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Journal articles on the topic 'Locomotion'
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1
Friedl, P., P. B. Noble, and K. S. Zänker. "T lymphocyte locomotion in a three-dimensional collagen matrix. Expression and function of cell adhesion molecules." Journal of Immunology 154, no. 10 (May 15, 1995): 4973–85. http://dx.doi.org/10.4049/jimmunol.154.10.4973.
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Abstract T cell locomotion within the extracellular matrix may be mediated by cell adhesion molecules. We investigated the expression and function of beta 1- and beta 2-integrins and CD44 on human peripheral CD4+ and CD8+ lymphocytes locomoting in a 3-D type I collagen matrix. Paths of randomly selected T cells were digitized from time-lapse videorecordings and were quantitatively analyzed. After the blocking of CD49b with mAb Gi9, the locomotion of a defined locomotor subset (50% of spontaneously locomoting cells) was inhibited. Anti-CD49d mAb HP2/1 and an activating anti-CD44 mAb (J173), respectively, induced transient recruitment (< 1 h) of previously nonmotile cells (10 to 35%). In contrast to the J173-induced short-term locomotion, hyaluronan incorporated within the matrix promoted locomotion for > 2 h. No significant effects were present for anti-CD49f (GoH3) and -CD11a (25.3) mAbs. After the addition of IL-8 to the matrix, rapid induction of locomotion in 20 to 30% of the cells (control) was evident, which was virtually abolished by anti-alpha 2- and alpha 6-integrin, and -CD11a mAbs. Thus, the locomotion of nonactivated and IL-8-activated T cells may involve different sets of integrins. Using flow cytometry, the development of a CD49b+CD29highCD44lowL-selectinlow T cell phenotype independent of activation markers including CD25, CD27, CD28, VLA-4, and CD45RA- to CD45RO-transition was observed after 4 days in the matrix. The initial development of spontaneous locomotion in the collagen matrix, however, was not accompanied by alterations in CAM surface staining and, therefore, may involve functional CAM activation rather than involving an increase in surface expression.
2
Brudzynski, Stefan M., Michael Wu, and Gordon J. Mogenson. "Decreases in rat locomotor activity as a result of changes in synaptic transmission to neurons within the mesencephalic locomotor region." Canadian Journal of Physiology and Pharmacology 71, no. 5-6 (May 1, 1993): 394–406. http://dx.doi.org/10.1139/y93-060.
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The mesencephalic locomotor region is defined as a functional region sending signals to the spinal cord generators of rhythmical limb movements for locomotion. It has been shown that the mesencephalic locomotor region plays a critical role in locomotion initiated from the nucleus accumbens or from the subpallidal region. However, there are conflicting data on whether synaptic input from the nucleus accumbens – subpallidal region to the mesencephalic locomotor region mediates locomotion. The purpose of the study was to determine the role of synaptic input to different subregions of the mesencephalic locomotor region in locomotion induced by injecting dopamine into the nucleus accumbens or by injecting picrotoxin into the subpallidal region in freely behaving rats. Synaptic transmission in the mesencephalic locomotor region was eliminated by excitotoxic lesions or was reversibly interrupted by injecting cobalt chloride, which can block synaptic transmission. Excitotoxic lesions or injections of cobalt into subregions of the mesencephalic locomotor region significantly decreased, although did not completely block, locomotion. The most effective sites for cobalt- and lesion-induced reduction in locomotion were consistent with localization of the mesencephalic locomotor region. Effective sites for cobalt and lesions markedly overlapped but were not identical. The results indicate that synaptic transmission within the mesencephalic locomotor region contributes to dopamine- or picrotoxin-induced locomotion.Key words: locomotion, mesencephalic locomotor region, nucleus accumbens, ventral pallidum, dopamine, picrotoxin, excitotoxins, cobalt chloride.
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Dai, X., B. R. Noga, J. R. Douglas, and L. M. Jordan. "Localization of Spinal Neurons Activated During Locomotion Using the c-fos Immunohistochemical Method." Journal of Neurophysiology 93, no. 6 (June 2005): 3442–52. http://dx.doi.org/10.1152/jn.00578.2004.
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The c-fos immunohistochemical method of activity-dependent labeling was used to localize locomotor-activated neurons in the adult cat spinal cord. In decerebrate cats, treadmill locomotion was evoked by electrical stimulation of the mesencephalic locomotor region (MLR). Spontaneous or MLR-evoked fictive locomotion was produced in decerebrate animals paralyzed with a neuromuscular blocking agent. After bouts of locomotion during a 7- to 9-h time period, the animals were perfused and the L3–S1 spinal cord segments removed for immunohistochemistry. Control animals were subjected to the same surgical procedures but no locomotor task. Labeled cells were concentrated in Rexed's laminae III and IV of the dorsal horn and laminae VII, VIII, and X of the intermediate zone/ventral horn after treadmill locomotion. Cells in laminae VII, VIII, and X were labeled after fictive locomotion, but labeling in the dorsal horn was much reduced. In control animals, c- fos labeling was a small fraction of that observed in the locomotor animals. The results suggest that labeled cells in laminae VII, VIII, and X are premotor interneurons involved in the production of locomotion, whereas the laminae III and IV cells are those activated during locomotion due to afferent feedback from the moving limb. c-fos-labeled cells were most numerous in the L5–L7 segments, consistent with the distribution of locomotor activated neurons detected through the use of MLR-evoked field potentials.
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Romaniuk, Jarosław, Stefan Kasicki, Oleg Kazennikov, and Viktor Selionov. "Respiratory responses to stimulation of spinal or medullary locomotor structures in decerebrate cats." Acta Neurobiologiae Experimentalis 54, no. 1 (March 31, 1994): 11–17. http://dx.doi.org/10.55782/ane-1994-997.
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Respiratory and locomotor EMG activity was recorded in cats after a precollicular post-mamillary decerebration. Locomotion was induced by stimulating either the dorsolateral funiculus (DLF) in the cervical spinal cord or the medullary locomotor strip (MLS). At the onset of locomotion, both ventilation and blood pressure were enhanced. During locomotion, the activity of external intercostal muscles decreased but that of the internal intercostal muscles increased. The respiratory pattern changed with the onset of stimulation. The locomotor movements were evoked after a delay. The inspiratory-inhibitory Hering-Breuer reflex was attenuated. Stimulation of the MLS and DLF evoked similar respiratory and circulatory effects. Our data resemble the effects observed during stimulation of the subthalamic or mesencephalic locomotor regions. We conclude that respiratory changes are part of an integrated response involved in the onset of exercise and are independent of the neuronal site where stimulation evoked locomotion. In contrast to previous reports, we suggest that the pattern of interaction among respiratory, circulatory, and locomotor systems does not have to be the specialty of supramedullary structures. Coupling between locomotion and breathing during the post-inspiratory phase suggests that this interaction occurs at the medullary level.
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Rossignol, S., E. Brustein, L. Bouyer, D. Barthélemy, C. Langlet, and H. Leblond. "Adaptive changes of locomotion after central and peripheral lesions." Canadian Journal of Physiology and Pharmacology 82, no. 8-9 (July 1, 2004): 617–27. http://dx.doi.org/10.1139/y04-068.
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This paper reviews findings on the adaptive changes of locomotion in cats after spinal cord or peripheral nerve lesions. From the results obtained after lesions of the ventral/ventrolateral pathways or the dorsal/dorsolateral pathways, we conclude that with extensive but partial spinal lesions, cats can regain voluntary quadrupedal locomotion on a treadmill. Although tract-specific deficits remain after such lesions, intact descending tracts can compensate for the lesioned tracts and access the spinal network to generate voluntary locomotion. Such neuroplasticity of locomotor control mechanisms is also demonstrated after peripheral nerve lesions in cats with intact or lesioned spinal cords. Some models have shown that recovery from such peripheral nerve lesions probably involves changes at the supra spinal and spinal levels. In the case of somesthesic denervation of the hindpaws, we demonstrated that cats with a complete spinal section need some cutaneous inputs to walk with a plantigrade locomotion, and that even in this spinal state, cats can adapt their locomotion to partial cutaneous denervation. Altogether, these results suggest that there is significant plasticity in spinal and supraspinal locomotor controls to justify the beneficial effects of early proactive and sustained locomotor training after central (Rossignol and Barbeau 1995; Barbeau et al. 1998) or peripheral lesions.Key words: spinal lesions, nerve lesions, locomotion, neuroplisticity, locomotor training.
6
Oldenborg, Per-Arne, and Janove Sehlin. "The Glucose Concentration Modulates N-Formyl-Methionyl-Leucyl-Phenylalanine (fMet-Leu-Phe)-Stimulated Chemokinesis in Normal Human Neutrophils." Bioscience Reports 19, no. 6 (December 1, 1999): 511–23. http://dx.doi.org/10.1023/a:1020286010551.
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The effects of glucose concentration on the chemokinetic effects of the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fMet-Leu-Phe) was evaluated for normal human neutrophils using a direct microscopic assay. fMet-Leu-Phe increased the rate of locomotion in the absence of glucose, but the chemokinetic effect of fMet-Leu-Phe was most potent at 5mM glucose and not further changed at 15 mM glucose. The chemokinetic effects of fMet-Leu-Phe and glucose were essentially the same in blood clot-isolated and gradient-isolated neutrophils. However, in gradient-isolated neutrophils, the rate of locomotion under different experimental conditions was strictly negatively correlated to the fraction of non-locomoting cells and the degree of adhesion to the substratum. These results indicate that the chemokinetic effects of fMet-Leu-Phe are regulated by the glucose concentration by inducing locomotor activity in otherwise non-locomoting cells and by improving adhesion to the substratum.
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Langlet, C., H. Leblond, and S. Rossignol. "Mid-Lumbar Segments Are Needed for the Expression of Locomotion in Chronic Spinal Cats." Journal of Neurophysiology 93, no. 5 (May 2005): 2474–88. http://dx.doi.org/10.1152/jn.00909.2004.
