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Kaneko T, Boulanger-Weill J, Isabella AJ, Moens CB. Position-independent functional refinement within the vagus motor topographic map. Cell Rep 2024; 43:114740. [PMID: 39325616 DOI: 10.1016/j.celrep.2024.114740] [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: 04/05/2024] [Revised: 07/23/2024] [Accepted: 08/26/2024] [Indexed: 09/28/2024] Open
Abstract
Motor neurons in the central nervous system often lie in a continuous topographic map, where neurons that innervate different body parts are spatially intermingled. This is the case for the efferent neurons of the vagus nerve, which innervate diverse muscle and organ targets in the head and viscera for brain-body communication. It remains elusive how neighboring motor neurons with different fixed peripheral axon targets develop the separate somatodendritic (input) connectivity they need to generate spatially precise body control. Here, we show that vagus motor neurons in the zebrafish indeed generate spatially appropriate peripheral responses to focal sensory stimulation even when they are transplanted into ectopic positions within the topographic map, indicating that circuit refinement occurs after the establishment of coarse topography. Refinement depends on motor neuron synaptic transmission, suggesting that an experience-dependent periphery-to-brain feedback mechanism establishes specific input connectivity among intermingled motor populations.
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Affiliation(s)
- Takuya Kaneko
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA.
| | - Jonathan Boulanger-Weill
- Department of Molecular and Cellular Biology, Faculty of Arts and Sciences, Harvard University, Cambridge, MA 02138, USA; Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Institut de la Vision, Paris, France
| | - Adam J Isabella
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA; Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Cecilia B Moens
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA.
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2
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Mechanisms Underlying the Recruitment of Inhibitory Interneurons in Fictive Swimming in Developing Xenopus laevis Tadpoles. J Neurosci 2023; 43:1387-1404. [PMID: 36693757 PMCID: PMC9987577 DOI: 10.1523/jneurosci.0520-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 10/27/2022] [Accepted: 12/02/2022] [Indexed: 01/26/2023] Open
Abstract
Developing spinal circuits generate patterned motor outputs while many neurons with high membrane resistances are still maturing. In the spinal cord of hatchling frog tadpoles of unknown sex, we found that the firing reliability in swimming of inhibitory interneurons with commissural and ipsilateral ascending axons was negatively correlated with their cellular membrane resistance. Further analyses showed that neurons with higher resistances had outward rectifying properties, low firing thresholds, and little delay in firing evoked by current injections. Input synaptic currents these neurons received during swimming, either compound, unitary current amplitudes, or unitary synaptic current numbers, were scaled with their membrane resistances, but their own synaptic outputs were correlated with membrane resistances of their postsynaptic partners. Analyses of neuronal dendritic and axonal lengths and their activities in swimming and cellular input resistances did not reveal a clear correlation pattern. Incorporating these electrical and synaptic properties into a computer swimming model produced robust swimming rhythms, whereas randomizing input synaptic strengths led to the breakdown of swimming rhythms, coupled with less synchronized spiking in the inhibitory interneurons. We conclude that the recruitment of these developing interneurons in swimming can be predicted by cellular input resistances, but the order is opposite to the motor-strength-based recruitment scheme depicted by Henneman's size principle. This form of recruitment/integration order in development before the emergence of refined motor control is progressive potentially with neuronal acquisition of mature electrical and synaptic properties, among which the scaling of input synaptic strengths with cellular input resistance plays a critical role.SIGNIFICANCE STATEMENT The mechanisms on how interneurons are recruited to participate in circuit function in developing neuronal systems are rarely investigated. In 2-d-old frog tadpole spinal cord, we found the recruitment of inhibitory interneurons in swimming is inversely correlated with cellular input resistances, opposite to the motor-strength-based recruitment order depicted by Henneman's size principle. Further analyses showed the amplitude of synaptic inputs that neurons received during swimming was inversely correlated with cellular input resistances. Randomizing/reversing the relation between input synaptic strengths and membrane resistances in modeling broke down swimming rhythms. Therefore, the recruitment or integration of these interneurons is conditional on the acquisition of several electrical and synaptic properties including the scaling of input synaptic strengths with cellular input resistances.
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3
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Spatiotemporal Modeling of Grip Forces Captures Proficiency in Manual Robot Control. BIOENGINEERING (BASEL, SWITZERLAND) 2023; 10:bioengineering10010059. [PMID: 36671631 PMCID: PMC9854605 DOI: 10.3390/bioengineering10010059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 12/19/2022] [Accepted: 12/27/2022] [Indexed: 01/06/2023]
Abstract
New technologies for monitoring grip forces during hand and finger movements in non-standard task contexts have provided unprecedented functional insights into somatosensory cognition. Somatosensory cognition is the basis of our ability to manipulate and transform objects of the physical world and to grasp them with the right amount of force. In previous work, the wireless tracking of grip-force signals recorded from biosensors in the palm of the human hand has permitted us to unravel some of the functional synergies that underlie perceptual and motor learning under conditions of non-standard and essentially unreliable sensory input. This paper builds on this previous work and discusses further, functionally motivated, analyses of individual grip-force data in manual robot control. Grip forces were recorded from various loci in the dominant and non-dominant hands of individuals with wearable wireless sensor technology. Statistical analyses bring to the fore skill-specific temporal variations in thousands of grip forces of a complete novice and a highly proficient expert in manual robot control. A brain-inspired neural network model that uses the output metric of a self-organizing pap with unsupervised winner-take-all learning was run on the sensor output from both hands of each user. The neural network metric expresses the difference between an input representation and its model representation at any given moment in time and reliably captures the differences between novice and expert performance in terms of grip-force variability.Functionally motivated spatiotemporal analysis of individual average grip forces, computed for time windows of constant size in the output of a restricted amount of task-relevant sensors in the dominant (preferred) hand, reveal finger-specific synergies reflecting robotic task skill. The analyses lead the way towards grip-force monitoring in real time. This will permit tracking task skill evolution in trainees, or identify individual proficiency levels in human robot-interaction, which represents unprecedented challenges for perceptual and motor adaptation in environmental contexts of high sensory uncertainty. Cross-disciplinary insights from systems neuroscience and cognitive behavioral science, and the predictive modeling of operator skills using parsimonious Artificial Intelligence (AI), will contribute towards improving the outcome of new types of surgery, in particular the single-port approaches such as NOTES (Natural Orifice Transluminal Endoscopic Surgery) and SILS (Single-Incision Laparoscopic Surgery).
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Dresp-Langley B. Grip force as a functional window to somatosensory cognition. Front Psychol 2022; 13:1026439. [DOI: 10.3389/fpsyg.2022.1026439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 09/26/2022] [Indexed: 11/13/2022] Open
Abstract
Analysis of grip force signals tailored to hand and finger movement evolution and changes in grip force control during task execution provide unprecedented functional insight into somatosensory cognition. Somatosensory cognition is the basis of our ability to act upon and to transform the physical world around us, to recognize objects on the basis of touch alone, and to grasp them with the right amount of force for lifting and manipulating them. Recent technology has permitted the wireless monitoring of grip force signals recorded from biosensors in the palm of the human hand to track and trace human grip forces deployed in cognitive tasks executed under conditions of variable sensory (visual, auditory) input. Non-invasive multi-finger grip force sensor technology can be exploited to explore functional interactions between somatosensory brain mechanisms and motor control, in particular during learning a cognitive task where the planning and strategic execution of hand movements is essential. Sensorial and cognitive processes underlying manual skills and/or hand-specific (dominant versus non-dominant hand) behaviors can be studied in a variety of contexts by probing selected measurement loci in the fingers and palm of the human hand. Thousands of sensor data recorded from multiple spatial locations can be approached statistically to breathe functional sense into the forces measured under specific task constraints. Grip force patterns in individual performance profiling may reveal the evolution of grip force control as a direct result of cognitive changes during task learning. Grip forces can be functionally mapped to from-global-to-local coding principles in brain networks governing somatosensory processes for motor control in cognitive tasks leading to a specific task expertise or skill. Under the light of a comprehensive overview of recent discoveries into the functional significance of human grip force variations, perspectives for future studies in cognition, in particular the cognitive control of strategic and task relevant hand movements in complex real-world precision task, are pointed out.
