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Tikidji-Hamburyan RA, Govindaiah G, Guido W, Colonnese MT. Synaptic and circuit mechanisms prevent detrimentally precise correlation in the developing mammalian visual system. eLife 2023; 12:e84333. [PMID: 37211984 PMCID: PMC10202458 DOI: 10.7554/elife.84333] [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: 10/20/2022] [Accepted: 04/25/2023] [Indexed: 05/23/2023] Open
Abstract
The developing visual thalamus and cortex extract positional information encoded in the correlated activity of retinal ganglion cells by synaptic plasticity, allowing for the refinement of connectivity. Here, we use a biophysical model of the visual thalamus during the initial visual circuit refinement period to explore the role of synaptic and circuit properties in the regulation of such neural correlations. We find that the NMDA receptor dominance, combined with weak recurrent excitation and inhibition characteristic of this age, prevents the emergence of spike-correlations between thalamocortical neurons on the millisecond timescale. Such precise correlations, which would emerge due to the broad, unrefined connections from the retina to the thalamus, reduce the spatial information contained by thalamic spikes, and therefore we term them 'parasitic' correlations. Our results suggest that developing synapses and circuits evolved mechanisms to compensate for such detrimental parasitic correlations arising from the unrefined and immature circuit.
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Affiliation(s)
| | - Gubbi Govindaiah
- Department of Anatomical Sciences and Neurobiology, University of LouisvilleLouisvilleUnited States
| | - William Guido
- Department of Anatomical Sciences and Neurobiology, University of LouisvilleLouisvilleUnited States
| | - Matthew T Colonnese
- Department of Pharmacology and Physiology, The George Washington UniversityWashingtonUnited States
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2
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Modeling cholinergic retinal waves: starburst amacrine cells shape wave generation, propagation, and direction bias. Sci Rep 2023; 13:2834. [PMID: 36808155 PMCID: PMC9938278 DOI: 10.1038/s41598-023-29572-2] [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: 08/09/2022] [Accepted: 02/07/2023] [Indexed: 02/19/2023] Open
Abstract
Stage II cholinergic retinal waves are one of the first instances of neural activity in the visual system as they are present at a developmental timepoint in which light-evoked activity remains largely undetectable. These waves of spontaneous neural activity sweeping across the developing retina are generated by starburst amacrine cells, depolarize retinal ganglion cells, and drive the refinement of retinofugal projections to numerous visual centers in the brain. Building from several well-established models, we assemble a spatial computational model of starburst amacrine cell-mediated wave generation and wave propagation that includes three significant advancements. First, we model the intrinsic spontaneous bursting of the starburst amacrine cells, including the slow afterhyperpolarization, which shapes the stochastic process of wave generation. Second, we establish a mechanism of wave propagation using reciprocal acetylcholine release, synchronizing the bursting activity of neighboring starburst amacrine cells. Third, we model the additional starburst amacrine cell release of GABA, changing the spatial propagation of retinal waves and in certain instances, the directional bias of the retinal wave front. In total, these advancements comprise a now more comprehensive model of wave generation, propagation, and direction bias.
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3
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Behpour S, Field DJ, Albert MV. On the Role of LGN/V1 Spontaneous Activity as an Innate Learning Pattern for Visual Development. Front Physiol 2021; 12:695431. [PMID: 34776991 PMCID: PMC8589027 DOI: 10.3389/fphys.2021.695431] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 10/05/2021] [Indexed: 11/16/2022] Open
Abstract
Correlated, spontaneous neural activity is known to play a necessary role in visual development, but the higher-order statistical structure of these coherent, amorphous patterns has only begun to emerge in the past decade. Several computational studies have demonstrated how this endogenous activity can be used to train a developing visual system. Models that generate spontaneous activity analogous to retinal waves have shown that these waves can serve as stimuli for efficient coding models of V1. This general strategy in development has one clear advantage: The same learning algorithm can be used both before and after eye-opening. This same insight can be applied to understanding LGN/V1 spontaneous activity. Although lateral geniculate nucleus (LGN) activity has been less discussed in the literature than retinal waves, here we argue that the waves found in the LGN have a number of properties that fill the role of a training pattern. We make the case that the role of “innate learning” with spontaneous activity is not only possible, but likely in later stages of visual development, and worth pursuing further using an efficient coding paradigm.
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Affiliation(s)
- Sahar Behpour
- Department of Information Science, University of North Texas, Denton, TX, United States
| | - David J Field
- Department of Psychology, Cornell University, Ithaca, NY, United States
| | - Mark V Albert
- Department of Computer Science and Engineering, University of North Texas, Denton, TX, United States.,Department of Biomedical Engineering, University of North Texas, Denton, TX, United States
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4
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Lovas JR, Yuste R. Ensemble synchronization in the reassembly of Hydra's nervous system. Curr Biol 2021; 31:3784-3796.e3. [PMID: 34297913 DOI: 10.1016/j.cub.2021.06.047] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 05/14/2021] [Accepted: 06/16/2021] [Indexed: 11/25/2022]
Abstract
Although much is known about how the structure of the nervous system develops, it is still unclear how its functional modularity arises. A dream experiment would be to observe the entire development of a nervous system, correlating the emergence of functional units with their associated behaviors. This is possible in the cnidarian Hydra vulgaris, which, after its complete dissociation into individual cells, can reassemble itself back together into a normal animal. We used calcium imaging to monitor the complete neuronal activity of dissociated Hydra as they reaggregated over several days. Initially uncoordinated neuronal activity became synchronized into coactive neuronal ensembles. These local modules then synchronized with others, building larger functional ensembles that eventually extended throughout the entire reaggregate, generating neuronal rhythms similar to those of intact animals. Global synchronization was not due to neurite outgrowth but to strengthening of functional connections between ensembles. We conclude that Hydra's nervous system achieves its functional reassembly through the hierarchical modularity of neuronal ensembles.
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Affiliation(s)
- Jonathan R Lovas
- Neurotechnology Center, Department Biological Sciences, Columbia University, New York, NY 10027, USA; Marine Biological Laboratory, Woods Hole, MA 02354, USA.
| | - Rafael Yuste
- Neurotechnology Center, Department Biological Sciences, Columbia University, New York, NY 10027, USA; Marine Biological Laboratory, Woods Hole, MA 02354, USA
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5
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Nakazawa S, Iwasato T. Spatial organization and transitions of spontaneous neuronal activities in the developing sensory cortex. Dev Growth Differ 2021; 63:323-339. [PMID: 34166527 DOI: 10.1111/dgd.12739] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 06/21/2021] [Accepted: 06/22/2021] [Indexed: 12/30/2022]
Abstract
The sensory cortex underlies our ability to perceive and interact with the external world. Sensory perceptions are controlled by specialized neuronal circuits established through fine-tuning, which relies largely on neuronal activity during the development. Spontaneous neuronal activity is an essential driving force of neuronal circuit refinement. At early developmental stages, sensory cortices display spontaneous activities originating from the periphery and characterized by correlated firing arranged spatially according to the modality. The firing patterns are reorganized over time and become sparse, which is typical for the mature brain. This review focuses mainly on rodent sensory cortices. First, the features of the spontaneous activities during early postnatal stages are described. Then, the developmental changes in the spatial organization of the spontaneous activities and the transition mechanisms involved are discussed. The identification of the principles controlling the spatial organization of spontaneous activities in the developing sensory cortex is essential to understand the self-organization process of neuronal circuits.
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Affiliation(s)
- Shingo Nakazawa
- Laboratory of Mammalian Neural Circuits, National Institute of Genetics, Mishima, Japan.,Department of Basic Neurosciences, University of Geneva, Geneva, Switzerland
| | - Takuji Iwasato
- Laboratory of Mammalian Neural Circuits, National Institute of Genetics, Mishima, Japan.,Department of Genetics, SOKENDAI (The Graduate University for Advanced Studies), Mishima, Japan
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6
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Redolfi N, Lodovichi C. Spontaneous Afferent Activity Carves Olfactory Circuits. Front Cell Neurosci 2021; 15:637536. [PMID: 33767612 PMCID: PMC7985084 DOI: 10.3389/fncel.2021.637536] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 02/08/2021] [Indexed: 12/11/2022] Open
Abstract
Electrical activity has a key role in shaping neuronal circuits during development. In most sensory modalities, early in development, internally generated spontaneous activity sculpts the initial layout of neuronal wiring. With the maturation of the sense organs, the system relies more on sensory-evoked electrical activity. Stimuli-driven neuronal discharge is required for the transformation of immature circuits in the specific patterns of neuronal connectivity that subserve normal brain function. The olfactory system (OS) differs from this organizational plan. Despite the important role of odorant receptors (ORs) in shaping olfactory topography, odor-evoked activity does not have a prominent role in refining neuronal wiring. On the contrary, afferent spontaneous discharge is required to achieve and maintain the specific diagram of connectivity that defines the topography of the olfactory bulb (OB). Here, we provide an overview of the development of olfactory topography, with a focus on the role of afferent spontaneous discharge in the formation and maintenance of the specific synaptic contacts that result in the topographic organization of the OB.