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In acute experiments performed in decerebrated and spinalized (T13) cats, an intraspinal injection of clonidine, a noradrenergic agonist, restricted to mid-lumbar segments L3–L4, can induce hindlimb locomotion, whereas yohimbine, a noradrenergic antagonist, can block spinal locomotion, and a second spinal lesion at L4 can abolish all locomotor activity. In the present study, we investigated whether the abolition of locomotion after this second spinal lesion was due to an acute spinal shock or to the functional disconnection of the rostral and caudal lumbar segments. In seven cats, first spinalized at T13 and having recovered treadmill locomotion, a second transection was performed at lower lumbar levels. Video and electromyographic recordings were used to evaluate locomotor performance. Results show that after a second transection at L2 or rostral L3 levels, spinal locomotion was maintained; when the second lesion was performed at caudal L3 or L4, all locomotor activity was abolished even after several weeks of attempted locomotor training; vigorous fast paw shakes (FPS) were observed in all cases; and after an intraperitoneal injection of clonidine in cats with a second transection below L4, perineal stimulation induced hyperextension of the hindlimbs but no locomotion. Considering that the main motoneuron pools of the hindlimbs are caudal to L4 and are still functional after the second spinal transection, as evidenced by the presence of FPS, we conclude that the mid-lumbar spinal segments are essential for the specific expression of spinal locomotion but not necessarily for other rhythmic motor patterns.
8
Yokoyama, Hikaru, Tetsuya Ogawa, Masahiro Shinya, Noritaka Kawashima, and Kimitaka Nakazawa. "Speed dependency in α-motoneuron activity and locomotor modules in human locomotion: indirect evidence for phylogenetically conserved spinal circuits." Proceedings of the Royal Society B: Biological Sciences 284, no. 1851 (March 29, 2017): 20170290. http://dx.doi.org/10.1098/rspb.2017.0290.
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Coordinated locomotor muscle activity is generated by the spinal central pattern generators (CPGs). Vertebrate studies have demonstrated the following two characteristics of the speed control mechanisms of the spinal CPGs: (i) rostral segment activation is indispensable for achieving high-speed locomotion; and (ii) specific combinations between spinal interneuronal modules and motoneuron (MN) pools are sequentially activated with increasing speed. Here, to investigate whether similar control mechanisms exist in humans, we examined spinal neural activity during varied-speed locomotion by mapping the distribution of MN activity in the spinal cord and extracting locomotor modules, which generate basic MN activation patterns. The MN activation patterns and the locomotor modules were analysed from multi-muscle electromyographic recordings. The reconstructed MN activity patterns were divided into the following three patterns depending on the speed of locomotion: slow walking, fast walking and running. During these three activation patterns, the proportion of the activity in rostral segments to that in caudal segments increased as locomotion speed increased. Additionally, the different MN activation patterns were generated by distinct combinations of locomotor modules. These results are consistent with the speed control mechanisms observed in vertebrates, suggesting phylogenetically conserved spinal mechanisms of neural control of locomotion.
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Domenici, P., D. González-Calderón, and R. S. Ferrari. "Locomotor performance in the sea urchin Paracentrotus lividus." Journal of the Marine Biological Association of the United Kingdom 83, no. 2 (March 20, 2003): 285–92. http://dx.doi.org/10.1017/s0025315403007094h.
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The locomotor performance of the Mediterranean sea urchin Paracentrotus lividus was investigated under laboratory conditions. Individuals were placed singly in the centre of a glass surface positioned either horizontally or vertically in tanks with seawater, and their locomotor activity was recorded. For locomotion on a horizontal surface, speed increased with both sea urchin diameter and their straightness of path. Speeds on a vertical surface were size-independent and not related to the straightness of path, although they were affected by vertical path orientation, with the highest speeds occurring for downward movements and the slowest speeds for the upward movements. Taken together, these results suggest that the scaling of sea urchin locomotion may follow similar laws to those of legged animals, for which locomotor performance increases with size on horizontal surface, while their relative cost of locomotion increases with body size on inclined surfaces. It is suggested that differences in horizontal vs vertical locomotion may also be related to differences in the underlying locomotor mechanisms, i.e. using adhesive appendices (tube feet) or levers (spines). In a second experiment, the sea urchin speed obtained during a negative phototactic response to a direct light stimulus was recorded. The results show that speed during light stimulation is higher than that during spontaneous locomotion in sea urchins of intermediate size (2·5–4 cm), suggesting that, in addition to the direction of locomotion as shown by previous studies, light can also have an effect on speed.
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Barthélemy, D., H. Leblond, and S. Rossignol. "Characteristics and Mechanisms of Locomotion Induced by Intraspinal Microstimulation and Dorsal Root Stimulation in Spinal Cats." Journal of Neurophysiology 97, no. 3 (March 2007): 1986–2000. http://dx.doi.org/10.1152/jn.00818.2006.
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Intraspinal microstimulation (ISMS) through a single microelectrode can induce locomotion in cats spinalized at T13 1 wk before (untrained) or after 3–5 wk of treadmill training. Here we study the optimal parameters of ISMS and the characteristics of locomotion evoked. ISMS was applied in the dorsal region of segments L3–S1 at different lateralities (midline to 2.5 mm) and after an intravenous injection of clonidine (noradrenergic agonist). Kinematics and electromyographic recordings were used to characterize locomotion. ISMS could induce a bilateral locomotor pattern similar to that obtained with perineal stimulation, and the characteristics of locomotion varied according to the spinal segment stimulated. Mechanisms by which ISMS could evoke locomotion were then investigated by stimulating, inactivating, or lesioning different spinal structures. Dorsal root stimulation (DRS), just like ISMS, could evoke a variety of ipsi- and bilateral nonlocomotor movements as well as locomotor responses. This suggests that sensory afferent pathways are involved in the production of locomotion by ISMS. Microinjections of yohimbine (noradrenergic antagonist) in L3 and L4 segments or a complete second spinal lesion at L3–L4 abolished all locomotor activity evoked by ISMS applied at more caudal segments. Progressive dorsoventral spinal lesions at L3 or L4 and restricted ventral lesions at L4 further suggest that the integrity of the ventral or ventrolateral funiculi as well as the L3–L4 segments are critical for the induction of locomotion by ISMS at L5 to S1 or by DRS at these caudal segments.
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Liu, Jun, and Larry M. Jordan. "Stimulation of the Parapyramidal Region of the Neonatal Rat Brain Stem Produces Locomotor-Like Activity Involving Spinal 5-HT7 and 5-HT2A Receptors." Journal of Neurophysiology 94, no. 2 (August 2005): 1392–404. http://dx.doi.org/10.1152/jn.00136.2005.
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Locomotion can be induced in rodents by direct application 5-hydroxytryptamine (5-HT) onto the spinal cord. Previous studies suggest important roles for 5-HT7 and 5-HT2A receptors in the locomotor effects of 5-HT. Here we show for the first time that activation of a discrete population of 5-HT neurons in the rodent brain stem produces locomotion and that the evoked locomotion requires 5-HT7 and 5-HT2A receptors. Cells localized in the parapyramidal region (PPR) of the mid-medulla produced locomotor-like activity as a result of either electrical or chemical stimulation, and PPR-evoked locomotor-like activity was blocked by antagonists to 5-HT2A and 5-HT7 receptors located on separate populations of neurons concentrated in different rostro-caudal regions. 5-HT7 receptor antagonists blocked locomotor-like activity when applied above the L3 segment; 5-HT2A receptor antagonists blocked locomotor-like activity only when applied below the L2 segment. 5-HT7 receptor antagonists decreased step cycle duration, consistent with an action on neurons involved in the rhythm-generating function of the central pattern generator (CPG) for locomotion. 5-HT2A antagonists reduced the amplitude of ventral root activity with only small effects on step cycle duration, suggesting an action directly on cells involved in the output stage of the pattern generator for locomotion, including motoneurons and premotor cells. Experiments with selective antagonists show that dopaminergic (D1, D2) and noradrenergic (α1, α2) receptors are not critical for PPR-evoked locomotor-like activity.
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Farrell, Jordan S., Matthew Lovett-Barron, Peter M. Klein, Fraser T. Sparks, Tilo Gschwind, Anna L. Ortiz, Biafra Ahanonu, et al. "Supramammillary regulation of locomotion and hippocampal activity." Science 374, no. 6574 (December 17, 2021): 1492–96. http://dx.doi.org/10.1126/science.abh4272.
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Locomotion-related signals in the brain To calculate where we are in space, continuous knowledge of one’ s speed is necessary. How does the brain know how fast the body is traveling during locomotion? Using in vivo calcium imaging, electrophysiology, optogenetics, cell tracing, and histology, Farrell et al . identified neurons in the rodent supramammillary nucleus of the hypothalamus that encode future locomotor speed and potently drive locomotion when stimulated. Because these locomotor neurons have extensive axons in brain areas that support spatial navigation, this cell type distributes this information selectively to areas that require knowledge of speed. This nucleus is functionally positioned between input from a higher-order cognitive center and the downstream midbrain where locomotor nuclei reside. —PRS
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Pham, Quang-Cuong, and Halim Hicheur. "On the Open-Loop and Feedback Processes That Underlie the Formation of Trajectories During Visual and Nonvisual Locomotion in Humans." Journal of Neurophysiology 102, no. 5 (November 2009): 2800–2815. http://dx.doi.org/10.1152/jn.00284.2009.
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We investigated the nature of the control mechanisms at work during goal-oriented locomotion. In particular, we tested the effects of vision, locomotor speed, and the presence of via points on the geometric and kinematic properties of locomotor trajectories. We first observed that the average trajectories recorded in visual and nonvisual locomotion were highly comparable, suggesting the existence of vision-independent processes underlying the formation of locomotor trajectories. Then by analyzing and comparing the variability around the average trajectories across different experimental conditions, we were able to demonstrate the existence of on-line feedback control in both visual and nonvisual locomotion and to clarify the relations between visual and nonvisual control strategies. Based on these insights, we designed a model in which maximum-smoothness and optimal feedback control principles account, respectively, for the open-loop and feedback processes. Taken together, the experimental and modeling findings provide a novel understanding of the nature of the motor, sensory, and “navigational” processes underlying goal-oriented locomotion.
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Tresch, Matthew C., and Ole Kiehn. "Population Reconstruction of the Locomotor Cycle From Interneuron Activity in the Mammalian Spinal Cord." Journal of Neurophysiology 83, no. 4 (April 1, 2000): 1972–78. http://dx.doi.org/10.1152/jn.2000.83.4.1972.