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Abstract
This selective review explores biologically inspired learning as a model for intelligent robot control and sensing technology on the basis of specific examples. Hebbian synaptic learning is discussed as a functionally relevant model for machine learning and intelligence, as explained on the basis of examples from the highly plastic biological neural networks of invertebrates and vertebrates. Its potential for adaptive learning and control without supervision, the generation of functional complexity, and control architectures based on self-organization is brought forward. Learning without prior knowledge based on excitatory and inhibitory neural mechanisms accounts for the process through which survival-relevant or task-relevant representations are either reinforced or suppressed. The basic mechanisms of unsupervised biological learning drive synaptic plasticity and adaptation for behavioral success in living brains with different levels of complexity. The insights collected here point toward the Hebbian model as a choice solution for “intelligent” robotics and sensor systems.
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Poliacikova G, Maurel-Zaffran C, Graba Y, Saurin AJ. Hox Proteins in the Regulation of Muscle Development. Front Cell Dev Biol 2021; 9:731996. [PMID: 34733846 PMCID: PMC8558437 DOI: 10.3389/fcell.2021.731996] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 09/28/2021] [Indexed: 11/13/2022] Open
Abstract
Hox genes encode evolutionary conserved transcription factors that specify the anterior-posterior axis in all bilaterians. Being well known for their role in patterning ectoderm-derivatives, such as CNS and spinal cord, Hox protein function is also crucial in mesodermal patterning. While well described in the case of the vertebrate skeleton, much less is known about Hox functions in the development of different muscle types. In contrast to vertebrates however, studies in the fruit fly, Drosophila melanogaster, have provided precious insights into the requirement of Hox at multiple stages of the myogenic process. Here, we provide a comprehensive overview of Hox protein function in Drosophila and vertebrate muscle development, with a focus on the molecular mechanisms underlying target gene regulation in this process. Emphasizing a tight ectoderm/mesoderm cross talk for proper locomotion, we discuss shared principles between CNS and muscle lineage specification and the emerging role of Hox in neuromuscular circuit establishment.
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Affiliation(s)
| | | | - Yacine Graba
- Aix-Marseille University, CNRS, IBDM, UMR 7288, Marseille, France
| | - Andrew J Saurin
- Aix-Marseille University, CNRS, IBDM, UMR 7288, Marseille, France
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Toscano E, Zampieri N. An atlas for unveiling the functional organization of spinal circuits. CELL REPORTS METHODS 2021; 1:100086. [PMID: 35474670 PMCID: PMC9017158 DOI: 10.1016/j.crmeth.2021.100086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Defining the positional organization of neurons in the spinal cord is critical for understanding their function. In this issue, Fiederling and colleagues present a method to accurately map position and connectivity of neurons in a universal three-dimensional spinal cord reference atlas.
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Affiliation(s)
- Elisa Toscano
- Max-Delbrück-Center for Molecular Medicine, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Niccolò Zampieri
- Max-Delbrück-Center for Molecular Medicine, Robert-Rössle-Str. 10, 13125 Berlin, Germany
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8
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Xu L, Guan NN, Huang CX, Hua Y, Song J. A neuronal circuit that generates the temporal motor sequence for the defensive response in zebrafish larvae. Curr Biol 2021; 31:3343-3357.e4. [PMID: 34289386 DOI: 10.1016/j.cub.2021.06.054] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 06/06/2021] [Accepted: 06/21/2021] [Indexed: 01/11/2023]
Abstract
Animals use a precisely timed motor sequence to escape predators. This requires the nervous system to coordinate several motor behaviors and execute them in a temporal and smooth manner. We here describe a neuronal circuit that faithfully generates a defensive motor sequence in zebrafish larvae. The temporally specific defensive motor sequence consists of an initial escape and a subsequent swim behavior and can be initiated by unilateral stimulation of a single Mauthner cell (M-cell). The smooth transition from escape behavior to swim behavior is achieved by activating a neuronal chain circuit, which permits an M-cell to drive descending neurons in bilateral nucleus of medial longitudinal fascicle (nMLF) via activation of an intermediate excitatory circuit formed by interconnected hindbrain cranial relay neurons. The sequential activation of M-cells and neurons in bilateral nMLF via activation of hindbrain cranial relay neurons ensures the smooth execution of escape and swim behaviors in a timely manner. We propose an existence of a serial model that executes a temporal motor sequence involving three different brain regions that initiates the escape behavior and triggers a subsequent swim. This model has general implications regarding the neural control of complex motor sequences.
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Affiliation(s)
- Lulu Xu
- Motor Control Laboratory, Translational Research Institute of Brain and Brain-Like Intelligence, Department of Anatomy, Histology and Embryology, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China
| | - Na N Guan
- Motor Control Laboratory, Translational Research Institute of Brain and Brain-Like Intelligence, Department of Anatomy, Histology and Embryology, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China; Clinical Center for Brain and Spinal Cord Research, Tongji University, 200092 Shanghai, China
| | - Chun-Xiao Huang
- Motor Control Laboratory, Translational Research Institute of Brain and Brain-Like Intelligence, Department of Anatomy, Histology and Embryology, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China
| | - Yunfeng Hua
- Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China
| | - Jianren Song
- Motor Control Laboratory, Translational Research Institute of Brain and Brain-Like Intelligence, Department of Anatomy, Histology and Embryology, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China; Clinical Center for Brain and Spinal Cord Research, Tongji University, 200092 Shanghai, China.
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9
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Shuster SA, Wagner MJ, Pan-Doh N, Ren J, Grutzner SM, Beier KT, Kim TH, Schnitzer MJ, Luo L. The relationship between birth timing, circuit wiring, and physiological response properties of cerebellar granule cells. Proc Natl Acad Sci U S A 2021; 118:e2101826118. [PMID: 34088841 PMCID: PMC8201928 DOI: 10.1073/pnas.2101826118] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Cerebellar granule cells (GrCs) are usually regarded as a uniform cell type that collectively expands the coding space of the cerebellum by integrating diverse combinations of mossy fiber inputs. Accordingly, stable molecularly or physiologically defined GrC subtypes within a single cerebellar region have not been reported. The only known cellular property that distinguishes otherwise homogeneous GrCs is the correspondence between GrC birth timing and the depth of the molecular layer to which their axons project. To determine the role birth timing plays in GrC wiring and function, we developed genetic strategies to access early- and late-born GrCs. We initiated retrograde monosynaptic rabies virus tracing from control (birth timing unrestricted), early-born, and late-born GrCs, revealing the different patterns of mossy fiber input to GrCs in vermis lobule 6 and simplex, as well as to early- and late-born GrCs of vermis lobule 6: sensory and motor nuclei provide more input to early-born GrCs, while basal pontine and cerebellar nuclei provide more input to late-born GrCs. In vivo multidepth two-photon Ca2+ imaging of axons of early- and late-born GrCs revealed representations of diverse task variables and stimuli by both populations, with modest differences in the proportions encoding movement, reward anticipation, and reward consumption. Our results suggest neither organized parallel processing nor completely random organization of mossy fiber→GrC circuitry but instead a moderate influence of birth timing on GrC wiring and encoding. Our imaging data also provide evidence that GrCs can represent generalized responses to aversive stimuli, in addition to recently described reward representations.
