Spatiotemporal characteristics of 5-HT and dopamine-induced rhythmic hindlimb activity in the in vitro neonatal rat

1996 ◽  
Vol 75 (4) ◽  
pp. 1472-1482 ◽  
Author(s):  
O. Kiehn ◽  
O. Kjaerulff
Keyword(s):  
Muscle Activity ◽  
Central Pattern Generators ◽  
Rhythmic Activity ◽  
Biceps Femoris ◽  
Ventral Root ◽  
Neonatal Rat ◽  
Cycle Duration ◽  
Spatiotemporal Characteristics ◽  
The Relationship

1. Rhythmic activity was induced with either serotonin (5-HT; 10-100 microM) or dopamine (0.1-1.0 mM), in the in vitro spinal cord preparation of neonatal rats, with one intact hindlimb attached. Patterns of activity were investigated with multiple EMG recordings and the spatiotemporal characteristics of 5-HT- and dopamine-induced activity compared. 2. Dopamine-induced rhythmic activity was slow (cycle duration: 2.2-70.1 s) and irregular, whereas rhythmic activity induced by 5-HT was fast (cycle duration: 1.3-5.1 s) and regular. 3. During 5-HT- and dopamine-induced rhythmic activity, the timing of muscular activity was similar for hip flexors and hip adductors, for semimembranosus (hip extensor), and for muscles controlling the ankle and the foot. 4. In contrast, notable differences in the phase in the pattern induced by 5-HT compared with that induced by dopamine were found in the biceps femoris, semitendinosus, and quadriceps muscles. Biceps femoris and semitendinosus (functional hip extensors and knee flexors) were always extensor-like during 5-HT-induced activity, whereas in dopamine, these muscles displayed flexor-like bursts and double bursts as well as extensor-like bursts. Lack of EMG activity in biceps femoris and semitendinosus was encountered also in dopamine. In rectus femoris, vastus lateralis, and vastus medialis (main function: knee extension), the activity was dominated by flexor-like bursts in 5-HT, whereas in dopamine the activity was shifted to a predominantly extensor-like pattern. 5. The relationship between flexor and extensor burst duration and cycle duration was more variable than described for locomotor activity in adult animals. 6. The relative timing of muscle activity was stable from P0 to P4. The most important difference between rats aged 0-1 days and rats aged 2-4 days was a delayed flexor-extensor transition in older animals. 7. The complex timing of hindlimb muscle activity was relatively unchanged after transecting all dorsal roots. 8. Finally, the relationship between flexor and extensor activity and ventral root discharges was determined. It was found that the L2 ventral root burst was in phase with simple flexors while the L5 burst coincide with the extensor phase. 9. We conclude, that 5-HT and dopamine can activate spinal central pattern generators (CPGs) that already at birth are able to produce distinct patterns of motor activity. Modulatory inputs thus seems to be able to reconfigure the CPGs to produce specific motor outputs.

Locomotor Rhythm Evoked by Ventrolateral Funiculus Stimulation in the Neonatal Rat Spinal Cord In Vitro

1997 ◽  
Vol 77 (1) ◽  
pp. 200-206 ◽  
Author(s):  
David S. K. Magnuson ◽  
Tammy C. Trinder
Keyword(s):  
Rhythmic Activity ◽  
Ventral Root ◽  
Neonatal Rat ◽  
Rat Spinal Cord ◽  
Locomotor Rhythm ◽  
Ventral Roots ◽  
Root Responses ◽  
Bilateral Projection ◽  
Ventrolateral Funiculus

