1
|
Sukhnandan R, Chen Q, Shen J, Pao S, Huan Y, Sutton GP, Gill JP, Chiel HJ, Webster-Wood VA. Full Hill-type muscle model of the I1/I3 retractor muscle complex in Aplysia californica. BIOLOGICAL CYBERNETICS 2024:10.1007/s00422-024-00990-3. [PMID: 38922432 DOI: 10.1007/s00422-024-00990-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 04/22/2024] [Indexed: 06/27/2024]
Abstract
The coordination of complex behavior requires knowledge of both neural dynamics and the mechanics of the periphery. The feeding system of Aplysia californica is an excellent model for investigating questions in soft body systems' neuromechanics because of its experimental tractability. Prior work has attempted to elucidate the mechanical properties of the periphery by using a Hill-type muscle model to characterize the force generation capabilities of the key protractor muscle responsible for moving Aplysia's grasper anteriorly, the I2 muscle. However, the I1/I3 muscle, which is the main driver of retractions of Aplysia's grasper, has not been characterized. Because of the importance of the musculature's properties in generating functional behavior, understanding the properties of muscles like the I1/I3 complex may help to create more realistic simulations of the feeding behavior of Aplysia, which can aid in greater understanding of the neuromechanics of soft-bodied systems. To bridge this gap, in this work, the I1/I3 muscle complex was characterized using force-frequency, length-tension, and force-velocity experiments and showed that a Hill-type model can accurately predict its force-generation properties. Furthermore, the muscle's peak isometric force and stiffness were found to exceed those of the I2 muscle, and these results were analyzed in the context of prior studies on the I1/I3 complex's kinematics in vivo.
Collapse
Affiliation(s)
- Ravesh Sukhnandan
- Department of Mechanical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA, 15213, USA
| | - Qianxue Chen
- Department of Biology, Case Western Reserve University, 2080 Adelbert Road, Cleveland, OH, 44106-7080, USA
| | - Jiayi Shen
- Department of Nutrition, Case Western Reserve University, 2080 Adelbert Road, Cleveland, OH, 44106-7080, USA
| | - Samantha Pao
- Department of Biology, Case Western Reserve University, 2080 Adelbert Road, Cleveland, OH, 44106-7080, USA
| | - Yu Huan
- Department of Biology, Case Western Reserve University, 2080 Adelbert Road, Cleveland, OH, 44106-7080, USA
| | - Gregory P Sutton
- School of Life and Environmental Sciences, University of Lincoln, Green Lane, Lincoln, LN67DL, UK
| | - Jeffrey P Gill
- Department of Biology, Case Western Reserve University, 2080 Adelbert Road, Cleveland, OH, 44106-7080, USA
| | - Hillel J Chiel
- Department of Biology, Case Western Reserve University, 2080 Adelbert Road, Cleveland, OH, 44106-7080, USA
- Department of Neurosciences, Case Western Reserve University, 2080 Adelbert Road, Cleveland, OH, 44106-7080, USA
- Department of Biomedical Engineering, Case Western Reserve University, 2080 Adelbert Road, Cleveland, OH, 44106-7080, USA
| | - Victoria A Webster-Wood
- Department of Mechanical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA, 15213, USA.
- Department of Biomedical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA, 15213, USA.
- McGowan Institute for Regenerative Medicine, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA, 15213, USA.
| |
Collapse
|
2
|
Zhao Q, Gribkova E, Shen Y, Cui J, Naughton N, Liu L, Seo J, Tong B, Gazzola M, Gillette R, Zhao H. Highly stretchable and customizable microneedle electrode arrays for intramuscular electromyography. SCIENCE ADVANCES 2024; 10:eadn7202. [PMID: 38691612 PMCID: PMC11062587 DOI: 10.1126/sciadv.adn7202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2023] [Accepted: 03/29/2024] [Indexed: 05/03/2024]
Abstract
Stretchable three-dimensional (3D) penetrating microelectrode arrays have potential utility in various fields, including neuroscience, tissue engineering, and wearable bioelectronics. These 3D microelectrode arrays can penetrate and conform to dynamically deforming tissues, thereby facilitating targeted sensing and stimulation of interior regions in a minimally invasive manner. However, fabricating custom stretchable 3D microelectrode arrays presents material integration and patterning challenges. In this study, we present the design, fabrication, and applications of stretchable microneedle electrode arrays (SMNEAs) for sensing local intramuscular electromyography signals ex vivo. We use a unique hybrid fabrication scheme based on laser micromachining, microfabrication, and transfer printing to enable scalable fabrication of individually addressable SMNEA with high device stretchability (60 to 90%). The electrode geometries and recording regions, impedance, array layout, and length distribution are highly customizable. We demonstrate the use of SMNEAs as bioelectronic interfaces in recording intramuscular electromyography from various muscle groups in the buccal mass of Aplysia.