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Affiliation(s)
- Nelly Redolfi
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Claudia Lodovichi
- Department of Biomedical Sciences, University of Padua, Padua, Italy.,Neuroscience Institute CNR, Padua, Italy.,Veneto Institute of Molecular Medicine, Padua, Italy.,Padova Neuroscience Center, University of Padua, Padua, Italy
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7
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Kähne M, Rüdiger S, Kihara AH, Lindner B. Gap junctions set the speed and nucleation rate of stage I retinal waves. PLoS Comput Biol 2019; 15:e1006355. [PMID: 31034472 PMCID: PMC6508742 DOI: 10.1371/journal.pcbi.1006355] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 05/09/2019] [Accepted: 11/27/2018] [Indexed: 11/18/2022] Open
Abstract
Spontaneous waves in the developing retina are essential in the formation of the retinotopic mapping in the visual system. From experiments in rabbits, it is known that the earliest type of retinal waves (stage I) is nucleated spontaneously, propagates at a speed of 451±91 μm/sec and relies on gap junction coupling between ganglion cells. Because gap junctions (electrical synapses) have short integration times, it has been argued that they cannot set the low speed of stage I retinal waves. Here, we present a theoretical study of a two-dimensional neural network of the ganglion cell layer with gap junction coupling and intrinsic noise. We demonstrate that this model can explain observed nucleation rates as well as the comparatively slow propagation speed of the waves. From the interaction between two coupled neurons, we estimate the wave speed in the model network. Furthermore, using simulations of small networks of neurons (N≤260), we estimate the nucleation rate in the form of an Arrhenius escape rate. These results allow for informed simulations of a realistically sized network, yielding values of the gap junction coupling and the intrinsic noise level that are in a physiologically plausible range.
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Affiliation(s)
- Malte Kähne
- Institut für Physik, Humboldt-Universität zu Berlin, Berlin, Germany
- * E-mail:
| | - Sten Rüdiger
- Institut für Physik, Humboldt-Universität zu Berlin, Berlin, Germany
| | | | - Benjamin Lindner
- Institut für Physik, Humboldt-Universität zu Berlin, Berlin, Germany
- Bernstein Center for Computational Neuroscience Berlin, Berlin, Germany
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8
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A biophysical model explains the spontaneous bursting behavior in the developing retina. Sci Rep 2019; 9:1859. [PMID: 30755684 PMCID: PMC6372601 DOI: 10.1038/s41598-018-38299-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 12/21/2018] [Indexed: 01/17/2023] Open
Abstract
During early development, waves of activity propagate across the retina and play a key role in the proper wiring of the early visual system. During a particular phase of the retina development (stage II) these waves are triggered by a transient network of neurons, called Starburst Amacrine Cells (SACs), showing a bursting activity which disappears upon further maturation. The underlying mechanisms of the spontaneous bursting and the transient excitability of immature SACs are not completely clear yet. While several models have attempted to reproduce retinal waves, none of them is able to mimic the rhythmic autonomous bursting of individual SACs and reveal how these cells change their intrinsic properties during development. Here, we introduce a mathematical model, grounded on biophysics, which enables us to reproduce the bursting activity of SACs and to propose a plausible, generic and robust, mechanism that generates it. The core parameters controlling repetitive firing are fast depolarizing V-gated calcium channels and hyperpolarizing V-gated potassium channels. The quiescent phase of bursting is controlled by a slow after hyperpolarization (sAHP), mediated by calcium-dependent potassium channels. Based on a bifurcation analysis we show how biophysical parameters, regulating calcium and potassium activity, control the spontaneously occurring fast oscillatory activity followed by long refractory periods in individual SACs. We make a testable experimental prediction on the role of voltage-dependent potassium channels on the excitability properties of SACs and on the evolution of this excitability along development. We also propose an explanation on how SACs can exhibit a large variability in their bursting periods, as observed experimentally within a SACs network as well as across different species, yet based on a simple, unique, mechanism. As we discuss, these observations at the cellular level have a deep impact on the retinal waves description.
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9
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Goodhill GJ. Theoretical Models of Neural Development. iScience 2018; 8:183-199. [PMID: 30321813 PMCID: PMC6197653 DOI: 10.1016/j.isci.2018.09.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 08/06/2018] [Accepted: 09/19/2018] [Indexed: 12/22/2022] Open
Abstract
Constructing a functioning nervous system requires the precise orchestration of a vast array of mechanical, molecular, and neural-activity-dependent cues. Theoretical models can play a vital role in helping to frame quantitative issues, reveal mathematical commonalities between apparently diverse systems, identify what is and what is not possible in principle, and test the abilities of specific mechanisms to explain the data. This review focuses on the progress that has been made over the last decade in our theoretical understanding of neural development.
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Affiliation(s)
- Geoffrey J Goodhill
- Queensland Brain Institute and School of Mathematics and Physics, The University of Queensland, St Lucia, QLD 4072, Australia.
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10
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Bennett JEM, Bair W. Refinement and Pattern Formation in Neural Circuits by the Interaction of Traveling Waves with Spike-Timing Dependent Plasticity. PLoS Comput Biol 2015; 11:e1004422. [PMID: 26308406 PMCID: PMC4550436 DOI: 10.1371/journal.pcbi.1004422] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 07/02/2015] [Indexed: 12/20/2022] Open
Abstract
Traveling waves in the developing brain are a prominent source of highly correlated spiking activity that may instruct the refinement of neural circuits. A candidate mechanism for mediating such refinement is spike-timing dependent plasticity (STDP), which translates correlated activity patterns into changes in synaptic strength. To assess the potential of these phenomena to build useful structure in developing neural circuits, we examined the interaction of wave activity with STDP rules in simple, biologically plausible models of spiking neurons. We derive an expression for the synaptic strength dynamics showing that, by mapping the time dependence of STDP into spatial interactions, traveling waves can build periodic synaptic connectivity patterns into feedforward circuits with a broad class of experimentally observed STDP rules. The spatial scale of the connectivity patterns increases with wave speed and STDP time constants. We verify these results with simulations and demonstrate their robustness to likely sources of noise. We show how this pattern formation ability, which is analogous to solutions of reaction-diffusion systems that have been widely applied to biological pattern formation, can be harnessed to instruct the refinement of postsynaptic receptive fields. Our results hold for rich, complex wave patterns in two dimensions and over several orders of magnitude in wave speeds and STDP time constants, and they provide predictions that can be tested under existing experimental paradigms. Our model generalizes across brain areas and STDP rules, allowing broad application to the ubiquitous occurrence of traveling waves and to wave-like activity patterns induced by moving stimuli. In several areas of the developing brain, waves of electrical activity trace out distinct patterns across the nervous tissue. These waves are intricately involved in developmental processes that set up the structural connections of the adult brain, but it is unclear what role the wave patterns play. Here, we examine how the strength of connections in these brain areas may change by a process called spike-timing dependent plasticity, which is sensitive to the precise times at which individual neurons become electrically active. We use mathematical models and simulations to show that interactions between waves and plasticity build highly structured patterns into the connections. The results of our model are analogous to many cases of biological pattern formation seen, for example, in zebra stripes, leopard spots and seashells. An important connectivity pattern we consider is the receptive field, which determines to a large extent the specific function of a neuron. We demonstrate how pattern formation can refine the shape of a receptive field and therefore the specificity of a neuron, and explore several ways in which pattern formation may be disrupted, providing clues regarding pathologies in receptive field development. Our theory makes several predictions that may be tested using existing experimental paradigms.
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Affiliation(s)
- James E. M. Bennett
- Dept. Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
- * E-mail:
| | - Wyeth Bair
- Dept. Biological Structure, University of Washington, Seattle, Washington, United States of America
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11
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Lansdell B, Ford K, Kutz JN. A reaction-diffusion model of cholinergic retinal waves. PLoS Comput Biol 2014; 10:e1003953. [PMID: 25474327 PMCID: PMC4256014 DOI: 10.1371/journal.pcbi.1003953] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 10/01/2014] [Indexed: 01/21/2023] Open
Abstract
Prior to receiving visual stimuli, spontaneous, correlated activity in the retina, called retinal waves, drives activity-dependent developmental programs. Early-stage waves mediated by acetylcholine (ACh) manifest as slow, spreading bursts of action potentials. They are believed to be initiated by the spontaneous firing of Starburst Amacrine Cells (SACs), whose dense, recurrent connectivity then propagates this activity laterally. Their inter-wave interval and shifting wave boundaries are the result of the slow after-hyperpolarization of the SACs creating an evolving mosaic of recruitable and refractory cells, which can and cannot participate in waves, respectively. Recent evidence suggests that cholinergic waves may be modulated by the extracellular concentration of ACh. Here, we construct a simplified, biophysically consistent, reaction-diffusion model of cholinergic retinal waves capable of recapitulating wave dynamics observed in mice retina recordings. The dense, recurrent connectivity of SACs is modeled through local, excitatory coupling occurring via the volume release and diffusion of ACh. In addition to simulation, we are thus able to use non-linear wave theory to connect wave features to underlying physiological parameters, making the model useful in determining appropriate pharmacological manipulations to experimentally produce waves of a prescribed spatiotemporal character. The model is used to determine how ACh mediated connectivity may modulate wave activity, and how parameters such as the spontaneous activation rate and sAHP refractory period contribute to critical wave size variability.