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Affiliation(s)
- S Andrew Shuster
- HHMI, Stanford University, Stanford, CA 94305
- Department of Biology, Stanford University, Stanford, CA 94305
- Neurosciences Graduate Program, Stanford University, Stanford, CA 94305
| | - Mark J Wagner
- HHMI, Stanford University, Stanford, CA 94305
- Department of Biology, Stanford University, Stanford, CA 94305
| | - Nathan Pan-Doh
- HHMI, Stanford University, Stanford, CA 94305
- Department of Biology, Stanford University, Stanford, CA 94305
| | - Jing Ren
- HHMI, Stanford University, Stanford, CA 94305
- Department of Biology, Stanford University, Stanford, CA 94305
- Medical Research Council Laboratory of Molecular Biology, Cambridge University, Cambridge CB2 0QH, United Kingdom
| | - Sophie M Grutzner
- HHMI, Stanford University, Stanford, CA 94305
- Department of Biology, Stanford University, Stanford, CA 94305
| | - Kevin T Beier
- HHMI, Stanford University, Stanford, CA 94305
- Department of Biology, Stanford University, Stanford, CA 94305
- Department of Physiology and Biophysics, University of California, Irvine, CA 92697
| | - Tony Hyun Kim
- HHMI, Stanford University, Stanford, CA 94305
- Department of Biology, Stanford University, Stanford, CA 94305
- Department of Applied Physics, Stanford University, Stanford, CA 94305
| | - Mark J Schnitzer
- HHMI, Stanford University, Stanford, CA 94305
- Department of Biology, Stanford University, Stanford, CA 94305
- Department of Applied Physics, Stanford University, Stanford, CA 94305
| | - Liqun Luo
- HHMI, Stanford University, Stanford, CA 94305;
- Department of Biology, Stanford University, Stanford, CA 94305
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10
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Kishore S, Cadoff EB, Agha MA, McLean DL. Orderly compartmental mapping of premotor inhibition in the developing zebrafish spinal cord. Science 2020; 370:431-436. [PMID: 33093104 DOI: 10.1126/science.abb4608] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 08/18/2020] [Indexed: 12/13/2022]
Abstract
In vertebrates, faster movements involve the orderly recruitment of different types of spinal motor neurons. However, it is not known how premotor inhibitory circuits are organized to ensure alternating motor output at different movement speeds. We found that different types of commissural inhibitory interneurons in zebrafish form compartmental microcircuits during development that align inhibitory strength and recruitment order. Axonal microcircuits develop first and provide the most potent premotor inhibition during the fastest movements, followed by perisomatic microcircuits, and then dendritic microcircuits that provide the weakest inhibition during the slowest movements. The conversion of a temporal sequence of neuronal development into a spatial pattern of inhibitory connections provides an "ontogenotopic" solution to the problem of shaping spinal motor output at different speeds of movement.
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Affiliation(s)
- Sandeep Kishore
- Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA
| | - Eli B Cadoff
- Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA
| | - Moneeza A Agha
- Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA
| | - David L McLean
- Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA.
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11
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Dresp-Langley B, Nageotte F, Zanne P, de Mathelin M. Correlating Grip Force Signals from Multiple Sensors Highlights Prehensile Control Strategies in a Complex Task-User System. Bioengineering (Basel) 2020; 7:E143. [PMID: 33182694 PMCID: PMC7711794 DOI: 10.3390/bioengineering7040143] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/04/2020] [Accepted: 11/07/2020] [Indexed: 11/16/2022] Open
Abstract
Wearable sensor systems with transmitting capabilities are currently employed for the biometric screening of exercise activities and other performance data. Such technology is generally wireless and enables the non-invasive monitoring of signals to track and trace user behaviors in real time. Examples include signals relative to hand and finger movements or force control reflected by individual grip force data. As will be shown here, these signals directly translate into task, skill, and hand-specific (dominant versus non-dominant hand) grip force profiles for different measurement loci in the fingers and palm of the hand. The present study draws from thousands of such sensor data recorded from multiple spatial locations. The individual grip force profiles of a highly proficient left-hander (expert), a right-handed dominant-hand-trained user, and a right-handed novice performing an image-guided, robot-assisted precision task with the dominant or the non-dominant hand are analyzed. The step-by-step statistical approach follows Tukey's "detective work" principle, guided by explicit functional assumptions relating to somatosensory receptive field organization in the human brain. Correlation analyses (Person's product moment) reveal skill-specific differences in co-variation patterns in the individual grip force profiles. These can be functionally mapped to from-global-to-local coding principles in the brain networks that govern grip force control and its optimization with a specific task expertise. Implications for the real-time monitoring of grip forces and performance training in complex task-user systems are brought forward.
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Affiliation(s)
- Birgitta Dresp-Langley
- ICube UMR 7357, Centre National de la Recherche Scientifique (CNRS), 75016 Paris, France
| | - Florent Nageotte
- ICube UMR 7357 Robotics Department, University of Strasbourg, 67081 Strasbourg, France; (F.N.); (P.Z.); (M.d.M.)
| | - Philippe Zanne
- ICube UMR 7357 Robotics Department, University of Strasbourg, 67081 Strasbourg, France; (F.N.); (P.Z.); (M.d.M.)
| | - Michel de Mathelin
- ICube UMR 7357 Robotics Department, University of Strasbourg, 67081 Strasbourg, France; (F.N.); (P.Z.); (M.d.M.)
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12
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Seven Properties of Self-Organization in the Human Brain. BIG DATA AND COGNITIVE COMPUTING 2020. [DOI: 10.3390/bdcc4020010] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The principle of self-organization has acquired a fundamental significance in the newly emerging field of computational philosophy. Self-organizing systems have been described in various domains in science and philosophy including physics, neuroscience, biology and medicine, ecology, and sociology. While system architecture and their general purpose may depend on domain-specific concepts and definitions, there are (at least) seven key properties of self-organization clearly identified in brain systems: (1) modular connectivity, (2) unsupervised learning, (3) adaptive ability, (4) functional resiliency, (5) functional plasticity, (6) from-local-to-global functional organization, and (7) dynamic system growth. These are defined here in the light of insight from neurobiology, cognitive neuroscience and Adaptive Resonance Theory (ART), and physics to show that self-organization achieves stability and functional plasticity while minimizing structural system complexity. A specific example informed by empirical research is discussed to illustrate how modularity, adaptive learning, and dynamic network growth enable stable yet plastic somatosensory representation for human grip force control. Implications for the design of “strong” artificial intelligence in robotics are brought forward.
