scholarly journals Adaptation to slope in locomotor-trained spinal cats with intact and self-reinnervated lateral gastrocnemius and soleus muscles

2020 ◽  
Vol 123 (1) ◽  
pp. 70-89
Author(s):  
Dwight Higgin ◽  
Alexander Krupka ◽  
Omid Haji Maghsoudi ◽  
Alexander N. Klishko ◽  
T. Richard Nichols ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Flat Surface ◽  
Weight Bearing ◽  
Locomotor Training ◽  
Sensorimotor Training ◽  
Spinal Transection ◽  
Lateral Gastrocnemius ◽  
Locomotor Recovery ◽  
Flat Surfaces ◽  
Locomotor Patterns

Sensorimotor training providing motion-dependent somatosensory feedback to spinal locomotor networks restores treadmill weight-bearing stepping on flat surfaces in spinal cats. In this study, we examined if locomotor ability on flat surfaces transfers to sloped surfaces and the contribution of length-dependent sensory feedback from lateral gastrocnemius (LG) and soleus (Sol) to locomotor recovery after spinal transection and locomotor training. We compared kinematics and muscle activity at different slopes (±10° and ±25°) in spinalized cats ( n = 8) trained to walk on a flat treadmill. Half of those animals had their right hindlimb LG/Sol nerve cut and reattached before spinal transection and locomotor training, a procedure called muscle self-reinnervation that leads to elimination of autogenic monosynaptic length feedback in spinally intact animals. All spinal animals trained on a flat surface were able to walk on slopes with minimal differences in walking kinematics and muscle activity between animals with/without LG/Sol self-reinnervation. We found minimal changes in kinematics and muscle activity at lower slopes (±10°), indicating that walking patterns obtained on flat surfaces are robust enough to accommodate low slopes. Contrary to results in spinal intact animals, force responses to muscle stretch largely returned in both SELF-REINNERVATED muscles for the trained spinalized animals. Overall, our results indicate that the locomotor patterns acquired with training on a level surface transfer to walking on low slopes and that spinalization may allow the recovery of autogenic monosynaptic length feedback following muscle self-reinnervation. NEW & NOTEWORTHY Spinal locomotor networks locomotor trained on a flat surface can adapt the locomotor output to slope walking, up to ±25° of slope, even with total absence of supraspinal CONTROL. Autogenic length feedback (stretch reflex) shows signs of recovery in spinalized animals, contrary to results in spinally intact animals.

scholarly journals Plasticity of connections underlying locomotor recovery after central and/or peripheral lesions in the adult mammals

2006 ◽  
Vol 361 (1473) ◽  
pp. 1647-1671 ◽  
Author(s):  
Serge Rossignol
Keyword(s):  
Functional Recovery ◽  
Peripheral Nerves ◽  
Adult Animal ◽  
Spinal Injury ◽  
Locomotor Training ◽  
Locomotor Recovery ◽  
Reflex Pathways ◽  
Intrinsic Capacity ◽  
Plastic Changes ◽  
Locomotor Patterns

This review discusses some aspects of plasticity of connections after spinal injury in adult animal models as a basis for functional recovery of locomotion. After reviewing some pitfalls that must be avoided when claiming functional recovery and the importance of a conceptual framework for the control of locomotion, locomotor recovery after spinal lesions, mainly in cats, is summarized. It is concluded that recovery is partly due to plastic changes within the existing spinal locomotor networks. Locomotor training appears to change the excitability of simple reflex pathways as well as more complex circuitry. The spinal cord possesses an intrinsic capacity to adapt to lesions of central tracts or peripheral nerves but, as a rule, adaptation to lesions entails changes at both spinal and supraspinal levels. A brief summary of the spinal capacity of the rat, mouse and human to express spinal locomotor patterns is given, indicating that the concepts derived mainly from work in the cat extend to other adult mammals. It is hoped that some of the issues presented will help to evaluate how plasticity of existing connections may combine with and potentiate treatments designed to promote regeneration to optimize remaining motor functions.

Retention of Hindlimb Stepping Ability in Adult Spinal Cats After the Cessation of Step Training

1999 ◽  
Vol 81 (1) ◽  
pp. 85-94 ◽  
Author(s):  
R. D. De Leon ◽  
J. A. Hodgson ◽  
R. R. Roy ◽  
V. R. Edgerton
Keyword(s):  
Weight Bearing ◽  
Activity Patterns ◽  
Motor Task ◽  
Full Weight Bearing ◽  
Electromyographic Activity ◽  
Locomotor Training ◽  
Neural Pathways ◽  
Step Cycle ◽  
Rapid Learning ◽  
Hindlimb Muscle