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Affiliation(s)
- Benjamin Lansdell
- Department of Applied Mathematics, University of Washington, Seattle, Washington, United States of America
| | - Kevin Ford
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, United States of America
| | - J. Nathan Kutz
- Department of Applied Mathematics, University of Washington, Seattle, Washington, United States of America
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12
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Dähne S, Wilbert N, Wiskott L. Slow feature analysis on retinal waves leads to V1 complex cells. PLoS Comput Biol 2014; 10:e1003564. [PMID: 24810948 PMCID: PMC4014395 DOI: 10.1371/journal.pcbi.1003564] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 12/20/2013] [Indexed: 11/20/2022] Open
Abstract
The developing visual system of many mammalian species is partially structured and organized even before the onset of vision. Spontaneous neural activity, which spreads in waves across the retina, has been suggested to play a major role in these prenatal structuring processes. Recently, it has been shown that when employing an efficient coding strategy, such as sparse coding, these retinal activity patterns lead to basis functions that resemble optimal stimuli of simple cells in primary visual cortex (V1). Here we present the results of applying a coding strategy that optimizes for temporal slowness, namely Slow Feature Analysis (SFA), to a biologically plausible model of retinal waves. Previously, SFA has been successfully applied to model parts of the visual system, most notably in reproducing a rich set of complex-cell features by training SFA with quasi-natural image sequences. In the present work, we obtain SFA units that share a number of properties with cortical complex-cells by training on simulated retinal waves. The emergence of two distinct properties of the SFA units (phase invariance and orientation tuning) is thoroughly investigated via control experiments and mathematical analysis of the input-output functions found by SFA. The results support the idea that retinal waves share relevant temporal and spatial properties with natural visual input. Hence, retinal waves seem suitable training stimuli to learn invariances and thereby shape the developing early visual system such that it is best prepared for coding input from the natural world.
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Affiliation(s)
- Sven Dähne
- Machine Learning Group, Department of Computer Science, Berlin Institute of Technology, Berlin, Germany
- Institute for Theoretical Biology, Humboldt-University, Berlin, Germany
- Bernstein Center for Computational Neuroscience, Berlin, Germany
| | - Niko Wilbert
- Institute for Theoretical Biology, Humboldt-University, Berlin, Germany
- Bernstein Center for Computational Neuroscience, Berlin, Germany
| | - Laurenz Wiskott
- Institute for Theoretical Biology, Humboldt-University, Berlin, Germany
- Bernstein Center for Computational Neuroscience, Berlin, Germany
- Institute for Neural Computation, Ruhr-University Bochum, Bochum, Germany
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13
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Watari H, Tose AJ, Bosma MM. Looping circuit: a novel mechanism for prolonged spontaneous [Ca2+]i increases in developing embryonic mouse brainstem. J Physiol 2013; 592:711-27. [PMID: 24366258 DOI: 10.1113/jphysiol.2013.265892] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Most cells maintain [Ca(2+)]i at extremely low levels; calcium entry usually occurs briefly, and within seconds it is cleared. However, at embryonic day 12.5 in the mouse brainstem, trains of spontaneous events occur with [Ca(2+)]i staying close to peak value, well above baseline, for minutes; we termed this 'bash bursts'. Here, we investigate the mechanism of this unusual activity using calcium imaging and electrophysiology. Bash bursts are triggered by an event originating at the mid-line of the rostral hindbrain and are usually the result of that event propagating repeatedly along a defined circular path. The looping circuit can either encompass both the midbrain and hindbrain or remain in the hindbrain only, and the type of loop determines the duration of a single lap time, 5 or 3 s, respectively. Bash bursts are supported by high membrane excitability of mid-line cells and are regulated by persistent inward 'window current' at rest, contributing to spontaneous activity. This looping circuit is an effective means for increasing [Ca(2+)]i at brief, regular intervals. Bash bursts disappear by embryonic day 13.5 via alteration of the looping circuit, curtailing the short epoch of bash bursts. The resulting sustained [Ca(2+)]i may influence development of raphe serotonergic and ventral tegmental dopaminergic neurons by modulating gene expression.
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Affiliation(s)
- Hirofumi Watari
- Department of Biology, Box 351800, University of Washington, Seattle, WA 98195, USA.
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14
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15
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Furman M, Xu HP, Crair MC. Competition driven by retinal waves promotes morphological and functional synaptic development of neurons in the superior colliculus. J Neurophysiol 2013; 110:1441-54. [PMID: 23741047 PMCID: PMC3763158 DOI: 10.1152/jn.01066.2012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Accepted: 06/03/2013] [Indexed: 11/22/2022] Open
Abstract
Prior to eye opening, waves of spontaneous activity sweep across the developing retina. These "retinal waves," together with genetically encoded molecular mechanisms, mediate the formation of visual maps in the brain. However, the specific role of wave activity in synapse development in retino-recipient brain regions is unclear. Here we compare the functional development of synapses and the morphological development of neurons in the superior colliculus (SC) of wild-type (WT) and transgenic (β2-TG) mice in which retinal wave propagation is spatially truncated (Xu HP, Furman M, Mineur YS, Chen H, King SL, Zenisek D, Zhou ZJ, Butts DA, Tian N, Picciotto MR, Crair MC. Neuron 70: 1115-1127, 2011). We use two recently developed brain slice preparations to examine neurons and synapses in the binocular vs. mainly monocular SC. We find that retinocollicular synaptic strength is reduced whereas the number of retinal inputs is increased in the binocular SC of β2-TG mice compared with WT mice. In contrast, in the mainly monocular SC the number of retinal inputs is normal in β2-TG mice, but, transiently, synapses are abnormally strong, possibly because of enhanced activity-dependent competition between local, "small" retinal wave domains. These findings demonstrate that retinal wave size plays an instructive role in the synaptic and morphological development of SC neurons, possibly through a competitive process among retinofugal axons.
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Affiliation(s)
- Moran Furman
- Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut
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16
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Watari H, Tose AJ, Bosma MM. Hyperpolarization of resting membrane potential causes retraction of spontaneous Ca(i)²⁺ transients during mouse embryonic circuit development. J Physiol 2012; 591:973-83. [PMID: 23165771 DOI: 10.1113/jphysiol.2012.244954] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Abstract Spontaneous activity supports developmental processes in many brain regions during embryogenesis, and the spatial extent and frequency of the spontaneous activity are tightly regulated by stage. In the developing mouse hindbrain, spontaneous activity propagates widely and the waves can cover the entire hindbrain at E11.5. The activity then retracts to waves that are spatially restricted to the rostral midline at E13.5, before disappearing altogether by E15.5. However, the mechanism of retraction is unknown. We studied passive membrane properties of cells that are spatiotemporally relevant to the pattern of retraction in mouse embryonic hindbrain using whole-cell patch clamp and imaging techniques. We find that membrane excitability progressively decreases due to hyperpolarization of resting membrane potential and increased resting conductance density between E11.5 and E15.5, in a spatiotemporal pattern correlated with the retraction sequence. Retraction can be acutely reversed by membrane depolarization at E15.5, and the induced events propagate similarly to spontaneous activity at earlier stages, though without involving gap junctional coupling. Manipulation of [K(+)](o) or [Cl(-)](o) reveals that membrane potential follows E(K) more closely than E(Cl), suggesting a dominant role for K(+) conductance in the membrane hyperpolarization. Reducing membrane excitability by hyperpolarization of the resting membrane potential and increasing resting conductance are effective mechanisms to desynchronize spontaneous activity in a spatiotemporal manner, while allowing information processing to occur at the synaptic and cellular level.
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Affiliation(s)
- Hirofumi Watari
- Graduate Program in Neurobiology & Behavior, University of Washington, Seattle, WA 98195, USA
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17
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Srinivasa N, Cho Y. Self-organizing spiking neural model for learning fault-tolerant spatio-motor transformations. IEEE TRANSACTIONS ON NEURAL NETWORKS AND LEARNING SYSTEMS 2012; 23:1526-1538. [PMID: 24807999 DOI: 10.1109/tnnls.2012.2207738] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In this paper, we present a spiking neural model that learns spatio-motor transformations. The model is in the form of a multilayered architecture consisting of integrate and fire neurons and synapses that employ spike-timing-dependent plasticity learning rule to enable the learning of such transformations. We developed a simple 2-degree-of-freedom robot-based reaching task which involves the learning of a nonlinear function. Computer simulations demonstrate the capability of such a model for learning the forward and inverse kinematics for such a task and hence to learn spatio-motor transformations. The interesting aspect of the model is its capacity to be tolerant to partial absence of sensory or motor inputs at various stages of learning. We believe that such a model lays the foundation for learning other complex functions and transformations in real-world scenarios.