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Lesion studies have shown that neuronal networks in the ventromedial regions of the neonatal rat spinal cord are critical for the production of locomotion. We examined whether the locomotor cycle could be accurately predicted based on the activity recorded in a population of spinal interneurons located in these regions during pharmacologically induced locomotion. We used a Bayesian probabilistic reconstruction procedure to predict the most likely phase of locomotion given the observed activity in the neuronal population. The population reconstruction was able to predict the correct locomotor phase with high accuracy using a relatively small number of neurons. This result demonstrates that although the spike activity of individual spinal interneurons in the ventromedial region is weak and varies from cycle to cycle, the locomotor phase can be accurately predicted when information from the population is combined. This result is consistent with the proposed involvement of interneurons within these regions of the spinal cord in the production of locomotion.
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Schwartz, Eric J., Tatyana Gerachshenko, and Simon Alford. "5-HT Prolongs Ventral Root Bursting Via Presynaptic Inhibition of Synaptic Activity During Fictive Locomotion in Lamprey." Journal of Neurophysiology 93, no. 2 (February 2005): 980–88. http://dx.doi.org/10.1152/jn.00669.2004.
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Locomotor pattern generation is maintained by integration of the intrinsic properties of spinal central pattern generator (CPG) neurons in conjunction with synaptic activity of the neural network. In the lamprey, the spinal locomotor CPG is modulated by 5-HT. On a cellular level, 5-HT presynaptically inhibits synaptic transmission and postsynaptically inhibits a Ca2+-activated K+ current responsible for the slow afterhyperpolarization (sAHP) that follows action potentials in ventral horn neurons. To understand the contribution of these cellular mechanisms to the modulation of the spinal CPG, we have tested the effect of selective 5-HT analogues against fictive locomotion initiated by bath application of N-methyl-d-aspartate (NMDA). We found that the 5-HT1D agonist, L694-247, dramatically prolongs the frequency of ventral root bursting. Furthermore, we show that L694-247 presynaptically inhibits synaptic transmission without altering postsynaptic Ca2+ -activated K+ currents. We also confirm that 5-HT inhibits synaptic transmission at concentrations that modulate locomotion. To examine the mechanism by which selective presynaptic inhibition modulates the frequency of fictive locomotion, we performed voltage- and current-clamp recordings of CPG neurons during locomotion. Our results show that 5-HT decreases glutamatergic synaptic drive within the locomotor CPG during fictive locomotion. Thus we conclude that presynaptic inhibition of neurotransmitter release contributes to 5-HT–mediated modulation of locomotor activity.
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Rossignol, Serge, Réjean Dubuc, and Jean-Pierre Gossard. "Dynamic Sensorimotor Interactions in Locomotion." Physiological Reviews 86, no. 1 (January 2006): 89–154. http://dx.doi.org/10.1152/physrev.00028.2005.
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Locomotion results from intricate dynamic interactions between a central program and feedback mechanisms. The central program relies fundamentally on a genetically determined spinal circuitry (central pattern generator) capable of generating the basic locomotor pattern and on various descending pathways that can trigger, stop, and steer locomotion. The feedback originates from muscles and skin afferents as well as from special senses (vision, audition, vestibular) and dynamically adapts the locomotor pattern to the requirements of the environment. The dynamic interactions are ensured by modulating transmission in locomotor pathways in a state- and phase-dependent manner. For instance, proprioceptive inputs from extensors can, during stance, adjust the timing and amplitude of muscle activities of the limbs to the speed of locomotion but be silenced during the opposite phase of the cycle. Similarly, skin afferents participate predominantly in the correction of limb and foot placement during stance on uneven terrain, but skin stimuli can evoke different types of responses depending on when they occur within the step cycle. Similarly, stimulation of descending pathways may affect the locomotor pattern in only certain phases of the step cycle. Section ii reviews dynamic sensorimotor interactions mainly through spinal pathways. Section iii describes how similar sensory inputs from the spinal or supraspinal levels can modify locomotion through descending pathways. The sensorimotor interactions occur obviously at several levels of the nervous system. Section iv summarizes presynaptic, interneuronal, and motoneuronal mechanisms that are common at these various levels. Together these mechanisms contribute to the continuous dynamic adjustment of sensorimotor interactions, ensuring that the central program and feedback mechanisms are congruous during locomotion.
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Yurube, Takashi, Masaaki Ito, Toru Takeoka, Nobuyoshi Watanabe, Hideyo Inaoka, Kenichiro Kakutani, Ryosuke Kuroda, and Kotaro Nishida. "Possible Improvement of the Sagittal Spinopelvic Alignment and Balance through “Locomotion Training” Exercises in Patients with “Locomotive Syndrome”: A Literature Review." Advances in Orthopedics 2019 (April 8, 2019): 1–7. http://dx.doi.org/10.1155/2019/6496901.
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On the basis of rapid population aging, in 2007, the Japanese Orthopaedic Association (JOA) proposed a new disease concept “locomotive syndrome” as a degenerative condition of reduced mobility due to the impairment of the musculoskeletal system. Worsened locomotive components, which consist of bones, joints, and intervertebral discs, and muscles and nerves, can lead to symptoms such as pain, limited range of motion, malalignment, impaired balance, and difficulty in walking, ultimately resulting in the requirement of nursing care. “Locomotive syndrome” has gained increased interest in Japan but still not worldwide. Hence, in this brief review, we summarize an updated definition, assessment, and management of “locomotive syndrome”. The JOA recommends “locomotion training” exercise intervention to be effective in maintaining motor function that comprises two simple exercises—squatting and single-leg standing. However, the extent to which exercises affect “locomotive syndrome” is unknown. Here, we further report hypothesis-generating patient cases who presented the improved sagittal spinopelvic alignment in standing radiographs and postural stability in piezoelectric force-plate measurements through our 6-month “locomotion training” outpatient rehabilitation program. It is noteworthy that “locomotion training” facilitated these improvements despite the presence of specific disorders including thoracic kyphosis and symptomatic lumbar spinal canal stenosis. This raises the need for further investigations to clarify effects of “locomotion training” exercises on the spinal alignment, global balance, and quality of life in patients with “locomotive syndrome”.
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Huang, A., B. R. Noga, P. A. Carr, B. Fedirchuk, and L. M. Jordan. "Spinal Cholinergic Neurons Activated During Locomotion: Localization and Electrophysiological Characterization." Journal of Neurophysiology 83, no. 6 (June 1, 2000): 3537–47. http://dx.doi.org/10.1152/jn.2000.83.6.3537.
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The objective of the present study was to determine the location of the cholinergic neurons activated in the spinal cord of decerebrate cats during fictive locomotion. Locomotion was induced by stimulation of the mesencephalic locomotor region (MLR). After bouts of locomotion during a 7–9 h period, the animals were perfused and the L3–S1 spinal cord segments removed. Cats in the control group were subjected to the same surgical procedures but no locomotor task. The tissues were sectioned and then stained by immunohistochemical methods for detection of the c-fos protein and choline acetyltransferase (ChAT) enzyme. The resultant c-fos labeling in the lumbar spinal cord was similar to that induced by fictive locomotion in the cat. ChAT-positive cells also clearly exhibited fictive locomotion induced c-fos labeling. Double labeling with c-fos and ChAT was observed in cells within ventral lamina VII, VIII, and possibly IX. Most of them were concentrated in the medial portion of lamina VII close to lamina X, similar in location to the partition and central canal cells found by Barber and collaborators. The number of ChAT and c-fos–labeled neurons was increased following fictive locomotion and was greatest in the intermediate gray, compared with dorsal and ventral regions. The results are consistent with the suggestion that cholinergic interneurons in the lumbar spinal cord are involved in the production of fictive locomotion. Cells in the regions positive for double-labeled cells were targeted for electrophysiological study during locomotion, intracellular filling, and subsequent processing for ChAT immunohistochemistry. Three cells identified in this way were vigorously active during locomotion in phase with ipsilateral extension, and they projected to the contralateral side of the spinal cord. Thus a new population of spinal cord cells can be defined: cholinergic partition cells with commissural projections that are active during the extension phase of locomotion.
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Kawashima, Noritaka, Daichi Nozaki, Masaki O. Abe, and Kimitaka Nakazawa. "Shaping Appropriate Locomotive Motor Output Through Interlimb Neural Pathway Within Spinal Cord in Humans." Journal of Neurophysiology 99, no. 6 (June 2008): 2946–55. http://dx.doi.org/10.1152/jn.00020.2008.
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Direct evidence supporting the contribution of upper limb motion on the generation of locomotive motor output in humans is still limited. Here, we aimed to examine the effect of upper limb motion on locomotor-like muscle activities in the lower limb in persons with spinal cord injury (SCI). By imposing passive locomotion-like leg movements, all cervical incomplete ( n = 7) and thoracic complete SCI subjects ( n = 5) exhibited locomotor-like muscle activity in their paralyzed soleus muscles. Upper limb movements in thoracic complete SCI subjects did not affect the electromyographic (EMG) pattern of the muscle activities. This is quite natural since neural connections in the spinal cord between regions controlling upper and lower limbs were completely lost in these subjects. On the other hand, in cervical incomplete SCI subjects, in whom such neural connections were at least partially preserved, the locomotor-like muscle activity was significantly affected by passively imposed upper limb movements. Specifically, the upper limb movements generally increased the soleus EMG activity during the backward swing phase, which corresponds to the stance phase in normal gait. Although some subjects showed a reduction of the EMG magnitude when arm motion was imposed, this was still consistent with locomotor-like motor output because the reduction of the EMG occurred during the forward swing phase corresponding to the swing phase. The present results indicate that the neural signal induced by the upper limb movements contributes not merely to enhance but also to shape the lower limb locomotive motor output, possibly through interlimb neural pathways. Such neural interaction between upper and lower limb motions could be an underlying neural mechanism of human bipedal locomotion.
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Prayogo, Michael, Rwahita Satyawati, Dyah Intania Sari, Damayanti Tinduh, Sri Mardjiati Mei Wulan, Yukio Mikami, and Soenarnatalina Melaniani. "Locomotion training addition to regular aerobic exercise improves walking speed and two-step test of the institutionalized older adult with Locomotive Syndrome stage 1: a randomized controlled trial." Bali Medical Journal 12, no. 1 (February 21, 2023): 771–75. http://dx.doi.org/10.15562/bmj.v12i1.4085.