Collapse
Affiliation(s)
- Qinai Zhao
- Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA, USA
- Center for Advanced Manufacturing, University of Southern California, Los Angeles, CA, USA
| | - Ekaterina Gribkova
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Coordinated Science Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Yiyang Shen
- Center for Advanced Manufacturing, University of Southern California, Los Angeles, CA, USA
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, USA
| | - Jilai Cui
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Coordinated Science Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Noel Naughton
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Liangshu Liu
- Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA, USA
- Center for Advanced Manufacturing, University of Southern California, Los Angeles, CA, USA
| | - Jaemin Seo
- Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA, USA
- Center for Advanced Manufacturing, University of Southern California, Los Angeles, CA, USA
| | - Baixin Tong
- Center for Advanced Manufacturing, University of Southern California, Los Angeles, CA, USA
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, USA
| | - Mattia Gazzola
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Rhanor Gillette
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Hangbo Zhao
- Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA, USA
- Center for Advanced Manufacturing, University of Southern California, Los Angeles, CA, USA
- Alfred E. Mann Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| |
Collapse
|
3
|
Krings W, Gorb SN. Performance of biological food processing interfaces: Perspectives on the science of mollusc radula. Biointerphases 2024; 19:030801. [PMID: 38940493 DOI: 10.1116/6.0003672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Accepted: 05/30/2024] [Indexed: 06/29/2024] Open
Abstract
The Mollusca comprises a diverse range of organisms, with the class Gastropoda alone boasting approximately 80 000 extant species. Their adaptability across various habitats is facilitated by the evolution of the radula, a key structure for food acquisition. The radula's composition and mechanical properties, including its chitinous membrane, teeth, and supporting structures, enable efficient food gathering and processing. Through adaptive tooth morphology and composition, an interplay between radular components is facilitated, which results in collective effects to withstand forces encountered during feeding and reduce structural failure, with the broad range of variations reflecting ecological niches. Furthermore, teeth consist of composite materials with sometimes high contents of iron, calcium, or silicon to reduce wear. During interaction with the food, the radula performs complex three-dimensional motions, challenging to document. Here, we provide a review on the morphology, the mechanical properties, the composition, and various other parameters that contribute to radular performance. Due to, e.g., the smallness of these structures, there are, however, limitations to radular research. However, numerical simulations and physical models tested on substrates offer avenues for further understanding radular function and performance during feeding. These studies not only advance our knowledge of molluscan biology and ecology but also provide inspirations for biomimetic design and further advances in materials engineering.
Collapse
Affiliation(s)
- Wencke Krings
- Department of Electron Microscopy, Institute of Cell and Systems Biology of Animals, Universität Hamburg, Martin-Luther-King-Platz 3, Hamburg 20146, Germany
- Department of Cariology, Endodontology and Periodontology, Universität Leipzig, Liebigstraße 12, Leipzig 04103, Germany
- Department of Mammalogy and Paleoanthropology, Leibniz Institute for the Analysis of Biodiversity Change, Martin-Luther-King-Platz 3, Hamburg 20146, Germany
- Department of Functional Morphology and Biomechanics, Zoological Institute, Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 1-9, Kiel 24118, Germany
| | - Stanislav N Gorb
- Department of Functional Morphology and Biomechanics, Zoological Institute, Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 1-9, Kiel 24118, Germany
| |
Collapse
|
4
|
Wang Y, Gill JP, Chiel HJ, Thomas PJ. Variational and phase response analysis for limit cycles with hard boundaries, with applications to neuromechanical control problems. BIOLOGICAL CYBERNETICS 2022; 116:687-710. [PMID: 36396795 PMCID: PMC9691512 DOI: 10.1007/s00422-022-00951-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 10/17/2022] [Indexed: 06/16/2023]
Abstract
Motor systems show an overall robustness, but because they are highly nonlinear, understanding how they achieve robustness is difficult. In many rhythmic systems, robustness against perturbations involves response of both the shape and the timing of the trajectory. This makes the study of robustness even more challenging. To understand how a motor system produces robust behaviors in a variable environment, we consider a neuromechanical model of motor patterns in the feeding apparatus of the marine mollusk Aplysia californica (Shaw et al. in J Comput Neurosci 38(1):25-51, 2015; Lyttle et al. in Biol Cybern 111(1):25-47, 2017). We established in (Wang et al. in SIAM J Appl Dyn Syst 20(2):701-744, 2021. https://doi.org/10.1137/20M1344974 ) the tools for studying combined shape and timing responses of limit cycle systems under sustained perturbations and here apply them to study robustness of the neuromechanical model against increased mechanical load during swallowing. Interestingly, we discover that nonlinear biomechanical properties confer resilience by immediately increasing resistance to applied loads. In contrast, the effect of changed sensory feedback signal is significantly delayed by the firing rates' hard boundary properties. Our analysis suggests that sensory feedback contributes to robustness in swallowing primarily by shifting the timing of neural activation involved in the power stroke of the motor cycle (retraction). This effect enables the system to generate stronger retractor muscle forces to compensate for the increased load, and hence achieve strong robustness. The approaches that we are applying to understanding a neuromechanical model in Aplysia, and the results that we have obtained, are likely to provide insights into the function of other motor systems that encounter changing mechanical loads and hard boundaries, both due to mechanical and neuronal firing properties.
Collapse
Affiliation(s)
- Yangyang Wang
- Department of Mathematics, The University of Iowa, Iowa City, IA 52242 USA
| | - Jeffrey P. Gill
- Department of Biology, Case Western Reserve University, Cleveland, OH 44106 USA
| | - Hillel J. Chiel
- Department of Biology, Case Western Reserve University, Cleveland, OH 44106 USA
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH 44106 USA
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106 USA
| | - Peter J. Thomas
- Departments of Mathematics, Applied Mathematics, and Statistics, Case Western Reserve University, Cleveland, OH 44106 USA
- Department of Biology, Case Western Reserve University, Cleveland, OH 44106 USA
- Department of Cognitive Science, Case Western Reserve University, Cleveland, OH 44106 USA
- Department of Data and Computer Science, Case Western Reserve University, Cleveland, OH 44106 USA
- Department of Electrical, Control and Systems Engineering, Case Western Reserve University, Cleveland, OH 44106 USA
| |
Collapse
|
5
|
Krings W, Karabacak H, Gorb SN. From the knitting shop: the first physical and dynamic model of the taenioglossan radula (Mollusca: Gastropoda) aids in unravelling functional principles of the radular morphology. J R Soc Interface 2021; 18:20210377. [PMID: 34520692 PMCID: PMC8440039 DOI: 10.1098/rsif.2021.0377] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 08/24/2021] [Indexed: 01/19/2023] Open
Abstract
The radula is the structure used for food processing in Mollusca. It can consist of a membrane with stiffer teeth, which is, together with alary processus, muscles and odontophoral cartilages, part of the buccal mass. In malacology, it is common practice to infer potential tooth functions from morphology. Thus, past approaches to explain functional principles are mainly hypothesis driven. Therefore, there is an urgent need for a workflow testing hypotheses on the function of teeth and buccal mass components and interaction of structures, which can contribute to understanding the structure as a whole. Here, in a non-conventional approach, we introduce a physical and dynamic radular model, based on morphological data of Spekia zonata (Gastropoda, Paludomidae). Structures were documented, computer-modelled, three-dimensional-printed and assembled to gather a simplistic but realistic physical and dynamic radular model. Such a bioinspired design enabled studying of radular kinematics and interaction of parts when underlain supporting structures were manipulated in a similar manner as could result from muscle contractions. The presented work is a first step to provide a constructional manual, paving the way for even more realistic physical radular models, which could be used for understanding radular functional morphology and for the development of novel gripping devices.
