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Morris MM, Hao 郝赵哲 ZZ, Berkowitz A. Electrophysiological Activity of Multifunctional and Behaviorally Specialized Spinal Neurons Involved in Swimming, Scratching, and Flexion Reflex in Turtles. eNeuro 2024; 11:ENEURO.0038-24.2024. [PMID: 38969499 PMCID: PMC11265262 DOI: 10.1523/eneuro.0038-24.2024] [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: 01/25/2024] [Revised: 06/11/2024] [Accepted: 06/26/2024] [Indexed: 07/07/2024] Open
Abstract
The adult turtle spinal cord can generate multiple kinds of limb movements, including swimming, three forms of scratching, and limb withdrawal (flexion reflex), even without brain input and sensory feedback. There are many multifunctional spinal neurons, activated during multiple motor patterns, and some behaviorally specialized neurons, activated during only one. How do multifunctional and behaviorally specialized neurons each contribute to motor output? We analyzed in vivo intracellular recordings of multifunctional and specialized neurons. Neurons tended to spike in the same phase of the hip-flexor (HF) activity cycle during swimming and scratching, though one preferred opposite phases. During both swimming and scratching, a larger fraction of multifunctional neurons than specialized neurons were highly rhythmic. One group of multifunctional neurons was active during the HF-on phase and another during the HF-off phase. Thus, HF-extensor alternation may be generated by a subset of multifunctional spinal neurons during both swimming and scratching. Scratch-specialized neurons and flexion reflex-selective neurons may instead trigger their respective motor patterns, by biasing activity of multifunctional neurons. In phase-averaged membrane potentials of multifunctional neurons, trough phases were more highly correlated between swimming and scratching than peak phases, suggesting that rhythmic inhibition plays a greater role than rhythmic excitation. We also provide the first intracellular recording of a turtle swim-specialized neuron: tonically excited during swimming but inactive during scratching and flexion reflex. It displayed an excitatory postsynaptic potential following each swim-evoking electrical stimulus and thus may be an intermediary between reticulospinal axons and the swimming CPG they activate.
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Affiliation(s)
- Madison M Morris
- School of Biological Sciences, University of Oklahoma, Norman, Oklahoma 73019
| | - Zhao-Zhe Hao 郝赵哲
- School of Biological Sciences, University of Oklahoma, Norman, Oklahoma 73019
| | - Ari Berkowitz
- School of Biological Sciences, University of Oklahoma, Norman, Oklahoma 73019
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Jonaitis J, Hibbard KL, McCafferty Layte K, Hiramoto A, Cardona A, Truman JW, Nose A, Zwart MF, Pulver SR. STEERING FROM THE REAR: COORDINATION OF CENTRAL PATTERN GENERATORS UNDERLYING NAVIGATION BY ASCENDING INTERNEURONS. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.17.598162. [PMID: 38948859 PMCID: PMC11212907 DOI: 10.1101/2024.06.17.598162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
Understanding how animals coordinate movements to achieve goals is a fundamental pursuit in neuroscience. Here we explore how neurons that reside in posterior lower-order regions of a locomotor system project to anterior higher-order regions to influence steering and navigation. We characterized the anatomy and functional role of a population of ascending interneurons in the ventral nerve cord of Drosophila larvae. Through electron microscopy reconstructions and light microscopy, we determined that the cholinergic 19f cells receive input primarily from premotor interneurons and synapse upon a diverse array of postsynaptic targets within the anterior segments including other 19f cells. Calcium imaging of 19f activity in isolated central nervous system (CNS) preparations in relation to motor neurons revealed that 19f neurons are recruited into most larval motor programmes. 19f activity lags behind motor neuron activity and as a population, the cells encode spatio-temporal patterns of locomotor activity in the larval CNS. Optogenetic manipulations of 19f cell activity in isolated CNS preparations revealed that they coordinate the activity of central pattern generators underlying exploratory headsweeps and forward locomotion in a context and location specific manner. In behaving animals, activating 19f cells suppressed exploratory headsweeps and slowed forward locomotion, while inhibition of 19f activity potentiated headsweeps, slowing forward movement. Inhibiting activity in 19f cells ultimately affected the ability of larvae to remain in the vicinity of an odor source during an olfactory navigation task. Overall, our findings provide insights into how ascending interneurons monitor motor activity and shape interactions amongst rhythm generators underlying complex navigational tasks.