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Background: Most nursing homes in Indonesia use only aerobic exercise as regular exercise for their resident. Locomotion Training is a combination of lower extremity strengthening and balance exercises. This study aims to determine the effects of the addition of locomotion training to regular aerobic exercise on Walking Speed (WS) and Two Step Test (TST) of institutionalized older adults with the locomotive syndrome (LS) stage 1. Methods: 24 older adults with locomotive syndrome stage 1 (mean age, 73.85 years) participated in the study and were randomly allocated to the Locomotion Training addition group (LTG) and control group (CG). Eight weeks of daily group-based aerobic exercise were conducted for 30 minutes for both groups. The LTG performed additional locomotion training 3 times per week, with a progressive increase of set and repetition at each activity according to the participant's tolerance. The measurement of WS and TST was collected at baseline and 3 days after the intervention was completed for each participant. Results: Twenty participants completed the study, ten from CG and ten from LTG. The results showed a significant statistical difference in WS and TST in LTG (p <0.05) but no improvement in the CG (p >0.05) after 8 weeks of intervention. Conclusion: In addition to regular aerobic exercise, Locomotion Training can improve WS and TST in the institutionalized older adult with locomotive syndrome stage 1.
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Delivet-Mongrain, Hugo, Hugues Leblond, and Serge Rossignol. "Effects of Localized Intraspinal Injections of a Noradrenergic Blocker on Locomotion of High Decerebrate Cats." Journal of Neurophysiology 100, no. 2 (August 2008): 907–21. http://dx.doi.org/10.1152/jn.90454.2008.
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Previous studies demonstrated that neuronal networks located in midlumbar segments (L3–L4) are critical for the expression of locomotion in cats following complete spinalization. In the present study the importance of several thoracolumbar segments (T8–L7) for the generation of spontaneous hindlimb locomotion in decerebrate cats was evaluated. Experiments were performed in high decerebrate cats ( n = 18) walking spontaneously. Yohimbine, an alpha2-noradrenergic antagonist, was microinjected intraspinally in various thoracolumbar segments. Locomotor performance was evaluated with kinematics and electromyographic (EMG) recordings before and after each injection. When and if spontaneous locomotion (SL) was abolished, skin or perineal stimuli (exteroceptive stimuli) were used to trigger locomotion (exteroceptive-induced locomotion [EL]). Yohimbine injections at L3 or L4 completely inhibited SL and EL. In contrast, injections at T8 did not interfere with SL or EL. Injections at T10, T11, T12, L5, L6, and L7 inhibited SL but EL could still be evoked. Injections at T13, L1, and L2 had similar effects except that the quality of locomotion evoked by exteroceptive stimulation declined. Combined injections at T13, L1, and L2 abolished SL and EL, in contrast to injections restricted to the same individual segments. Simultaneous injections at L5, L6, and L7 also abolished SL but EL could still be induced. These results suggest that noradrenergic mechanisms in L3–L4 segments are involved in the expression of locomotion in decerebrate cats, whereas antagonizing noradrenergic inputs in individual rostral or caudal segments may alter the expression and overall quality of the locomotor pattern without abolishing locomotion.
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Brownstone, Robert M., Sherry Krawitz, and Larry M. Jordan. "Reversal of the late phase of spike frequency adaptation in cat spinal motoneurons during fictive locomotion." Journal of Neurophysiology 105, no. 3 (March 2011): 1045–50. http://dx.doi.org/10.1152/jn.00411.2010.
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In spinal motoneurons, late spike frequency adaptation (SFA) is defined as the slowing of the firing rate over tens of seconds and can be seen during sustained or intermittent current injection. Although the function of late SFA is not known, it may result in a decrease in force production over time, or muscle fatigue. Because locomotion can persist for long periods of time without fatigue, late SFA was studied using intracellular recordings from adult cat motoneurons during fictive locomotion. Of eight lumbar motoneurons studied, all showed late adaptation during control conditions, but none demonstrated late adaptation during locomotor activity. The most consistent properties that correlated with the presence or absence of late SFA were those related to availability of fast, inactivating sodium channels, particularly action potential rate of rise. Evidence of the reversal of late SFA during locomotion was present for several minutes following locomotor trials, consistent with the suggestion that SFA is modulated through slow metabotropic pathways. The abolition of late adaptation in spinal motoneurons during fictive locomotion is an example of a state-dependent change in the “intrinsic” properties of mammalian motoneurons. This change contributes to increased excitability of motoneurons during locomotion and results in robust firing during sustained locomotion.
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Gerasimenko, Yury, Chet Preston, Hui Zhong, Roland R. Roy, V. Reggie Edgerton, and Prithvi K. Shah. "Rostral lumbar segments are the key controllers of hindlimb locomotor rhythmicity in the adult spinal rat." Journal of Neurophysiology 122, no. 2 (August 1, 2019): 585–600. http://dx.doi.org/10.1152/jn.00810.2018.
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The precise location and functional organization of the spinal neuronal locomotor-related networks in adult mammals remain unclear. Our recent neurophysiological findings provided empirical evidence that the rostral lumbar spinal cord segments play a critical role in the initiation and generation of the rhythmic activation patterns necessary for hindlimb locomotion in adult spinal rats. Since added epidural stimulation at the S1 segments significantly enhanced the motor output generated by L2 stimulation, these data also suggested that the sacral spinal cord provides a strong facilitory influence in rhythm initiation and generation. However, whether L2 will initiate hindlimb locomotion in the absence of S1 segments, and whether S1 segments can facilitate locomotion in the absence of L2 segments remain unknown. Herein, adult rats received complete spinal cord transections at T8 and then at either L2 or S1. Rats with spinal cord transections at T8 and S1 remained capable of generating coordinated hindlimb locomotion when receiving epidural stimulation at L2 and when ensembles of locomotor related loadbearing input were present. In contrast, minimal locomotion was observed when S1 stimulation was delivered after spinal cord transections at T8 and L2. Results were similar when the nonspecific serotonergic agonists were administered. These results demonstrate in adult rats that rostral lumbar segments are essential for the regulation of hindlimb locomotor rhythmicity. In addition, the more caudal spinal networks alone cannot control locomotion in the absence of the rostral segments around L2 even when loadbearing rhythmic proprioceptive afferent input is imposed. NEW & NOTEWORTHY The exact location of the spinal neuronal locomotor-related networks in adult mammals remains unknown. The present data demonstrate that when the rostral lumbar spinal segments (~L2) are completely eliminated in thoracic spinal adult rats, hindlimb stepping is not possible with neurochemical modulation of the lumbosacral cord. In contrast, eliminating the sacral cord retains stepping ability. These observations highlight the importance of rostral lumbar segments in generating effective mammalian locomotion.
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Liu, Jun, Turgay Akay, Peter B. Hedlund, Keir G. Pearson, and Larry M. Jordan. "Spinal 5-HT7 Receptors Are Critical for Alternating Activity During Locomotion: In Vitro Neonatal and In Vivo Adult Studies Using 5-HT7 Receptor Knockout Mice." Journal of Neurophysiology 102, no. 1 (July 2009): 337–48. http://dx.doi.org/10.1152/jn.91239.2008.
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5-HT7 receptors have been implicated in the control of locomotion. Here we use 5-HT7 receptor knockout mice to rigorously test whether 5-HT acts at the 5-HT7 receptor to control locomotor-like activity in the neonatal mouse spinal cord in vitro and voluntary locomotion in adult mice. We found that 5-HT applied onto in vitro spinal cords of 5-HT7+/+ mice produced locomotor-like activity that was disrupted and subsequently blocked by the 5-HT7 receptor antagonist SB-269970. In spinal cords isolated from 5-HT7−/− mice, 5-HT produced either uncoordinated rhythmic activity or resulted in synchronous discharges of the ventral roots. SB-269970 had no effect on 5-HT-induced rhythmic activity in the 5-HT7−/− mice. In adult in vivo experiments, SB-269970 applied directly to the spinal cord consistently disrupted locomotion and produced prolonged-extension of the hindlimbs in 5-HT7+/+ but not 5-HT7−/− mice. Disrupted EMG activity produced by SB-269970 in vivo was similar to the uncoordinated rhythmic activity produced by the drug in vitro. Moreover, 5-HT7−/− mice displayed greater maximal extension at the hip and ankle joints than 5-HT7+/+ animals during voluntary locomotion. These results suggest that spinal 5-HT7 receptors are required for the production and coordination of 5-HT-induced locomotor-like activity in the neonatal mouse and are important for the coordination of voluntary locomotion in adult mice. We conclude that spinal 5-HT7 receptors are critical for alternating activity during locomotion.
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Studholme, Keith M., Heinrich S. Gompf, and Lawrence P. Morin. "Brief light stimulation during the mouse nocturnal activity phase simultaneously induces a decline in core temperature and locomotor activity followed by EEG-determined sleep." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 304, no. 6 (March 15, 2013): R459—R471. http://dx.doi.org/10.1152/ajpregu.00460.2012.
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Light exerts a variety of effects on mammals. Unexpectedly, one of these effects is the cessation of nocturnal locomotion and the induction of behavioral sleep (photosomnolence). Here, we extend the initial observations in several ways, including the fundamental demonstration that core body temperature (Tc) drops substantially (about 1.5°C) in response to the light stimulation at CT15 or CT18 in a manner suggesting that the change is a direct response to light rather than simply a result of the locomotor suppression. The results show that 1) the decline of locomotion and Tc begin soon after nocturnal light stimulation; 2) the variability in the magnitude and onset of light-induced locomotor suppression is very large, whereas the variability in Tc is very small; 3) Tc recovers from the light-induced decline in advance of the recovery of locomotion; 4) under entrained and freerunning conditions, the daily late afternoon Tc increase occurs in advance of the corresponding increase in wheel running; and 5) toward the end of the subjective night, the nocturnally elevated Tc persists longer than does locomotor activity. Finally, EEG measurements confirm light-induced sleep and, when Tc or locomotion was measured, show their temporal association with sleep onset. Both EEG- and immobility-based sleep detection methods confirm rapid induction of light-induced sleep. The similarities between light-induced loss of locomotion and drop in Tc suggest a common cause for parallel responses. The photosomnolence response may be contingent upon both the absence of locomotion and a simultaneous low Tc.
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Ren, Lin, Ling Yuan, Qingyu Gao, Rui Teng, Jing Wang, and Irving R. Epstein. "Chemomechanical origin of directed locomotion driven by internal chemical signals." Science Advances 6, no. 18 (May 2020): eaaz9125. http://dx.doi.org/10.1126/sciadv.aaz9125.
