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Vincent JA, Gabriel HM, Deardorff AS, Nardelli P, Fyffe REW, Burkholder T, Cope TC. Muscle proprioceptors in adult rat: mechanosensory signaling and synapse distribution in spinal cord. J Neurophysiol 2017; 118:2687-2701. [PMID: 28814636 PMCID: PMC5672542 DOI: 10.1152/jn.00497.2017] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 08/15/2017] [Accepted: 08/16/2017] [Indexed: 12/23/2022] Open
Abstract
The characteristic signaling and intraspinal projections of muscle proprioceptors best described in the cat are often generalized across mammalian species. However, species-dependent adaptations within this system seem necessary to accommodate asymmetric scaling of length, velocity, and force information required by the physics of movement. In the present study we report mechanosensory responses and intraspinal destinations of three classes of muscle proprioceptors. Proprioceptors from triceps surae muscles in adult female Wistar rats anesthetized with isoflurane were physiologically classified as muscle spindle group Ia or II or as tendon organ group Ib afferents, studied for their firing responses to passive-muscle stretch, and in some cases labeled and imaged for axon projections and varicosities in spinal segments. Afferent projections and the laminar distributions of provisional synapses in rats closely resembled those found in the cat. Afferent signaling of muscle kinematics was also similar to reports in the cat, but rat Ib afferents fired robustly during passive-muscle stretch and Ia afferents displayed an exaggerated dynamic response, even after locomotor scaling was accounted for. These differences in mechanosensory signaling by muscle proprioceptors may represent adaptations for movement control in different animal species.NEW & NOTEWORTHY Muscle sensory neurons signal information necessary for controlling limb movements. The information encoded and transmitted by muscle proprioceptors to networks in the spinal cord is known in detail only for the cat, but differences in size and behavior of other species challenge the presumed generalizability. This report presents the first findings detailing specializations in mechanosensory signaling and intraspinal targets for functionally identified subtypes of muscle proprioceptors in the rat.
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Affiliation(s)
- Jacob A Vincent
- Department of Neuroscience, Cell Biology, and Physiology, Wright State University, Dayton, Ohio
| | - Hanna M Gabriel
- Department of Neuroscience, Cell Biology, and Physiology, Wright State University, Dayton, Ohio
| | - Adam S Deardorff
- Department of Neuroscience, Cell Biology, and Physiology, Wright State University, Dayton, Ohio
| | - Paul Nardelli
- Department of Neuroscience, Cell Biology, and Physiology, Wright State University, Dayton, Ohio
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia; and
| | - Robert E W Fyffe
- Department of Neuroscience, Cell Biology, and Physiology, Wright State University, Dayton, Ohio
| | - Thomas Burkholder
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia; and
| | - Timothy C Cope
- Department of Neuroscience, Cell Biology, and Physiology, Wright State University, Dayton, Ohio;
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia; and
- School of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia
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Evolutionary psychologists need to distinguish between the evolutionary process, ancestral selection pressures, and psychological mechanisms. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025577] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Selfishness reexamined: No man is an island. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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How useful is a concept such as muscle partitioning? Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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The physiological basis and implications of differential motor activation. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Selfish genes and ingroup altruism. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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A Comparative approach to muscle function. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x0002505x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Abstract
AbstractSocial dilemmas occur when the pursuit of self-interest by individuals in a group leads to less than optimal collective outcomes for everyone in the group. A critical assumption in the human sciences is that people's choices in such dilemmas are individualistic, selfish, and rational. Hence, cooperation in the support of group welfare will only occur if there are selfish incentives that convert the social dilemma into a nondilemma. In recent years, inclusive fitness theories have lent weight to such traditional views of rational selfishness on Darwinian grounds. To show that cooperation is based on selfish incentives, however, one must provide evidence that people do not cooperate without such incentives. In a series of experimental social dilemmas, subjects were instructed to make single, anonymous choices about whether or not to contribute money for a shared “bonus” that would be provided only if enough other people in the group also contributed their money. Noncontributors cited selfish reasons for their choices; contributors did not. If people are allowed to engage in discussion, they will contribute resources at high rates, frequently on irrational grounds, to promote group welfare. These findings are consistent with previous research on ingroup biasing effects that cannot be explained by “economic man” or “selfish gene” theories. An alternative explanation is that sociality was a primary factor shaping the evolution of Homo sapiens. The cognitive and affective mechanisms underlying such choices evolved under selection pressures on small groups for developing and maintaining group membership and for predicting and controlling the behavior of other group members. This sociality hypothesis organizes previously inexplicable and disparate phenomena in a Darwinian framework and makes novel predictions about human choice.
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Continuous and discrete models and measures of speech events. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Partitioning hypothesis in perspective. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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A multiple source, or, is a striped apple more striped than a striped orange? Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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The use of mathematical models in perceptual theory. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Ecological and social factors in hominid evolution. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Central partitioning may be altered during high-frequency activation of the lamotoneuron connection. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Speech perception by ear, eye, hand, and mind. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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What is the organization, scope, and functional significance of partitioning? Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Abstract
AbstractStudies have shown that in the mammalian neuromuscular system stretch reflexes are localized within individual muscles. Neuromuscular compartmentalization, the partitioning of sensory output from muscles, and the partitioning of segmental pathways to motor nuclei have also been demonstrated. This evidence indicates that individual motor nuclei and the muscles they innervate are not homogeneous functional units. An analysis of the functional significance of reflex localization and partitioning suggests that segmental control mechanisms are based on subdivisions of motor nuclei–muscle complexes. A partitioned organization of segmental control mechanisms could utilize (1) the potential functional diversity of muscle fiber types, (2) the variety of mechanical actions of individual muscles arising from their distributed origins and insertions, and (3) diverse architectural features such as intramuscular variations in pinnation and complex in-series and in-parallel arrangements of muscle fibers. The differentiated activity observed in some muscles during natural movements also calls for localized segmental control mechanisms. Partitioning may also play a role in mechanical interactions between contracting motor units and in increasing the stability of neuromuscular systems. The functional advantages of reflex localization and partitioning suggest they are probably common features of segmental systems, whose organization reflects the structure and function of their associated neuromuscular systems.
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Do we need two souls to explain cooperation? Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Acoustic reflex partitioning in the stapedius. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Reflex partitioning and differential control of human motor units. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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On the regional distribution of muscle spindles. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x0002522x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Central versus peripheral aspects of neuromuscular regionalization. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Functional partitioning of motor unit populations. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Is sensory-motor partitioning a good hypothesis? Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Clumping and splitting in the neuromuscular system. Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00025085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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