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13
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Balaskas N, Ng D, Zampieri N. The Positional Logic of Sensory-Motor Reflex Circuit Assembly. Neuroscience 2020; 450:142-150. [PMID: 32387250 DOI: 10.1016/j.neuroscience.2020.04.038] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 04/11/2020] [Accepted: 04/22/2020] [Indexed: 12/18/2022]
Abstract
Throughout his scientific career, Tom Jessell pioneered the spinal cord as a model system to study the molecular programs of neural specification, axon guidance, and connection specificity. His contributions to these fields and more broadly to that of developmental neuroscience will continue to inspire and define many generations of researchers. It is challenging to capture all of Tom's findings in one essay, and therefore, here we wish to briefly highlight his contributions to the problem of connection specificity, with a focus on the spinal sensory-motor reflex circuit. In particular, emphasis will be placed on discoveries from his laboratory that revealed a significant role of positional strategies in establishing selective sensory-motor connections. This work introduced novel principles of neuronal connectivity that may apply to how precise circuit wiring occurs throughout the nervous system.
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Affiliation(s)
- Nikolaos Balaskas
- The Mortimer B. Zuckerman Mind, Brain, and Behavior Institute, Department of Neuroscience, Columbia University, New York, NY 10027, USA.
| | - David Ng
- The Mortimer B. Zuckerman Mind, Brain, and Behavior Institute, Columbia University, New York, NY 10027, USA.
| | - Niccolò Zampieri
- Max-Delbrück-Center for Molecular Medicine Berlin-Buch, Robert-Rössle-Str. 10, 13125 Berlin, Germany.
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14
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Balaskas N, Abbott LF, Jessell TM, Ng D. Positional Strategies for Connection Specificity and Synaptic Organization in Spinal Sensory-Motor Circuits. Neuron 2019; 102:1143-1156.e4. [PMID: 31076274 DOI: 10.1016/j.neuron.2019.04.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 02/04/2019] [Accepted: 03/29/2019] [Indexed: 11/17/2022]
Abstract
Proprioceptive sensory axons in the spinal cord form selective connections with motor neuron partners, but the strategies that confer such selectivity remain uncertain. We show that muscle-specific sensory axons project to motor neurons along topographically organized angular trajectories and that motor pools exhibit diverse dendritic arbors. On the basis of spatial constraints on axo-dendritic interactions, we propose positional strategies that can account for sensory-motor connectivity and synaptic organization. These strategies rely on two patterning principles. First, the degree of axo-dendritic overlap reduces the number of potential post-synaptic partners. Second, a close correlation between the small angle of axo-dendritic approach and the formation of synaptic clusters imposes specificity of connections when sensory axons intersect multiple motor pools with overlapping dendritic arbors. Our study identifies positional strategies with prominent roles in the organization of spinal sensory-motor circuits.
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Affiliation(s)
- Nikolaos Balaskas
- The Mortimer B. Zuckerman Mind, Brain, and Behavior Institute, Department of Neuroscience, Columbia University, New York, NY 10027, USA.
| | - L F Abbott
- The Mortimer B. Zuckerman Mind, Brain, and Behavior Institute, Department of Neuroscience, Columbia University, New York, NY 10027, USA; Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - Thomas M Jessell
- Departments of Neuroscience, and Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - David Ng
- The Mortimer B. Zuckerman Mind, Brain, and Behavior Institute, Department of Neuroscience, Columbia University, New York, NY 10027, USA.
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15
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Pujala A, Koyama M. Chronology-based architecture of descending circuits that underlie the development of locomotor repertoire after birth. eLife 2019; 8:42135. [PMID: 30801247 PMCID: PMC6449084 DOI: 10.7554/elife.42135] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 02/22/2019] [Indexed: 12/17/2022] Open
Abstract
The emergence of new and increasingly sophisticated behaviors after birth is accompanied by dramatic increase of newly established synaptic connections in the nervous system. Little is known, however, of how nascent connections are organized to support such new behaviors alongside existing ones. To understand this, in the larval zebrafish we examined the development of spinal pathways from hindbrain V2a neurons and the role of these pathways in the development of locomotion. We found that new projections are continually layered laterally to existing neuropil, and give rise to distinct pathways that function in parallel to existing pathways. Across these chronologically layered pathways, the connectivity patterns and biophysical properties vary systematically to support a behavioral repertoire with a wide range of kinematics and dynamics. Such layering of new parallel circuits equipped with systematically changing properties may be central to the postnatal diversification and increasing sophistication of an animal’s behavioral repertoire. Newborn babies have limited abilities. Indeed, most of our actions shortly after birth are the result of reflexes that serve our most basic need: to stay alive. As we get older, however, our behaviour gradually becomes more sophisticated. During this time, the billions of cells in our brain form new connections to build intricate ‘circuits’ of neurons that allow for more complicated thoughts and actions. It is clear that the brain circuits that support new behaviours must develop in a way that does not interfere with the existing circuits that are vital for survival. However, the challenge has been to find a way to peer into a brain as it develops to see how these new circuits form. In recent years, zebrafish have revolutionised research into neuronal circuits in animals. Developing over the course of a few days, these small transparent fish provide a window into the brain during the earliest stages of development. Indeed, the circuits of neurons that descend from the brain and connect to the spinal cord have already been mapped in these animals. Now, Pujala and Koyama have begun to follow the careful development of these ‘descending’ neurons, and relate it to the appearance of new behaviours in young zebrafish. Time-lapse imaging with a fluorescent protein that is active only in specific descending neurons revealed that new circuits are laid down over existing ones, like the growth rings in a tree. Next, at different timepoints in zebrafish development, Pujala and Koyama traced these neurons backwards from the spine to the brain to identify which connections formed first. This showed that the spinal connections develop one after the other, in the same order that the neurons mature. Next, Pujala and Koyama asked how the activity of neurons that mature early or late in development relates to specific behaviours in young zebrafish. Early-born circuits connect to neurons that produce powerful, reflex-driven, whole-body movements such as an escape response. The later circuits connect to different neurons through slower, less direct pathways; the late-born neurons also generate the refined movements that are acquired later in a zebrafish’s development and help the fish to explore its environment. These findings show that descending circuits in zebrafish run parallel to each other, but with distinct connections and properties that allow them to control different kinds of movements. While this study was conducted using an animal model, a better understanding of how such circuits develop and the movements they control may one day aid the treatment of patients with neurodegenerative diseases or injuries where connections have been lost.
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Affiliation(s)
- Avinash Pujala
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Minoru Koyama
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
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16
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Berg EM, Björnfors ER, Pallucchi I, Picton LD, El Manira A. Principles Governing Locomotion in Vertebrates: Lessons From Zebrafish. Front Neural Circuits 2018; 12:73. [PMID: 30271327 PMCID: PMC6146226 DOI: 10.3389/fncir.2018.00073] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 08/27/2018] [Indexed: 11/24/2022] Open
Abstract
Locomotor behaviors are critical for survival and enable animals to navigate their environment, find food and evade predators. The circuits in the brain and spinal cord that initiate and maintain such different modes of locomotion in vertebrates have been studied in numerous species for over a century. In recent decades, the zebrafish has emerged as one of the main model systems for the study of locomotion, owing to its experimental amenability, and work in zebrafish has revealed numerous new insights into locomotor circuit function. Here, we review the literature that has led to our current understanding of the neural circuits controlling swimming and escape in zebrafish. We highlight recent studies that have enriched our comprehension of key topics, such as the interactions between premotor excitatory interneurons (INs) and motoneurons (MNs), supraspinal and spinal circuits that coordinate escape maneuvers, and developmental changes in overall circuit composition. We also discuss roles for neuromodulators and sensory inputs in modifying the relative strengths of constituent circuit components to provide flexibility in zebrafish behavior, allowing the animal to accommodate changes in the environment. We aim to provide a coherent framework for understanding the circuitry in the brain and spinal cord of zebrafish that allows the animal to flexibly transition between different speeds, and modes, of locomotion.