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Asymmetry in the interaction between an individual and its environment is generally considered essential for the directional properties of active matter, but can directional locomotions and their transitions be generated only from intrinsic chemical dynamics and its modulation? Here, we examine this question by simulating the locomotion of a bioinspired active gel in a homogeneous environment. We find that autonomous directional locomotion emerges in the absence of asymmetric interaction with the environment and that a transition between modes of gel locomotion can be induced by adjusting the spatially uniform intensity of illumination or certain kinetic and mechanical system parameters. The internal wave dynamics and its structural modulation act as the impetus for signal-driven active locomotion in a manner similar to the way in which an animal’s locomotion is generated via driving by nerve pulses. Our results may have implications for the development of soft robots and biomimetic materials.
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Wolff, Jonas O. "Locomotion and kinematics of arachnids." Journal of Comparative Physiology A 207, no. 2 (March 2021): 99–103. http://dx.doi.org/10.1007/s00359-021-01478-2.
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AbstractA basic feature of animals is the capability to move and disperse. Arachnids are one of the oldest lineages of terrestrial animals and characterized by an octopodal locomotor apparatus with hydraulic limb extension. Their locomotion repertoire includes running, climbing, jumping, but also swimming, diving, abseiling, rolling, gliding and -passively- even flying. Studying the unique locomotor functions and movement ecology of arachnids is important for an integrative understanding of the ecology and evolution of this diverse and ubiquitous animal group. Beyond biology, arachnid locomotion is inspiring robotic engineers. The aim of this special issue is to display the state of the interdisciplinary research on arachnid locomotion, linking physiology and biomechanics with ecology, ethology and evolutionary biology. It comprises five reviews and ten original research reports covering diverse topics, ranging from the neurophysiology of arachnid movement, the allometry and sexual dimorphism of running kinematics, the effect of autotomy or heavy body parts on locomotor efficiency, and the evolution of silk-spinning choreography, to the biophysics of ballooning and ballistic webs. This closes a significant gap in the literature on animal biomechanics.
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Fouad, K., M. M. Rank, R. Vavrek, K. C. Murray, L. Sanelli, and D. J. Bennett. "Locomotion After Spinal Cord Injury Depends on Constitutive Activity in Serotonin Receptors." Journal of Neurophysiology 104, no. 6 (December 2010): 2975–84. http://dx.doi.org/10.1152/jn.00499.2010.
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Following spinal cord injury (SCI) neurons caudal to the injury are capable of rhythmic locomotor-related activity that can form the basis for substantial functional recovery of stepping despite the loss of crucial brain stem-derived neuromodulators like serotonin (5-HT). Here we investigated the contribution of constitutive 5-HT2 receptor activity (activity in the absence of 5-HT) to locomotion after SCI. We used a staggered hemisection injury model in rats to study this because these rats showed a robust recovery of locomotor function and yet a loss of most descending axons. Immunolabeling for 5-HT showed little remaining 5-HT below the injury, and locomotor ability was not correlated with the amount of residual 5-HT. Furthermore, blocking 5-HT2 receptors with an intrathecal (IT) application of the neutral antagonist SB242084 did not affect locomotion (locomotor score and kinematics were unaffected), further indicating that residual 5-HT below the injury did not contribute to generation of locomotion. As a positive control, we found that the same application of SB242084 completely antagonized the muscle activity induced by exogenous application of the 5-HT2 receptor agonists alpha-methyl-5-HT (IT). In contrast, blocking constitutive 5-HT2 receptor activity with the potent inverse agonist SB206553 (IT) severely impaired stepping as assessed with kinematic recordings, eliminating most hindlimb weight support and overall reducing the locomotor score in both hind legs. However, even in the most severely impaired animals, rhythmic sweeping movements of the hindlimb feet were still visible during forelimb locomotion, suggesting that SB206553 did not completely eliminate locomotor drive to the motoneurons or motoneuron excitability. The same application of SB206553 had no affect on stepping in normal rats. Thus while normal rats can compensate for loss of 5-HT2 receptor activity, after severe spinal cord injury rats require constitutive activity in these 5-HT2 receptors to produce locomotion.
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Mori, Shigemi, Toshihiro Matsui, Bunya Kuze, Mitsuru Asanome, Katsumi Nakajima, and Kiyoji Matsuyama. "Stimulation of a Restricted Region in the Midline Cerebellar White Matter Evokes Coordinated Quadrupedal Locomotion in the Decerebrate Cat." Journal of Neurophysiology 82, no. 1 (July 1, 1999): 290–300. http://dx.doi.org/10.1152/jn.1999.82.1.290.
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In the reflexively standing acute decerebrate cat, we have previously shown that pulse train microstimulation of the hook bundle of Russel in the midline of the cerebellar white matter, through which crossed fastigiofugal fibers decussate, augments the postural tone of neck, trunk, fore-, and hindlimb extensor muscles. In the present study we examined the possible role of such stimulation in evoking locomotion as the animal is supported by a rubber hammock with its feet contacting the moving surface of a treadmill. We were able to provoke well-coordinated, bilaterally symmetrical, fore- and hindlimb movements, whose cycle time and pattern were controlled by appropriate changes in stimulus intensity and treadmill speed. We carefully and systematically mapped this cerebellar locomotor region (CLR) through repeated dorsoventral penetrations with a glass-coated tungsten microelectrode in a single animal and between animals. We found that the optimal locus for evoking locomotion was centered on the midline, at Horsley-Clarke coordinates H0 and P7.0, and extended over a rostrocaudal and dorsolateral range of ∼0.5 mm. The lowest effective stimulus intensity at the optimal site was in the range of 5–8 μA. Along penetration tracks to left or right of the midline, effective stimulus intensity increased and evoked locomotor patterns were no longer symmetrical, but rather shifted toward the contralateral limbs. In the same animals, controlled locomotion was evoked by stimulating the mesencephalic locomotor region (MLR). With concomitant stimulation of the optimal sites in the CLR and the MLR, each at subthreshold strength, locomotor movements identical to those seen with suprathreshold stimulation of each site alone were evoked. With concomitant stimulation at suprathreshold strength for each site, locomotion became vigorous, with a shortened cycle time. After making ablative lesions at either the CLR or MLR (unilateral or bilateral), controlled locomotion was still evoked at the prior stimulus strength by stimulating the remaining site. Together, these results demonstrate that selective stimulation of the hook bundle of Russel in the midsagittal plane of the cerebellar white matter evokes “controlled” locomotion identical to that evoked by stimulating the MLR. We have shown that the fastigial nucleus is one of the supraspinal locomotion inducing sites and that it can independently and simultaneously trigger brain stem and spinal locomotor subprograms formerly believed to be the domain of various brain stem regions including the MLR and the subthalamic locomotor region.
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Niu, Xuelei, and Jianxin Xu. "Modeling, Control and Locomotion Planning of an Anguilliform Robotic Fish." Unmanned Systems 02, no. 04 (October 2014): 295–321. http://dx.doi.org/10.1142/s230138501440007x.
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In this paper, mathematical model, control law design, different locomotion patterns, and locomotion planning are presented for an Anguilliform robotic fish. The robotic fish, consisted of links and joints, are driven by torques applied to the joints. Considering kinematic constraints, Lagrangian formulation is used to obtain the mathematical model of the robotic fish. The model reveals the relation between motion of the fish and external forces. Computed torque control method is first applied, which can provide satisfactory tracking performance for reference joint angles. To deal with parameter uncertainties, sliding model control is adopted. Three locomotion patterns — forward locomotion, backward locomotion, and turning locomotion — are realized by assigning appropriate reference angles to the joints, and the three locomotions are verified by experiments and simulations. A new form of central pattern generator (CPG) model is presented, which consists of three-dimensional coupled Andronov–Hopf oscillators, artificial neural network, and outer amplitude modulator. By using this CPG model, swimming pattern of a real Anguilliform fish is successfully applied to the robotic fish in an experiment.
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Verneuil, Jérémy, Cécile Brocard, Virginie Trouplin, Laurent Villard, Julie Peyronnet-Roux, and Frédéric Brocard. "The M-current works in tandem with the persistent sodium current to set the speed of locomotion." PLOS Biology 18, no. 11 (November 13, 2020): e3000738. http://dx.doi.org/10.1371/journal.pbio.3000738.
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The central pattern generator (CPG) for locomotion is a set of pacemaker neurons endowed with inherent bursting driven by the persistent sodium current (INaP). How they proceed to regulate the locomotor rhythm remained unknown. Here, in neonatal rodents, we identified a persistent potassium current critical in regulating pacemakers and locomotion speed. This current recapitulates features of the M-current (IM): a subthreshold noninactivating outward current blocked by 10,10-bis(4-pyridinylmethyl)-9(10H)-anthracenone dihydrochloride (XE991) and enhanced by N-(2-chloro-5-pyrimidinyl)-3,4-difluorobenzamide (ICA73). Immunostaining and mutant mice highlight an important role of Kv7.2-containing channels in mediating IM. Pharmacological modulation of IM regulates the emergence and the frequency regime of both pacemaker and CPG activities and controls the speed of locomotion. Computational models captured these results and showed how an interplay between IM and INaP endows the locomotor CPG with rhythmogenic properties. Overall, this study provides fundamental insights into how IM and INaP work in tandem to set the speed of locomotion.
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Wu, Michael, Stefan M. Brudzynski, and Gordon J. Mogenson. "Functional interaction of dopamine and glutamate in the nucleus accumbens in the regulation of locomotion." Canadian Journal of Physiology and Pharmacology 71, no. 5-6 (May 1, 1993): 407–13. http://dx.doi.org/10.1139/y93-061.
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The interaction of dopamine and glutamate in the nucleus accumbens in the regulation of locomotion was investigated. Microinjection of N-methyl-D-aspartic acid (NMDA, a glutamatergic NMDA receptor agonist) or α-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA, a quisqualic receptor agonist which is a glutamatergic non-NMDA receptor agonist) into the nucleus accumbens caused a substantial increase in locomotor activity. This increase in locomotor activity was significantly reduced by prior administration of the dopamine D2 agonist quinpirole, but not the D1 agonist, SKF 38393, into the same brain sites. The reduction in locomotion produced by quinpirole was dose dependent. Eight days after the ventral tegmental area was lesioned with 6-hydroxydopamine to destroy the dopamine projection and the axon terminals of the mesolimbic dopamine neurons in nucleus accumbens, the hyperkinetic effects produced by injections of NMDA and AMPA into the nucleus accumbens were substantially reduced. These results suggested that the glutamate agonist induced locomotion is mediated by dopamine. Thus, it appears that NMDA- or AMPA-induced locomotion is due to the activation of glutamate receptors on the mesolimbic dopamine terminals in the nucleus accumbens which release dopamine and subsequently increase locomotion.Key words: nucleus accumbens, dopamine, glutamate, quinpirole, locomotion, N-methyl-D-aspartic acid, α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid.