Magnuson, David S. K. and Tammy C. Trinder. Locomotor rhythm evoked by ventrolateral funiculus stimulation in the neonatal rat spinal cord in vitro. J. Neurophysiol. 77: 200–206, 1997. Spinal cords from 2- to 8-day-old rats, maintained in vitro, were used to investigate the effects of discrete electrical stimuli applied to the ventrolateral funiculus (VLF) on motor neuron activity recorded from the lumbar ventral roots. Short trains of stimuli (1–3 s) delivered to one VLF in the low cervical region elicited rhythmic activity that persisted for up to 30 s. Responses consisted of short periods of activity (1–5 s) occurring simultaneously in the ipsilateral L5 and contralateral L3 ventral roots that alternated with similar bursts of activity in the ipsilateral L3 ventral root, a pattern consistent with locomotion. The rhythmicity of the ventral root responses to VLF stimulation was not affected by midsagittal sectioning of the preparation rostral to T10 and/or caudal to L4. Midsagittal sectioning of the lower thoracic or upper lumbar segments, however, disrupted the rhythmicity of the ventral root responses, leaving only long-duration simultaneous activation of the ipsilateral roots following VLF stimulus trains. The minimum lesion that effectively abolished the rhythmicity was one that divided only the L2 and L3 segments. In preparations rendered arrhythmic to VLF stimulation by an L2/L3 midsagittal lesion, rhythmicity could still be induced by N-methyl-d-aspartate (NMDA; 2–5 μM) and serotonin (5-HT; 20–50 μM), a drug combination commonly used to induce locomotor-like rhythmicity and air-stepping in vitro. Field potentials recorded following single stimuli delivered to the VLF revealed short-latency, large-amplitude responses in the ventral horn and intermediate gray both ipsilateral and contralateral to the stimulus site at T12 and L2. These observations suggest that 1) the discrete pathway under study may be an important descending locomotor command pathway and 2) this pathway has a strong bilateral projection in the lower thoracic and upper lumbar segments that is crucial for the initiation of VLF-induced rhythmic motor output. The induction of rhythmicity by NMDA/5-HT in an L2/L3-lesioned preparation suggests that these two rhythmogenic mechanisms may represent different levels within the circuitry that comprises the central pattern generator for locomotion. The rhythmic activity resulting from VLF stimulation is dependent on a bilateral projection that can be bypassed by the generalized excitation and subsequent rhythmicity that results from bath application of the NMDA/5-HT combination.

Differential Effects of Opioids on Sacrocaudal Afferent Pathways and Central Pattern Generators in the Neonatal Rat Spinal Cord

2007 ◽  
Vol 97 (4) ◽  
pp. 2875-2886 ◽  
Author(s):  
D. Blivis ◽  
G. Z. Mentis ◽  
M. J. O'Donovan ◽  
A. Lev-Tov
Keyword(s):  
Spinal Cord ◽  
Opioid Receptor ◽  
Central Pattern Generators ◽  
Rhythmic Activity ◽  
Ventral Horn ◽  
Neonatal Rat ◽  
Experimental Chamber ◽  
Afferent Pathways ◽  
Anatomical Basis ◽  
Ventromedial Medulla

The effects of opioids on sacrocaudal afferent (SCA) pathways and the pattern-generating circuitry of the thoracolumbar and sacrocaudal segments of the spinal cord were studied in isolated spinal cord and brain stem-spinal cord preparations of the neonatal rat. The locomotor and tail moving rhythm produced by activation of nociceptive and nonnociceptive sacrocaudal afferents was completely blocked by specific application of the μ-opioid receptor agonist [d-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin acetate salt (DAMGO) to the sacrocaudal but not the thoracolumbar segments of the spinal cord. The rhythmic activity could be restored after addition of the opioid receptor antagonist naloxone to the experimental chamber. The opioid block of the SCA-induced rhythm is not due to impaired rhythmogenic capacity of the spinal cord because a robust rhythmic activity could be initiated in the thoracolumbar and sacrocaudal segments in the presence of DAMGO, either by stimulation of the ventromedial medulla or by bath application of N-methyl-d-aspartate/serotonin. We suggest that the opioid block of the SCA-induced rhythm involves suppression of synaptic transmission through sacrocaudal interneurons interposed between SCA and the pattern-generating circuitry. The expression of μ opioid receptors in several groups of dorsal, intermediate and ventral horn interneurons in the sacrocaudal segments of the cord, documented in this study, provides an anatomical basis for this suggestion.

scholarly journals Muscle Activity and Morphology in Slalom Skiing by a Single-Leg Amputee Ski Racer: A Case Study of a Paralympic Athlete

2021 ◽  
pp. 500-5007
Author(s):  
Yusuke Ishige ◽  
Shinsuke Yoshioka ◽  
Noriko Hakamada ◽  
Yuki Inaba
Keyword(s):  
Muscle Activity ◽  
Elite Athlete ◽  
Vastus Lateralis ◽  
Biceps Femoris ◽  
Cross Sectional ◽  
Measurement Units ◽  
The Mean ◽  
The Right ◽  
The Relationship