Collapse
Affiliation(s)
- Wencke Krings
- Department of Mammalogy and Paleoanthropology, Center of Natural History (CeNak), Universität Hamburg, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany
- Functional Morphology and Biomechanics, Zoological Institute of the Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 9, 24118 Kiel, Germany
| | - Hasan Karabacak
- Department of Mammalogy and Paleoanthropology, Center of Natural History (CeNak), Universität Hamburg, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany
| | - Stanislav N. Gorb
- Functional Morphology and Biomechanics, Zoological Institute of the Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 9, 24118 Kiel, Germany
| |
Collapse
|
6
|
|
7
|
Krings W, Neumann C, Neiber MT, Kovalev A, Gorb SN. Radular force performance of stylommatophoran gastropods (Mollusca) with distinct body masses. Sci Rep 2021; 11:10560. [PMID: 34006949 PMCID: PMC8131350 DOI: 10.1038/s41598-021-89892-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 05/04/2021] [Indexed: 01/06/2023] Open
Abstract
The forces exerted by the animal's food processing structures can be important parameters when studying trophic specializations to specific food spectra. Even though molluscs represent the second largest animal phylum, exhibiting an incredible biodiversity accompanied by the establishment of distinct ecological niches including the foraging on a variety of ingesta types, only few studies focused on the biomechanical performance of their feeding organs. To lay a keystone for future research in this direction, we investigated the in vivo forces exerted by the molluscan food gathering and processing structure, the radula, for five stylommatophoran species (Gastropoda). The chosen species and individuals have a similar radular morphology and motion, but as they represent different body mass classes, we were enabled to relate the forces to body mass. Radular forces were measured along two axes using force transducers which allowed us to correlate forces with the distinct phases of radular motion. A radular force quotient, AFQ = mean Absolute Force/bodymass0.67, of 4.3 could be determined which can be used further for the prediction of forces generated in Gastropoda. Additionally, some specimens were dissected and the radular musculature mass as well as the radular mass and dimensions were documented. Our results depict the positive correlation between body mass, radular musculature mass, and exerted force. Additionally, it was clearly observed that the radular motion phases, exerting the highest forces during feeding, changed with regard to the ingesta size: all smaller gastropods rather approached the food by a horizontal, sawing-like radular motion leading to the consumption of rather small food particles, whereas larger gastropods rather pulled the ingesta in vertical direction by radula and jaw resulting in the tearing of larger pieces.
Collapse
Affiliation(s)
- Wencke Krings
- Department of Mammalogy and Palaeoanthropology, Center of Natural History (CeNak), Universität Hamburg, Martin-Luther-King-Platz 3, 20146, Hamburg, Germany. .,Department of Functional Morphology and Biomechanics, Zoological Institute, Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 9, 24118, Kiel, Germany.
| | - Charlotte Neumann
- Department of Mammalogy and Palaeoanthropology, Center of Natural History (CeNak), Universität Hamburg, Martin-Luther-King-Platz 3, 20146, Hamburg, Germany
| | - Marco T Neiber
- Department of Animal Diversity, Center of Natural History (CeNak), Universität Hamburg, Martin-Luther-King-Platz 3, 20146, Hamburg, Germany
| | - Alexander Kovalev
- Department of Functional Morphology and Biomechanics, Zoological Institute, Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 9, 24118, Kiel, Germany
| | - Stanislav N Gorb
- Department of Functional Morphology and Biomechanics, Zoological Institute, Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 9, 24118, Kiel, Germany
| |
Collapse
|
8
|
Yu Z, Thomas PJ. Dynamical consequences of sensory feedback in a half-center oscillator coupled to a simple motor system. BIOLOGICAL CYBERNETICS 2021; 115:135-160. [PMID: 33656573 PMCID: PMC8510507 DOI: 10.1007/s00422-021-00864-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 01/27/2021] [Indexed: 06/12/2023]
Abstract
We investigate a simple model for motor pattern generation that combines central pattern generator (CPG) dynamics with a sensory feedback (FB) mechanism. Our CPG comprises a half-center oscillator with conductance-based Morris-Lecar model neurons. Output from the CPG drives a push-pull motor system with biomechanics based on experimental data. A sensory feedback conductance from the muscles allows modulation of the CPG activity. We consider parameters under which the isolated CPG system has either "escape" or "release" dynamics, and we study both inhibitory and excitatory feedback conductances. We find that increasing the FB conductance relative to the CPG conductance makes the system more robust against external perturbations, but more susceptible to internal noise. Conversely, increasing the CPG conductance relative to the FB conductance has the opposite effects. We find that the "closed-loop" system, with sensory feedback in place, exhibits a richer repertoire of behaviors than the "open-loop" system, with motion determined entirely by the CPG dynamics. Moreover, we find that purely feedback-driven motor patterns, analogous to a chain reflex, occur only in the inhibition-mediated system. Finally, for pattern generation systems with inhibition-mediated sensory feedback, we find that the distinction between escape- and release-mediated CPG mechanisms is diminished in the presence of internal noise. Our observations support an anti-reductionist view of neuromotor physiology: Understanding mechanisms of robust motor control requires studying not only the central pattern generator circuit in isolation, but the intact closed-loop system as a whole.
