scholarly journals Neural Interactions in Developing Rhythmogenic Spinal Networks: Insights From Computational Modeling

2020 ◽  
Vol 14 ◽  
Author(s):  
Natalia A. Shevtsova ◽  
Ngoc T. Ha ◽  
Ilya A. Rybak ◽  
Kimberly J. Dougherty
Keyword(s):  
Locomotor Activity ◽  
Electrical Coupling ◽  
Rhythmic Activity ◽  
Mechanistic Explanation ◽  
Neuronal Population ◽  
Locomotor Rhythm ◽  
Junctional Coupling ◽  
Neural Interactions ◽  
Chemical Synapses ◽  
Gap Junctional

The mechanisms involved in generation of rhythmic locomotor activity in the mammalian spinal cord remain poorly understood. These mechanisms supposedly rely on both intrinsic properties of constituting neurons and interactions between them. A subset of Shox2 neurons was suggested to contribute to generation of spinal locomotor activity, but the possible cellular basis for rhythmic bursting in these neurons remains unknown. Ha and Dougherty (2018) recently revealed the presence of bidirectional electrical coupling between Shox2 neurons in neonatal spinal cords, which can be critically involved in neuronal synchronization and generation of populational bursting. Gap junctional connections found between functionally-related Shox2 interneurons decrease with age, possibly being replaced by increasing interactions through chemical synapses. Here, we developed a computational model of a heterogeneous population of neurons sparsely connected by electrical or/and chemical synapses and investigated the dependence of frequency of populational bursting on the type and strength of neuronal interconnections. The model proposes a mechanistic explanation that can account for the emergence of a synchronized rhythmic activity in the neuronal population and provides insights into the possible role of gap junctional coupling between Shox2 neurons in the spinal mechanisms for locomotor rhythm generation.

scholarly journals Neural interactions in developing rhythmogenic spinal networks: Insights from computational modeling

2020 ◽  
Author(s):  
Natalia A. Shevtsova ◽  
Ngoc T. Ha ◽  
Ilya A. Rybak ◽  
Kimberly J. Dougherty
Keyword(s):  
Locomotor Activity ◽  
Electrical Coupling ◽  
Rhythmic Activity ◽  
Mechanistic Explanation ◽  
Neuronal Population ◽  
Intrinsic Properties ◽  
Locomotor Rhythm ◽  
Neural Interactions ◽  
Chemical Synapses ◽  
Gap Junctional

AbstractThe mechanisms involved in generation of rhythmic locomotor activity in the mammalian spinal cord remain poorly understood. These mechanisms supposedly rely on both intrinsic properties of constituting neurons and interactions between them. A subset of Shox2 neurons was found to contribute to generation of spinal locomotor activity, but the possible cellular basis for rhythmic bursting in these neurons remains unknown. Ha and Dougherty (2018) recently revealed the presence of bidirectional electrical coupling between Shox2 neurons in neonatal spinal cords, which can be critically involved in neuronal synchronization and generation of populational bursting. Gap junctional connections found between functionally-related Shox2 interneurons decrease with age, possibly being replaced by increasing interactions through chemical synapses. Here, we developed a computational model of a heterogeneous population of neurons sparsely connected by electrical or/and chemical synapses and investigated the dependence of frequency of populational bursting on the type and strength of neuronal interconnections. The model proposes a mechanistic explanation for emergence of a synchronized rhythmic activity in the neuronal population and provides insights into the mechanisms of the locomotor rhythm generation.

scholarly journals Spinal Shox2 interneuron interconnectivity related to function and development

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Ngoc T Ha ◽  
Kimberly J Dougherty
Keyword(s):  
Electrical Coupling ◽  
Network Activity ◽  
Rhythm Generation ◽  
Electrical Synapses ◽  
Locomotor Rhythm ◽  
Junctional Coupling ◽  
Gap Junctional ◽  
Electrical Connections ◽  
Gap Junctional Coupling ◽  
Developing Mice

Neuronal networks generating hindlimb locomotion are located in the spinal cord. The mechanisms underlying spinal rhythmogenesis are unknown but network activity and interconnectivity of excitatory interneurons likely play prominent roles. Here, we investigate interconnectivity within the Shox2 interneuron population, a subset of which has been suggested to be involved in locomotor rhythm generation, using paired recordings in isolated spinal cords or slices from transgenic mice. Sparse unidirectional connections consistent with chemical synaptic transmission and prominent bidirectional connections mediated by electrical synapses were present within distinct subsets of Shox2 interneurons. Moreover, bidirectional electrical connections were preferentially found between functionally-related Shox2 interneurons. Though prevalent in neonatal mice, electrical coupling began to decline in incidence and strength in mice ~ 3 weeks of age. Overall, our data suggest that gap junctional coupling promotes synchronization of Shox2 interneurons, and may be implicated in locomotor rhythmicity in developing mice.