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18
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Xu HP, Furman M, Mineur YS, Chen H, King SL, Zenisek D, Zhou ZJ, Butts DA, Tian N, Picciotto MR, Crair MC. An instructive role for patterned spontaneous retinal activity in mouse visual map development. Neuron 2011; 70:1115-27. [PMID: 21689598 DOI: 10.1016/j.neuron.2011.04.028] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/05/2011] [Indexed: 10/18/2022]
Abstract
Complex neural circuits in the mammalian brain develop through a combination of genetic instruction and activity-dependent refinement. The relative role of these factors and the form of neuronal activity responsible for circuit development is a matter of significant debate. In the mammalian visual system, retinal ganglion cell projections to the brain are mapped with respect to retinotopic location and eye of origin. We manipulated the pattern of spontaneous retinal waves present during development without changing overall activity levels through the transgenic expression of β2-nicotinic acetylcholine receptors in retinal ganglion cells of mice. We used this manipulation to demonstrate that spontaneous retinal activity is not just permissive, but instructive in the emergence of eye-specific segregation and retinotopic refinement in the mouse visual system. This suggests that specific patterns of spontaneous activity throughout the developing brain are essential in the emergence of specific and distinct patterns of neuronal connectivity.
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Affiliation(s)
- Hong-ping Xu
- Department of Neurobiology, Yale University School of Medicine, New Haven, CT 06510, USA.
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19
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Gjorgjieva J, Eglen SJ. Modeling developmental patterns of spontaneous activity. Curr Opin Neurobiol 2011; 21:679-84. [PMID: 21684148 DOI: 10.1016/j.conb.2011.05.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Revised: 05/17/2011] [Accepted: 05/22/2011] [Indexed: 11/25/2022]
Abstract
Spontaneous activity is found in many regions of the developing nervous system; such activity is thought to be instructive for guiding developmental processes. In particular, the developing retina generates correlated patterns of activity known as retinal waves. We review the main theoretical models that have been developed to study the mechanisms for generation and propagation of retinal waves. Much of the progress in this field has been due to the close interaction between experimentalists and theorists in analyzing and modeling spontaneous activity. We conclude by describing spontaneous activity models in other systems and suggestions for future modeling work.
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Affiliation(s)
- Julijana Gjorgjieva
- Cambridge Computational Biology Institute, Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 0WA, UK
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20
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Conhaim J, Easton CR, Becker MI, Barahimi M, Cedarbaum ER, Moore JG, Mather LF, Dabagh S, Minter DJ, Moen SP, Moody WJ. Developmental changes in propagation patterns and transmitter dependence of waves of spontaneous activity in the mouse cerebral cortex. J Physiol 2011; 589:2529-41. [PMID: 21486817 PMCID: PMC3115823 DOI: 10.1113/jphysiol.2010.202382] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Accepted: 03/23/2011] [Indexed: 02/01/2023] Open
Abstract
Waves of spontaneous electrical activity propagate across many regions of the central nervous system during specific stages of early development. The patterns of wave propagation are critical in the activation of many activity-dependent developmental programs. It is not known how the mechanisms that initiate and propagate spontaneous waves operate during periods in which major changes in neuronal structure and function are taking place. We have recently reported that spontaneous waves of activity propagate across the neonatal mouse cerebral cortex and that these waves are initiated at pacemaker sites in the septal nucleus and ventral cortex. Here we show that spontaneous waves occur between embryonic day 18 (E18) and postnatal day 12 (P12), and that during that period they undergo major changes in transmitter dependence and propagation patterns. At early stages, spontaneous waves are largely GABA dependent and are mostly confined to the septum and ventral cortex. As development proceeds, wave initiation depends increasingly on AMPA-type glutamate receptors, and an ever increasing fraction of waves propagate into the dorsal cortex. The initiation sites and restricted propagation of waves at early stages are highly correlated with the position of GABAergic neurons in the cortex. The later switch to a glutamate-based mechanism allows propagation of waves into the dorsal cortex, and appears to be a compensatory mechanism that ensures continued wave generation even as GABA transmission becomes inhibitory.
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Affiliation(s)
- Jay Conhaim
- Department of Biology, University of Washington, Seattle, WA 98195, USA
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21
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Tabak J, Mascagni M, Bertram R. Mechanism for the universal pattern of activity in developing neuronal networks. J Neurophysiol 2010; 103:2208-21. [PMID: 20164396 DOI: 10.1152/jn.00857.2009] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Spontaneous episodic activity is a fundamental mode of operation of developing networks. Surprisingly, the duration of an episode of activity correlates with the length of the silent interval that precedes it, but not with the interval that follows. Here we use a modeling approach to explain this characteristic, but thus far unexplained, feature of developing networks. Because the correlation pattern is observed in networks with different structures and components, a satisfactory model needs to generate the right pattern of activity regardless of the details of network architecture or individual cell properties. We thus developed simple models incorporating excitatory coupling between heterogeneous neurons and activity-dependent synaptic depression. These models robustly generated episodic activity with the correct correlation pattern. The correlation pattern resulted from episodes being triggered at random levels of recovery from depression while they terminated around the same level of depression. To explain this fundamental difference between episode onset and termination, we used a mean field model, where only average activity and average level of recovery from synaptic depression are considered. In this model, episode onset is highly sensitive to inputs. Thus noise resulting from random coincidences in the spike times of individual neurons led to the high variability at episode onset and to the observed correlation pattern. This work further shows that networks with widely different architectures, different cell types, and different functions all operate according to the same general mechanism early in their development.
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Affiliation(s)
- Joël Tabak
- Dept. of Biological Science, BRF 206, Florida State Univ., Tallahassee, FL 32306, USA.
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22
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Blankenship AG, Feller MB. Mechanisms underlying spontaneous patterned activity in developing neural circuits. Nat Rev Neurosci 2009; 11:18-29. [PMID: 19953103 DOI: 10.1038/nrn2759] [Citation(s) in RCA: 518] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Patterned, spontaneous activity occurs in many developing neural circuits, including the retina, the cochlea, the spinal cord, the cerebellum and the hippocampus, where it provides signals that are important for the development of neurons and their connections. Despite there being differences in adult architecture and output across these various circuits, the patterns of spontaneous network activity and the mechanisms that generate it are remarkably similar. The mechanisms can include a depolarizing action of GABA (gamma-aminobutyric acid), transient synaptic connections, extrasynaptic transmission, gap junction coupling and the presence of pacemaker-like neurons. Interestingly, spontaneous activity is robust; if one element of a circuit is disrupted another will generate similar activity. This research suggests that developing neural circuits exhibit transient and tunable features that maintain a source of correlated activity during crucial stages of development.
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Affiliation(s)
- Aaron G Blankenship
- Neurosciences Graduate Program, University of California, San Diego, La Jolla, California 92093, USA
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23
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Godfrey KB, Eglen SJ. Theoretical models of spontaneous activity generation and propagation in the developing retina. MOLECULAR BIOSYSTEMS 2009; 5:1527-35. [PMID: 19763323 DOI: 10.1039/b907213f] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Spontaneous neural activity is present in many parts of the developing nervous system, including visual, auditory and motor areas. In the developing retina, nearby neurons are spontaneously active and produce propagating patterns of activity, known as retinal waves. Such activity is thought to instruct the refinement of retinal axons. In this article we review several computational models used to help evaluate the mechanisms that might be responsible for the generation of retinal waves. We then discuss the models relative to the molecular mechanisms underlying wave activity, including gap junctions, neurotransmitters and second messenger systems. We examine how well the models represent these mechanisms and propose areas for future modelling research. The retinal wave models are also discussed in relation to models of spontaneous activity in other areas of the developing nervous system.
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Affiliation(s)
- Keith B Godfrey
- Cambridge Computational Biology Institute, Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge, UK
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24
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Lischalk JW, Easton CR, Moody WJ. Bilaterally propagating waves of spontaneous activity arising from discrete pacemakers in the neonatal mouse cerebral cortex. Dev Neurobiol 2009; 69:407-14. [PMID: 19263415 DOI: 10.1002/dneu.20708] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Spontaneous electrical activity that moves in synchronized waves across large populations of neurons plays widespread and important roles in nervous system development. The propagation patterns of such waves can encode the spatial location of neurons to their downstream targets and strengthen synaptic connections in coherent spatial patterns. Such waves can arise as an emergent property of mutually excitatory neural networks, or can be driven by a discrete pacemaker. In the mouse cerebral cortex, spontaneous synchronized activity occurs for approximately 72 h of development centered on the day of birth. It is not known whether this activity is driven by a discrete pacemaker or occurs as an emergent network property. Here we show that this activity propagates as a wave that is initiated at either of two homologous pacemakers in the temporal region, and then propagates rapidly across both sides of the brain. When these regions of origin are surgically isolated, waves do not occur. Therefore, this cortical spontaneous activity is a bilateral wave that originates from a discrete subset of pacemaker neurons.