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Bury, Stanisław, Bartosz Borczyk, and Tomasz Skawiński. "Ventral scale width in snakes depends on habitat but not hunting strategy." Biological Journal of the Linnean Society 128, no. 4 (October 9, 2019): 987–93. http://dx.doi.org/10.1093/biolinnean/blz116.
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Abstract Environment and lifestyle induce substantial variation in the mechanisms of locomotion in vertebrates. A spectrum of adaptations related to locomotion is also present in limbless taxa, especially snakes, which have radiated successfully into a wide range of habitats. The majority of studies concerning habitat-driven variation in locomotor mechanisms of snakes have focused on the musculoskeletal system. Far less recognized is the variation in the morphology of ventral scales, which are another pivotal component of the locomotor system in snakes. Here, we investigated patterns of interspecific variation in the width of ventral scales in terms of lifestyle (hunting mode) and habitat occupied in 55 species of snakes belonging to eight families. We found that increasing terrestriality was associated with enlarged ventral scales. Reduction instead of maintenance of the width of ventral scales was observed in aquatic species, suggesting that wide ventral scales set constraints on aquatic locomotion. In terrestrial species, no significant differences were observed in terms of arboreality or hunting mode, which suggests overall optimization in the size of ventral scales towards terrestrial locomotion. Association between the width of ventral scales and locomotion can result in a habitat-dependent costs of abnormalities in ventral scale morphology, commonly observed in snakes.
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Le Ray, Didier, Sandrine S. Bertrand, and Réjean Dubuc. "Cholinergic Modulation of Locomotor Circuits in Vertebrates." International Journal of Molecular Sciences 23, no. 18 (September 14, 2022): 10738. http://dx.doi.org/10.3390/ijms231810738.
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Locomotion is a basic motor act essential for survival. Amongst other things, it allows animals to move in their environment to seek food, escape predators, or seek mates for reproduction. The neural mechanisms involved in the control of locomotion have been examined in many vertebrate species and a clearer picture is progressively emerging. The basic muscle synergies responsible for propulsion are generated by neural networks located in the spinal cord. In turn, descending supraspinal inputs are responsible for starting, maintaining, and stopping locomotion as well as for steering and controlling speed. Several neurotransmitter systems play a crucial role in modulating the neural activity during locomotion. For instance, cholinergic inputs act both at the spinal and supraspinal levels and the underlying mechanisms are the focus of the present review. Much information gained on supraspinal cholinergic modulation of locomotion was obtained from the lamprey model. Nicotinic cholinergic inputs increase the level of excitation of brainstem descending command neurons, the reticulospinal neurons (RSNs), whereas muscarinic inputs activate a select group of hindbrain neurons that project to the RSNs to boost their level of excitation. Muscarinic inputs also reduce the transmission of sensory inputs in the brainstem, a phenomenon that could help in sustaining goal directed locomotion. In the spinal cord, intrinsic cholinergic inputs strongly modulate the activity of interneurons and motoneurons to control the locomotor output. Altogether, the present review underlines the importance of the cholinergic inputs in the modulation of locomotor activity in vertebrates.
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Glasheen, J. W., and T. A. McMahon. "Arms are different from legs: mechanics and energetics of human hand-running." Journal of Applied Physiology 78, no. 4 (April 1, 1995): 1280–87. http://dx.doi.org/10.1152/jappl.1995.78.4.1280.
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To determine whether nonlocomotor limbs (arms) differ from locomotor limbs (legs), we trained human subjects to run on their hands while supporting a fraction of their body weight. We wanted to know whether the low cost of force production and the speed-independent limb stiffness of locomotor limbs were characteristics associated with locomotion or were inherent properties of all limbs. We found that the limb stiffness of the human arm increases by 135% over less than a fourfold range in peak vertical force. In contrast, human legs and a variety of other mammalian locomotor limbs maintain a constant stiffness, regardless of speed and loading, for normal running. In addition, we explored the energetics of locomotion in hand-running. The economy of force generation (in J/N) is invariant with speed, as is found in legged locomotion. However, our results show that the metabolic cost of force generation while running on human arms is four to five times greater than the cost of force generation for the locomotor limbs of running quadrupeds.
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Rossignol, Serge, Connie Chau, Edna Brustein, Marc Bélanger, Hughes Barbeau, and Trevor Drew. "Locomotor capacities after complete and partial lesions of the spinal cord." Acta Neurobiologiae Experimentalis 56, no. 1 (March 31, 1996): 449–63. http://dx.doi.org/10.55782/ane-1996-1148.
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This paper first reviews some of the observations made on the locomotor capabilities of several animal species with a special emphasis on cats and including primates and man after complete spinal lesions. We show that animals can perform well-coordinated walking movements of the hindlimbs when they are placed on a treadmill belt and that this locomotion is also adaptable to speed and perturbations. Cats with partial spinal lesions of the ventral and ventrolateral parts of the cord can perform voluntary quadrupedal locomotion overground or on the treadmill albeit with deficits in weight support and interlimb coordination. We also show that some drugs such as clonidine (an alpha-2 noradrenergic agonist) can be used to trigger locomotion in early-spinal cats and discuss the effects of various neurotransmitter systems on the expression of the locomotor pattern in both complete and partial spinal cats. It is concluded that a pharmacological approach could be used, in combination with other approaches, such as locomotor training and functional electrical stimulation, to improve locomotor functions after spinal cord injuries in humans.
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Campos, Joseph J., Bennett I. Bertenthal, and Rosanne Kermoian. "Early Experience and Emotional Development: The Emergence of Wariness of Heights." Psychological Science 3, no. 1 (January 1992): 61–64. http://dx.doi.org/10.1111/j.1467-9280.1992.tb00259.x.
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Because of its biological adaptive value, wariness of heights is widely believed to be innate or under maturational control. In this report, we present evidence contrary to this hypothesis, and show the importance of locomotor experience for emotional development. Four studies bearing on this conclusion have shown that (1) when age is held constant, locomotor experience accounts for wariness of heights; (2) “artificial” experience locomoting in a walker generates evidence of wariness of heights; (3) an orthopedically handicapped infant tested longitudinally did not show wariness of heights so long as he had no locomotor experience; and (4) regardless of the age when infants begin to crawl, it is the duration of locomotor experience and not age that predicts avoidance of heights. These findings suggest that when infants begin to crawl, experiences generated by locomotion make possible the development of wariness of heights.
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Giroux, Nathalie, Connie Chau, Hugues Barbeau, Tomás A. Reader, and Serge Rossignol. "Effects of Intrathecal Glutamatergic Drugs on Locomotion. II. NMDA and AP-5 in Intact and Late Spinal Cats." Journal of Neurophysiology 90, no. 2 (August 2003): 1027–45. http://dx.doi.org/10.1152/jn.00758.2002.
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In a previous article, we have shown that, in cats, intrathecal injections of N-methyl-d-aspartate (NMDA) in the first few days after spinalization at T13 do not induce locomotion as in many other spinal preparations. This is in contrast to alpha-2 noradrenergic receptor stimulation, which can trigger locomotion at this early stage. However, it is known that spinal cats do recover spontaneous locomotion in the absence of descending noradrenergic pathways and that the spinal pattern generator must then depend on other neurotransmitters still present in the cord such as excitatory amino acids. In the present paper, therefore we look at the effects of intrathecal NMDA, a glutamatergic agonist, and 2-amino-5-phosphonovaleric acid (AP-5), an NMDA receptor blocker, in both intact and late spinal cats. Low doses of NMDA had no major effect on the locomotor pattern in both intact and late spinal cats. Larger doses of NMDA in the chronic spinal cat initially produced an increase in the general excitability followed by more regular locomotion. AP-5 in intact cats caused a decrease in the amplitude of the flexion reflex and induced a bilateral foot drag as well as some decrease in weight support but it did not prevent locomotion. However, in late spinal cats, the same dose of AP-5 blocked locomotion completely. These results indicate that NMDA receptors may be critical for the spontaneous expression of spinal locomotion. It is proposed that the basic locomotor rhythmicity in cats is NMDA-dependent and that normally this glutamatergic mechanism is modulated by other neurotransmitters, such as 5-HT and NA.
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Stewart, J. E., H. Barbeau, and S. Gauthier. "Modulation of Locomotor Patterns and Spasticity with Clonidine in Spinal Cord Injured Patients." Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques 18, no. 3 (August 1991): 321–32. http://dx.doi.org/10.1017/s0317167100031887.
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ABSTRACT:This double blind cross-over study, involving 9 chronic spinal cord injured (SCI) patients (6 paraplegic and 3 paretic), was a first attempt to investigate the effects of the noradrenergic agonist, clonidine, on the modulation of the locomotor pattern and spasticity in patients with spinal cord lesions. Electromyographic (EMG), footswitch and video recordings were made as the patients walked on a treadmill with the support of an overhead harness if needed. Overground locomotion was also assessed in the paretic patients. All 3 spastic paretic patients had kinematic deviations and abnormal EMG recruitment profiles during the premedication or placebo sessions. With clonidine therapy one patient demonstrated a marked improvement in locomotor function. This patient progressed from non-ambulation to limited independent ambulation as the extent of coactivation in antogonist muscles decreased. The other 2 paretics who presented limited spasticity showed minimal changes while on clonidine. In the paraplegic patients, clonidine did not elicit locomotor activity, although there were marked reductions in stretch reactions and clonus during assisted locomotion. They remained incapable of locomotion, either during the control period or during the clonidine therapy. These results indicate that clonidine may be a potentially useful medication for both locomotion and certain manifestations of spasticity in SCI patients but further investigation is warranted.
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Giuliodori, Mauricio J., Heidi L. Lujan, Whitney S. Briggs, and Stephen E. DiCarlo. "A model of locomotor-respiratory coupling in quadrupeds." Advances in Physiology Education 33, no. 4 (December 2009): 315–18. http://dx.doi.org/10.1152/advan.00057.2009.