Collapse
Affiliation(s)
- Zhuojun Yu
- Mathematics, Applied Mathematics and Statistics, Case Western Reserve University, Cleveland, OH, 44106, USA.
| | - Peter J Thomas
- Mathematics, Applied Mathematics and Statistics, Case Western Reserve University, Cleveland, OH, 44106, USA
- Department of Biology, Case Western Reserve University, Cleveland, OH, 44106, USA
- Department of Cognitive Science, Case Western Reserve University, Cleveland, OH, 44106, USA
- Department of Computer and Data Science, Case Western Reserve University, Cleveland, OH, 44106, USA
- Department of Electrical, Computer and Systems Engineering, Case Western Reserve University, Cleveland, OH, 44106, USA
| |
Collapse
|
9
|
Wang Y, Gill JP, Chiel HJ, Thomas PJ. Shape versus timing: linear responses of a limit cycle with hard boundaries under instantaneous and static perturbation. SIAM JOURNAL ON APPLIED DYNAMICAL SYSTEMS 2021; 20:701-744. [PMID: 37207037 PMCID: PMC10194846 DOI: 10.1137/20m1344974] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
When dynamical systems that produce rhythmic behaviors operate within hard limits, they may exhibit limit cycles with sliding components, that is, closed isolated periodic orbits that make and break contact with a constraint surface. Examples include heel-ground interaction in locomotion, firing rate rectification in neural networks, and stick-slip oscillators. In many rhythmic systems, robustness against external perturbations involves response of both the shape and the timing of the limit cycle trajectory. The existing methods of infinitesimal phase response curve (iPRC) and variational analysis are well established for quantifying changes in timing and shape, respectively, for smooth systems. These tools have recently been extended to nonsmooth dynamics with transversal crossing boundaries. In this work, we further extend the iPRC method to nonsmooth systems with sliding components, which enables us to make predictions about the synchronization properties of weakly coupled stick-slip oscillators. We observe a new feature of the isochrons in a planar limit cycle with hard sliding boundaries: a nonsmooth kink in the asymptotic phase function, originating from the point at which the limit cycle smoothly departs the constraint surface, and propagating away from the hard boundary into the interior of the domain. Moreover, the classical variational analysis neglects timing information and is restricted to instantaneous perturbations. By defining the "infinitesimal shape response curve" (iSRC), we incorporate timing sensitivity of an oscillator to describe the shape response of this oscillator to parametric perturbations. In order to extract timing information, we also develop a "local timing response curve" (lTRC) that measures the timing sensitivity of a limit cycle within any given region. We demonstrate in a specific example that taking into account local timing sensitivity in a nonsmooth system greatly improves the accuracy of the iSRC over global timing analysis given by the iPRC.
Collapse
Affiliation(s)
- Yangyang Wang
- Department of Mathematics, The University of Iowa, Iowa City, IA 52242, USA
| | - Jeffrey P Gill
- Department of Biology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Hillel J Chiel
- Departments of Biology, Neurosciences and Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Peter J Thomas
- Departments of Biology, Mathematics, Applied Mathematics, and Statistics, Case Western Reserve University, Cleveland, OH 44106, USA
| |
Collapse
|
10
|
Webster-Wood VA, Gill JP, Thomas PJ, Chiel HJ. Control for multifunctionality: bioinspired control based on feeding in Aplysia californica. BIOLOGICAL CYBERNETICS 2020; 114:557-588. [PMID: 33301053 PMCID: PMC8543386 DOI: 10.1007/s00422-020-00851-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 11/20/2020] [Indexed: 06/12/2023]
Abstract
Animals exhibit remarkable feats of behavioral flexibility and multifunctional control that remain challenging for robotic systems. The neural and morphological basis of multifunctionality in animals can provide a source of bioinspiration for robotic controllers. However, many existing approaches to modeling biological neural networks rely on computationally expensive models and tend to focus solely on the nervous system, often neglecting the biomechanics of the periphery. As a consequence, while these models are excellent tools for neuroscience, they fail to predict functional behavior in real time, which is a critical capability for robotic control. To meet the need for real-time multifunctional control, we have developed a hybrid Boolean model framework capable of modeling neural bursting activity and simple biomechanics at speeds faster than real time. Using this approach, we present a multifunctional model of Aplysia californica feeding that qualitatively reproduces three key feeding behaviors (biting, swallowing, and rejection), demonstrates behavioral switching in response to external sensory cues, and incorporates both known neural connectivity and a simple bioinspired mechanical model of the feeding apparatus. We demonstrate that the model can be used for formulating testable hypotheses and discuss the implications of this approach for robotic control and neuroscience.
Collapse
Affiliation(s)
- Victoria A Webster-Wood
- Department of Mechanical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA, 15213, USA.
- Department of Biomedical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA, 15213, USA.
- McGowan Institute for Regenerative Medicine, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA, 15213, USA.
