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Lodi M, Shilnikov AL, Storace M. Design Principles for Central Pattern Generators With Preset Rhythms. IEEE TRANSACTIONS ON NEURAL NETWORKS AND LEARNING SYSTEMS 2020; 31:3658-3669. [PMID: 31722491 DOI: 10.1109/tnnls.2019.2945637] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
This article is concerned with the design of synthetic central pattern generators (CPGs). Biological CPGs are neural circuits that determine a variety of rhythmic activities, including locomotion, in animals. A synthetic CPG is a network of dynamical elements (here called cells) properly coupled by various synapses to emulate rhythms produced by a biological CPG. We focus on CPGs for locomotion of quadrupeds and present our design approach, based on the principles of nonlinear dynamics, bifurcation theory, and parameter optimization. This approach lets us design the synthetic CPG with a set of desired rhythms and switch between them as the parameter representing the control actions from the brain is varied. The developed four-cell CPG can produce four distinct gaits: walk, trot, gallop, and bound, similar to the mouse locomotion. The robustness and adaptability of the network design principles are verified using different cell and synapse models.
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Krishnamurthy P, Silberberg G, Lansner A. Long-range recruitment of Martinotti cells causes surround suppression and promotes saliency in an attractor network model. Front Neural Circuits 2015; 9:60. [PMID: 26528143 PMCID: PMC4604243 DOI: 10.3389/fncir.2015.00060] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 09/23/2015] [Indexed: 11/13/2022] Open
Abstract
Although the importance of long-range connections for cortical information processing has been acknowledged for a long time, most studies focused on the long-range interactions between excitatory cortical neurons. Inhibitory interneurons play an important role in cortical computation and have thus far been studied mainly with respect to their local synaptic interactions within the cortical microcircuitry. A recent study showed that long-range excitatory connections onto Martinotti cells (MC) mediate surround suppression. Here we have extended our previously reported attractor network of pyramidal cells (PC) and MC by introducing long-range connections targeting MC. We have demonstrated how the network with Martinotti cell-mediated long-range inhibition gives rise to surround suppression and also promotes saliency of locations at which simple non-uniformities in the stimulus field are introduced. Furthermore, our analysis suggests that the presynaptic dynamics of MC is only ancillary to its orientation tuning property in enabling the network with saliency detection. Lastly, we have also implemented a disinhibitory pathway mediated by another interneuron type (VIP interneurons), which inhibits MC and abolishes surround suppression.
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Affiliation(s)
- Pradeep Krishnamurthy
- Department of Numerical Analysis and Computer Science, Stockholm University Stockholm, Sweden ; Department of Computational Biology, School of Computer Science and Communication, Royal Institute of Technology (KTH) Stockholm, Sweden
| | - Gilad Silberberg
- Department of Neuroscience, Karolinska Institutet Stockholm, Sweden
| | - Anders Lansner
- Department of Numerical Analysis and Computer Science, Stockholm University Stockholm, Sweden ; Department of Computational Biology, School of Computer Science and Communication, Royal Institute of Technology (KTH) Stockholm, Sweden
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Belykh I, Reimbayev R, Zhao K. Synergistic effect of repulsive inhibition in synchronization of excitatory networks. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:062919. [PMID: 26172784 DOI: 10.1103/physreve.91.062919] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Indexed: 06/04/2023]
Abstract
We show that the addition of pairwise repulsive inhibition to excitatory networks of bursting neurons induces synchrony, in contrast to one's expectations. Through stability analysis, we reveal the mechanism underlying this purely synergistic phenomenon and demonstrate that it originates from the transition between different types of bursting, caused by excitatory-inhibitory synaptic coupling. This effect is generic and observed in different models of bursting neurons and fast synaptic interactions. We also find a universal scaling law for the synchronization stability condition for large networks in terms of the number of excitatory and inhibitory inputs each neuron receives, regardless of the network size and topology. This general law is in sharp contrast with linearly coupled networks with positive (attractive) and negative (repulsive) coupling where the placement and structure of negative connections heavily affect synchronization.
