scholarly journals Preferred locomotor phase of activity of lumbar interneurons during air-stepping in subchronic spinal cats

2011 ◽  
Vol 105 (3) ◽  
pp. 1011-1022 ◽  
Author(s):  
Nicholas AuYong ◽  
Karen Ollivier-Lanvin ◽  
Michel A. Lemay
Keyword(s):  
Spinal Cord ◽  
Traveling Wave ◽  
Spatial Organization ◽  
Activity Patterns ◽  
Circular Statistics ◽  
Distributed Network ◽  
Step Cycle ◽  
Spinal Interneurons ◽  
Wave Network ◽  
Flexion And Extension

Spinal locomotor circuits are intrinsically capable of driving a variety of behaviors such as stepping, scratching, and swimming. Based on an observed rostrocaudal wave of activity in the motoneuronal firing during locomotor tasks, the traveling-wave hypothesis proposes that spinal interneuronal firing follows a similar rostrocaudal pattern of activation, suggesting the presence of spatially organized interneuronal modules within the spinal motor system. In this study, we examined if the spatial organization of the lumbar interneuronal activity patterns during locomotor activity in the adult mammalian spinal cord was consistent with a traveling-wave organizational scheme. The activity of spinal interneurons within the lumbar intermediate zone was examined during air-stepping in subchronic spinal cats. The preferred phase of interneuronal activity during a step cycle was determined using circular statistics. We found that the preferred phases of lumbar interneurons from both sides of the cord were evenly distributed over the entire step cycle with no indication of functional groupings. However, when units were subcategorized according to spinal hemicords, the preferred phases of units on each side largely fell around the period of extensor muscle activity on each side. In addition, there was no correlation between the preferred phases of units and their rostrocaudal locations along the spinal cord with preferred phases corresponding to both flexion and extension phases of the step cycle found at every rostrocaudal level of the cord. These results are consistent with the hypothesis that interneurons operate as part of a longitudinally distributed network rather than a rostrocaudally organized traveling-wave network.

scholarly journals Population spatiotemporal dynamics of spinal intermediate zone interneurons during air-stepping in adult spinal cats

2011 ◽  
Vol 106 (4) ◽  
pp. 1943-1953 ◽  
Author(s):  
Nicholas AuYong ◽  
Karen Ollivier-Lanvin ◽  
Michel A. Lemay
Keyword(s):  
Spinal Cord ◽  
Spatial Organization ◽  
Transition Period ◽  
Spatiotemporal Dynamics ◽  
Intermediate Zone ◽  
Continuous Measure ◽  
Electrode Arrays ◽  
Step Cycle ◽  
Population Activity ◽  
Left And Right

The lumbar spinal cord circuitry can autonomously generate locomotion, but it remains to be determined which types of neurons constitute the locomotor generator and how their population activity is organized spatially in the mammalian spinal cord. In this study, we investigated the spatiotemporal dynamics of the spinal interneuronal population activity in the intermediate zone of the adult mammalian cord. Segmental interneuronal population activity was examined via multiunit activity (MUA) during air-stepping initiated by perineal stimulation in subchronic spinal cats. In contrast to single-unit activity, MUA provides a continuous measure of neuronal activity within a ∼100-μm volume around the recording electrode. MUA was recorded during air-stepping, along with hindlimb muscle activity, from segments L3 to L7 with two multichannel electrode arrays placed into the left and right hemicord intermediate zones (lamina V–VII). The phasic modulation and spatial organization of MUA dynamics were examined in relation to the locomotor cycle. Our results show that segmental population activity is modulated with respect to the ipsilateral step cycle during air-stepping, with maximal activity occurring near the ipsilateral swing to stance transition period. The phase difference between the population activity within the left and right hemicords was also found to correlate to the left-right alternation of the step cycle. Furthermore, examination of MUA throughout the rostrocaudal extent showed no differences in population dynamics between segmental levels, suggesting that the spinal interneurons targeted in this study may operate as part of a distributed “clock” mechanism rather than a rostrocaudal oscillation as seen with motoneuronal activity.

scholarly journals Evaluation of Human Disturbance on the Activity of Medium–Large Mammals in Myanmar Tropical Forests