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25
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Alvarez-Lacalle E, Moses E. Slow and fast pulses in 1-D cultures of excitatory neurons. J Comput Neurosci 2009; 26:475-93. [DOI: 10.1007/s10827-008-0123-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Revised: 09/29/2008] [Accepted: 11/04/2008] [Indexed: 10/21/2022]
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26
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Thivierge JP. How does non-random spontaneous activity contribute to brain development? Neural Netw 2009; 22:901-12. [PMID: 19196491 DOI: 10.1016/j.neunet.2009.01.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Revised: 07/17/2008] [Accepted: 01/01/2009] [Indexed: 11/28/2022]
Abstract
Highly non-random forms of spontaneous activity are proposed to play an instrumental role in the early development of the visual system. However, both the fundamental properties of spontaneous activity required to drive map formation, as well as the exact role of this information remain largely unknown. Here, a realistic computational model of spontaneous retinal waves is employed to demonstrate that both the amplitude and frequency of waves may play determining roles in retinocollicular map formation. Furthermore, results obtained with different learning rules show that spike precision in the order of milliseconds may be instrumental to neural development: a rule based on precise spike interactions (spike-timing-dependent plasticity) reduced the density of aberrant projections to the SC to a markedly greater extent than a rule based on interactions at much broader time-scale (correlation-based plasticity). Taken together, these results argue for an important role of spontaneous yet highly non-random activity, along with temporally precise learning rules, in the formation of neural circuits.
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Affiliation(s)
- Jean-Philippe Thivierge
- Department of Psychological and Brain Sciences, Indiana University, 1101 East Tenth Street, Bloomington, IN 47405, USA.
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27
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Couzin ID. Collective cognition in animal groups. Trends Cogn Sci 2009; 13:36-43. [DOI: 10.1016/j.tics.2008.10.002] [Citation(s) in RCA: 430] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2008] [Revised: 10/16/2008] [Accepted: 10/17/2008] [Indexed: 10/21/2022]
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28
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Albert MV, Schnabel A, Field DJ. Innate visual learning through spontaneous activity patterns. PLoS Comput Biol 2008; 4:e1000137. [PMID: 18670593 PMCID: PMC2446436 DOI: 10.1371/journal.pcbi.1000137] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Accepted: 06/19/2008] [Indexed: 11/23/2022] Open
Abstract
Patterns of spontaneous activity in the developing retina, LGN, and cortex are necessary for the proper development of visual cortex. With these patterns intact, the primary visual cortices of many newborn animals develop properties similar to those of the adult cortex but without the training benefit of visual experience. Previous models have demonstrated how V1 responses can be initialized through mechanisms specific to development and prior to visual experience, such as using axonal guidance cues or relying on simple, pairwise correlations on spontaneous activity with additional developmental constraints. We argue that these spontaneous patterns may be better understood as part of an "innate learning" strategy, which learns similarly on activity both before and during visual experience. With an abstraction of spontaneous activity models, we show how the visual system may be able to bootstrap an efficient code for its natural environment prior to external visual experience, and we continue the same refinement strategy upon natural experience. The patterns are generated through simple, local interactions and contain the same relevant statistical properties of retinal waves and hypothesized waves in the LGN and V1. An efficient encoding of these patterns resembles a sparse coding of natural images by producing neurons with localized, oriented, bandpass structure-the same code found in early visual cortical cells. We address the relevance of higher-order statistical properties of spontaneous activity, how this relates to a system that may adapt similarly on activity prior to and during natural experience, and how these concepts ultimately relate to an efficient coding of our natural world.
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Affiliation(s)
- Mark V. Albert
- Field of Computational Biology, Cornell University, Ithaca, New York, United States of America
- Department of Psychology, Cornell University, Ithaca, New York, United States of America
| | - Adam Schnabel
- Department of Psychology, Cornell University, Ithaca, New York, United States of America
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, Massachusetts, United States of America
| | - David J. Field
- Field of Computational Biology, Cornell University, Ithaca, New York, United States of America
- Department of Psychology, Cornell University, Ithaca, New York, United States of America
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29
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Abstract
AbstractChallenges to visual prediction as an organizing concept come from three main sources: (1) from observations arising from the results of experiments employing unpredictable motion, (2) from the assertions that motor processes compensate for all neural delays, and (3) from multiple interpretations specific to the flash-lag effect. One clarification that has emerged is that visual prediction is a process that either complements or reflects non-visual (e.g., motor) prediction.
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30
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Godfrey KB, Swindale NV. Retinal wave behavior through activity-dependent refractory periods. PLoS Comput Biol 2008; 3:e245. [PMID: 18052546 PMCID: PMC2098868 DOI: 10.1371/journal.pcbi.0030245] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2007] [Accepted: 10/24/2007] [Indexed: 11/30/2022] Open
Abstract
In the developing mammalian visual system, spontaneous retinal ganglion cell (RGC) activity contributes to and drives several aspects of visual system organization. This spontaneous activity takes the form of spreading patches of synchronized bursting that slowly advance across portions of the retina. These patches are non-repeating and tile the retina in minutes. Several transmitter systems are known to be involved, but the basic mechanism underlying wave production is still not well-understood. We present a model for retinal waves that focuses on acetylcholine mediated waves but whose principles are adaptable to other developmental stages. Its assumptions are that a) spontaneous depolarizations of amacrine cells drive wave activity; b) amacrine cells are locally connected, and c) cells receiving more input during their depolarization are subsequently less responsive and have longer periods between spontaneous depolarizations. The resulting model produces waves with non-repeating borders and randomly distributed initiation points. The wave generation mechanism appears to be chaotic and does not require neural noise to produce this wave behavior. Variations in parameter settings allow the model to produce waves that are similar in size, frequency, and velocity to those observed in several species. Our results suggest that retinal wave behavior results from activity-dependent refractory periods and that the average velocity of retinal waves depends on the duration a cell is excitatory: longer periods of excitation result in slower waves. In contrast to previous studies, we find that a single layer of cells is sufficient for wave generation. The principles described here are very general and may be adaptable to the description of spontaneous wave activity in other areas of the nervous system. Neurons from the immature retina extend axons that make connections in the visual centers of the brain. Chemical markers provide guidance for these axons, but patterned neural activity is necessary to refine their connections. Much of this activity occurs in a distinctive pattern of waves before the retina is responsive to light, but it is not known how these waves are generated. In this study, we describe a simple mechanism that can explain the production of retinal waves. We use the knowledge that immature retinal cells are spontaneously active and show that waves will result if cells that receive more input when they are spontaneously active have longer intervals between activity. The resulting model reproduces experimentally observed waves in a variety of species, including ferret, chick, mouse, rabbit, and turtle, both at the level of individual cells and of the entire retina. The behavior appears intrinsically chaotic and the model is not tied to the properties of any particular biochemical pathway. We suggest that this mechanism could underlie not only the spontaneous patterns of activity that are generated in the retina but other areas of the developing brain as well.
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Affiliation(s)
- Keith B Godfrey
- Department of Opthamology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
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31
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Butts DA, Kanold PO, Shatz CJ. A burst-based "Hebbian" learning rule at retinogeniculate synapses links retinal waves to activity-dependent refinement. PLoS Biol 2007; 5:e61. [PMID: 17341130 PMCID: PMC1808114 DOI: 10.1371/journal.pbio.0050061] [Citation(s) in RCA: 149] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2006] [Accepted: 12/29/2006] [Indexed: 12/01/2022] Open
Abstract
Patterned spontaneous activity in the developing retina is necessary to drive synaptic refinement in the lateral geniculate nucleus (LGN). Using perforated patch recordings from neurons in LGN slices during the period of eye segregation, we examine how such burst-based activity can instruct this refinement. Retinogeniculate synapses have a novel learning rule that depends on the latencies between pre- and postsynaptic bursts on the order of one second: coincident bursts produce long-lasting synaptic enhancement, whereas non-overlapping bursts produce mild synaptic weakening. It is consistent with “Hebbian” development thought to exist at this synapse, and we demonstrate computationally that such a rule can robustly use retinal waves to drive eye segregation and retinotopic refinement. Thus, by measuring plasticity induced by natural activity patterns, synaptic learning rules can be linked directly to their larger role in instructing the patterning of neural connectivity. The brain is comprised of an immense number of connections between neurons, and clever strategies are required to achieve the correct wiring during development. One common strategy uses neural activity itself as feedback to instruct individual connections (synapses) through synaptic learning rules that delineate which patterns of activity strengthen the synapse and which weaken it. Throughout life, such activity-dependent synaptic changes are likely driven by experience and are thought to underlie learning and memory, but during early stages of development, they are often driven by activity spontaneously generated within the brain. Here, we study connections in the visual pathway between the retina and lateral geniculate nucleus (LGN), which—to develop correctly—require spontaneous “retinal waves” before the eye is responsive to light. By replaying the retinal wave activity as it appears at single LGN synapses, we observe a novel learning rule that describes a relatively simple computation for the developing synapse in the context of retinal wave activity. We then demonstrate how this learning rule is matched to properties of the retinal waves in order to robustly drive the synaptic refinement that occurs in the visual system. A novel learning rule describes a simple computation by which retinal wave activity robustly drives the synaptic refinement that occurs in the visual system.