de Leon, R. D., J. A. Hodgson, R. R. Roy, and V. R. Edgerton. Retention of hindlimb stepping ability in adult spinal cats after the cessation of step training. J. Neurophysiol. 81: 85–94, 1999. Adult spinal cats were trained to perform bipedal hindlimb locomotion on a treadmill for 6–12 wk. After each animal acquired the ability to step, locomotor training was withheld, and stepping was reexamined 6 and 12 wk after training ended. The performance characteristics, hindlimb muscle electromyographic activity patterns, and kinematic characteristics of the step cycle that were acquired with training were largely maintained when training was withheld for 6 wk. However, after 12 wk without training, locomotor performance declined, i.e., stumbling was more frequent, and the ability to consistently execute full weight-bearing steps at any treadmill speed decreased. In addition, the height that the paw was lifted during the swing phase decreased, and a smaller range of extension in the hindlimbs occurred during the E3 phase of stance. When three of the spinal cats underwent 1 wk of retraining, stepping ability was regained more rapidly than when trained initially. The finding that stepping ability in trained adult spinal cats can persist for 6 wk without training provides further evidence that training-induced enhancement of stepping is learned in the spinal cats and that a memory of the enhanced stepping is stored in the spinal networks. However, it appears that the spinal cord can forget how to consistently execute stepping if that task is not practiced for 12 wk. The more rapid learning that occurred with retraining is also consistent with a learning phenomenon. These results in conjunction with our earlier findings suggest that the efficacy of the neural pathways that execute a motor task is highly dependent on the periodic activation of those pathways in a sequence compatible with that motor task.

Small theropod and bird teeth from the late Cretaceous (late Campanian) Judith River Group, Alberta

2002 ◽  
Vol 76 (4) ◽  
pp. 751-763 ◽  
Author(s):  
Julia T. Sankey ◽  
Donald B. Brinkman ◽  
Merrilee Guenther ◽  
Philip J. Currie
Keyword(s):  
Late Cretaceous ◽  
Flat Surface ◽  
Flat Surfaces ◽  
Wear Pattern ◽  
A Share

A collection of over 1,700 small theropod teeth from the Judith River Group (Campanian;˜79.5–74 Ma) allows our understanding of the diversity and variation of small theropods in this assemblage to be refined. In addition to the previously recognized taxa, a series of morphologically distinct groups are recognized that may represent distinct taxa in some cases. Teeth with the Paronychodon-like features of a flat surface with longitudinal ridges on one side are resolved into a few discrete morphotypes. Two of these are included in Paronychodon lacustris and two additional morphotypes are hypothesized to represent distinct taxa, here referred to as ?Dromaeosaurus morphotype A and Genus and species indet. A. The teeth of Paronychodon lacustris and ?Dromaeosaurus morphotype A share a distinctive wear pattern that suggests tooth functioning involved contact between the flat surfaces of opposing teeth. Two species of Richardoestesia, R. gilmorei and R. isosceles, are present in the assemblage. Additionally, bird teeth are identified in the assemblage and are described in this review.Bivariate plots were used to document the variation in the theropod teeth, especially in the features that distinguish between Richardoestesia gilmorei, R. isosceles, Saurornitholestes, and Dromaeosaurus. Considerable overlap is present in all plots, so although the teeth are morphologically distinct, they are not easily distinguished by quantitative means.

scholarly journals Designing bioinspired surfaces for water collection from fog

2018 ◽  
Vol 377 (2138) ◽  
pp. 20180269 ◽  
Author(s):  
Dev Gurera ◽  
Bharat Bhushan
Keyword(s):  
Flat Surface ◽  
Unit Area ◽  
Water Repellency ◽  
Vertical Axis ◽  
Collection Rate ◽  
Flat Surfaces ◽  
Single Cone ◽  
Water Collection ◽  
The Difference ◽  
Conical Surfaces

A systematic study is presented on various water collectors, bioinspired by desert beetles, desert grass and cacti. Three water collecting mechanisms including heterogeneous wettability, grooved surfaces, and Laplace pressure gradient, were investigated on flat, cylindrical, conical surfaces, and conical array. It is found that higher water repellency in flat surfaces results in higher water collection rate and inclination angle (with respect to the vertical axis) has little effect. Surfaces with heterogeneous wettability have higher water collection rate than surfaces with homogeneous wettability. Both cylindrical and conical surfaces resulted in comparable water collection rate. However, only the cone transported the water droplets to its base. Heterogeneity, higher inclination and grooves increased the water collection rate. A cone has a higher collection rate per unit area than a flat surface with the same wettability. An array of cones has higher collection rate per unit area than a single cone, because droplets in a conical array coalesce, leading to higher frequency of droplets falling. Adding heterogeneity further increases the difference. Based on the findings, scaled-up designs of beetle-, grass- and cactus-inspired surfaces and nets are presented. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology’.

scholarly journals Laser-written colours on silver: optical effect of alumina coating