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Affiliation(s)
- Eva M Berg
- Department of Neuroscience, Karolinska Institute (KI), Stockholm, Sweden
| | | | - Irene Pallucchi
- Department of Neuroscience, Karolinska Institute (KI), Stockholm, Sweden
| | - Laurence D Picton
- Department of Neuroscience, Karolinska Institute (KI), Stockholm, Sweden
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17
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Delineating the Diversity of Spinal Interneurons in Locomotor Circuits. J Neurosci 2017; 37:10835-10841. [PMID: 29118212 DOI: 10.1523/jneurosci.1829-17.2017] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 09/27/2017] [Accepted: 10/11/2017] [Indexed: 11/21/2022] Open
Abstract
Locomotion is common to all animals and is essential for survival. Neural circuits located in the spinal cord have been shown to be necessary and sufficient for the generation and control of the basic locomotor rhythm by activating muscles on either side of the body in a specific sequence. Activity in these neural circuits determines the speed, gait pattern, and direction of movement, so the specific locomotor pattern generated relies on the diversity of the neurons within spinal locomotor circuits. Here, we review findings demonstrating that developmental genetics can be used to identify populations of neurons that comprise these circuits and focus on recent work indicating that many of these populations can be further subdivided into distinct subtypes, with each likely to play complementary functions during locomotion. Finally, we discuss data describing the manner in which these populations interact with each other to produce efficient, task-dependent locomotion.
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18
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Zhang J, Weinrich JAP, Russ JB, Comer JD, Bommareddy PK, DiCasoli RJ, Wright CVE, Li Y, van Roessel PJ, Kaltschmidt JA. A Role for Dystonia-Associated Genes in Spinal GABAergic Interneuron Circuitry. Cell Rep 2017; 21:666-678. [PMID: 29045835 PMCID: PMC5658202 DOI: 10.1016/j.celrep.2017.09.079] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 09/08/2017] [Accepted: 09/24/2017] [Indexed: 12/17/2022] Open
Abstract
Spinal interneurons are critical modulators of motor circuit function. In the dorsal spinal cord, a set of interneurons called GABApre presynaptically inhibits proprioceptive sensory afferent terminals, thus negatively regulating sensory-motor signaling. Although deficits in presynaptic inhibition have been inferred in human motor diseases, including dystonia, it remains unclear whether GABApre circuit components are altered in these conditions. Here, we use developmental timing to show that GABApre neurons are a late Ptf1a-expressing subclass and localize to the intermediate spinal cord. Using a microarray screen to identify genes expressed in this intermediate population, we find the kelch-like family member Klhl14, implicated in dystonia through its direct binding with torsion-dystonia-related protein Tor1a. Furthermore, in Tor1a mutant mice in which Klhl14 and Tor1a binding is disrupted, formation of GABApre sensory afferent synapses is impaired. Our findings suggest a potential contribution of GABApre neurons to the deficits in presynaptic inhibition observed in dystonia.
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Affiliation(s)
- Juliet Zhang
- Developmental Biology Program, Sloan Kettering Institute, New York, NY 10065, USA; Neuroscience Program, Weill Cornell Graduate School of Medical Sciences, Weill Cornell Medicine, New York, NY 10065, USA
| | - Jarret A P Weinrich
- Developmental Biology Program, Sloan Kettering Institute, New York, NY 10065, USA; Biochemistry, Cell and Molecular Biology Program, Weill Cornell Graduate School of Medical Sciences, Weill Cornell Medicine, New York, NY 10065, USA
| | - Jeffrey B Russ
- Developmental Biology Program, Sloan Kettering Institute, New York, NY 10065, USA; Neuroscience Program, Weill Cornell Graduate School of Medical Sciences, Weill Cornell Medicine, New York, NY 10065, USA; Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY 10065, USA
| | - John D Comer
- Developmental Biology Program, Sloan Kettering Institute, New York, NY 10065, USA; Neuroscience Program, Weill Cornell Graduate School of Medical Sciences, Weill Cornell Medicine, New York, NY 10065, USA; Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY 10065, USA
| | - Praveen K Bommareddy
- Developmental Biology Program, Sloan Kettering Institute, New York, NY 10065, USA
| | - Richard J DiCasoli
- Developmental Biology Program, Sloan Kettering Institute, New York, NY 10065, USA
| | - Christopher V E Wright
- Vanderbilt University Program in Developmental Biology, Vanderbilt Center for Stem Cell Biology, Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Yuqing Li
- Department of Neurology, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Peter J van Roessel
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Julia A Kaltschmidt
- Developmental Biology Program, Sloan Kettering Institute, New York, NY 10065, USA; Neuroscience Program, Weill Cornell Graduate School of Medical Sciences, Weill Cornell Medicine, New York, NY 10065, USA; Biochemistry, Cell and Molecular Biology Program, Weill Cornell Graduate School of Medical Sciences, Weill Cornell Medicine, New York, NY 10065, USA; Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA 94305, USA.
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19
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Yan Q, Zhai L, Zhang B, Dallman JE. Spatial patterning of excitatory and inhibitory neuropil territories during spinal circuit development. J Comp Neurol 2017; 525:1649-1667. [PMID: 27997694 DOI: 10.1002/cne.24152] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Revised: 10/13/2016] [Accepted: 11/14/2016] [Indexed: 01/04/2023]
Abstract
To generate rhythmic motor behaviors, both single neurons and neural circuits require a balance between excitatory inputs that trigger action potentials and inhibitory inputs that promote a stable resting potential (E/I balance). Previous studies have focused on individual neurons and have shown that, over a short spatial scale, excitatory and inhibitory (E/I) synapses tend to form structured territories with inhibitory inputs enriched on cell bodies and proximal dendrites and excitatory inputs on distal dendrites. However, systems-level E/I patterns, at spatial scales larger than single neurons, are largely uncharted. We used immunostaining for PSD-95 and gephyrin postsynaptic scaffolding proteins as proxies for excitatory and inhibitory synapses, respectively, to quantify the numbers and map the distributions of E/I synapses in zebrafish spinal cord at both an embryonic stage and a larval stage. At the embryonic stage, we found that PSD-95 puncta outnumber gephyrin puncta, with the number of gephyrin puncta increasing to match that of PSD-95 puncta at the larval stage. At both stages, PSD-95 puncta are enriched in the most lateral neuropil corresponding to distal dendrites while gephyrin puncta are enriched on neuronal somata and in the medial neuropil. Significantly, similar to synaptic puncta, neuronal processes also exhibit medial-lateral territories at both developmental stages with enrichment of glutamatergic (excitatory) processes laterally and glycinergic (inhibitory) processes medially. This establishment of neuropil excitatory-inhibitory structure largely precedes dendritic arborization of primary motor neurons, suggesting that the structured neuropil could provide a framework for the development of E/I balance at the cellular level. J. Comp. Neurol. 525:1649-1667, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Qing Yan
- Department of Biology, Cox Science Center, University of Miami, 1301 Memorial Drive, Coral Gables, Florida
| | - Lu Zhai
- Department of Biology, Cox Science Center, University of Miami, 1301 Memorial Drive, Coral Gables, Florida
| | - Bo Zhang
- Department of Biology, Cox Science Center, University of Miami, 1301 Memorial Drive, Coral Gables, Florida
| | - Julia E Dallman
- Department of Biology, Cox Science Center, University of Miami, 1301 Memorial Drive, Coral Gables, Florida
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20
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McArthur KL, Fetcho JR. Key Features of Structural and Functional Organization of Zebrafish Facial Motor Neurons Are Resilient to Disruption of Neuronal Migration. Curr Biol 2017; 27:1746-1756.e5. [PMID: 28602649 DOI: 10.1016/j.cub.2017.05.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 01/15/2017] [Accepted: 05/10/2017] [Indexed: 11/30/2022]
Abstract
The location of neurons early in development can be critical for their ability to differentiate and receive normal synaptic inputs. Indeed, disruptions in neuronal positioning lead to a variety of neurological disorders. Neurons have, however, shifted their positions across phylogeny, suggesting that changes in location do not always spell functional disaster. To investigate the functional consequences of abnormal positioning, we leveraged previously reported genetic perturbations to disrupt normal neuronal migration-and thus positioning-in a population of cranial motor neurons, the facial branchiomotor neurons (FBMNs). We used a combination of topographical, morphological, physiological, and behavioral analyses to determine whether key functional features of FBMNs were still established in migration mutants, in spite of a dramatic rostrocaudal repositioning of these neurons in hindbrain. We discovered that FBMNs seem remarkably resilient to a disruption in positioning, suggesting that they may not rely heavily on rostrocaudal positioning to guide their functional development. Thus, the role of positioning may vary across the developing nervous system, with some populations-like facial motor neurons-exhibiting greater resilience to abnormal positioning that permits them to shift location as a part of evolutionary change.