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Affiliation(s)
- Daniel A Butts
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, United States of America.
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32
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McCabe AK, Chisholm SL, Picken-Bahrey HL, Moody WJ. The self-regulating nature of spontaneous synchronized activity in developing mouse cortical neurones. J Physiol 2006; 577:155-67. [PMID: 16945966 PMCID: PMC2000675 DOI: 10.1113/jphysiol.2006.117523] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Waves of spontaneous electrical activity that are highly synchronized across large populations of neurones occur throughout the developing mammalian central nervous system. The stages at which this activity occurs are tightly regulated to allow activity-dependent developmental programmes to be initiated correctly. What determines the onset and cessation of spontaneous synchronous activity (SSA) in a particular region of the nervous system, however, remains unclear. We have tested the hypothesis that activity itself triggers developmental changes in intrinsic and circuit properties that determine the stages at which SSA occurs. To do this we exposed cultured slices of mouse neocortex to tetrodotoxin (TTX) to block SSA, which normally occurs between embryonic day 17 (E17) and postnatal day 3 (P3). In control cultured slices, SSA rarely occurs after P3. In TTX-treated slices, however, SSA was generated from P3 (the day of TTX removal) until at least P10. This indicates that in the absence of spontaneous activity, the mechanisms that normally determine the timing of SSA are not initiated, and that a compensatory response occurs that shifts the time of SSA occurrence to later developmental stages.
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Affiliation(s)
- Annette K McCabe
- Department of Biology, University of Washington, Seattle, WA 98195, USA
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33
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French DA, Gruenstein EI. An integrate-and-fire model for synchronized bursting in a network of cultured cortical neurons. J Comput Neurosci 2006; 21:227-41. [PMID: 16951925 DOI: 10.1007/s10827-006-7815-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2004] [Revised: 11/15/2005] [Accepted: 02/16/2006] [Indexed: 11/29/2022]
Abstract
It has been suggested that spontaneous synchronous neuronal activity is an essential step in the formation of functional networks in the central nervous system. The key features of this type of activity consist of bursts of action potentials with associated spikes of elevated cytoplasmic calcium. These features are also observed in networks of rat cortical neurons that have been formed in culture. Experimental studies of these cultured networks have led to several hypotheses for the mechanisms underlying the observed synchronized oscillations. In this paper, bursting integrate-and-fire type mathematical models for regular spiking (RS) and intrinsic bursting (IB) neurons are introduced and incorporated through a small-world connection scheme into a two-dimensional excitatory network similar to those in the cultured network. This computer model exhibits spontaneous synchronous activity through mechanisms similar to those hypothesized for the cultured experimental networks. Traces of the membrane potential and cytoplasmic calcium from the model closely match those obtained from experiments. We also consider the impact on network behavior of the IB neurons, the geometry and the small world connection scheme.
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Affiliation(s)
- D A French
- Department of Mathematical Sciences, University of Cincinnati, Cincinnati, OH 45221-0025, USA.
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34
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Tabak J, O'Donovan MJ, Rinzel J. Differential control of active and silent phases in relaxation models of neuronal rhythms. J Comput Neurosci 2006; 21:307-28. [PMID: 16896520 DOI: 10.1007/s10827-006-8862-7] [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: 03/21/2005] [Revised: 03/16/2006] [Accepted: 04/18/2006] [Indexed: 10/24/2022]
Abstract
Rhythmic bursting activity, found in many biological systems, serves a variety of important functions. Such activity is composed of episodes, or bursts (the active phase, AP) that are separated by quiescent periods (the silent phase, SP). Here, we use mean field, firing rate models of excitatory neural network activity to study how AP and SP durations depend on two critical network parameters that control network connectivity and cellular excitability. In these models, the AP and SP correspond to the network's underlying bistability on a fast time scale due to rapid recurrent excitatory connectivity. Activity switches between the AP and SP because of two types of slow negative feedback: synaptic depression-which has a divisive effect on the network input/output function, or cellular adaptation-a subtractive effect on the input/output function. We show that if a model incorporates the divisive process (regardless of the presence of the subtractive process), then increasing cellular excitability will speed up the activity, mostly by decreasing the silent phase. Reciprocally, if the subtractive process is present, increasing the excitatory connectivity will slow down the activity, mostly by lengthening the active phase. We also show that the model incorporating both slow processes is less sensitive to parameter variations than the models with only one process. Finally, we note that these network models are formally analogous to a type of cellular pacemaker and thus similar results apply to these cellular pacemakers.
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Affiliation(s)
- Joël Tabak
- Laboratory of Neural Control, NINDS/NIH, Bethesda, MD, 20892, USA
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35
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Colicos MA, Firth SI, Bosze J, Goldstein J, Feller MB. Emergence of realistic retinal networks in culture promoted by the superior colliculus. Dev Neurosci 2005; 26:406-16. [PMID: 15855770 DOI: 10.1159/000082283] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2004] [Accepted: 07/20/2004] [Indexed: 11/19/2022] Open
Abstract
The developing retina is characterized by 'retinal waves', spontaneous depolarizations that propagate through a developing network of interneurons and retinal ganglion cells. Although the circuitry underlying retinal waves is well characterized, the secreted factors that are critical for its normal development are not defined. Dissociated cell culture provides an ideal system for defining these factors; however, it is difficult to recapitulate retinal circuitry in culture. Here we demonstrate that by culturing dissociated retinal neurons in the presence of cells from the superior colliculus (SC), retinal neurons form networks that are similar to those described in the intact retina. Whole-cell voltage clamp recordings reveal the presence of a spontaneously active network of interneurons. In addition, we observed spontaneous, propagating activity reminiscent of that observed in the intact retina. We propose that the presence of factors secreted from the SC results in the development of networks that reproduce critical features of the intact retina.
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Affiliation(s)
- Michael A Colicos
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
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36
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Moody WJ, Bosma MM. Ion Channel Development, Spontaneous Activity, and Activity-Dependent Development in Nerve and Muscle Cells. Physiol Rev 2005; 85:883-941. [PMID: 15987798 DOI: 10.1152/physrev.00017.2004] [Citation(s) in RCA: 274] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
At specific stages of development, nerve and muscle cells generate spontaneous electrical activity that is required for normal maturation of intrinsic excitability and synaptic connectivity. The patterns of this spontaneous activity are not simply immature versions of the mature activity, but rather are highly specialized to initiate and control many aspects of neuronal development. The configuration of voltage- and ligand-gated ion channels that are expressed early in development regulate the timing and waveform of this activity. They also regulate Ca2+influx during spontaneous activity, which is the first step in triggering activity-dependent developmental programs. For these reasons, the properties of voltage- and ligand-gated ion channels expressed by developing neurons and muscle cells often differ markedly from those of adult cells. When viewed from this perspective, the reasons for complex patterns of ion channel emergence and regression during development become much clearer.
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Affiliation(s)
- William J Moody
- Department of Biology, University of Washington, Seattle, Washington 98195, USA.
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37
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Torborg CL, Feller MB. Spontaneous patterned retinal activity and the refinement of retinal projections. Prog Neurobiol 2005; 76:213-35. [PMID: 16280194 DOI: 10.1016/j.pneurobio.2005.09.002] [Citation(s) in RCA: 205] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2005] [Revised: 08/30/2005] [Accepted: 09/22/2005] [Indexed: 11/22/2022]
Abstract
A characteristic feature of sensory circuits is the existence of orderly connections that represent maps of sensory space. A major research focus in developmental neurobiology is to elucidate the relative contributions of neural activity and guidance molecules in sensory map formation. Two model systems for addressing map formation are the retinotopic map formed by retinal projections to the superior colliculus (SC) (or its non-mammalian homolog, the optic tectum (OT)), and the eye-specific map formed by retinal projections to the lateral geniculate nucleus of the thalamus. In mammals, a substantial portion of retinotopic and eye-specific refinement of retinal axons occurs before vision is possible, but at a time when there is a robust, patterned spontaneous retinal activity called retinal waves. Though complete blockade of retinal activity disrupts normal map refinement, attempts at more refined perturbations, such as pharmacological and genetic manipulations that alter features of retinal waves critical for map refinement, remain controversial. Here we review: (1) the mechanisms that underlie the generation of retinal waves; (2) recent experiments that have investigated a role for guidance molecules and retinal activity in map refinement; and (3) experiments that have implicated various signaling cascades, both in retinal ganglion cells (RGCs) and their post-synaptic targets, in map refinement. It is likely that an understanding of retinal activity, guidance molecules, downstream signaling cascades, and the interactions between these biological systems will be critical to elucidating the mechanisms of sensory map formation.