Nanophotonics ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 807-822 ◽  
Author(s):  
Jean-Michel Guay ◽  
Antonino Calà Lesina ◽  
Graham Killaire ◽  
Peter G. Gordon ◽  
Choloong Hahn ◽  
...  
Keyword(s):  
Time Domain ◽  
Finite Difference Time Domain ◽  
Flat Surface ◽  
Atomic Layer ◽  
Alumina Coating ◽  
Optical Effect ◽  
Alumina Film ◽  
Flat Surfaces ◽  
Layer Deposition ◽  
Difference Time

AbstractIn this paper we discuss the optical response of laser-written plasmonic colours on silver coated via the atomic layer deposition of alumina. These colours are due to nanoparticles distributed on a flat surface and on a surface with periodic topographical features (i.e. ripples). The colours are observed to shift with increasing alumina film thickness. The colours produced by surfaces with ripples recover their original vibrancy and hue after the deposition of film of thickness ~60 nm, while colours arising from flat surfaces gradually fade and never recover. Analysis of the surfaces identifies periodic topographical features to be responsible for this behaviour. Finite-difference time-domain simulations unravel the role played by the alumina thickness in colour formation and confirm the rotations and recovery of colours for increasing alumina thickness. The coloured surfaces were evaluated for applications in colourimetric and radiometric sensing showing large sensitivities of up to 3.06/nm and 3.19 nm/nm, respectively. The colourimetric and radiometric sensitivities are observed to be colour dependent.

Treadmill training promotes spinal changes leading to locomotor recovery after partial spinal cord injury in cats

2013 ◽  
Vol 109 (12) ◽  
pp. 2909-2922 ◽  
Author(s):  
Marina Martinez ◽  
Hugo Delivet-Mongrain ◽  
Serge Rossignol
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Treadmill Training ◽  
Locomotor Training ◽  
Locomotor Recovery ◽  
Thoracic Level ◽  
Spinal Circuitry ◽  
Cord Injury ◽  
Locomotor Deficits ◽  
Spinal Hemisection

After a spinal hemisection at thoracic level in cats, the paretic hindlimb progressively recovers locomotion without treadmill training but asymmetries between hindlimbs persist for several weeks and can be seen even after a further complete spinal transection at T13. To promote optimal locomotor recovery after hemisection, such asymmetrical changes need to be corrected. In the present study we determined if the locomotor deficits induced by a spinal hemisection can be corrected by locomotor training and, if so, whether the spinal stepping after the complete spinal cord transection is also more symmetrical. This would indicate that locomotor training in the hemisected period induces efficient changes in the spinal cord itself. Sixteen adult cats were first submitted to a spinal hemisection at T10. One group received 3 wk of treadmill training, whereas the second group did not. Detailed kinematic and electromyographic analyses showed that a 3-wk period of locomotor training was sufficient to improve the quality and symmetry of walking of the hindlimbs. Moreover, after the complete spinal lesion was performed, all the trained cats reexpressed bilateral and symmetrical hindlimb locomotion within 24 h. By contrast, the locomotor pattern of the untrained cats remained asymmetrical, and the hindlimb on the side of the hemisection was still deficient. This study highlights the beneficial role of locomotor training in facilitating bilateral and symmetrical functional plastic changes within the spinal circuitry and in promoting locomotor recovery after an incomplete spinal cord injury.

Tonic-to-phasic shift of lumbo-pelvic muscle activity during 8 weeks of bed rest and 6-months follow up

2007 ◽  
Vol 103 (1) ◽  
pp. 48-54 ◽  
Author(s):  
Daniel L. Belavý ◽  
Carolyn A. Richardson ◽  
Stephen J. Wilson ◽  
Dieter Felsenberg ◽  
Jörn Rittweger
Keyword(s):  
Motor Control ◽  
Skill Acquisition ◽  
Muscle Activity ◽  
Muscle Activation ◽  
Weight Bearing ◽  
Young Male ◽  
Bed Rest ◽  
Movement Model ◽  
Musculoskeletal Function

Prior motor control studies in unloading have shown a tonic-to-phasic shift in muscle activation, particularly in the short extensors. Tonic muscle activity is considered critical for normal musculoskeletal function. The shift from tonic-to-phasic muscle activity has not been systematically studied in humans in unloading nor at the lumbo-pelvic (LP) region. Ten healthy young male subjects underwent 8 wk of bed rest with 6-mo follow up as part of the “Berlin Bed-Rest Study.” A repetitive knee movement model performed in the prone position is used to stimulate tonic holding LP muscle activity, as measured by superficial EMG. Tonic and phasic activation patterns were quantified by relative height of burst vs. baseline electromyographic linear-envelope signal components. Statistical analysis shows a shift toward greater phasic activity during bed rest and follow up ( P < 0.001) with a significant interaction across muscles ( P < 0.001) specifically affecting the short lumbar extensors. These changes appear unrelated to skill acquisition over time ( P all ≥0.196). This change of a shift from tonic LP muscle activation to phasic is in line with prior research on the effects of reduced weight bearing on motor control.

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