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Affiliation(s)
- Julius Jonaitis
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, UK
| | | | | | - Atsuki Hiramoto
- Department of Complexity Science and Engineering, Graduate School of Frontier Sciences, The University of Tokyo, Chiba, Japan
| | - Albert Cardona
- HHMI Janelia Research Campus, Ashburn, VA, USA
- Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge, UK
- MRC Laboratory of Molecular Biology, Cambridge UK
| | - James W. Truman
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA, USA
| | - Akinao Nose
- Department of Complexity Science and Engineering, Graduate School of Frontier Sciences, The University of Tokyo, Chiba, Japan
- Department of Physics, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Maarten F. Zwart
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, UK
- Centre of Biophotonics, University of St Andrews, St Andrews, UK
- Institute for Behavioural and Neural Sciences, University of St Andrews, St Andrews, UK
| | - Stefan R. Pulver
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, UK
- Centre of Biophotonics, University of St Andrews, St Andrews, UK
- Institute for Behavioural and Neural Sciences, University of St Andrews, St Andrews, UK
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Abstract
According to the commonly accepted opinion, memory engrams are formed and stored at the level of neural networks due to a change in the strength of synaptic connections between neurons. This hypothesis of synaptic plasticity (HSP), formulated by Donald Hebb in the 1940s, continues to dominate the directions of experimental studies and the interpretations of experimental results in the field. The universal acceptance of the HSP has transformed it from a hypothesis into an incontrovertible theory. In this article, I show that the entire body of experimental and clinical data obtained in studies of long-term memory in mammals and humans is inconsistent with the HSP. Instead, these data suggest that long-term memory is formed and stored at the intracellular level where it is reliably protected from ongoing synaptic activity, including pathological epileptic activity. It seems that the generally accepted HSP became a serious obstacle to understanding the mechanisms of memory and that progress in this field requires rethinking this doctrine and shifting experimental efforts toward exploring the intracellular mechanisms.
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Affiliation(s)
- Yuri I Arshavsky
- BioCircuits Institute, University of California San Diego, La Jolla, CA, USA
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Dynamic simulation of non-programmed gait generation of quadruped robot. ARTIFICIAL LIFE AND ROBOTICS 2022. [DOI: 10.1007/s10015-022-00765-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Klishko AN, Akyildiz A, Mehta-Desai R, Prilutsky BI. Common and distinct muscle synergies during level and slope locomotion in the cat. J Neurophysiol 2021; 126:493-515. [PMID: 34191619 DOI: 10.1152/jn.00310.2020] [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] [Indexed: 02/07/2023] Open
Abstract
Although it is well established that the motor control system is modular, the organization of muscle synergies during locomotion and their change with ground slope are not completely understood. For example, typical reciprocal flexor-extensor muscle synergies of level walking in cats break down in downslope: one-joint hip extensors are silent throughout the stride cycle, whereas hindlimb flexors demonstrate an additional stance phase-related electromyogram (EMG) burst (Smith JL, Carlson-Kuhta P, Trank TV. J Neurophysiol 79: 1702-1716, 1998). Here, we investigated muscle synergies during level, upslope (27°), and downslope (-27°) walking in adult cats to examine common and distinct features of modular organization of locomotor EMG activity. Cluster analysis of EMG burst onset-offset times of 12 hindlimb muscles revealed five flexor and extensor burst groups that were generally shared across slopes. Stance-related bursts of flexor muscles in downslope were placed in a burst group from level and upslope walking formed by the rectus femoris. Walking upslope changed swing/stance phase durations of level walking but not the cycle duration. Five muscle synergies computed using non-negative matrix factorization accounted for at least 95% of variance in EMG patterns in each slope. Five synergies were shared between level and upslope walking, whereas only three of those were shared with downslope synergies; these synergies were active during the swing phase and phase transitions. Two stance-related synergies of downslope walking were distinct; they comprised a mixture of flexors and extensors. We suggest that the modular organization of muscle activity during level and slope walking results from interactions between motion-related sensory feedback, CPG, and supraspinal inputs.NEW & NOTEWORTHY We demonstrated that the atypical EMG activities during cat downslope walking, silent one-joint hip extensors and stance-related EMG bursts in flexors, have many features shared with activities of level and upslope walking. Majority of EMG burst groups and muscle synergies were shared among these slopes, and upslope modulated the swing/stance phase duration but not cycle duration. Thus, synergistic EMG activities in all slopes might result from a shared CPG receiving somatosensory and supraspinal inputs.