| | - Jeffrey P Gill
- Department of Biology, Case Western Reserve University, 2080 Adelbert Road, Cleveland, OH, 44106-7080, USA
| | - Peter J Thomas
- Department of Mathematics, Applied Mathematics and Statistics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106-4901, USA
- Department of Biology, Department of Cognitive Science, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106-4901, USA
- Department of Electrical Computer and Systems Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106-4901, USA
| | - Hillel J Chiel
- Department of Biology, Case Western Reserve University, 2080 Adelbert Road, Cleveland, OH, 44106-7080, USA
- Department of Neurosciences, Case Western Reserve University, 2080 Adelbert Road, Cleveland, OH, 44106-7080, USA
- Department of Biomedical Engineering, Case Western Reserve University, 2080 Adelbert Road, Cleveland, OH, 44106-7080, USA
| |
Collapse
|
11
|
Gill JP, Chiel HJ. Rapid Adaptation to Changing Mechanical Load by Ordered Recruitment of Identified Motor Neurons. eNeuro 2020; 7:ENEURO.0016-20.2020. [PMID: 32332081 PMCID: PMC7242813 DOI: 10.1523/eneuro.0016-20.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 02/28/2020] [Indexed: 02/07/2023] Open
Abstract
As they interact with their environment and encounter challenges, animals adjust their behavior on a moment-to-moment basis to maintain task fitness. This dynamic process of adaptive motor control occurs in the nervous system, but an understanding of the biomechanics of the body is essential to properly interpret the behavioral outcomes. To study how animals respond to changing task conditions, we used a model system in which the functional roles of identified neurons and the relevant biomechanics are well understood and can be studied in intact behaving animals: feeding in the marine mollusc Aplysia We monitored the motor neuronal output of the feeding circuitry as intact animals fed on uniform food stimuli under unloaded and loaded conditions, and we measured the force of retraction during loaded swallows. We observed a previously undescribed pattern of force generation, which can be explained within the appropriate biomechanical context by the activity of just a few key, identified motor neurons. We show that, when encountering load, animals recruit identified retractor muscle motor neurons for longer and at higher frequency to increase retraction force duration. Our results identify a mode by which animals robustly adjust behavior to their environment, which is experimentally tractable to further mechanistic investigation.
Collapse
Affiliation(s)
- Jeffrey P Gill
- Department of Biology, Case Western Reserve University, Cleveland, Ohio 44106-7080
| | - Hillel J Chiel
- Departments of Biology, Neurosciences, and Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106-7080
| |
Collapse
|
12
|
Kehl CE, Wu J, Lu S, Neustadter DM, Drushel RF, Smoldt RK, Chiel HJ. Soft-surface grasping: radular opening in Aplysia californica. J Exp Biol 2019; 222:jeb191254. [PMID: 31350299 PMCID: PMC6739808 DOI: 10.1242/jeb.191254] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 07/01/2019] [Indexed: 12/22/2022]
Abstract
Grasping soft, irregular material is challenging both for animals and robots. The feeding systems of many animals have adapted to this challenge. In particular, the feeding system of the marine mollusk Aplysia californica, a generalist herbivore, allows it to grasp and ingest seaweeds of varying shape, texture and toughness. On the surface of the grasper of A. californica is a structure known as the radula, a thin flexible cartilaginous sheet with fine teeth. Previous in vitro studies suggested that intrinsic muscles, I7, are responsible for opening the radula. Lesioning I7 in vivo does not prevent animals from grasping and ingesting food. New in vitro studies demonstrate that a set of fine muscle fibers on the ventral surface of the radula - the sub-radular fibers (SRFs) - mediate opening movements even if the I7 muscles are absent. Both in vitro and in vivo lesions demonstrate that removing the SRFs leads to profound deficits in radular opening, and significantly reduces feeding efficiency. A theoretical biomechanical analysis of the actions of the SRFs suggests that they induce the radular surface to open around a central crease in the radular surface and to arch the radular surface, allowing it to softly conform to irregular material. A three-dimensional model of the radular surface, based on in vivo observations and magnetic resonance imaging of intact animals, provides support for the biomechanical analysis. These results suggest how a soft grasper can work during feeding, and suggest novel designs for artificial soft graspers.
Collapse
Affiliation(s)
- Catherine E Kehl
- Department of Biology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Joey Wu
- Department of Biology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Sisi Lu
- Department of Biology, Case Western Reserve University, Cleveland, OH 44106, USA
| | | | - Richard F Drushel
- Department of Biology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Rebekah K Smoldt
- Department of Biology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Hillel J Chiel
- Department of Biology, Case Western Reserve University, Cleveland, OH 44106, USA
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH 44106, USA
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| |
Collapse
|
13
|
Dashevskiy T, Cymbalyuk G. Propensity for Bistability of Bursting and Silence in the Leech Heart Interneuron. Front Comput Neurosci 2018; 12:5. [PMID: 29467641 PMCID: PMC5808133 DOI: 10.3389/fncom.2018.00005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 01/12/2018] [Indexed: 12/15/2022] Open
Abstract
The coexistence of neuronal activity regimes has been reported under normal and pathological conditions. Such multistability could enhance the flexibility of the nervous system and has many implications for motor control, memory, and decision making. Multistability is commonly promoted by neuromodulation targeting specific membrane ionic currents. Here, we investigated how modulation of different ionic currents could affect the neuronal propensity for bistability. We considered a leech heart interneuron model. It exhibits bistability of bursting and silence in a narrow range of the leak current parameters, conductance (gleak) and reversal potential (Eleak). We assessed the propensity for bistability of the model by using bifurcation diagrams. On the diagram (gleak, Eleak), we mapped bursting and silent regimes. For the canonical value of Eleak we determined the range of gleak which supported the bistability. We use this range as an index of propensity for bistability. We investigated how this index was affected by alterations of ionic currents. We systematically changed their conductances, one at a time, and built corresponding bifurcation diagrams in parameter planes of the maximal conductance of a given current and the leak conductance. We found that conductance of only one current substantially affected the index of propensity; the increase of the maximal conductance of the hyperpolarization-activated cationic current increased the propensity index. The second conductance with the strongest effect was the conductance of the low-threshold fast Ca2+ current; its reduction increased the propensity index although the effect was about two times smaller in magnitude. Analyzing the model with both changes applied simultaneously, we found that the diagram (gleak, Eleak) showed a progressively expanded area of bistability of bursting and silence.