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Affiliation(s)
- Christine L Torborg
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0357, USA
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38
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Firth SI, Wang CT, Feller MB. Retinal waves: mechanisms and function in visual system development. Cell Calcium 2005; 37:425-32. [PMID: 15820390 DOI: 10.1016/j.ceca.2005.01.010] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2004] [Accepted: 01/06/2005] [Indexed: 11/23/2022]
Abstract
A characteristic feature of developing neural networks is spontaneous periodic activity. In the developing retina, retinal ganglion cells fire bursts of action potentials that drive large increases in intracellular calcium concentration with a periodicity of minutes. These periodic bursts of action potentials propagate across the developing inner retina as waves, driving neighboring retinal ganglion cells to fire in a correlated fashion. Here we will review recent progress in elucidating the mechanisms in mammals underlying retinal wave propagation and those regulating the periodicity with which these retinal waves occur. In addition, we will review recent experiments indicating that retinal waves are critical for refining retinal projections to their primary targets in the central visual system and may be involved in driving developmental processes within the retina itself.
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Affiliation(s)
- Sally I Firth
- Neurobiology Section, Division of Biological Sciences, Pacific Hall 3127, University of California at San Diego, 9500 Gilman Dr, La Jolla, CA, 92093-0357, USA
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Linkenkaer-Hansen K, Nikulin VV, Palva JM, Kaila K, Ilmoniemi RJ. Stimulus-induced change in long-range temporal correlations and scaling behaviour of sensorimotor oscillations. Eur J Neurosci 2004; 19:203-11. [PMID: 14750978 DOI: 10.1111/j.1460-9568.2004.03116.x] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The human brain spontaneously generates large-scale network oscillations at around 10 and 20 Hz. The amplitude envelope of these oscillations fluctuates intermittently and was recently reported to exhibit power-law decay of the autocorrelation for hundreds of seconds. This indicates that the underlying networks are in a dynamic state resembling the self-organized critical state known to exist in many complex systems. Based on the mechanism of how correlations emerge in these systems, we hypothesized that the physiological basis of long-range power-law correlations is the buildup of a memory of past activity by a continuous modification of the network's functional connectivity by the ongoing oscillations. In this framework, exogenous perturbations of ongoing oscillations would degrade or abolish this dynamic network memory. We investigated the sensitivity of the temporal correlations in sensorimotor 10- and 20-Hz oscillations to median nerve stimulation that is known to have immediate effects on ongoing oscillations. Our results show that the amplitude fluctuations of these oscillations were effectively modulated by the somatosensory stimuli but still exhibited long-range temporal correlations and power-law scaling behaviour. The magnitude of the temporal correlations was, however, attenuated and the power-law exponents were decreased. This implies that the stimuli indeed degraded the network's memory of its past.
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Abstract
Even without active pacemaker mechanisms, temporally patterned synchronization of neural network activity can emerge spontaneously and is involved in neural development and information processing. Generation of spontaneous synchronization is thought to arise as an alternating sequence between a state of elevated excitation followed by a period of quiescence associated with neuronal and/or synaptic refractoriness. However, the cellular factors controlling recruitment and timing of synchronized events have remained difficult to specify, although the specific temporal pattern of spontaneous rhythmogenesis determines its impact on developmental processes. We studied spontaneous synchronization in a model of 600-1,000 integrate-and-fire neurons interconnected with a probability of 5-30%. One-third of neurons generated spontaneous discharges and provided a background of intrinsic activity to the network. The heterogeneity and random coupling of these neurons maintained this background activity asynchronous. Refractoriness was modeled either by use-dependent synaptic depression or by cellular afterhyperpolarization. In both cases, the recruitment of neurons into spontaneous synchronized discharges was determined by the interplay of refractory mechanisms with stochastic fluctuations in background activity. Subgroups of easily recruitable neurons served as amplifiers of these fluctuations, thereby initiating a cascade-like recruitment of neurons ("avalanche effect"). In contrast, timing depended on the precise implementation of neuronal refractoriness and synaptic connectivity. With synaptic depression, neuronal synchronization always occurred stochastically, whereas with cellular afterhyperpolarization, stochastic turned into periodic behavior with increasing synaptic strength. These results associate the type of refractory mechanism with the temporal statistics and the mechanism of synchronization, thereby providing a framework for differentiating between cellular mechanisms of spontaneous rhythmogenesis.
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Affiliation(s)
- Urs Achim Wiedemann
- Centre Européen de Recherche Nucléaire, Theory Division, CH-1211 Geneva 23, Switzerland
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41
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Abstract
Mammalian retinal degenerations initiated by gene defects in rods, cones or the retinal pigmented epithelium (RPE) often trigger loss of the sensory retina, effectively leaving the neural retina deafferented. The neural retina responds to this challenge by remodeling, first by subtle changes in neuronal structure and later by large-scale reorganization. Retinal degenerations in the mammalian retina generally progress through three phases. Phase 1 initiates with expression of a primary insult, followed by phase 2 photoreceptor death that ablates the sensory retina via initial photoreceptor stress, phenotype deconstruction, irreversible stress and cell death, including bystander effects or loss of trophic support. The loss of cones heralds phase 3: a protracted period of global remodeling of the remnant neural retina. Remodeling resembles the responses of many CNS assemblies to deafferentation or trauma, and includes neuronal cell death, neuronal and glial migration, elaboration of new neurites and synapses, rewiring of retinal circuits, glial hypertrophy and the evolution of a fibrotic glial seal that isolates the remnant neural retina from the surviving RPE and choroid. In early phase 2, stressed photoreceptors sprout anomalous neurites that often reach the inner plexiform and ganglion cell layers. As death of rods and cones progresses, bipolar and horizontal cells are deafferented and retract most of their dendrites. Horizontal cells develop anomalous axonal processes and dendritic stalks that enter the inner plexiform layer. Dendrite truncation in rod bipolar cells is accompanied by revision of their macromolecular phenotype, including the loss of functioning mGluR6 transduction. After ablation of the sensory retina, Müller cells increase intermediate filament synthesis, forming a dense fibrotic layer in the remnant subretinal space. This layer invests the remnant retina and seals it from access via the choroidal route. Evidence of bipolar cell death begins in phase 1 or 2 in some animal models, but depletion of all neuronal classes is evident in phase 3. As remodeling progresses over months and years, more neurons are lost and patches of the ganglion cell layer can become depleted. Some survivor neurons of all classes elaborate new neurites, many of which form fascicles that travel hundreds of microns through the retina, often beneath the distal glial seal. These and other processes form new synaptic microneuromas in the remnant inner nuclear layer as well as cryptic connections throughout the retina. Remodeling activity peaks at mid-phase 3, where neuronal somas actively migrate on glial surfaces. Some amacrine and bipolar cells move into the former ganglion cell layer while other amacrine cells are everted through the inner nuclear layer to the glial seal. Remodeled retinas engage in anomalous self-signaling via rewired circuits that might not support vision even if they could be driven anew by cellular or bionic agents. We propose that survivor neurons actively seek excitation as sources of homeostatic Ca(2+) fluxes. In late phase 3, neuron loss continues and the retina becomes increasingly glial in composition. Retinal remodeling is not plasticity, but represents the invocation of mechanisms resembling developmental and CNS plasticities. Together, neuronal remodeling and the formation of the glial seal may abrogate many cellular and bionic rescue strategies. However, survivor neurons appear to be stable, healthy, active cells and given the evidence of their reactivity to deafferentation, it may be possible to influence their emergent rewiring and migration habits.
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Affiliation(s)
- Robert E Marc
- John A. Moran Eye Center, Department of Ophthalmology, University of Utah School of Medicine, 50 N Medical Center, Salt Lake City, UT 84132, USA
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42
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Abstract
Developing networks can generate bursting activity despite the absence of pacemaker cells and inhibitory synapses. Bursts are generated by positive feedback through excitatory connections and terminated by a slow depression of network excitability. Similar activity has been observed in cultures of spinal neurons containing inhibitory synapses. Is burst generation in these cultures operating according to the mechanism proposed for developing networks? To answer this question without perturbing the activity, we analyzed the burst pattern of individual neurons in active cultures. We observed a correlation between burst size and preceding interburst interval and a rapid rise and progressive decrease in firing rate during a burst. These findings are consistent with the mechanism of burst generation proposed for developing networks.