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 290
Author(s):  
Giacomo Cremonesi ◽  
Francesco Bisi ◽  
Lorenzo Gaffi ◽  
Thet Zaw ◽  
Hla Naing ◽  
...  
Keyword(s):  
Human Disturbance ◽  
Daily Activity ◽  
Wildlife Conservation ◽  
Activity Patterns ◽  
Circular Statistics ◽  
Large Mammals ◽  
Human Presence ◽  
Significant Difference ◽  
The Status ◽  
Statistical Approaches

The effects of human disturbance represent one of the major threats for wildlife conservation. Many studies have shown that wildlife avoids or reduces direct contact with human activities through changes in activity patterns, and by minimizing spatiotemporal overlap. In this study, we investigated the possible effects of human presence on the temporal activity of medium-to-large mammals using two areas in Myanmar that differ in the intensity of human disturbance. We monitored temporal segregation mechanisms using camera trapping data and with two statistical approaches: daily activity overlaps between humans and wildlife and circular statistics. We did not find a significant difference in overlapping activity between areas but, thanks to circular statistics, we found that some species show changes in activity patterns, suggesting temporal avoidance. We observed that the daily activity of five species differed between areas of Myanmar, likely adopting mechanisms to reduce overlap in areas highly frequented by humans. Interestingly, these species are all threatened by hunting or poaching activities, four of which have been described in literature as “cathemeral”, or species that are active through day and night. This study suggests that some species adapt their behavior, at least partially, to avoid human presence in habitats with higher anthropic occurrence and increase our knowledge on the status of medium–large mammals in a poorly studied country as Myanmar.

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

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

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

scholarly journals Spinal microcircuits comprising dI3 interneurons are necessary for motor functional recovery following spinal cord transection

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Tuan V Bui ◽  
Nicolas Stifani ◽  
Turgay Akay ◽  
Robert M Brownstone
Keyword(s):  
Spinal Cord ◽  
Functional Recovery ◽  
Motor System ◽  
Motor Training ◽  
Prediction Errors ◽  
Spinal Interneurons ◽  
Motor Activities ◽  
Afferent Inputs ◽  
To Receive ◽  
Sensory Prediction

The spinal cord has the capacity to coordinate motor activities such as locomotion. Following spinal transection, functional activity can be regained, to a degree, following motor training. To identify microcircuits involved in this recovery, we studied a population of mouse spinal interneurons known to receive direct afferent inputs and project to intermediate and ventral regions of the spinal cord. We demonstrate that while dI3 interneurons are not necessary for normal locomotor activity, locomotor circuits rhythmically inhibit them and dI3 interneurons can activate these circuits. Removing dI3 interneurons from spinal microcircuits by eliminating their synaptic transmission left locomotion more or less unchanged, but abolished functional recovery, indicating that dI3 interneurons are a necessary cellular substrate for motor system plasticity following transection. We suggest that dI3 interneurons compare inputs from locomotor circuits with sensory afferent inputs to compute sensory prediction errors that then modify locomotor circuits to effect motor recovery.

Multiple Effects of Serotonin and Acetylcholine on Hyperpolarization-Activated Inward Current in Locomotor Activity-Related Neurons in Cfos-EGFP Mice

2010 ◽  
Vol 104 (1) ◽  
pp. 366-381 ◽  
Author(s):  
Yue Dai ◽  
Larry M. Jordan
Keyword(s):  
Spinal Cord ◽  
Motor System ◽  
Reversal Potential ◽  
Rhythmic Activity ◽  
Maximal Conductance ◽  
Inward Current ◽  
Spinal Interneurons ◽  
Whole Cell Patch Clamp ◽  
Activation Rate ◽  
Maximal Activation