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Affiliation(s)
- Kimberly L McArthur
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - Joseph R Fetcho
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA.
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21
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Wreden CC, Meng JL, Feng W, Chi W, Marshall ZD, Heckscher ES. Temporal Cohorts of Lineage-Related Neurons Perform Analogous Functions in Distinct Sensorimotor Circuits. Curr Biol 2017; 27:1521-1528.e4. [PMID: 28502656 DOI: 10.1016/j.cub.2017.04.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 03/21/2017] [Accepted: 04/13/2017] [Indexed: 11/18/2022]
Abstract
Neuronal stem cell lineages are the fundamental developmental units of the brain, and neuronal circuits are the fundamental functional units of the brain. Determining lineage-circuitry relationships is essential for deciphering the developmental logic of circuit assembly. While the spatial distribution of lineage-related neurons has been investigated in a few brain regions [1-9], an important, but unaddressed question is whether temporal information that diversifies neuronal progeny within a single lineage also impacts circuit assembly. Circuits in the sensorimotor system (e.g., spinal cord) are thought to be assembled sequentially [10-14], making this an ideal brain region for investigating the circuit-level impact of temporal patterning within a lineage. Here, we use intersectional genetics, optogenetics, high-throughput behavioral analysis, single-neuron labeling, connectomics, and calcium imaging to determine how a set of bona fide lineage-related interneurons contribute to sensorimotor circuitry in the Drosophila larva. We show that Even-skipped lateral interneurons (ELs) are sensory processing interneurons. Late-born ELs contribute to a proprioceptive body posture circuit, whereas early-born ELs contribute to a mechanosensitive escape circuit. These data support a model in which a single neuronal stem cell can produce a large number of interneurons with similar functional capacity that are distributed into different circuits based on birth timing. In summary, these data establish a link between temporal specification of neuronal identity and circuit assembly at the single-cell level.
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Affiliation(s)
- Christopher C Wreden
- Department of Molecular Genetics and Cell Biology, University of Chicago, 920 East 58(th) Street, Chicago, IL 60637, USA
| | - Julia L Meng
- Program in Cell and Molecular Biology, University of Chicago, 920 East 58(th) Street, Chicago, IL 60637, USA
| | - Weidong Feng
- Committee on Development, Regeneration, and Stem Cell Biology, University of Chicago, 920 East 58(th) Street, Chicago, IL 60637, USA
| | - Wanhao Chi
- Committee on Genetics, Genomics, and Systems Biology, University of Chicago, 920 East 58(th) Street, Chicago, IL 60637, USA
| | - Zarion D Marshall
- Department of Molecular Genetics and Cell Biology, University of Chicago, 920 East 58(th) Street, Chicago, IL 60637, USA
| | - Ellie S Heckscher
- Department of Molecular Genetics and Cell Biology, University of Chicago, 920 East 58(th) Street, Chicago, IL 60637, USA; Program in Cell and Molecular Biology, University of Chicago, 920 East 58(th) Street, Chicago, IL 60637, USA; Committee on Development, Regeneration, and Stem Cell Biology, University of Chicago, 920 East 58(th) Street, Chicago, IL 60637, USA; Committee on Genetics, Genomics, and Systems Biology, University of Chicago, 920 East 58(th) Street, Chicago, IL 60637, USA.
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22
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Dasen JS. Master or servant? emerging roles for motor neuron subtypes in the construction and evolution of locomotor circuits. Curr Opin Neurobiol 2017; 42:25-32. [PMID: 27907815 PMCID: PMC5316365 DOI: 10.1016/j.conb.2016.11.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 11/05/2016] [Accepted: 11/13/2016] [Indexed: 01/23/2023]
Abstract
Execution of motor behaviors relies on the ability of circuits within the nervous system to engage functionally relevant subtypes of spinal motor neurons. While much attention has been given to the role of networks of spinal interneurons on setting the rhythm and pattern of output from locomotor circuits, recent studies suggest that motor neurons themselves can exert an instructive role in shaping the wiring and functional properties of locomotor networks. Alteration in the distribution of motor neuron subtypes also appears to have contributed to evolutionary transitions in the locomotor strategies used by land vertebrates. This review describes emerging evidence that motor neuron-derived cues can have a profound influence on the organization, wiring, and evolutionary diversification of locomotor circuits.
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Affiliation(s)
- Jeremy S Dasen
- Neuroscience Institute, Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY 10016, USA.
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23
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Ding B, Cave JW, Dobner PR, Mullikin-Kilpatrick D, Bartzokis M, Zhu H, Chow CW, Gronostajski RM, Kilpatrick DL. Reciprocal autoregulation by NFI occupancy and ETV1 promotes the developmental expression of dendrite-synapse genes in cerebellar granule neurons. Mol Biol Cell 2016; 27:1488-99. [PMID: 26941328 PMCID: PMC4850036 DOI: 10.1091/mbc.e15-07-0476] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 02/25/2016] [Indexed: 12/30/2022] Open
Abstract
Temporal control of dendritogenesis is poorly understood. Mutual feedback between NFIA temporal occupancy and ETV1 drives the timing of gene expression associated with dendrite formation in maturing neurons. A sequential timing model is proposed in which ETV1 autoregulation precedes activation of downstream NFIA/ETV1 coregulated genes. Nuclear Factor One (NFI) transcription factors regulate temporal gene expression required for dendritogenesis and synaptogenesis via delayed occupancy of target promoters in developing cerebellar granule neurons (CGNs). Mechanisms that promote NFI temporal occupancy have not been previously defined. We show here that the transcription factor ETV1 directly binds to and is required for expression and NFI occupancy of a cohort of NFI-dependent genes in CGNs maturing in vivo. Expression of ETV1 is low in early postnatal cerebellum and increases with maturation, mirroring NFI temporal occupancy of coregulated target genes. Precocious expression of ETV1 in mouse CGNs accelerated onset of expression and NFI temporal occupancy of late target genes and enhanced Map2(+) neurite outgrowth. ETV1 also activated expression and NFI occupancy of the Etv1 gene itself, and this autoregulatory loop preceded ETV1 binding and activation of other coregulated target genes in vivo. These findings suggest a potential model in which ETV1 activates NFI temporal binding to a subset of late-expressed genes in a stepwise manner by initial positive feedback regulation of the Etv1 gene itself followed by activation of downstream coregulated targets as ETV1 expression increases. Sequential transcription factor autoregulation and subsequent binding to downstream promoters may provide an intrinsic developmental timer for dendrite/synapse gene expression.