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Affiliation(s)
- Joël Tabak
- Laboratory of Neural Control, Section on Developmental Neurobiology, NINDS/NIH, Room 3A50, Building 49, NIH Campus, Bethesda, MD 10892, USA.
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Harris RE, Coulombe MG, Feller MB. Dissociated retinal neurons form periodically active synaptic circuits. J Neurophysiol 2002; 88:188-95. [PMID: 12091544 DOI: 10.1152/jn.00722.2001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Throughout the developing nervous system, immature circuits generate rhythmic activity patterns that influence the formation of adult networks. The cellular mechanisms underlying this spontaneous, correlated activity can be studied in dissociated neuronal cultures. Using calcium imaging and whole cell recording, we showed that cultured dissociated mammalian retinal neurons form networks that produce spontaneous, correlated, highly periodic activity. As the culture matures, the spatial correlations of the periodic calcium transients evolve from being highly synchronized across neighboring cells to propagating across the culture in a wavelike manner reminiscent of retinal waves recorded in vivo. Spontaneous calcium transients and synaptic currents were blocked either by cadmium, tetrodotoxin, or the glutamate receptor antagonist 6,7-dinitroquinoxaline, indicating that the periodic activity was driven primarily by synaptic transmission between retinal ganglion cells. Evoked responses between pairs of ganglion cells exhibited paired-pulse synaptic depression, and the time constant of recovery from this depression was similar to the interval between periodic events. These results suggest that synaptic depression may regulate the frequency of network activity. Together, these findings provide insight into how networks containing primarily excitatory connections generate highly correlated activity.
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Affiliation(s)
- Richard E Harris
- Synapse Formation and Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
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45
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Abstract
Neural activity is often required for the final stages of synaptic refinement during brain development. It is thought that learning rules acting at the individual synapse level, which specify how pre- and postsynaptic activity lead to changes in synaptic efficacy, underlie such activity-dependent development. How such rules might function in vivo can be addressed in the retinogeniculate system because the input activity from the retina and its importance in development are both known. In fact, detailed studies of retinal waves have revealed their complex spatiotemporal properties, providing insights into the mechanisms that use such activity to guide development. First of all, the information useful for development is contained in the retinal waves and can be quantified, placing constraints on synaptic learning rules that use this information. Furthermore, knowing the distribution of activity over the entire set of inputs makes it possible to address a necessary component of developmental refinement: rules governing competition between synaptic inputs. In this way, the detailed knowledge of retinal input and lateral geniculate nucleus development provides a unique opportunity to relate the rules of synaptic plasticity directly to their role in development.
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Affiliation(s)
- Daniel A Butts
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA.
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Abstract
Cells in the early stages of starvation-induced fruiting body development migrate in a highly organized periodic pattern of equispaced accumulations that move as traveling waves. Two sets of waves are observed moving in opposite directions with the same wavelength and speed. To learn how the behavior of individual cells contributes to the wave pattern, fluorescent cells were tracked within a rippling population. These cells exhibit at least three types of organized behavior. First, most cell movement occurs along the same axis as the rippling movement. Second, there is a high degree of cell alignment parallel to the direction of rippling, as indicated by the biased movement. Third, by controlling the reversal frequency, cell movement becomes periodic in a rippling field. The periodicity of individual cells matches the period of macroscopic rippling. This last behavior is unique to a rippling population and, on the basis of Myxococcus xanthus genetic data, we conclude that this periodicity is linked to the C signal, a nondiffusible cell contact-mediated signaling molecule. When two cells moving in opposite directions meet end to end, they transmit the C signal to each other and in response reverse their gliding direction. This model of traveling waves represents a new mode of biological pattern formation that depends on cell-contact interactions rather than reaction diffusion.
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Affiliation(s)
- R Welch
- Department of Developmental Biology, B300 Beckman Center, 279 Campus Drive, Stanford University, Stanford, CA 94305. USA
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Staley KJ, Bains JS, Yee A, Hellier J, Longacher JM. Statistical model relating CA3 burst probability to recovery from burst-induced depression at recurrent collateral synapses. J Neurophysiol 2001; 86:2736-47. [PMID: 11731533 DOI: 10.1152/jn.2001.86.6.2736] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
When neuronal excitability is increased in area CA3 of the hippocampus in vitro, the pyramidal cells generate periodic bursts of action potentials that are synchronized across the network. We have previously provided evidence that synaptic depression at the excitatory recurrent collateral synapses in the CA3 network terminates each population burst so that the next burst cannot begin until these synapses have recovered. These findings raise the possibility that burst timing can be described in terms of the probability of recovery of this population of synapses. Here we demonstrate that when neuronal excitability is changed in the CA3 network, the mean and variance of the interburst interval change in a manner that is consistent with a timing mechanism comprised of a pool of exponentially relaxing pacemakers. The relaxation time constant of these pacemakers is the same as the time constant describing the recovery from activity-dependent depression of recurrent collateral synapses. Recovery was estimated from the rate of spontaneous transmitter release versus time elapsed since the last CA3 burst. Pharmacological and long-term alterations of synaptic strength and network excitability affected CA3 burst timing as predicted by the cumulative binomial distribution if the burst pace-maker consists of a pool of recovering recurrent synapses. These findings indicate that the recovery of a pool of synapses from burst-induced depression is a sufficient explanation for burst timing in the in vitro CA3 neuronal network. These findings also demonstrate how information regarding the nature of a pacemaker can be derived from the temporal pattern of synchronous network activity. This information could also be extracted from less accessible networks such as those generating interictal epileptiform discharges in vivo.
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Affiliation(s)
- K J Staley
- Department of Pediatrics, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
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Singer JH, Mirotznik RR, Feller MB. Potentiation of L-type calcium channels reveals nonsynaptic mechanisms that correlate spontaneous activity in the developing mammalian retina. J Neurosci 2001; 21:8514-22. [PMID: 11606640 PMCID: PMC6762803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
Although correlated neural activity is a hallmark of many regions of the developing nervous system, the neural events underlying its propagation remain largely unknown. In the developing vertebrate retina, waves of spontaneous, correlated neural activity sweep across the ganglion cell layer. Here, we demonstrate that L-type Ca(2+) channel agonists induce large, frequent, rapidly propagating waves of neural activity in the developing retina. In contrast to retinal waves that have been described previously, these L-type Ca(2+) channel agonist-potentiated waves propagate independent of fast synaptic transmission. Bath application of nicotinic acetylcholine, AMPA, NMDA, glycine, and GABA(A) receptor antagonists does not alter the velocity, frequency, or size of the potentiated waves. Additionally, these antagonists do not alter the frequency or magnitude of spontaneous depolarizations that are recorded in individual retinal ganglion cells. Like normal retinal waves, however, the area over which the potentiated waves propagate is reduced dramatically by 18alpha-glycyrrhetinic acid, a blocker of gap junctions. Additionally, like normal retinal waves, L-type Ca(2+) channel agonist-potentiated waves are abolished by adenosine deaminase, which degrades extracellular adenosine, and by aminophylline, a general adenosine receptor antagonist, indicating that they are dependent on adenosine-mediated signaling. Our study indicates that although the precise spatiotemporal properties of retinal waves are shaped by local synaptic inputs, activity may be propagated through the developing mammalian retina by nonsynaptic pathways.
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Affiliation(s)
- J H Singer
- Synapse Formation and Function Unit, National Institutes of Health, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland 20892, USA.
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Zhou ZJ. The function of the cholinergic system in the developing mammalian retina. PROGRESS IN BRAIN RESEARCH 2001; 131:599-613. [PMID: 11420974 DOI: 10.1016/s0079-6123(01)31047-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Affiliation(s)
- Z J Zhou
- Departments of Physiology and Biophysics and Ophthalmology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
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50
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Abstract
In this review, we summarize the main stages of structural and functional development of retinal ganglion cells (RGCs). We first consider the various mechanisms that are involved in restructuring of dendritic trees. To date, many mechanisms have been implicated including target-dependent factors, interactions from neighboring RGCs, and afferent signaling. We also review recent evidence showing how rapidly such dendritic remodeling might occur, along with the intracellular signaling pathways underlying these rearrangements. Concurrent with such structural changes, the functional responses of RGCs also alter during maturation, from sub-threshold firing to reliable spiking patterns. Here we consider the development of intrinsic membrane properties and how they might contribute to the spontaneous firing patterns observed before the onset of vision. We then review the mechanisms by which this spontaneous activity becomes correlated across neighboring RGCs to form waves of activity. Finally, the relative importance of spontaneous versus light-evoked activity is discussed in relation to the emergence of mature receptive field properties.
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Affiliation(s)
- E Sernagor
- Department of Neurobiology, Medical School, University of Newcastle upon Tyne, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
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