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Locomotion and respiration are not independent phenomena in running mammals because locomotion and respiration both rely on cyclic movements of the ribs, sternum, and associated musculature. Thus, constraints are imposed on locomotor and respiratory function by virtue of their linkage. Specifically, locomotion imposes mechanical constraints on breathing that require the respiratory cycle to be synchronized with gait. Thus, many mammals, including humans, synchronize respiration with the movement of the limbs during locomotion. For example, quadrupeds synchronize locomotor and respiratory cycles at a 1:1 ratio (stride/breath) over a wide range of speeds. Interestingly, quadrupeds maintain an almost constant stride frequency (and therefore respiratory frequency) at different speeds. To increase speed, quadrupeds lengthen their stride. Accordingly, to increase minute ventilation, quadrupeds must increase tidal volume since respiratory rate is coupled with stride frequency. We developed a simple, inexpensive, and easy to build model to demonstrate this concept. A model was chosen because models significantly enhance student understanding. Students are drawn into discussion by the power of learning that is associated with manipulating and thinking about objects. Building and using this model strengthen the concept that locomotor-respiratory coupling provides a basis for the appropriate matching of lung ventilation to running speed and metabolic power.
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Cheron, G., M. Duvinage, C. De Saedeleer, T. Castermans, A. Bengoetxea, M. Petieau, K. Seetharaman, et al. "From Spinal Central Pattern Generators to Cortical Network: Integrated BCI for Walking Rehabilitation." Neural Plasticity 2012 (2012): 1–13. http://dx.doi.org/10.1155/2012/375148.
Full textAbstract:
Success in locomotor rehabilitation programs can be improved with the use of brain-computer interfaces (BCIs). Although a wealth of research has demonstrated that locomotion is largely controlled by spinal mechanisms, the brain is of utmost importance in monitoring locomotor patterns and therefore contains information regarding central pattern generation functioning. In addition, there is also a tight coordination between the upper and lower limbs, which can also be useful in controlling locomotion. The current paper critically investigates different approaches that are applicable to this field: the use of electroencephalogram (EEG), upper limb electromyogram (EMG), or a hybrid of the two neurophysiological signals to control assistive exoskeletons used in locomotion based on programmable central pattern generators (PCPGs) or dynamic recurrent neural networks (DRNNs). Plantar surface tactile stimulation devices combined with virtual reality may provide the sensation of walking while in a supine position for use of training brain signals generated during locomotion. These methods may exploit mechanisms of brain plasticity and assist in the neurorehabilitation of gait in a variety of clinical conditions, including stroke, spinal trauma, multiple sclerosis, and cerebral palsy.
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Brustein, Edna, and Serge Rossignol. "Recovery of Locomotion After Ventral and Ventrolateral Spinal Lesions in the Cat. II. Effects of Noradrenergic and Serotoninergic Drugs." Journal of Neurophysiology 81, no. 4 (April 1, 1999): 1513–30. http://dx.doi.org/10.1152/jn.1999.81.4.1513.
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Recovery of locomotion after ventral and ventrolateral spinal lesions in the cat. II. Effects of noradrenergic and serotoninergic drugs. The effects of serotoninergic and noradrenergic drugs (applied intrathecally) on treadmill locomotion were evaluated in two adult cats subjected to a ventral and ventrolateral spinal lesion (T13). Despite the extensive spinal lesion, severely damaging important descending pathways such as the reticulo- and vestibulospinal tracts, both cats recovered quadrupedal voluntary locomotion. As detailed in a previous paper, the locomotor recovery occurred in three stages defined as early period, when the animal could not walk with its hindlimbs, recovery period, when progressive improvement occurred, and plateau period,when a more stable locomotor performance was observed. At this latter stage, the cats suffered from postural and locomotor deficits, such as poor lateral stability, irregular stepping of the hindlimbs, and inconsistent homolateral fore- and hindlimb coupling. The present study aimed at evaluating the potential of serotoninergic and/or noradrenergic drugs to improve the locomotor abilities in the early and late stages. Both cats were implanted chronically with an intrathecal cannula and electromyographic (EMG) electrodes, which allowed determination, under similar recording conditions, of the locomotor performance pre- and postlesion and comparisons of the effects of different drugs. EMG and kinematic analyses showed that norepinephrine (NE) injected in early and plateau periods improved the regularity of the hindlimb stepping and stabilized the interlimb coupling, permitting to maintain constant locomotion for longer periods of time. Methoxamine, the α1-agonist (tested only at the plateau period), had similar effects. In contrast, the α2-agonist, clonidine, deteriorated walking. Serotoninergic drugs, such as the neurotransmitter itself, serotonin ( 5HT), the precursor 5-hydroxytryptophan ( 5HTP), and the agonist quipazine improved the locomotion by increasing regularity of the hindlimb stepping and by increasing the step cycle duration. In contrast, the 5HT1A agonist 8-hydroxy-dipropylaminotetralin ( DPAT) caused foot drag in one of the cats, resulting in frequent stumbling. Injection of combination of methoxamine and quipazine resulted in maintained, regular stepping with smooth movements and good lateral stability. Our results show that the effects of drugs can be integrated to the residual voluntary locomotion and improve some of its postural aspects. However, this work shows clearly that the effects of drugs (such as clonidine) may depend on whether or not the spinal lesion is complete. In a clinical context, this may suggest that different classes of drugs could be used in patients with different types of spinal cord injuries. Possible mechanisms underlying the effect of noradrenergic and serotoninergic drugs on the locomotion after partial spinal lesions are discussed.
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Noga, Brian R., Dawn M. G. Johnson, Mirta I. Riesgo, and Alberto Pinzon. "Locomotor-Activated Neurons of the Cat. I. Serotonergic Innervation and Co-Localization of 5-HT7, 5-HT2A, and 5-HT1A Receptors in the Thoraco-Lumbar Spinal Cord." Journal of Neurophysiology 102, no. 3 (September 2009): 1560–76. http://dx.doi.org/10.1152/jn.91179.2008.
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Monoamines are strong modulators and/or activators of spinal locomotor networks. Thus monoaminergic fibers likely contact neurons involved in generating locomotion. The aim of the present study was to investigate the serotonergic innervation of locomotor-activated neurons within the thoraco-lumbar spinal cord following induction of hindlimb locomotion. This was determined by immunohistochemical co-localization of serotonin (5-HT) fibers or 5-HT7/5-HT2A/5-HT1A receptors with cells expressing the activity-dependent marker c-fos. Experiments were performed on paralyzed, decerebrate cats in which locomotion was induced by electrical stimulation of the mesencephalic locomotor region. Abundant c-fos immunoreactive cells were observed in laminae VII and VIII throughout the thoraco-lumbar segments of locomotor animals. Control sections from the same segments showed significantly fewer labeled neurons, mostly within the dorsal horn. Multiple serotonergic boutons were found in close apposition to the majority (80–100%) of locomotor cells, which were most abundant in lumbar segments L3–7. 5-HT7 receptor immunoreactivity was observed on cells across the thoraco-lumbar segments (T7–L7), in a dorsoventral gradient. Most locomotor-activated cells co-localized with 5-HT7, 5-HT2A, and 5-HT1A receptors, with largest numbers in laminae VII and VIII. Co-localization of c-fos and 5-HT7 receptor was highest in the L5–L7 segments (>90%) and decreased rostrally (to ∼50%) due to the absence of receptors on cells within the intermediolateral nucleus. In contrast, 60–80 and 35–80% of c-fos immunoreactive cells stained positive for 5-HT2A and 5-HT1A receptors, respectively, with no rostrocaudal gradient. These results indicate that serotonergic modulation of locomotion likely involves 5-HT7/5-HT2A/5-HT1A receptors located on the soma and proximal dendrites of serotonergic-innervated locomotor-activated neurons within laminae VII and VIII of thoraco-lumbar segments.
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Shefchyk, S. J., and L. M. Jordan. "Excitatory and inhibitory postsynaptic potentials in alpha-motoneurons produced during fictive locomotion by stimulation of the mesencephalic locomotor region." Journal of Neurophysiology 53, no. 6 (June 1, 1985): 1345–55. http://dx.doi.org/10.1152/jn.1985.53.6.1345.
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We tested the hypothesis that stimulation of the mesencephalic locomotor region (MLR) activates polysynaptic pathways that project to lumbar spinal motoneurons and are involved in the initiation of locomotion. Fictive locomotion was produced by MLR stimulation, and intracellular records of evoked postsynaptic potentials (PSPs) in alpha-motoneurons were computer analyzed. Stimulation of sites in the MLR that were maximally effective for the initiation of locomotion produced excitatory and inhibitory postsynaptic potentials (EPSPs and IPSPs) in all the motoneurons examined. The amplitudes of the PSPs increased as locomotion commenced. The EPSPs were largest during the depolarized phase of the step cycle, and in 17 of our 22 cells the EPSP was replaced by an IPSP of slightly longer latency during the hyperpolarized phase. The mean latency of the EPSPs measured from the stimulus artifact produced by stimulation of the MLR was 5.1 ms (3.0-7.0 ms). In all cases, the IPSP occurred 0.6 ms or more after the onset of the EPSP in the same cell. Later PSPs were sometimes observed as well. The effects of constant current injection on the membrane potential oscillations associated with fictive locomotion (locomotor drive potentials) were examined. The results showed that the amplitudes of the locomotor drive potentials (LDPs) could be affected by depolarizing and hyperpolarizing current injection. The data is consistent with the LDP having a predominant inhibitory component, which is more readily altered by current injection than is the excitatory component. The effect of constant current injections on the MLR-evoked PSPs was also examined, and it was observed that both EPSPs and IPSPs could be affected by the injected currents. The EPSPs increased in amplitude with constant hyperpolarizing current injection, and this fact rules out the possibility that the EPSP is actually a reversed IPSP. The IPSP was decreased in amplitude by hyperpolarizing current injection. Combined stimulation of the MLR and the ipsilateral high-threshold muscle or cutaneous afferents produced facilitation of both short- and long-latency MLR-evoked PSPs, suggesting that the two pathways share common interneurons. The possibility that the long-latency PSPs are produced by rapid oscillation in the locomotor central pattern generator is discussed. We concluded that MLR stimulation that evokes fictive locomotion produces both excitation and inhibition of spinal motoneurons. Spinal interneuronal systems are implicated and may be those involved in the initiation and control of locomotion. The probable relay sites for the descending pathway from the MLR to motoneurons are discussed.