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Affiliation(s)
- Baojin Ding
- Department of Microbiology and Physiological Systems and Program in Neuroscience, University of Massachusetts Medical School, Worcester, MA 01605
| | - John W Cave
- Burke Medical Research Institute, White Plains, NY 10605 Weill Cornell Medical College, Brain and Mind Research Institute, New York, NY 10065
| | - Paul R Dobner
- Department of Microbiology and Physiological Systems and Program in Neuroscience, University of Massachusetts Medical School, Worcester, MA 01605
| | - Debra Mullikin-Kilpatrick
- Department of Microbiology and Physiological Systems and Program in Neuroscience, University of Massachusetts Medical School, Worcester, MA 01605
| | - Marina Bartzokis
- Department of Microbiology and Physiological Systems and Program in Neuroscience, University of Massachusetts Medical School, Worcester, MA 01605
| | - Hong Zhu
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Chi-Wing Chow
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Richard M Gronostajski
- Department of Biochemistry, Program in Neuroscience and Developmental Genomics Group, New York State Center of Excellence in Bioinformatics and Life Sciences, University at Buffalo, Buffalo, NY 14203
| | - Daniel L Kilpatrick
- Department of Microbiology and Physiological Systems and Program in Neuroscience, University of Massachusetts Medical School, Worcester, MA 01605
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24
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Darabid H, Perez-Gonzalez AP, Robitaille R. Neuromuscular synaptogenesis: coordinating partners with multiple functions. Nat Rev Neurosci 2014; 15:630-1. [DOI: 10.1038/nrn3821] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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25
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Jung H, Mazzoni EO, Soshnikova N, Hanley O, Venkatesh B, Duboule D, Dasen JS. Evolving Hox activity profiles govern diversity in locomotor systems. Dev Cell 2014; 29:171-87. [PMID: 24746670 DOI: 10.1016/j.devcel.2014.03.008] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 03/07/2014] [Accepted: 03/13/2014] [Indexed: 11/28/2022]
Abstract
The emergence of limb-driven locomotor behaviors was a key event in the evolution of vertebrates and fostered the transition from aquatic to terrestrial life. We show that the generation of limb-projecting lateral motor column (LMC) neurons in mice relies on a transcriptional autoregulatory module initiated via transient activity of multiple genes within the HoxA and HoxC clusters. Repression of this module at thoracic levels restricts expression of LMC determinants, thus dictating LMC position relative to the limbs. This suppression is mediated by a key regulatory domain that is specifically found in the Hoxc9 proteins of appendage-bearing vertebrates. The profile of Hoxc9 expression inversely correlates with LMC position in land vertebrates and likely accounts for the absence of LMC neurons in limbless species such as snakes. Thus, modulation of both Hoxc9 protein function and Hoxc9 gene expression likely contributed to evolutionary transitions between undulatory and ambulatory motor circuit connectivity programs.
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Affiliation(s)
- Heekyung Jung
- Howard Hughes Medical Institute, NYU Neuroscience Institute, Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY 10016, USA
| | | | - Natalia Soshnikova
- Department of Genetics and Evolution, University of Geneva, Sciences III, Quai Ernest-Ansermet 30, 1211 Geneva 4, Switzerland; Institute of Molecular Biology, Ackermannweg 4, 55128 Mainz, Germany
| | - Olivia Hanley
- Howard Hughes Medical Institute, NYU Neuroscience Institute, Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY 10016, USA
| | - Byrappa Venkatesh
- Comparative Genomics Laboratory, Institute of Molecular and Cell Biology, A(∗)STAR, Biopolis, Singapore 138673, Singapore; Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Denis Duboule
- Department of Genetics and Evolution, University of Geneva, Sciences III, Quai Ernest-Ansermet 30, 1211 Geneva 4, Switzerland; School of Life Sciences, Ecole Polytechnique Fédérale, 1015 Lausanne, Switzerland
| | - Jeremy S Dasen
- Howard Hughes Medical Institute, NYU Neuroscience Institute, Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY 10016, USA.
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26
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Laumonnerie C, Da Silva RV, Kania A, Wilson SI. Netrin 1 and Dcc signalling are required for confinement of central axons within the central nervous system. Development 2014; 141:594-603. [DOI: 10.1242/dev.099606] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The establishment of anatomically stereotyped axonal projections is fundamental to neuronal function. While most neurons project their axons within the central nervous system (CNS), only axons of centrally born motoneurons and peripherally born sensory neurons link the CNS and peripheral nervous system (PNS) together by navigating through specialized CNS/PNS transition zones. Such selective restriction is of importance because inappropriate CNS axonal exit could lead to loss of correct connectivity and also to gain of erroneous functions. However, to date, surprisingly little is known about the molecular-genetic mechanisms that regulate how central axons are confined within the CNS during development. Here, we show that netrin 1/Dcc/Unc5 chemotropism contributes to axonal confinement within the CNS. In both Ntn1 and Dcc mutant mouse embryos, some spinal interneuronal axons exit the CNS by traversing the CNS/PNS transition zones normally reserved for motor and sensory axons. We provide evidence that netrin 1 signalling preserves CNS/PNS axonal integrity in three ways: (1) netrin 1/Dcc ventral attraction diverts axons away from potential exit points; (2) a Dcc/Unc5c-dependent netrin 1 chemoinhibitory barrier in the dorsolateral spinal cord prevents interneurons from being close to the dorsal CNS/PNS transition zone; and (3) a netrin 1/Dcc-dependent, Unc5c-independent mechanism that actively prevents exit from the CNS. Together, these findings provide insights into the molecular mechanisms that maintain CNS/PNS integrity and, to the best of our knowledge, present the first evidence that chemotropic signalling regulates interneuronal CNS axonal confinement in vertebrates.
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Affiliation(s)
| | - Ronan V. Da Silva
- Institut de Recherches Cliniques de Montréal, Montréal, QC H2W 1R7, Canada
- McGill University Integrated Program in Neuroscience, Montreal, QC H3A 2B4, Canada
| | - Artur Kania
- Institut de Recherches Cliniques de Montréal, Montréal, QC H2W 1R7, Canada
- McGill University Integrated Program in Neuroscience, Montreal, QC H3A 2B4, Canada
- Département de Médecine, Université de Montréal, Montréal, QC H3T 1J4, Canada
- Division of Experimental Medicine and Departments of Biology, and Anatomy and Cell Biology, McGill University, Montréal, QC H3A 1A3, Canada
| | - Sara I. Wilson
- Umeå Centre for Molecular Medicine, Umeå University, 901-87 Umeå, Sweden
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27
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The cell biology of synaptic specificity during development. Curr Opin Neurobiol 2013; 23:1018-26. [PMID: 23932598 DOI: 10.1016/j.conb.2013.07.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 07/09/2013] [Accepted: 07/10/2013] [Indexed: 02/05/2023]
Abstract
Proper circuit connectivity is critical for nervous system function. Connectivity derives from the interaction of two interdependent modules: synaptic specificity and synaptic assembly. Specificity involves both targeting of neurons to specific laminar regions and the formation of synapses onto defined subcellular areas. In this review, we focus discussion on recently elucidated molecular mechanisms that control synaptic specificity and link them to synapse assembly. We use these molecular pathways to underscore fundamental cell biological concepts that underpin, and help explain, the rules governing synaptic specificity.