Collapse
Affiliation(s)
- Tatiana Dashevskiy
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States.,Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Gennady Cymbalyuk
- Neuroscience Institute, Georgia State University, Atlanta, GA, United States
| |
Collapse
|
14
|
Lyttle DN, Gill JP, Shaw KM, Thomas PJ, Chiel HJ. Robustness, flexibility, and sensitivity in a multifunctional motor control model. BIOLOGICAL CYBERNETICS 2017; 111:25-47. [PMID: 28004255 PMCID: PMC5326633 DOI: 10.1007/s00422-016-0704-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 10/07/2016] [Indexed: 05/25/2023]
Abstract
Motor systems must adapt to perturbations and changing conditions both within and outside the body. We refer to the ability of a system to maintain performance despite perturbations as "robustness," and the ability of a system to deploy alternative strategies that improve fitness as "flexibility." Different classes of pattern-generating circuits yield dynamics with differential sensitivities to perturbations and parameter variation. Depending on the task and the type of perturbation, high sensitivity can either facilitate or hinder robustness and flexibility. Here we explore the role of multiple coexisting oscillatory modes and sensory feedback in allowing multiphasic motor pattern generation to be both robust and flexible. As a concrete example, we focus on a nominal neuromechanical model of triphasic motor patterns in the feeding apparatus of the marine mollusk Aplysia californica. We find that the model can operate within two distinct oscillatory modes and that the system exhibits bistability between the two. In the "heteroclinic mode," higher sensitivity makes the system more robust to changing mechanical loads, but less robust to internal parameter variations. In the "limit cycle mode," lower sensitivity makes the system more robust to changes in internal parameter values, but less robust to changes in mechanical load. Finally, we show that overall performance on a variable feeding task is improved when the system can flexibly transition between oscillatory modes in response to the changing demands of the task. Thus, our results suggest that the interplay of sensory feedback and multiple oscillatory modes can allow motor systems to be both robust and flexible in a variable environment.
Collapse
Affiliation(s)
- David N Lyttle
- Department of Mathematics and Biology, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH, 44106, USA.
| | - Jeffrey P Gill
- Department of Biology, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH, 44106, USA
| | - Kendrick M Shaw
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Peter J Thomas
- Department of Mathematics, Applied Mathematics, and Statistics, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH, 44106, USA
| | - Hillel J Chiel
- Department of Biology, Neurosciences and Biomedical Engineering, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH, 44106, USA
| |
Collapse
|
15
|
Lyttle DN, Gill JP, Shaw KM, Thomas PJ, Chiel HJ. Neuromechanical bistability contributes to robust and flexible behavior in a model of motor pattern generation. BMC Neurosci 2015. [PMCID: PMC4697503 DOI: 10.1186/1471-2202-16-s1-p33] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
16
|
Cullins MJ, Shaw KM, Gill JP, Chiel HJ. Motor neuronal activity varies least among individuals when it matters most for behavior. J Neurophysiol 2014; 113:981-1000. [PMID: 25411463 DOI: 10.1152/jn.00729.2014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
How does motor neuronal variability affect behavior? To explore this question, we quantified activity of multiple individual identified motor neurons mediating biting and swallowing in intact, behaving Aplysia californica by recording from the protractor muscle and the three nerves containing the majority of motor neurons controlling the feeding musculature. We measured multiple motor components: duration of the activity of identified motor neurons as well as their relative timing. At the same time, we measured behavioral efficacy: amplitude of grasping movement during biting and amplitude of net inward food movement during swallowing. We observed that the total duration of the behaviors varied: Within animals, biting duration shortened from the first to the second and third bites; between animals, biting and swallowing durations varied. To study other sources of variation, motor components were divided by behavior duration (i.e., normalized). Even after normalization, distributions of motor component durations could distinguish animals as unique individuals. However, the degree to which a motor component varied among individuals depended on the role of that motor component in a behavior. Motor neuronal activity that was essential for the expression of biting or swallowing was similar among animals, whereas motor neuronal activity that was not essential for that behavior varied more from individual to individual. These results suggest that motor neuronal activity that matters most for the expression of a particular behavior may vary least from individual to individual. Shaping individual variability to ensure behavioral efficacy may be a general principle for the operation of motor systems.
Collapse
Affiliation(s)
- Miranda J Cullins
- Departments of Biology, Neurosciences, and Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio
| | - Kendrick M Shaw
- Departments of Biology, Neurosciences, and Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio
| | - Jeffrey P Gill
- Departments of Biology, Neurosciences, and Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio
| | - Hillel J Chiel
- Departments of Biology, Neurosciences, and Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio
| |
Collapse
|
17
|
The significance of dynamical architecture for adaptive responses to mechanical loads during rhythmic behavior. J Comput Neurosci 2014; 38:25-51. [PMID: 25182251 PMCID: PMC4544651 DOI: 10.1007/s10827-014-0519-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2013] [Revised: 06/25/2014] [Accepted: 07/22/2014] [Indexed: 11/21/2022]
Abstract
Many behaviors require reliably generating sequences of motor activity while adapting the activity to incoming sensory information. This process has often been conceptually explained as either fully dependent on sensory input (a chain reflex) or fully independent of sensory input (an idealized central pattern generator, or CPG), although the consensus of the field is that most neural pattern generators lie somewhere between these two extremes. Many mathematical models of neural pattern generators use limit cycles to generate the sequence of behaviors, but other models, such as a heteroclinic channel (an attracting chain of saddle points), have been suggested. To explore the range of intermediate behaviors between CPGs and chain reflexes, in this paper we describe a nominal model of swallowing in Aplysia californica. Depending upon the value of a single parameter, the model can transition from a generic limit cycle regime to a heteroclinic regime (where the trajectory slows as it passes near saddle points). We then study the behavior of the system in these two regimes and compare the behavior of the models with behavior recorded in the animal in vivo and in vitro. We show that while both pattern generators can generate similar behavior, the stable heteroclinic channel can better respond to changes in sensory input induced by load, and that the response matches the changes seen when a load is added in vivo. We then show that the underlying stable heteroclinic channel architecture exhibits dramatic slowing of activity when sensory and endogenous input is reduced, and show that similar slowing with removal of proprioception is seen in vitro. Finally, we show that the distributions of burst lengths seen in vivo are better matched by the distribution expected from a system operating in the heteroclinic regime than that expected from a generic limit cycle. These observations suggest that generic limit cycle models may fail to capture key aspects of Aplysia feeding behavior, and that alternative architectures such as heteroclinic channels may provide better descriptions.
