Neuronal control of turtle hindlimb motor rhythms

Stein, P. D.

doi:10.1007/s00359-004-0568-6

Cited by 100 publications

(124 citation statements)

References 80 publications

Supporting

Mentioning

117

Contrasting

Order By: Relevance

“…Since biting is an attempt to grasp food, the animal must be able to rapidly switch from biting to swallowing once it does grasp food. Similar flexibility is seen in multifunctional vertebrate systems, such as the turtle scratch system (Berkowitz 2010;Stein 2005).…”

Section: Variability Biomechanics and Behaviormentioning

confidence: 77%

Motor neuronal activity varies least among individuals when it matters most for behavior

Cullins

Shaw

Gill

et al. 2015

Journal of Neurophysiology

View full text Add to dashboard Cite

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.

show abstract

Section: Variability Biomechanics and Behaviormentioning

confidence: 77%

Motor neuronal activity varies least among individuals when it matters most for behavior

Cullins

Shaw

Gill

et al. 2015

Journal of Neurophysiology

View full text Add to dashboard Cite

show abstract

“…During fictive locomotion (e.g., Grillner and Zangger 1979;Jordan, 1991;Turkin and Hamm, 2004;Lafreniere-Roula and McCrea 2005) and treadmill locomotion (Duysens, 1977) in the cat and during the scratch reflex in the turtle (Stein 2005) and the cat (Lafreniere-Roula and McCrea 2005), rhythmic bursts of motoneuron activity can be absent (deleted) for a few cycles. During these deletions activity fails simultaneously in multiple synergist motoneuron pools and becomes tonic in multiple antagonists.…”

Section: Single Level Half-center Models Of the Cpgmentioning

confidence: 99%

“…Their ideas were further developed in a proposal for a CPG architecture in which separate "modules" or unit burst generators (UBG) controlled subsets of motoneurons (see Grillner 1981). However, despite the attractiveness of this proposal, the UBG model has not yet provided explicit solutions for the generation of complex motoneuron activity patterns.The existence of mixed-synergy motor patterns, e.g., the co-activation of some extensors with the ankle flexors during paw shake in the cat (Carter and Smith, 1986a,b;Koshland and Smith, 1989;Pearson and Rossignol, 1991), has also been raised as evidence against a simple halfcenter organization of the locomotor CPG (see Stein and Smith, 1997;Stein 2005). Paw shake is a specialized reflex in which cutaneous stimulation (e.g., water or tape on the paw or other parts of the limb) evokes a fast rhythm (the shake) in that limb.…”

mentioning

confidence: 99%

“…The existence of mixed-synergy motor patterns, e.g., the co-activation of some extensors with the ankle flexors during paw shake in the cat (Carter and Smith, 1986a,b;Koshland and Smith, 1989;Pearson and Rossignol, 1991), has also been raised as evidence against a simple halfcenter organization of the locomotor CPG (see Stein and Smith, 1997;Stein 2005). Paw shake is a specialized reflex in which cutaneous stimulation (e.g., water or tape on the paw or other parts of the limb) evokes a fast rhythm (the shake) in that limb.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Organization of mammalian locomotor rhythm and pattern generation

McCrea

Rybak

2008

Brain Research Reviews

603

506

View full text Add to dashboard Cite

Central pattern generators (CPGs) located in the spinal cord produce the coordinated activation of flexor and extensor motoneurons during locomotion. Previously proposed architectures for the spinal locomotor CPG have included the classical half-center oscillator and the unit burst generator (UBG) comprised of multiple coupled oscillators. We have recently proposed another organization in which a two-level CPG has a common rhythm generator (RG) that controls the operation of the pattern formation (PF) circuitry responsible for motoneuron activation. These architectures are discussed in relation to recent data obtained during fictive locomotion in the decerebrate cat. The data show that the CPG can maintain the period and phase of locomotor oscillations both during spontaneous deletions of motoneuron activity and during sensory stimulation affecting motoneuron activity throughout the limb. The proposed two-level CPG organization has been investigated with a computational model which incorporates interactions between the CPG, spinal circuits and afferent inputs. The model includes interacting populations of spinal interneurons and motoneurons modeled in the Hodgkin-Huxley style. Our simulations demonstrate that a relatively simple CPG with separate RG and PF networks can realistically reproduce many experimental phenomena including spontaneous deletions of motoneuron activity and a variety of effects of afferent stimulation. The model suggests plausible explanations for a number of features of real CPG operation that would be difficult to explain in the framework of the classical single-level CPG organization. Some modeling predictions and directions for further studies of locomotor CPG organization are discussed. KeywordsCPG; computational models; spinal cord; decerebrate; cat Half-center organization of the central pattern generatorMore than 90 years ago, T. Graham Brown (1911) demonstrated that the cat spinal cord can generate a locomotor rhythm in the absence of input from higher centers and afferent feedback. These and later investigations led to the widely accepted concept of central pattern generators Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access Author ManuscriptBrain Res Rev. Author manuscript; available in PMC 2009 January 1. Published in final edited form as:Brain Res Rev. 2008 January ; 57(1): 134-146. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript (CPGs) which reside within the central nervous systems of invertebrates and vertebrates and control various rhythmic movements. Graham Brown (1914) also proposed...