Hyperpolarization-activated inward current ( Ih) has been shown to be involved in production of bursting during various forms of rhythmic activity. However, details of Ih in spinal interneurons related to locomotion remain unknown. Using Cfos-EGFP transgenic mice (P6–P12) we are able to target the spinal interneurons activated by locomotion. Following a locomotor task, whole cell patch-clamp recordings were obtained from ventral EGFP+ neurons in spinal cord slices (T13–L4, 200–250 μm). Ih was found in 51% of EGFP+ neurons ( n = 149) with almost even distribution in lamina VII (51%), VIII (47%), and X (55%). Ih could be blocked by ZD7288 (10–20 μM) or cesium (1–1.5 mM) but was insensitive to barium (2–2.5 mM). Ih activated at −80.1 ± 9.2 mV with half-maximal activation −95.5 ± 13.3 mV, activation rate 10.0 ± 3.2 mV, time constant 745 ± 501 ms, maximal conductance 1.0 ± 0.7 nS, and reversal potential −34.3 ± 3.6 mV. 5-HT (15–20 μM) and ACh (20–30 μM) produced variable effects on Ih. 5-HT increased Ih in 43% of EGFP+ neurons ( n = 37), decreased Ih in 24%, and had no effect on Ih in 33% of the neurons. ACh decreased Ih in 67% of EGFP+ neurons ( n = 18) with unchanged Ih in 33% of the neurons. This study characterizes the Ih in locomotor-related interneurons and is the first to demonstrate the variable effects of 5-HT and ACh on Ih in rodent spinal interneurons. The finding of 5-HT and ACh-induced reduction of Ih in EGFP+ neurons suggests a novel mechanism that the motor system could use to limit the participation of certain neurons in locomotion.

Intrinsic Properties Shape the Firing Pattern of Ventral Horn Interneurons From the Spinal Cord of the Adult Turtle

2006 ◽  
Vol 96 (5) ◽  
pp. 2670-2677 ◽  
Author(s):  
Morten Smith ◽  
Jean-François Perrier
Keyword(s):  
Spinal Cord ◽  
Activity Patterns ◽  
Ventral Horn ◽  
Inward Rectification ◽  
Intrinsic Properties ◽  
Patch Clamp Technique ◽  
Firing Patterns ◽  
Pharmacological Tests ◽  
Low Threshold

Interneurons in the ventral horn of the spinal cord play a central role in motor control. In adult vertebrates, their intrinsic properties are poorly described because of the lack of in vitro preparations from the spinal cord of mature mammals. Taking advantage of the high resistance to anoxia in the adult turtle, we used a slice preparation from the spinal cord. We used the whole cell blind patch-clamp technique to record from ventral horn interneurons. We characterized their firing patterns in response to depolarizing current pulses and found that all the interneurons fired repetitively. They displayed bursting, adapting, delayed, accelerating, or oscillating firing patterns. By combining electrophysiological and pharmacological tests, we showed that interneurons expressed slow inward rectification, plateau potential, voltage-sensitive transient outward rectification, and low-threshold spikes. These results demonstrate a diversity of intrinsic properties that may enable a rich repertoire of activity patterns in the network of ventral horn interneurons.

Spinal Cord Coordination of Hindlimb Movements in the Turtle: Intralimb Temporal Relationships During Scratching and Swimming

1997 ◽  
Vol 78 (3) ◽  
pp. 1394-1403 ◽  
Author(s):  
Edelle C. Field ◽  
Paul S. G. Stein
Keyword(s):  
Spinal Cord ◽  
Motor Neuron ◽  
Activity Patterns ◽  
Angular Position ◽  
Knee Extension ◽  
Neuron Activity ◽  
Spinal Circuitry ◽  
Temporal Relationships ◽  
Kinematic Analyses ◽  
Behavioral Event

Field, Edelle C. and Paul S. G. Stein. Spinal cord coordination of hindlimb movements in the turtle: intralimb temporal relationships during scratching and swimming. J. Neurophysiol. 78: 1394–1403, 1997. Spinal cord neuronal circuits generate motor neuron activity patterns responsible for rhythmic hindlimb behaviors such as scratching and swimming. Kinematic analyses of limb movements generated by this motor neuron output reveal important characteristics of these behaviors. Intralimb kinematics of the turtle hindlimb were characterized during five distinct rhythmic forms of behavior: three forms of scratching and two forms of swimming. In each movement cycle for each form, the angles of the hip and knee joints were measured as well as the timing of a behavioral event, e.g., rub onset in scratching or powerstroke onset in swimming. There were distinct differences between the kinematics of different forms of the same behavior, e.g., rostral scratch versus pocket scratch. In contrast, there were striking similarities between forms of different behaviors, e.g., rostral scratch versus forward swimming. For each form of behavior there was a characteristic angular position of the hip at the onset of each behavioral event (rub or powerstroke). The phase of the onset of knee extension within the hip position cycle occurred while the hip was flexing in the rostral scratch and forward swim and while the hip was extending in the pocket scratch, caudal scratch, and back-paddling form of swimming. The phase of the onset of the behavioral event was not statistically different between rostral scratch and forward swim; nor was it different between pocket scratch and caudal scratch. These observations of similarities at the movement level support the suggestion that further similarities, such as shared spinal circuitry, may be present at the neural circuitry level as well.