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Alvarez FJ, Benito-Gonzalez A, Siembab VC. Principles of interneuron development learned from Renshaw cells and the motoneuron recurrent inhibitory circuit. Ann N Y Acad Sci 2013; 1279:22-31. [PMID: 23530999 DOI: 10.1111/nyas.12084] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Renshaw cells provide a convenient model to study spinal circuit development during the emergence of motor behaviors with the goal of capturing principles of interneuron specification and circuit construction. This work is facilitated by a long history of research that generated essential knowledge about the characteristics that define Renshaw cells and the recurrent inhibitory circuit they form with motoneurons. In this review, we summarize recent data on the specification of Renshaw cells and their connections. A major insight from these studies is that the basic Renshaw cell phenotype is specified before circuit assembly, a result of their early neurogenesis and migration. Connectivity is later added, constrained by their placement in the spinal cord. Finally, different rates of synapse proliferation alter the relative weights of different inputs on postnatal Renshaw cells. Based on this work some general principles on the integration of spinal interneurons in developing motor circuits are derived.
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Temporal regulation of nuclear factor one occupancy by calcineurin/NFAT governs a voltage-sensitive developmental switch in late maturing neurons. J Neurosci 2013; 33:2860-72. [PMID: 23407945 DOI: 10.1523/jneurosci.3533-12.2013] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Dendrite and synapse development are critical for establishing appropriate neuronal circuits, and disrupted timing of these events can alter neural connectivity. Using microarrays, we have identified a nuclear factor I (NFI)-regulated temporal switch program linked to dendrite formation in developing mouse cerebellar granule neurons (CGNs). NFI function was required for upregulation of many synapse-related genes as well as downregulation of genes expressed in immature CGNs. Chromatin immunoprecipitation analysis revealed that a central feature of this program was temporally regulated NFI occupancy of late-expressed gene promoters. Developing CGNs undergo a hyperpolarizing shift in membrane potential, and depolarization inhibits their dendritic and synaptic maturation via activation of calcineurin (CaN) (Okazawa et al., 2009). Maintaining immature CGNs in a depolarized state blocked NFI temporal occupancy of late-expressed genes and the NFI switch program via activation of the CaN/nuclear factor of activated T-cells, cytoplasmic (NFATc) pathway and promotion of late-gene occupancy by NFATc4, and these mechanisms inhibited dendritogenesis. Conversely, inhibition of the CaN/NFATc pathway in CGNs maturing under physiological nondepolarizing conditions upregulated the NFI switch program, NFI temporal occupancy, and dendrite formation. NFATc4 occupied the promoters of late-expressed NFI program genes in immature mouse cerebellum, and its binding was temporally downregulated with development. Further, NFI temporal binding and switch gene expression were upregulated in the developing cerebellum of Nfatc4 (-/-) mice. These findings define a novel NFI switch and temporal occupancy program that forms a critical link between membrane potential/CaN and dendritic maturation in CGNs. CaN inhibits the program and NFI occupancy in immature CGNs by promoting NFATc4 binding to late-expressed genes. As maturing CGNs become more hyperpolarized, NFATc4 binding declines leading to onset of NFI temporal binding and the NFI switch program.
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Decoding the rules of recruitment of excitatory interneurons in the adult zebrafish locomotor network. Proc Natl Acad Sci U S A 2012; 109:E3631-9. [PMID: 23236181 DOI: 10.1073/pnas.1216256110] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Neural networks in the spinal cord transform signals from the brain into coordinated locomotor movements. An optimal adjustment of the speed of locomotion entails a precise order of recruitment of interneurons underlying excitation within these networks. However, the mechanisms encoding the recruitment threshold of excitatory interneurons have remained unclear. Here we show, using a juvenile/adult zebrafish preparation, that excitatory V2a interneurons are incrementally recruited with increased swimming frequency. The order of recruitment is not imprinted by the topography or the input resistance of the V2a interneurons. Rather, it is determined by scaling the effect of excitatory synaptic currents by the input resistance. We also show that the locomotor networks are composed of multiple microcircuits encompassing subsets of V2a interneurons and motoneurons that are recruited in a continuum with increased swimming speeds. Thus, our results provide insights into the organization and mechanisms determining the recruitment of spinal microcircuits to ensure optimal execution of locomotor movements.
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Yoon YJ, White SL, Ni X, Gokin AP, Martin-Caraballo M. Downregulation of GluA2 AMPA receptor subunits reduces the dendritic arborization of developing spinal motoneurons. PLoS One 2012; 7:e49879. [PMID: 23226228 PMCID: PMC3511505 DOI: 10.1371/journal.pone.0049879] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Accepted: 10/15/2012] [Indexed: 11/19/2022] Open
Abstract
AMPA receptors lacking the GluA2 subunit allow a significant influx of Ca(2+) ions. Although Ca(2+)-permeable AMPA receptors are a familiar feature at early stages of development, the functional significance of these receptors during the maturation of the nervous system remains to be established. Chicken lumbar motoneurons express Ca(2+)-permeable AMPA receptors at E6 but the Ca(2+) permeability of AMPA receptors decreases ∼3-fold by E11. Considering that activity-dependent changes in intracellular Ca(2+) regulates dendritic outgrowth, in this study we investigated whether downregulation of GluA2 expression during a critical period of development alters the dendritic arborization of spinal motoneurons in ovo. We use an avian replication-competent retroviral vector RCASBP (B) carrying the marker red fluorescent protein (RFP) and a GluA2 RNAi construct to downregulate GluA2 expression. Chicken embryos were infected at E2 with one of the following constructs: RCASBP(B)-RFP, RCASBP(B)-RFP-scrambled RNAi, or RCASBP(B)-RFP-GluA2 RNAi. Infection of chicken embryos at E2 resulted in widespread expression of RFP throughout the spinal cord with ≥60% of Islet1/2-positive motoneurons infected, resulting in a significant reduction in GluA2 protein expression. Downregulation of GluA2 expression had no effect on the dendritic arborization of E6 motoneurons. However, downregulation of GluA2 expression caused a significant reduction in the dendritic arborization of E11 motoneurons. Neither motoneuron survival nor maturation of network activity was affected by changes in GluA2 expression. These findings demonstrate that increased GluA2 expression and changes in the Ca(2+) permeability of AMPA receptors regulate the dendritic arborization of spinal cord motoneurons during a critical period of development.
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Affiliation(s)
- Yone J. Yoon
- Department of Biology, University of Vermont, Burlington, Vermont, United States of America
| | - Sheryl L. White
- Department of Anatomy and Neurobiology, College of Medicine, University of Vermont, Burlington, Vermont, United States of America
| | - Xianglian Ni
- Department of Biology, University of Vermont, Burlington, Vermont, United States of America
| | - Alexander P. Gokin
- Department of Biology, University of Vermont, Burlington, Vermont, United States of America
| | - Miguel Martin-Caraballo
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland Eastern Shore, Princess Anne, Maryland, United States of America
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Arber S. Motor Circuits in Action: Specification, Connectivity, and Function. Neuron 2012; 74:975-89. [DOI: 10.1016/j.neuron.2012.05.011] [Citation(s) in RCA: 187] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/14/2012] [Indexed: 10/28/2022]
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