show abstract

“…In response to evidence that the central pattern generator (CPG) could produce a more complex motor output than just a mere flexor-extensor alternation (9), the unit burst generator (UBG) model was proposed (18). According to this theory, separate modules can generate a rhythm in close muscle synergies and are distributed around each joint (18,19), or in the swimming network in each hemisegment (20). The UBGs therefore generate a local rhythmic activity that during locomotion will be recruited so that they form an interconnected network of rhythm generators.…”

mentioning

confidence: 99%

Optogenetic dissection reveals multiple rhythmogenic modules underlying locomotion

Hägglund

Dougherty

Borgius

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

159

181

View full text Add to dashboard Cite

Neural networks in the spinal cord known as central pattern generators produce the sequential activation of muscles needed for locomotion. The overall locomotor network architectures in limbed vertebrates have been much debated, and no consensus exists as to how they are structured. Here, we use optogenetics to dissect the excitatory and inhibitory neuronal populations and probe the organization of the mammalian central pattern generator. We find that locomotor-like rhythmic bursting can be induced unilaterally or independently in flexor or extensor networks. Furthermore, we show that individual flexor motor neuron pools can be recruited into bursting without any activity in other nearby flexor motor neuron pools. Our experiments differentiate among several proposed models for rhythm generation in the vertebrates and show that the basic structure underlying the locomotor network has a distributed organization with many intrinsically rhythmogenic modules.channelrhodopsin-2 | halorhodopsin | motor neurons | interneurons S pinal cord networks that drive and coordinate walking are, to a large extent, innate. Even in species that do not walk at birth, such as rodents and humans, the networks that generate walking are already present (1, 2). The early development of functional locomotor networks has been exploited and studied in the neonatal rodent spinal cord in vitro preparation in which locomotor-like activity can be induced pharmacologically or by electrical activation of descending or afferent fibers (3-6). The mammalian locomotor networks have also been studied by using the adult cat where locomotor-like activity similarly can be induced pharmacologically or electrically (7-9). A general notion from these studies is that forelimb and hindlimb locomotion are controlled by independent limb-controlling circuits (10) and that rhythm-generating excitatory neurons, and pattern-generating neurons, interact to produce the coordinated motor output (11)(12)(13)(14). The network layout within these limb-controlling circuits has, however, been debated. A number of conceptual models have been advanced. The classical half-center model asserts that flexor and extensor bursting is generated by two reciprocally coupled half-centers driving all flexors and extensors (8, 15). The flexor burst generator model is asymmetric and consists of a flexor burst generator that provides active excitation of flexor motor neurons and inhibition of extensor motor neurons that are otherwise tonically active (14,16,17). In response to evidence that the central pattern generator (CPG) could produce a more complex motor output than just a mere flexor-extensor alternation (9), the unit burst generator (UBG) model was proposed (18). According to this theory, separate modules can generate a rhythm in close muscle synergies and are distributed around each joint (18,19), or in the swimming network in each hemisegment (20). The UBGs therefore generate a local rhythmic activity that during locomotion will be recruited so that they form an interconnected n...

show abstract

Neuronal control of turtle hindlimb motor rhythms

Cited by 100 publications

References 80 publications

Motor neuronal activity varies least among individuals when it matters most for behavior

Motor neuronal activity varies least among individuals when it matters most for behavior

Organization of mammalian locomotor rhythm and pattern generation

Optogenetic dissection reveals multiple rhythmogenic modules underlying locomotion

Contact Info

Product

Resources

About