Collapse
|
18
|
McManus JM, Lu H, Cullins MJ, Chiel HJ. Differential activation of an identified motor neuron and neuromodulation provide Aplysia's retractor muscle an additional function. J Neurophysiol 2014; 112:778-91. [PMID: 24805081 DOI: 10.1152/jn.00148.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
To survive, animals must use the same peripheral structures to perform a variety of tasks. How does a nervous system employ one muscle to perform multiple functions? We addressed this question through work on the I3 jaw muscle of the marine mollusk Aplysia californica's feeding system. This muscle mediates retraction of Aplysia's food grasper in multiple feeding responses and is innervated by a pool of identified neurons that activate different muscle regions. One I3 motor neuron, B38, is active in the protraction phase, rather than the retraction phase, suggesting the muscle has an additional function. We used intracellular, extracellular, and muscle force recordings in several in vitro preparations as well as recordings of nerve and muscle activity from intact, behaving animals to characterize B38's activation of the muscle and its activity in different behavior types. We show that B38 specifically activates the anterior region of I3 and is specifically recruited during one behavior, swallowing. The function of this protraction-phase jaw muscle contraction is to hold food; thus the I3 muscle has an additional function beyond mediating retraction. We additionally show that B38's typical activity during in vivo swallowing is insufficient to generate force in an unmodulated muscle and that intrinsic and extrinsic modulation shift the force-frequency relationship to allow contraction. Using methods that traverse levels from individual neuron to muscle to intact animal, we show how regional muscle activation, differential motor neuron recruitment, and neuromodulation are key components in Aplysia's generation of multifunctionality.
Collapse
Affiliation(s)
- Jeffrey M McManus
- Department of Biology, Case Western Reserve University, Cleveland, Ohio
| | - Hui Lu
- Department of Biology, Case Western Reserve University, Cleveland, Ohio
| | - Miranda J Cullins
- Department of Biology, Case Western Reserve University, Cleveland, Ohio
| | - Hillel J Chiel
- Department of Biology, Case Western Reserve University, Cleveland, Ohio; Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio; and Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio
| |
Collapse
|
19
|
Iyengar BG, Chou CJ, Vandamme KM, Klose MK, Zhao X, Akhtar-Danesh N, Campos AR, Atwood HL. Silencing synaptic communication between random interneurons duringDrosophilalarval locomotion. GENES BRAIN AND BEHAVIOR 2011; 10:883-900. [DOI: 10.1111/j.1601-183x.2011.00729.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
|
20
|
Abstract
Although it is widely recognized that adaptive behavior emerges from the ongoing interactions among the nervous system, the body, and the environment, it has only become possible in recent years to experimentally study and to simulate these interacting systems. We briefly review work on molluscan feeding, maintenance of postural control in cats and humans, simulations of locomotion in lamprey, insect, cat and salamander, and active vibrissal sensing in rats to illustrate the insights that can be derived from studies of neural control and sensing within a biomechanical context. These studies illustrate that control may be shared between the nervous system and the periphery, that neural activity organizes degrees of freedom into biomechanically meaningful subsets, that mechanics alone may play crucial roles in enforcing gait patterns, and that mechanics of sensors is crucial for their function.
Collapse
|
21
|
Abstract
The ability of distinct anatomical circuits to generate multiple behavioral patterns is widespread among vertebrate and invertebrate species. These multifunctional neuronal circuits are the result of multistable neural dynamics and modular organization. The evidence suggests multifunctional circuits can be classified by distinct architectures, yet the activity patterns of individual neurons involved in more than one behavior can vary dramatically. Several mechanisms, including sensory input, the parallel activity of projection neurons, neuromodulation, and biomechanics, are responsible for the switching between patterns. Recent advances in both analytical and experimental tools have aided the study of these complex circuits.
Collapse
Affiliation(s)
- K L Briggman
- Department of Biomedical Optics, Max Planck Institute for Medical Research, Heidelberg, 69120 Germany.
| | | |
Collapse
|
22
|
Neustadter DM, Herman RL, Drushel RF, Chestek DW, Chiel HJ. The kinematics of multifunctionality: comparisons of biting and swallowing in Aplysia californica. ACTA ACUST UNITED AC 2007; 210:238-60. [PMID: 17210961 DOI: 10.1242/jeb.02654] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
What are the mechanisms of multifunctionality, i.e. the use of the same peripheral structures for multiple behaviors? We studied this question using the multifunctional feeding apparatus of the marine mollusk Aplysia californica, in which the same muscles mediate biting (an attempt to grasp food) and swallowing (ingestion of food). Biting and swallowing responses were compared using magnetic resonance imaging of intact, behaving animals and a three-dimensional kinematic model. Biting is associated with larger amplitude protractions of the grasper (radula/odontophore) than swallowing, and smaller retractions. Larger biting protractions than in swallowing appear to be due to a more anterior position of the grasper as the behavior begins, a larger amplitude contraction of protractor muscle I2, and contraction of the posterior portion of the I1/I3/jaw complex. The posterior I1/I3/jaw complex may be context-dependent, i.e. its mechanical context changes the direction of the force it exerts. Thus, the posterior of I1/I3 may aid protraction near the peak of biting, whereas the entire I1/I3/jaw complex acts as a retractor during swallowing. In addition, larger amplitude closure of the grasper during swallowing allows an animal to exert more force as it ingests food. These results demonstrate that differential deployment of the periphery can mediate multifunctionality.