Reversal of the influence of group Ib afferents from plantaris on activity in medial gastrocnemius muscle during locomotor activity

1993 ◽  
Vol 70 (3) ◽  
pp. 1009-1017 ◽  
Author(s):  
K. G. Pearson ◽  
D. F. Collins
Keyword(s):  
Locomotor Activity ◽  
Rhythmic Activity ◽  
Medial Gastrocnemius ◽  
Plantaris Muscle ◽  
Excitatory Effect ◽  
Locomotor Rhythm ◽  
Group I ◽  
Stimulus Train ◽  
Excitatory Action ◽  
Group I Afferents

1. Rhythmic locomotor activity was evoked in clonidine-treated acute and chronic spinal cats, and the effect of stimulating group I afferents from the plantaris muscle on the timing and magnitude of bursts in medial gastrocnemius (MG) motoneurons was examined. 2. The locomotor rhythm was entrained when group I afferents in the plantaris nerve were electrically stimulated with trains of stimuli presented at rates above and below the intrinsic frequency of the rhythmic activity. During entrainment at rates higher than the intrinsic frequency, a burst of activity in ipsilateral MG motoneurons was initiated approximately 40 ms after the onset of each stimulus train. At lower rates of entrainment the onset of MG bursts preceded the onset of the stimulus trains, and each stimulus train had an excitatory effect on the MG burst with a latency in the range of 30-50 ms. A similar excitatory effect was observed when the stimulus trains were triggered at a preset delay after the endogenous generation of the MG bursts. 3. The excitatory action of plantaris group I afferents on the MG motoneurons was only seen during periods of locomotor activity. In the absence of rhythmic activity, the same stimulus trains reduced any ongoing tonic activity in MG motoneurons. 4. Vibration of the plantaris muscle to preferentially activate group Ia afferents neither entrained the locomotor rhythm nor increased the magnitude of the MG bursts. 5. We conclude that during locomotor activity, input from group Ib afferents of the plantaris muscle has an excitatory action on the system of interneurons generating the extensor bursts, i.e., on the extensor half-center of the central rhythm generator.(ABSTRACT TRUNCATED AT 400 WORDS)

A circadian rhythm in the locomotive behaviour of the giant garden slug Limax maximus

1977 ◽  
Vol 66 (1) ◽  
pp. 47-64
Author(s):  
P. G. Sokolove ◽  
C. M. Beiswanger ◽  
D. J. Prior ◽  
A. Gelperin
Keyword(s):  
Circadian Rhythm ◽  
Locomotor Activity ◽  
Phase Angle ◽  
Circadian Rhythmicity ◽  
Constant Darkness ◽  
Light Cycle ◽  
Circadian Activity ◽  
Locomotor Rhythm ◽  
Activity Peak ◽  
Limax Maximus

The locomotor activity of the garden slug Limax maximus was examined for components of circadian rhythmicity. Behavioural (running wheel) studies clearly demonstrated that the activity satisfies the principal criteria of circadian rhythmicity. In constant darkness at a constant temperature, the locomotor activity freeran with a period of about 24 h (range 23-6-24-6 h). The rhythm was also expressed in constant light with a period for individual slugs that tended to be shorter in LL than in DD. The period of the rhythm was temperature compensated (11–5-21-5 degrees C) with a Q10 approximately equal to 1–00. The locomotor rhythm could be entrained to 24 h LD cycles such that the circadian activity peak occurred during the dark. The phase angle between the onset of activity and lights-off was not fixed, but was a function of the photoperiod of the entraining light cycle.

Bursting in Inhibitory Interneuronal Networks: A Role for Gap-Junctional Coupling

1999 ◽  
Vol 81 (3) ◽  
pp. 1274-1283 ◽  
Author(s):  
F. K. Skinner ◽  
L. Zhang ◽  
J. L. Perez Velazquez ◽  
P. L. Carlen
Keyword(s):  
Theoretical Work ◽  
Oscillatory Behavior ◽  
Minimal Network ◽  
Junctional Coupling ◽  
Synchronization Mechanisms ◽  
The Individual ◽  
Gap Junctional ◽  
Gap Junctional Coupling ◽  
Inhibitory Networks