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Park, Sung Ho, and Dong Pyo Hong. "Optimal Locomotive Control Parameters of Biologically Inspired Four-Legged Walking Machine." Applied Mechanics and Materials 607 (July 2014): 397–404. http://dx.doi.org/10.4028/www.scientific.net/amm.607.397.
Full textAbstract:
Mechanical models have been more on technical rather than on biological concepts, which yield unstable locomotion with low speed. Structural and locomotive characteristics of living creatures are copied and modeled with 13 links, 12 joints and body, from the mechanical engineering viewpoint. Quadruped models are simulated as a time variable for the one cycle. Torques at joints are calculated and finally converted to total consumed energy. Variables, specifying structure and locomotion, are applied to the simulation as a time function, and the optimal variables which minimize energy expenditure are derived which can be directly applied to the Quadruped locomotion.
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Park, Sung Ho, and Dong Pyo Hong. "Optimal Locomotive Parameters of Four-Legged Bio-Robot by Minimizing Energy Consumption." Advanced Materials Research 945-949 (June 2014): 1435–41. http://dx.doi.org/10.4028/www.scientific.net/amr.945-949.1435.
Full textAbstract:
Four-Legged walking robot is mechanically modeled by copying mammals, which have 13 links and 12 joints. But mechanical models are more on technical rather than on biological concepts, which yield unstable locomotion with low speed. Advanced biological locomotive phenomena and their structural characteristics are applied to the mechanical model and simulated for the one cycle. Torques at joints are calculated and finally converted to total consumed energy. Variables, specifying structure and locomotion, are applied to the simulation as a time function, and the optimal variables which minimize energy expenditure are derived which can be directly applied to the Quadruped locomotion.
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Chen, Yi, Lu Chen, Rongliang Liu, Yu Wang, Xiang Yang Chen, and Jonathan R. Wolpaw. "Locomotor impact of beneficial or nonbeneficial H-reflex conditioning after spinal cord injury." Journal of Neurophysiology 111, no. 6 (March 15, 2014): 1249–58. http://dx.doi.org/10.1152/jn.00756.2013.
Full textAbstract:
When new motor learning changes neurons and synapses in the spinal cord, it may affect previously learned behaviors that depend on the same spinal neurons and synapses. To explore these effects, we used operant conditioning to strengthen or weaken the right soleus H-reflex pathway in rats in which a right spinal cord contusion had impaired locomotion. When up-conditioning increased the H-reflex, locomotion improved. Steps became longer, and step-cycle asymmetry (i.e., limping) disappeared. In contrast, when down-conditioning decreased the H-reflex, locomotion did not worsen. Steps did not become shorter, and asymmetry did not increase. Electromyographic and kinematic analyses explained how H-reflex increase improved locomotion and why H-reflex decrease did not further impair it. Although the impact of up-conditioning or down-conditioning on the H-reflex pathway was still present during locomotion, only up-conditioning affected the soleus locomotor burst. Additionally, compensatory plasticity apparently prevented the weaker H-reflex pathway caused by down-conditioning from weakening the locomotor burst and further impairing locomotion. The results support the hypothesis that the state of the spinal cord is a “negotiated equilibrium” that serves all the behaviors that depend on it. When new learning changes the spinal cord, old behaviors undergo concurrent relearning that preserves or improves their key features. Thus, if an old behavior has been impaired by trauma or disease, spinal reflex conditioning, by changing a specific pathway and triggering a new negotiation, may enable recovery beyond that achieved simply by practicing the old behavior. Spinal reflex conditioning protocols might complement other neurorehabilitation methods and enhance recovery.
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Giroux, Nathalie, Tomás A. Reader, and Serge Rossignol. "Comparison of the Effect of Intrathecal Administration of Clonidine and Yohimbine on the Locomotion of Intact and Spinal Cats." Journal of Neurophysiology 85, no. 6 (June 1, 2001): 2516–36. http://dx.doi.org/10.1152/jn.2001.85.6.2516.
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Several studies have shown that noradrenergic mechanisms are important for locomotion. For instance, L-dihydroxyphenylalanine (L-DOPA) can initiate “fictive” locomotion in immobilized acutely spinalized cats and α2-noradrenergic agonists, such as 2,6,-dichloro- N-2-imidazolidinylid-enebenzenamine (clonidine), can induce treadmill locomotion soon after spinalization. However, the activation of noradrenergic receptors may be not essential for the basic locomotor rhythmicity because chronic spinal cats can walk with the hindlimbs on a treadmill in the absence of noradrenergic stimulation because the descending pathways are completely severed. This suggests that locomotion, in intact and spinal conditions, is probably expressed and controlled through different neurotransmitter mechanisms. To test this hypothesis, we compared the effect of the α2 agonist, clonidine, and the antagonist (16α, 17α)-17-hydroxy yohimbine-16-carboxylic acid methyl ester hydrochloride (yohimbine), injected intrathecally at L3–L4before and after spinalization in the same cats chronically implanted with electrodes to record electromyograms (EMGs). In intact cats, clonidine (50–150 μg/100 μl) modulated the locomotor pattern slightly causing a decrease in duration of the step cycle accompanied with some variation of EMG burst amplitude and duration. In the spinal state, clonidine could trigger robust and sustained hind limb locomotion in the first week after the spinalization at a time when the cats were paraplegic. Later, after the spontaneous recovery of a stable locomotor pattern, clonidine prolonged the cycle duration, increased the amplitude and duration of flexor and extensor bursts, and augmented the foot drag at the onset of swing. In intact cats, yohimbine at high doses (800–1600 μg/100 μl) caused major walking difficulties characterized by asymmetric stepping, stumbling with poor lateral stability, and, at smaller doses (400 μg/100 μl), only had slight effects such as abduction of one of the hindlimbs and the turning of the hindquarters to one side. After spinalization, yohimbine had no effect even at the largest doses. These results indicate that, in the intact state, noradrenergic mechanisms probably play an important role in the control of locomotion since blocking the receptors results in a marked disruption of walking. In the spinal state, although the receptors are still present and functional since they can be activated by clonidine, they are seemingly not critical for the spontaneous expression of spinal locomotion since their blockade by yohimbine does not impair spinal locomotion. It is postulated therefore that the expression of spinal locomotion must depend on the activation of other types of receptors, probably related to excitatory amino acids.
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Beyeler, Anna, Charles Métais, Denis Combes, John Simmers, and Didier Le Ray. "Metamorphosis-Induced Changes in the Coupling of Spinal Thoraco-Lumbar Motor Outputs During Swimming in Xenopus laevis." Journal of Neurophysiology 100, no. 3 (September 2008): 1372–83. http://dx.doi.org/10.1152/jn.00023.2008.
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Anuran metamorphosis includes a complete remodeling of the animal's biomechanical apparatus, requiring a corresponding functional reorganization of underlying central neural circuitry. This involves changes that must occur in the coordination between the motor outputs of different spinal segments to harmonize locomotor and postural functions as the limbs grow and the tail regresses. In premetamorphic Xenopus laevis tadpoles, axial motor output drives rostrocaudally propagating segmental myotomal contractions that generate propulsive body undulations. During metamorphosis, the anterior axial musculature of the tadpole progressively evolves into dorsal muscles in the postmetamorphic froglet in which some of these back muscles lose their implicit locomotor function to serve exclusively in postural control in the adult. To understand how locomotor and postural systems interact during locomotion in juvenile Xenopus, we have investigated the coordination between postural back and hindlimb muscle activity during free forward swimming. Axial/dorsal muscles, which contract in bilateral alternation during undulatory swimming in premetamorphic tadpoles, change their left-right coordination to become activated in phase with bilaterally synchronous hindlimb extensions in locomoting juveniles. Based on in vitro electrophysiological experiments as well as specific spinal lesions in vivo, a spinal cord region was delimited in which propriospinal interactions are directly responsible for the coordination between leg and back muscle contractions. Our findings therefore indicate that dynamic postural adjustments during adult Xenopus locomotion are mediated by local intraspinal pathways through which the lumbar generator for hindlimb propulsive kicking provides caudorostral commands to thoracic spinal circuitry controlling the dorsal trunk musculature.
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Misiaszek, John E., and Keir G. Pearson. "Stretch of Quadriceps Inhibits the Soleus H Reflex During Locomotion in Decerebrate Cats." Journal of Neurophysiology 78, no. 6 (December 1, 1997): 2975–84. http://dx.doi.org/10.1152/jn.1997.78.6.2975.
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Misiaszek, John E. and Keir G. Pearson. Stretch of quadriceps inhibits the soleus H reflex during locomotion in decerebrate cats. J. Neurophysiol. 78: 2975–2984, 1997. Previously, it has been demonstrated that afferent signals from the quadriceps muscles can suppress H reflexes in humans during passive movements of the leg. To establish whether afferent input from quadriceps contributes to the modulation of the soleus H reflex during locomotion, the soleus H reflex was conditioned with stretches of the quadriceps muscle during bouts of spontaneous treadmill locomotion in decerebrate cats. We hypothesized that 1) in the absence of locomotion such conditioning would lead to suppression of the soleus H reflex and 2) this would be retained during periods of locomotor activity. In the absence of locomotion, slow sinusoidal stretches (0.2 Hz, 8 mm) of quadriceps cyclically modulated the amplitude of the soleus H reflex. The H reflex amplitude was least during the lengthening of the quadriceps and greatest as quadriceps shortened. Further, low-amplitude vibrations (48–78 μm) applied to the patellar tendon suppressed the reflex, indicating that the muscle spindle primaries were the receptor eliciting the effect. During bouts of locomotion, ramp stretches of quadriceps were applied during the extensor phase of the locomotor rhythm. Soleus H reflexes sampled at two points during the stance phase were reduced compared with phase-matched controls. The background level of the soleus electromyographic activity was not influenced by the applied stretches to quadriceps, either during locomotion or in the absence of locomotion. This indicates that the excitability of the soleus motoneuron pool was not influenced by the stretching of quadriceps, and that the inhibition of the soleus H reflex is due to presynaptic inhibition. We conclude that group Ia afferent feedback from quadriceps contributes to the regulation of the soleus H reflex during the stance phase of locomotion in decerebrate cats. This afferent mediated source of regulation of the H reflex, or monosynaptic stretch reflex, would allow for rapid alterations in reflex gain according to the dynamic needs of the animal. During early stance, this source of regulation might suppress the soleus stretch reflex to allow adequate yielding at the ankle and facilitate the movement of the body over the foot.