Collapse
Affiliation(s)
- David M Neustadter
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | | | | | | | | |
Collapse
|
23
|
Ye H, Morton DW, Chiel HJ. Neuromechanics of multifunctionality during rejection in Aplysia californica. J Neurosci 2006; 26:10743-55. [PMID: 17050713 PMCID: PMC6674742 DOI: 10.1523/jneurosci.3143-06.2006] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
How are the same muscles and neurons used to generate qualitatively different behaviors? We studied this question by analyzing the biomechanical and neural mechanisms of rejection responses in the marine mollusk Aplysia californica and compared these mechanisms with those used to generate swallowing responses (Ye et al., 2006). During rejection, the central grasper of the feeding structure closes to push inedible food out of the buccal cavity. This contrasts with swallowing, during which the grasper is open as it moves toward the jaws (protracts). We examined how the shape change of the grasper during rejection mechanically reconfigured the surrounding musculature. Grasper shape change increased the effectiveness of protractor muscle I2. The closed grasper alters the function of another muscle, the hinge, which becomes capable of inducing ventral rotations of rejected material. In contrast, during large-amplitude swallows, the hinge muscle mediates dorsal rotations of ingested material. Finally, after the grasper opens, its change in shape induces a delay in the activation of other surrounding muscles, the I1/I3/jaw complex, whose premature activation would close the halves of the grasper and induce it to pull inedible material back inward. The delay in activation of the I1/I3/jaw complex is partially attributable to identified multiaction neurons B4/B5. The results suggest that multifunctionality emerges from a periphery in which flexible coalitions of muscles may perform different functions in different mechanical contexts and in which neural circuitry is capable of reorganizing to exploit these coalitions by changes in phasing, duration, and intensity of motor neuronal activation.
Collapse
Affiliation(s)
- Hui Ye
- Departments of Biomedical Engineering
| | | | - Hillel J. Chiel
- Departments of Biomedical Engineering
- Neurosciences, and
- Biology, Case Western Reserve University, Cleveland, Ohio 44106-7080
| |
Collapse
|
24
|
Prinz AA. Insights from models of rhythmic motor systems. Curr Opin Neurobiol 2006; 16:615-20. [PMID: 17056249 DOI: 10.1016/j.conb.2006.10.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2006] [Accepted: 10/12/2006] [Indexed: 10/24/2022]
Abstract
Computational models of rhythmic motor systems are valuable tools for the study of motor pattern generation and control. Recent modeling advances, together with experimental results, suggest that rhythmic behaviors, such as breathing or walking, are influenced by complex interactions among motor system components. Such interactions occur at all levels of organization, from the subcellular through to the cellular, synaptic, and network levels to the level of neuromuscular interactions and that of the whole organism. Simultaneously, safety mechanisms at all levels contribute to network stability and the generation of robust motor patterns.
Collapse
Affiliation(s)
- Astrid A Prinz
- Emory University Department of Biology, Rollins Research Center, 1510 Clifton Road, Atlanta, GA 30322 USA.
| |
Collapse
|
25
|
Abstract
Bernstein (1967) hypothesized that preparation of the periphery was crucial for correct responses to motor output. To test this hypothesis in a behaving animal, we examined the roles of two identified motor neurons, B7 and B8, which contribute to feeding behavior in the marine mollusk Aplysia californica. Neuron B7 innervates a hinge muscle and has no overt behavioral effect during smaller-amplitude (type A) swallows, because the hinge muscle is too short to exert force. Neuron B8 activates a muscle (I4) that acts solely to grasp material during type A swallows. During larger-amplitude (type B) swallows, the behavioral actions of both motor neurons change, because the larger-amplitude anterior movement of the grasper sets up the periphery to respond differently to motor outputs. The larger anterior movement stretches the hinge muscle, so that activating neuron B7 mediates the initial retraction phase of swallowing. The changed position of the I4 muscle allows neuron B8 not only to induce grasping but also to pull material into the buccal cavity, contributing to retraction. Thus, larger-amplitude swallows are associated with the expression of two new degrees of freedom (use of the hinge to retract and use of the grasper to retract) that are essential for mediating type B swallows. These results provide a direct demonstration of Bernstein's hypothesis that properly positioning the periphery can be crucial for its ability to correctly respond to motor output and also demonstrate that biomechanical context can alter the functions of identified motor neurons.
Collapse
|
26
|
Novakovic VA, Sutton GP, Neustadter DM, Beer RD, Chiel HJ. Mechanical reconfiguration mediates swallowing and rejection in Aplysia californica. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2006; 192:857-70. [PMID: 16586084 DOI: 10.1007/s00359-006-0124-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2005] [Revised: 03/08/2006] [Accepted: 03/11/2006] [Indexed: 10/24/2022]
Abstract
Muscular hydrostats, such as tongues, trunks or tentacles, have fewer constraints on their degrees of freedom than musculoskeletal systems, so changes in a structure's shape may alter the positions and lengths of other components (i.e., induce mechanical reconfiguration). We studied mechanical reconfiguration during rejection and swallowing in the marine mollusk Aplysia californica. During rejection, inedible material is pushed out of an animal's buccal cavity. The grasper (radula/odontophore) closes on inedible material, and then a posterior muscle, I2, pushes the grasper toward the jaws (protracts it). After the material is released, an anterior muscle complex (the I1/I3/jaw complex) pushes the grasper toward the esophagus (retracts it). During swallowing, the grasper is protracted open, and then retracts closed, pulling in food. Grasper closure changes its shape. Magnetic resonance images show that grasper closure lengthens I2. A kinetic model quantified the changes in the ability of I2 and I1/I3 to exert force as grasper shape changed. Grasper closure increases I2's ability to protract during rejection, and increases I1/I3's ability to retract during swallowing. Motor neurons controlling radular closure may therefore affect the behavioral outputs of I2's and I1/I3's motor neurons. Thus, motor neurons may modulate the outputs of other motor neurons through mechanical reconfiguration.
Collapse
Affiliation(s)
- Valerie A Novakovic
- Department of Biology, Case Western Reserve University, 2080 Adelbert Road, Cleveland, OH 44106, USA
| | | | | | | | | |
Collapse
|