Spatial organization and activity patterns of ocelots (Leopardus pardalis) in a protected subtropical forest of Brazil

2019 ◽  
Vol 64 (4) ◽  
pp. 503-510
Author(s):  
Fernando C. C. Azevedo ◽  
Jan K. F. Mähler ◽  
Cibele B. Indrusiak ◽  
Daniel Scognamillo ◽  
Valéria A. Conforti ◽  
...  
Keyword(s):  
Spatial Organization ◽  
Activity Patterns ◽  
Subtropical Forest ◽  
Leopardus Pardalis

Spinomuscular Coherence in Monkeys Performing a Precision Grip Task

2008 ◽  
Vol 99 (4) ◽  
pp. 2012-2020 ◽  
Author(s):  
Tomohiko Takei ◽  
Kazuhiko Seki
Keyword(s):  
Spinal Cord ◽  
Sensorimotor Integration ◽  
Unique Feature ◽  
Cervical Spinal Cord ◽  
Precision Grip ◽  
Muscle Physiology ◽  
Field Potentials ◽  
Spinal Interneurons ◽  
Arm Muscles ◽  
The Brain

We recorded local field potentials (LFPs) from cervical spinal cord (C5–C8) in monkeys performing a precision grip task and examined their coherence with electromyographic (EMG) activities (spinomuscular coherence) recorded from hand and arm muscles. Among 164 LFP-EMG pairs, significant coherence was found in 34 pairs (21%). We classified the coherence into two groups based on its frequency range, narrowband coherence, and broadband coherence. The narrowband coherence was restricted to discrete frequencies in the range of 14–55 Hz and was widespread throughout the superficial and deep gray matter. In contrast, the broadband coherence distributed between 10 and 95 Hz and was found only in the ventral half of the spinal cord. The narrowband coherence suggests that oscillations, which have been described in many motor control areas of the brain, could also pass though spinal interneurons to affect motor output and sensorimotor integration. On the other hand, the broadband coherence could be a unique feature of spinal motoneuron-muscle physiology.

Nonspiking local interneurons in insect leg motor control. II. Role of nonspiking local interneurons in the control of leg swing during walking

1995 ◽  
Vol 73 (5) ◽  
pp. 1861-1875 ◽  
Author(s):  
H. Wolf ◽  
A. Buschges
Keyword(s):  
Activity Patterns ◽  
Current Injection ◽  
Step Cycle ◽  
Trigger Mechanism ◽  
Local Interneurons ◽  
Swing Movement ◽  
Leg Movement ◽  
Muscle Groups ◽  
Interneuron Activity

1. Nonspiking local interneurons (NSIs) were recorded intracellularly in the mesothoracic ganglion of semi-intact locusts walking on a treadwheel. Interneurons were characterized by their connectivity to motoneurons. Their activity patterns in the step cycle and the effect current injection had on the leg movement were analyzed. We examined interneurons that provided excitatory or inhibitory synaptic drive to a subset of motoneurons active during the swing movement of walking. 2. Interneuron activity was observed to support or oppose the actual leg movement. Both supporting and opposing interneurons were active simultaneously, lending support to the idea that the actual motor output of walking is generated by the adjustment of parallel antagonistic pathways of signal processing. 3. The examined interneurons showed qualitatively the same patterns of activity during forward and backward walking. This indicates that swing movement in both situations may be generated by similar neuronal networks (although the mechanism of movement reversal remains unclear). 4. At least two functional types of NSIs could be distinguished. First, there were interneurons whose depolarization patterns showed distinct variability, often correlated with duration or amplitude of the swing movement. As a rule, current injection had minor, if any, effects on leg movement. Populations of these interneurons appear to be involved in the control of a coordinated swing movement by driving appropriate sets of muscle groups. The second type of NSIs showed more stereotyped activity patterns that varied relatively little with changes in the swing movement. Current injection had strong effects on the leg movement and could, for example, arrest the leg in the stance phase. These interneurons appear to be primarily involved in the trigger mechanism of leg swing.

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