The aim of this study was to clarify the characteristics of skiing by a single-leg amputee ski racer from the viewpoints of muscle activity, morphology, and the relationship between both elements through comparisons with those of a non-disabled ski racer. One elite athlete, classified as LW2 (left thigh amputation), and one non-disabled athlete, as a control, participated in this study. The cross-sectional area of thigh muscles was measured through magnetic resonance imaging. Additionally, muscle activities and joint and segment kinematics during slalom skiing were measured using electromyography and inertial measurement units, respectively. The muscle activities and joint kinematics of the amputee racer in the turn in which he performed with the inside edge of the ski were similar to those of the outside leg of the non-disabled racer over a turn. In contrast, at the turn in which the amputee racer performed with the outside edge (more difficult side), the amputee racer largely activated the biceps femoris (BF) in the first half of the turn compared to the non-disabled racer. The reason could be to control the angular momentum of the trunk during the forward tilting motion. This is because a greater activity of the BF was observed during the period in which the forward tilt of the trunk was increased, and the mean activity of the BF was the greatest during the first half of the right turn in which the range of the motion of the forward tilt was the greatest. In terms of muscle morphology of the amputee racer, a significant hypertrophy of the BF and vastus lateralis was observed compared to the non-disabled racers. The well-developed BF was considered to be related to the large activity during the turn performed with the outside edge of the ski.

scholarly journals Relationship of Performance Measures and Muscle Activity between a 180° Change of Direction Task and Different Countermovement Jumps

Sports ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 47 ◽  
Author(s):  
Hallvard Nygaard Falch ◽  
Håvard Guldteig Rædergård ◽  
Roland Van den Tillaar
Keyword(s):  
Performance Measures ◽  
Muscle Activity ◽  
Muscle Activation ◽  
Biceps Femoris ◽  
Soccer Players ◽  
Countermovement Jump ◽  
Change Of Direction ◽  
Relationship Of ◽  
The Relationship ◽  
Adductor Longus

The ability to rapidly perform change of direction (COD) is crucial for performance in Soccer. COD speed is thought to share similarities with countermovement jumps in kinematics and muscle activation. Thus, the objective of the current study was to investigate the relationship between muscle activities in performance measures of a modified 505-agility test and different countermovement jumps. Twenty-one experienced soccer players performed a COD test including the 505-agility test and uni- and bi-lateral horizontal and vertical countermovement jumps. The main findings were that the vertical bilateral and horizontal unilateral countermovement jump were able to predict total time to complete the COD, but not 505-agility time. Muscle activity in the COD and countermovement jumps was only distinguished by a higher peak muscle activity for the adductor longus, semitendinosus and biceps femoris in the COD to stabilize the hip and decelerate knee joint movements when turning compared with the jumps. Conclusively, the relationship between performance in countermovement jumps and total time to complete the COD test was due to longer sprint distances, which makes the distinction between performances bigger. Peak muscle activity of most muscles is similar between the jumps and the COD step, indicating similar muscular demands between these activities.

Contribution of Commissural Projections to Bulbospinal Activation of Locomotion in the In Vitro Neonatal Rat Spinal Cord

2009 ◽  
Vol 101 (3) ◽  
pp. 1171-1178 ◽  
Author(s):  
Kristine C. Cowley ◽  
Eugene Zaporozhets ◽  
Raed A. Joundi ◽  
Brian J. Schmidt
Keyword(s):  
Spinal Cord ◽  
Brain Stem ◽  
Rhythmic Activity ◽  
Conus Medullaris ◽  
Neonatal Rat ◽  
Thoracolumbar Junction ◽  
Junction Region ◽  
Locomotor Rhythm ◽  
Wide Range

Commissural projections are required for left-right coordination during locomotion. However, their role, if any, in rhythm production is unknown. This study uses the neonatal rat in vitro brain stem–spinal cord model to examine the rostrocaudal distribution of locomotor-related commissural projections and study whether commissural connections are needed for the generation of hindlimb rhythmic activity in response to electrical stimulation of the brain stem. Midsagittal lesions were made at a wide range of rostrocaudal levels. Locomotor-like activity persisted in some preparations despite midsagittal lesions extending from C1 to the mid-L1 level or from the conus medullaris to the T12/13 junction. In some preparations, midsagittal lesions throughout the entire spinal cord had no effect on locomotor-like activity if two or three contiguous segments remained intact. Those bridging segments had to include the T13 and/or L1 levels. These observations suggested that commissural projections in the thoracolumbar junction region were critical. However, locomotor-like activity was also elicited in preparations with limited midsagittal lesions focused on the thoracolumbar junction (T12 through L1 or L2 inclusive). In other experiments, locomotor-like activity was evoked by bath-applied 5-hydroxytryptamine (5-HT) and N-methyl-d-aspartate (NMDA). Appropriate side-to-side coordination was observed, even when only one segment remained bilaterally intact. Commissural projections traversing the thoracolumbar junction region were most effective. In combination, these results suggest that locomotor-related commissural projections are redundantly distributed along a bi-directional gradient that centers on the thoracolumbar junction. This commissural system not only provides a robust left-right coordinating mechanism but also supports locomotor rhythm generation in response to brain stem stimulation.