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Affiliation(s)
- Igor Belykh
- Department of Mathematics and Statistics and Neuroscience Institute, Georgia State University, 30 Pryor Street, Atlanta, Georgia 30303, USA
| | - Reimbay Reimbayev
- Department of Mathematics and Statistics and Neuroscience Institute, Georgia State University, 30 Pryor Street, Atlanta, Georgia 30303, USA
| | - Kun Zhao
- Department of Mathematics and Statistics and Neuroscience Institute, Georgia State University, 30 Pryor Street, Atlanta, Georgia 30303, USA
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Krishnamurthy P, Silberberg G, Lansner A. A cortical attractor network with Martinotti cells driven by facilitating synapses. PLoS One 2012; 7:e30752. [PMID: 22523533 PMCID: PMC3327695 DOI: 10.1371/journal.pone.0030752] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Accepted: 12/21/2011] [Indexed: 12/02/2022] Open
Abstract
The population of pyramidal cells significantly outnumbers the inhibitory interneurons in the neocortex, while at the same time the diversity of interneuron types is much more pronounced. One acknowledged key role of inhibition is to control the rate and patterning of pyramidal cell firing via negative feedback, but most likely the diversity of inhibitory pathways is matched by a corresponding diversity of functional roles. An important distinguishing feature of cortical interneurons is the variability of the short-term plasticity properties of synapses received from pyramidal cells. The Martinotti cell type has recently come under scrutiny due to the distinctly facilitating nature of the synapses they receive from pyramidal cells. This distinguishes these neurons from basket cells and other inhibitory interneurons typically targeted by depressing synapses. A key aspect of the work reported here has been to pinpoint the role of this variability. We first set out to reproduce quantitatively based on in vitro data the di-synaptic inhibitory microcircuit connecting two pyramidal cells via one or a few Martinotti cells. In a second step, we embedded this microcircuit in a previously developed attractor memory network model of neocortical layers 2/3. This model network demonstrated that basket cells with their characteristic depressing synapses are the first to discharge when the network enters an attractor state and that Martinotti cells respond with a delay, thereby shifting the excitation-inhibition balance and acting to terminate the attractor state. A parameter sensitivity analysis suggested that Martinotti cells might, in fact, play a dominant role in setting the attractor dwell time and thus cortical speed of processing, with cellular adaptation and synaptic depression having a less prominent role than previously thought.
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Affiliation(s)
- Pradeep Krishnamurthy
- Department of Numerical Analysis and Computer Science, Stockholm University, Stockholm, Sweden
- School of Computer Science and Communication, Department of Computational Biology, Royal Institute of Technology (KTH), Stockholm, Sweden
| | - Gilad Silberberg
- Nobel Institute of Neurophysiology, Department of Neuroscience, Karolinska Institute, Stockholm, Sweden
| | - Anders Lansner
- Department of Numerical Analysis and Computer Science, Stockholm University, Stockholm, Sweden
- School of Computer Science and Communication, Department of Computational Biology, Royal Institute of Technology (KTH), Stockholm, Sweden
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Abstract
In his theory of functional polarity, Ramon y Cajal first identified the soma and dendrites as the principal recipient compartments of a neuron and the axon as its main output structure. Despite notable exceptions in other parts of the nervous system (Schoppa and Urban, 2003; Wässle, 2004; Howard et al., 2005), this route of signal propagation has been shown to underlie the functional properties of most neocortical circuits studied so far. Recent evidence, however, suggests that neocortical excitatory cells may trigger the release of the inhibitory neurotransmitter GABA by directly depolarizing the axon terminals of inhibitory interneurons, thus bypassing their somatodendritic compartments (Ren et al., 2007). By using a combination of optical and electrophysiological approaches, we find that synaptically released glutamate fails to trigger GABA release through a direct action on GABAergic terminals under physiological conditions. Rather, our evidence suggests that glutamate triggers GABA release only after somatodendritic depolarization and action potential generation at GABAergic interneurons. These data indicate that neocortical inhibition is recruited by classical somatodendritic integration rather than direct activation of interneuron axon terminals.
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Proximity of excitatory and inhibitory axon terminals adjacent to pyramidal cell bodies provides a putative basis for nonsynaptic interactions. Proc Natl Acad Sci U S A 2009; 106:9878-83. [PMID: 19487685 DOI: 10.1073/pnas.0900330106] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Although pyramidal cells are the main excitatory neurons in the cerebral cortex, it has recently been reported that they can evoke inhibitory postsynaptic currents in neighboring pyramidal neurons. These inhibitory effects were proposed to be mediated by putative axo-axonic excitatory synapses between the axon terminals of pyramidal cells and perisomatic inhibitory axon terminals [Ren M, Yoshimura Y, Takada N, Horibe S, Komatsu Y (2007) Science 316:758-761]. However, the existence of this type of axo-axonic synapse was not found using serial section electron microscopy. Instead, we observed that inhibitory axon terminals synapsing on pyramidal cell bodies were frequently apposed by terminals that established excitatory synapses with neighbouring dendrites. We propose that a spillover of glutamate from these excitatory synapses can activate the adjacent inhibitory axo-somatic terminals.