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Affiliation(s)
- Alexander N Klishko
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
| | - Adil Akyildiz
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
| | - Ricky Mehta-Desai
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
| | - Boris I Prilutsky
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
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Takei Y, Morishita K, Tazawa R, Saito K. Active Gaits Generation of Quadruped Robot Using Pulse-Type Hardware Neuron Models. Biomimetics (Basel) 2021. [DOI: 10.5772/intechopen.95760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
In this chapter, the authors will propose the active gait generation of a quadruped robot. We developed the quadruped robot system using self-inhibited pulse-type hardware neuron models (P-HNMs) as a solution to elucidate the gait generation method. We feedbacked pressures at the robot system’s each foot to P-HNM and varied the joints’ angular velocity individually. We experimented with making the robot walk from an upright position on a flat floor. As a result of the experiment, we confirmed that the robot system spontaneously generates walk gait and trot gait according to the moving speed. Also, we clarified the process by which the robot actively generates gaits from the upright state. These results suggest that animals may generate gait using a similarly simple method because P-HNM mimics biological neurons’ function. Furthermore, it shows that our robot system can generate gaits adaptively and quite easily.
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Olivares E, Izquierdo EJ, Beer RD. A Neuromechanical Model of Multiple Network Rhythmic Pattern Generators for Forward Locomotion in C. elegans. Front Comput Neurosci 2021; 15:572339. [PMID: 33679357 PMCID: PMC7930337 DOI: 10.3389/fncom.2021.572339] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Accepted: 01/21/2021] [Indexed: 12/04/2022] Open
Abstract
Multiple mechanisms contribute to the generation, propagation, and coordination of the rhythmic patterns necessary for locomotion in Caenorhabditis elegans. Current experiments have focused on two possibilities: pacemaker neurons and stretch-receptor feedback. Here, we focus on whether it is possible that a chain of multiple network rhythmic pattern generators in the ventral nerve cord also contribute to locomotion. We use a simulation model to search for parameters of the anatomically constrained ventral nerve cord circuit that, when embodied and situated, can drive forward locomotion on agar, in the absence of pacemaker neurons or stretch-receptor feedback. Systematic exploration of the space of possible solutions reveals that there are multiple configurations that result in locomotion that is consistent with certain aspects of the kinematics of worm locomotion on agar. Analysis of the best solutions reveals that gap junctions between different classes of motorneurons in the ventral nerve cord can play key roles in coordinating the multiple rhythmic pattern generators.