Neuronal Bursting Induced by NK3 Receptor Activation in the Neonatal Rat Spinal Cord In Vitro

2001 ◽  
Vol 86 (6) ◽  
pp. 2939-2950 ◽  
Author(s):  
Cristina Marchetti ◽  
Andrea Nistri
Keyword(s):  
Spinal Cord ◽  
Membrane Potential ◽  
Dorsal Root ◽  
Extracellular Recording ◽  
Rhythmic Activity ◽  
Input Resistance ◽  
Receptor Activation ◽  
Neonatal Rat ◽  
Rat Spinal Cord

Intracellular recording from lumbar motoneurons and extracellular recording from ventral roots of the neonatal rat isolated spinal cord were used to study the mechanisms responsible for the excitation mediated by NK3 tachykinin receptors. The selective NK3 agonists senktide or [MePhe7]neurokinin B induced a slow depolarization with superimposed oscillations (mean period ± SD was 2.8 ± 0.8 s) that, in the majority of cases, showed left-right alternation at segmental level and were synchronous between L2 and L5 of the same side. During agonist wash out (5–20 min) a delayed form of hyperexcitability emerged consisting of bursts lasting 8 ± 2 s (average interburst interval 55 ± 21 s) with superimposed oscillations usually with homosegmental alternation and heterosegmental synchronicity. Such bursting was accompanied by depression of GABAergic dorsal root potentials evoked by dorsal root stimulation and of the recurrent inhibitory postsynaptic potential recorded from motoneurons. Despite bursting, motoneuron membrane potential returned to baseline while input resistance was increased. Bursts were a network-dependent phenomenon triggered by previous NK3 receptor activation because bursting was suppressed by glutamate receptor antagonists and was insensitive to motoneuron membrane potential or subsequent application of an NK3 receptor antagonist. NK3 receptors operated synergistically with N-methyl-d-aspartate (NMDA) and 5-hydroxytryptamine (5-HT) to trigger fully alternating locomotor-like rhythms while NK3 receptor antagonism disrupted the same rhythm. In summary, in the neonatal rat spinal cord NK3 receptors could trigger rhythmic activity predominantly with alternation at segmental level but with synchronous coupling between ipsilateral motor pools. NK3receptor activation could also facilitate fictive locomotor patterns induced by NMDA and 5-HT.

Medullary regions for neurogenesis of gasping: noeud vital or noeuds vitals?

1996 ◽  
Vol 81 (5) ◽  
pp. 1865-1877 ◽  
Author(s):  
Walter M. St. John
Keyword(s):  
Mammalian Species ◽  
Respiratory Rhythm ◽  
Rhythmic Activity ◽  
Neonatal Rat ◽  
Rhythm Generation ◽  
Bötzinger Complex ◽  
Per Se ◽  
Respiratory Rhythm Generation

St. John, Walter M. Medullary regions for neurogenesis of gasping: noeud vital or noeuds vitals? J. Appl. Physiol. 81(5): 1865–1877, 1996.—Gasping is a critical mechanism for survival in that it serves as a mechanism for autoresuscitation when eupnea fails. Eupnea and gasping are separable patterns of automatic ventilatory activity in all mammalian species from the day of birth. The neurogenesis of the gasp is dependent on the discharge of neurons in the rostroventral medulla. This gasping center overlaps a region termed “the pre-Bötzinger complex.” Neuronal activities of this complex, characterized in an in vitro brain stem spinal cord preparation of the neonatal rat, have been hypothesized to underlie respiratory rhythm generation. Yet, the rhythmic activity of this in vitro preparation is markedly different from eupnea but identical with gasping in vivo. In eupnea, medullary neuronal activities generating the gasp and the identical rhythm of the in vitro preparation are incorporated into a portion of the pontomedullary circuit defining eupneic ventilatory activity. However, these medullary neuronal activities do not appear critical for the neurogenesis of eupnea, per se.

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