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Polysynaptic subcircuits in the neocortex: spatial and temporal diversity. Curr Opin Neurobiol 2009; 18:332-7. [PMID: 18801433 DOI: 10.1016/j.conb.2008.08.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Revised: 08/15/2008] [Accepted: 08/18/2008] [Indexed: 11/23/2022]
Abstract
Inhibitory pathways in the neocortex display a variety of temporal and spatial patterns, maintaining a dynamic balance with excitatory synaptic activity. Recent studies have revealed prevalent polysynaptic subcircuits within the neocortical microcircuitry. These subcircuits involve excitatory and inhibitory connections that are activated by neurons both in supragranular and infragranular cortical layers and mediated by different mechanisms. Interestingly, in these subcircuits inhibition is induced by discharge of pyramidal cells, and excitation is caused by specific types of GABAergic interneurons. The different polysynaptic subcircuits are discussed with respect to their spatial and temporal properties and their possible functional role in cortical processing.
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Kriener B, Tetzlaff T, Aertsen A, Diesmann M, Rotter S. Correlations and Population Dynamics in Cortical Networks. Neural Comput 2008; 20:2185-226. [DOI: 10.1162/neco.2008.02-07-474] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
The function of cortical networks depends on the collective interplay between neurons and neuronal populations, which is reflected in the correlation of signals that can be recorded at different levels. To correctly interpret these observations it is important to understand the origin of neuronal correlations. Here we study how cells in large recurrent networks of excitatory and inhibitory neurons interact and how the associated correlations affect stationary states of idle network activity. We demonstrate that the structure of the connectivity matrix of such networks induces considerable correlations between synaptic currents as well as between subthreshold membrane potentials, provided Dale's principle is respected. If, in contrast, synaptic weights are randomly distributed, input correlations can vanish, even for densely connected networks. Although correlations are strongly attenuated when proceeding from membrane potentials to action potentials (spikes), the resulting weak correlations in the spike output can cause substantial fluctuations in the population activity, even in highly diluted networks. We show that simple mean-field models that take the structure of the coupling matrix into account can adequately describe the power spectra of the population activity. The consequences of Dale's principle on correlations and rate fluctuations are discussed in the light of recent experimental findings.
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Affiliation(s)
- Birgit Kriener
- Bernstein Center for Computational Neuroscience, and Neurobiology and Biophysics, Faculty of Biology, Albert-Ludwigs-University, D-79104 Freiburg, Germany
| | - Tom Tetzlaff
- Bernstein Center for Computational Neuroscience, Albert-Ludwigs-University, D-79104 Freiburg, Germany, and Institute of Mathematical Sciences and Technology, Norwegian University of Life Sciences, N-1432 Ås, Norway
| | - Ad Aertsen
- Bernstein Center for Computational Neuroscience, and Neurobiology and Biophysics, Faculty of Biology, Albert-Ludwigs-University, D-79104 Freiburg, Germany
| | - Markus Diesmann
- Bernstein Center for Computational Neuroscience, Albert-Ludwigs-University, D-79104 Freiburg, Germany, and Brain Science Institute, RIKEN, Wako City, Saitama 351-0198, Japan
| | - Stefan Rotter
- Bernstein Center for Computational Neuroscience, Albert-Ludwigs-University, D-79104 Freiburg, Germany, and Theory and Data Analysis, Institute for Frontier Areas of Psychology and Mental Health, D-79098 Freiburg, Germany
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Abstract
Although often overshadowed by factors influencing seizure initiation, seizure termination is a critical step in the return to the interictal state. Understanding the mechanisms contributing to seizure termination could potentially identify novel targets for anticonvulsant drug development and may also highlight the pathophysiological processes contributing to seizure initiation. In this article, we review known physiological mechanisms contributing to seizure termination and discuss additional mechanisms that are likely to be relevant even though specific data are not yet available. This review is organized according to successively increasing "size scales"-from membranes to synapses to networks to circuits. We first discuss mechanisms of seizure termination acting at the shortest distances and affecting the excitable membranes of neurons in the seizure onset zone. Next we consider the contributions of ensembles of neurons and glia interacting at intermediate distances within the region of the seizure onset zone. Lastly, we consider the contribution of brain nuclei, such as the substantia nigra pars reticulata (SNR), that are capable of modulating seizures and exert their influence over the seizure onset zone (and neighboring areas) from a relatively great-in neuroanatomical terms-distance. It is our hope that the attention to the mechanisms contributing to seizure termination will stimulate novel avenues of epilepsy research and will contribute to improved patient care.
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Affiliation(s)
- Fred A Lado
- The Saul R. Korey Department of Neurology, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York, NY 10461, USA.
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