Bursting in inhibitory interneuronal networks: a role for gap-junctional coupling. Much work now emphasizes the concept that interneuronal networks play critical roles in generating synchronized, oscillatory behavior. Experimental work has shown that functional inhibitory networks alone can produce synchronized activity, and theoretical work has demonstrated how synchrony could occur in mutually inhibitory networks. Even though gap junctions are known to exist between interneurons, their role is far from clear. We present a mechanism by which synchronized bursting can be produced in a minimal network of mutually inhibitory and gap-junctionally coupled neurons. The bursting relies on the presence of persistent sodium and slowly inactivating potassium currents in the individual neurons. Both GABAA inhibitory currents and gap-junctional coupling are required for stable bursting behavior to be obtained. Typically, the role of gap-junctional coupling is focused on synchronization mechanisms. However, these results suggest that a possible role of gap-junctional coupling may lie in the generation and stabilization of bursting oscillatory behavior.

scholarly journals Locomotor activity of the terrestrial slug, Limax maximus: response to progressive dehydration

1985 ◽  
Vol 116 (1) ◽  
pp. 323-330
Author(s):  
S. D. Hess ◽  
D. J. Prior
Keyword(s):  
Locomotor Activity ◽  
Locomotor Rhythm ◽  
Limax Maximus ◽  
Drying Conditions

The circadian locomotor rhythm of the terrestrial slug, Limax maximus, was measured with activity wheels during exposure to both humid and drying conditions. Slugs kept in wet wheels (100% RH) remained fully hydrated while those in dry wheels (less than 30% RH) experienced progressive dehydration. Transfer of slugs from a wet wheel to a dry wheel resulted in an increase in the intensity and duration of their patterned locomotor activity that persisted for 3 days. Once the slugs were returned to wet wheels, their locomotor activity returned to normal.

scholarly journals TNF-α plus IL-1β Induces Opposite Regulation of Hemichannels and Gap Junctions in Mesangial Cells Through a RhoA/ROCK-dependent Pathway

2021 ◽  
Author(s):  
Claudia M. Lucero ◽  
Marcelo A. León ◽  
Paola Fernández ◽  
Juan A. Orellana ◽  
Victoria Velarde ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Connexin 43 ◽  
Mesangial Cells ◽  
Thiobarbituric Acid ◽  
Progressive Increase ◽  
Cell Coupling ◽  
Inflammatory Conditions ◽  
Junctional Communication ◽  
Junctional Coupling ◽  
Gap Junctional

Connexin 43 (Cx43) is expressed in kidneys and constitutes a feedforward mechanism leading to inflammation in other tissues where they form hemichannels and gap junction channels. However, the possible functional relationship between these membrane channels and their role in damaged renal cells remains unknown. Here, analyses of ethidium uptake and thiobarbituric acid reactive species revealed that TNF-α plus IL-1β increase Cx43 hemichannel activity and oxidative stress in MES-13 cells, a cell line derived from mesangial cells. The latter also was accompanied by a reduction in gap junctional communication, whereas western blotting analysis showed a progressive increase of phosphorylated MYPT (a substrate of RhoA/ROCK) and Cx43 upon TNF-α/IL-1β treatment. Additionally, inhibition of RhoA/ROCK strongly diminished the TNF-α/IL-1β-induced activation of Cx43 hemichannels and reduction in gap junctional coupling. We propose that activation of Cx43 hemichannels and inhibition of cell coupling during pro-inflammatory conditions could contribute to oxidative stress and damage of mesangial cells via the RhoA/ROCK pathway.

scholarly journals Short-term depression of gap junctional coupling in reticular thalamic neurons of absence epileptic rats

2016 ◽  
Vol 594 (19) ◽  
pp. 5695-5710 ◽  
Author(s):  
Denise Kohmann ◽  
Annika Lüttjohann ◽  
Thomas Seidenbecher ◽  
Philippe Coulon ◽  
Hans-Christian Pape
Keyword(s):  
Short Term ◽  
Thalamic Neurons ◽  
Junctional Coupling ◽  
Gap Junctional ◽  
Gap Junctional Coupling

Prolonged epileptiform bursting induced by 0-Mg2+ in rat hippocampal slices depends on gap junctional coupling

Neuroscience ◽  
2001 ◽  
Vol 105 (3) ◽  
pp. 579-587 ◽  
Author(s):  
R Köhling ◽  
S.J Gladwell ◽  
E Bracci ◽  
M Vreugdenhil ◽  
J.G.R Jefferys
Keyword(s):  
Hippocampal Slices ◽  
Junctional Coupling ◽  
Gap Junctional ◽  
Gap Junctional Coupling
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