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Affiliation(s)
- Erick Olivares
- Cognitive Science Program, Indiana University Bloomington, Bloomington, IN, United States
| | - Eduardo J. Izquierdo
- Cognitive Science Program, Indiana University Bloomington, Bloomington, IN, United States
- Luddy School of Informatics, Computing, and Engineering, Indiana University Bloomington, Bloomington, IN, United States
| | - Randall D. Beer
- Cognitive Science Program, Indiana University Bloomington, Bloomington, IN, United States
- Luddy School of Informatics, Computing, and Engineering, Indiana University Bloomington, Bloomington, IN, United States
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Berkowitz A. Expanding our horizons: central pattern generation in the context of complex activity sequences. J Exp Biol 2019; 222:222/20/jeb192054. [DOI: 10.1242/jeb.192054] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
ABSTRACT
Central pattern generators (CPGs) are central nervous system (CNS) networks that can generate coordinated output in the absence of patterned sensory input. For decades, this concept was applied almost exclusively to simple, innate, rhythmic movements with essentially identical cycles that repeat continually (e.g. respiration) or episodically (e.g. locomotion). But many natural movement sequences are not simple rhythms, as they include different elements in a complex order, and some involve learning. The concepts and experimental approaches of CPG research have also been applied to the neural control of complex movement sequences, such as birdsong, though this is not widely appreciated. Experimental approaches to the investigation of CPG networks, both for simple rhythms and for complex activity sequences, have shown that: (1) brief activation of the CPG elicits a long-lasting naturalistic activity sequence; (2) electrical stimulation of CPG elements alters the timing of subsequent cycles or sequence elements; and (3) warming or cooling CPG elements respectively speeds up or slows down the rhythm or sequence rate. The CPG concept has also been applied to the activity rhythms of populations of mammalian cortical neurons. CPG concepts and methods might further be applied to a variety of fixed action patterns typically used in courtship, rivalry, nest building and prey capture. These complex movements could be generated by CPGs within CPGs (‘nested’ CPGs). Stereotypical, non-motor, non-rhythmic neuronal activity sequences may also be generated by CPGs. My goal here is to highlight previous applications of the CPG concept to complex but stereotypical activity sequences and to suggest additional possible applications, which might provoke new hypotheses and experiments.
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Affiliation(s)
- Ari Berkowitz
- Department of Biology and Cellular & Behavioral Neurobiology Graduate Program, University of Oklahoma, Norman, OK 73019, USA
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Koglin T, Sándor B, Gros C. When the goal is to generate a series of activities: A self-organized simulated robot arm. PLoS One 2019; 14:e0217004. [PMID: 31216272 PMCID: PMC6584010 DOI: 10.1371/journal.pone.0217004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 04/09/2019] [Indexed: 11/19/2022] Open
Abstract
Behavior is characterized by sequences of goal oriented conducts, such as food uptake, socializing and resting. Classically, one would define for each task a corresponding satisfaction level, with the agent engaging, at a given time, in the activity having the lowest satisfaction level. Alternatively, one may consider that the agent follows the overarching objective to generate sequences of distinct activities. To achieve a balanced distribution of activities would then be the primary goal, and not to master a specific task. In this setting the agent would show two types of behaviors, task-oriented and task-searching phases, with the latter interseeding the former. We study the emergence of autonomous task switching for the case of a simulated robot arm. Grasping one of several moving objects corresponds in this setting to a specific activity. Overall, the arm should follow a given object temporarily and then move away, in order to search for a new target and reengage. We show that this behavior can be generated robustly when modeling the arm as an adaptive dynamical system. The dissipation function is in this approach time dependent. The arm is in a dissipative state when searching for a nearby object, dissipating energy on approach. Once close, the dissipation function starts to increase, with the eventual sign change implying that the arm will take up energy and wander off. The resulting explorative state ends when the dissipation function becomes again negative and the arm selects a new target. We believe that our approach may be generalized to generate self-organized sequences of activities in general.
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Affiliation(s)
- Tim Koglin
- Institute for Theoretical Physics, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Bulcsú Sándor
- Department of Physics, Babeș-Bolyai University, Cluj-Napoca, Romania
- * E-mail:
| | - Claudius Gros
- Institute for Theoretical Physics, Goethe University Frankfurt, Frankfurt am Main, Germany
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