMID: 18060489 DOI: 10.1007/s10827-007-0063-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2006] [Revised: 10/30/2007] [Accepted: 10/30/2007] [Indexed: 12/01/2022]
Abstract
Mitral cells, the principal output neurons of the olfactory bulb, receive direct synaptic activation from primary sensory neurons. Shunting inhibitory inputs delivered by granule cell interneurons onto mitral cell lateral dendrites, while poorly positioned to prevent spike initiation, are believed to influence spike timing and underlie coordinated field potential oscillations. We investigated this phenomenon in a reduced compartmental mitral cell model suitable for incorporation into network simulations. Lateral dendritic shunt conductances delayed spiking to a degree dependent on both their electrotonic distance and phase of onset. Moreover, when the afferent activation of mitral cells was loosely coordinated in time, recurrent inhibition significantly narrowed the distribution of mitral cell spike times, illustrating a tendency towards coordinated synchronous activity. However, if mitral cell activity was initially disorganized, recurrent inhibition actually increased the variance in spike timing. This result suggests an essential role for early mechanisms of temporal coordination in olfaction, such as sniffing and the initial synchronization of mitral cell intrinsic oscillations by periglomerular cell-mediated inhibition.
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Affiliation(s)
- François David
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA.
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27
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Cleland TA, Johnson BA, Leon M, Linster C. Relational representation in the olfactory system. Proc Natl Acad Sci U S A 2007; 104:1953-8. [PMID: 17261800 PMCID: PMC1794271 DOI: 10.1073/pnas.0608564104] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The perceptual quality of odors usually is robust to variability in concentration. However, maps of neural activation across the olfactory bulb glomerular layer are not stable in this respect; rather, glomerular odor representations both broaden and intensify as odorant concentrations are increased. The relative levels of activation among glomeruli, in contrast, remain relatively stable across concentrations, suggesting that the representation of odor quality may rely on these relational activity patterns. However, the neural normalization mechanisms enabling extraction of such relational representations are unclear. Using glomerular imaging activity profiles from the rat olfactory bulb together with computational modeling, we here show that (i) global normalization preserves concentration-independent odor-quality information; (ii) perceptual similarities, as assessed behaviorally, are better predicted by normalized than by raw bulbar activity profiles; and (iii) a recurrent excitatory circuit recently described in the olfactory bulb is capable of performing such normalization. We show that global feed-forward normalization in a sensory system is behaviorally relevant, and that a center-surround neural architecture does not necessarily imply center-surround function.
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Affiliation(s)
- Thomas A. Cleland
- *Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853; and
| | - Brett A. Johnson
- Department of Neurobiology and Behavior, University of California, Irvine, CA 92697
| | - Michael Leon
- Department of Neurobiology and Behavior, University of California, Irvine, CA 92697
- To whom correspondence should be addressed. E-mail:
| | - Christiane Linster
- *Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853; and
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28
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Mandairon N, Ferretti CJ, Stack CM, Rubin DB, Cleland TA, Linster C. Cholinergic modulation in the olfactory bulb influences spontaneous olfactory discrimination in adult rats. Eur J Neurosci 2006; 24:3234-44. [PMID: 17156384 DOI: 10.1111/j.1460-9568.2006.05212.x] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cholinergic neuromodulation in the olfactory bulb has been hypothesized to regulate mitral cell molecular receptive ranges and the behavioral discrimination of similar odorants. We tested the effects of cholinergic modulation in the olfactory bulb of cannulated rats by bilaterally infusing cholinergic agents into the olfactory bulbs and measuring the rats' performances on separate spontaneous and motivated odor-discrimination tasks. Specifically, 6 microL/bulb infusions of vehicle (0.9% saline), the muscarinic antagonist scopolamine (7.6 mM and 38 mM), the nicotinic antagonist mecamylamine hydrochloride (3.8 mM and 19 mM), a combination of both antagonists, or the acetylcholinesterase inhibitor neostigmine (8.7 mM) were made 20 min prior to testing on an olfactory cross-habituation task or a rewarded, forced-choice odor-discrimination task. Spontaneous discrimination between chemically related odorants was abolished when nicotinic receptors were blocked in the olfactory bulb, and enhanced when the efficacy of cholinergic inputs was increased with neostigmine. Blocking muscarinic receptors reduced but did not abolish odor discrimination. Interestingly, no behavioral effects of modulating either nicotinic or muscarinic receptors were observed when rats were trained on a reward-motivated odor-discrimination task. Computational modeling of glomerular circuitry demonstrates that known nicotinic cholinergic effects on bulbar neurons suffice to explain these results.
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Affiliation(s)
- Nathalie Mandairon
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA.
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