Properties of Renshaw cells excited by recurrent collaterals of pudendal motoneurons in the cat

2009 ◽  
Vol 65 ◽  
pp. S167
Author(s):  
Ken Muramatsu ◽  
Masatoshi Niwa ◽  
Kenji Sato ◽  
Sei-Ichi Sasaki
Keyword(s):  
Renshaw Cells ◽  
Recurrent Collaterals

scholarly journals Comparison of the Inhibition of Renshaw Cells During Subthreshold and Suprathreshold Conditions Using Anatomically and Physiologically Realistic Models

2005 ◽  
Vol 94 (3) ◽  
pp. 1688-1698 ◽  
Author(s):  
Tuan V. Bui ◽  
Dianne E. Dewey ◽  
Robert E. W. Fyffe ◽  
P. Ken Rose
Keyword(s):  
Voltage Clamp ◽  
Relative Effectiveness ◽  
Operating Conditions ◽  
Synaptic Activity ◽  
Inhibitory Synapses ◽  
Renshaw Cells ◽  
Effective Inhibition ◽  
Voltage Clamping ◽  
Recurrent Collaterals ◽  
Excitatory Drive

Inhibitory synaptic inputs to Renshaw cells are concentrated on the soma and the juxtasomatic dendrites. In the present study, we investigated whether this proximal bias leads to more effective inhibition under different neuronal operating conditions. Using compartmental models based on detailed anatomical measurements of intracellularly stained Renshaw cells, we compared the inhibition produced by glycine/γ-aminobutyric acid-A (GABAA) synapses when distributed with a proximal bias to the inhibition produced when the same synapses were distributed uniformly (i.e., with no regional bias). The comparison was conducted in subthreshold and suprathreshold conditions. The latter were mimicked by voltage clamping the soma to −55 mV. The voltage clamp reduces nonlinear interactions between excitatory and inhibitory synapses. We hypothesized that for electrotonically compact cells such as Renshaw cells, the strength of the inhibition would become much less dependent on synaptic location in suprathreshold conditions. This hypothesis was not confirmed. The inhibition produced when inhibitory inputs were proximally distributed was always stronger than when the same inputs were uniformly distributed. In fact, the relative effectiveness of proximally distributed inhibitory inputs over uniformly distributed synapses was greater in suprathreshold conditions than that in subthreshold conditions. The somatic voltage clamp minimized saturation of inhibitory driving potentials. Because this effect was greatest near the soma, the current produced by more distal synapses suffered a greater loss because of saturation. Conversely, in subthreshold conditions, the effectiveness of proximal synapses was substantially reduced at high levels of background synaptic activity because of saturation. Our results suggest glycine/GABAA synapses on Renshaw cells are strategically distributed to block the powerful excitatory drive produced by recurrent collaterals from motoneurons.

Structure-function relationships in the primate superior colliculus. I. Morphological classification of efferent neurons

1988 ◽  
Vol 60 (1) ◽  
pp. 232-262 ◽  
Author(s):  
A. K. Moschovakis ◽  
A. B. Karabelas ◽  
S. M. Highstein
Keyword(s):  
Superior Colliculus ◽  
Medium Size ◽  
Cerebral Peduncle ◽  
Parent Cell ◽  
Morphological Classification ◽  
Dendritic Trees ◽  
Efferent Neurons ◽  
Recurrent Collaterals ◽  
Stimulation Of

1. Neurons in the superior colliculus (SC) of anesthetized paralyzed squirrel monkeys were injected intracellularly with horseradish peroxidase (HRP) to establish a morphological classification of tectal efferent neurons in this species. These neurons were physiologically identified by their antidromic responses following stimulation of the contralateral predorsal bundle or SC. These cells also responded with postsynaptic potentials to stimulation of the ipsilateral substantia nigra and cerebral peduncle and the contralateral tectum. 2. Quantitative light microscopic analysis of the somatodendritic profiles and axonal trajectories of 27 recovered cells revealed the existence of three major groups of tectal efferent neurons: L (n = 7), X (n = 8), and T (n = 12). 3. L neurons are small or medium size cells with relatively elaborate dendritic trees and are located mainly in the superficial layers of the SC. They participate in the ipsilateral descending and dorsal ascending tectofugal bundles. Intrinsic collaterals of L axons deploy a large number of boutons both near the parent cell body and more ventrally within the deeper tectal layers. 4. X neurons are mostly large in size and multipolar in shape with relatively complex dendritic trees. Their cell bodies are situated mainly in the stratum griseum intermedium and occasionally in the stratum opticum. Axons of X neurons participate in the crossed descending and ipsilateral ventral ascending projections of the SC. In addition, the axonal system of about half of the X neurons includes recurrent collaterals. 5. T neurons are located mainly in the ventral stratum opticum and the dorsal stratum griseum intermedium. They have small or medium-sized, trapezoid or ovoid cell bodies and relatively simple radiating or vertical dendritic trees. Their axons usually participate in two of the major tectofugal bundles besides providing a commissural component and recurrent collaterals. 6. Morphological details revealed in the present study support the notion that distinct tectofugal axonal systems originate from efferent neurons of the primate SC that differ both as to their location in the tectum as well as the appearance of their somata and dendritic trees. The resulting morphological classification of tectal efferent cells provides a framework for the analysis of tectal function in terms of populations of identified neurons.

Sensorimotor Integration at the Dorsal Column Nuclei

Physiology ◽  
1999 ◽  
Vol 14 (6) ◽  
pp. 231-237
Author(s):  
Jorge Mariño ◽  
Luis Martinez ◽  
Antonio Canedo
Keyword(s):  
Sensorimotor Integration ◽  
Receptive Fields ◽  
Central Zone ◽  
Spatial Localization ◽  
Peripheral Zone ◽  
Dorsal Column ◽  
Primary Afferents ◽  
Zone Of Inhibition ◽  
Dorsal Column Nuclei ◽  
Recurrent Collaterals

Interaction among primary afferents, corticofugal fibers, and intrinsic elements allows for sensorimotor integration at the dorsal column nuclei. The interneurons permit the spatial localization, the recurrent collaterals synchronize the activity of projecting cells with overlapping receptive fields, and the corticofugal fibers induce a central zone of activity surrounded by a peripheral zone of inhibition.

INHIBITORY CONVERGENCE UPON RENSHAW CELLS

1964 ◽  
Vol 27 (6) ◽  
pp. 1063-1079 ◽  
Author(s):  
Victor J. Wilson ◽  
William H. Talbot ◽  
Masamichi Kato
Keyword(s):  
Renshaw Cells

scholarly journals Axonal projections of Renshaw cells in the thoracic spinal cord

2013 ◽  
Vol 1 (6) ◽  
pp. e00161 ◽  
Author(s):  
Shane A. Saywell ◽  
Timothy W. Ford ◽  
Peter A. Kirkwood
Keyword(s):  
Spinal Cord ◽  
Renshaw Cells ◽  
Thoracic Spinal Cord ◽  
Axonal Projections ◽  
Thoracic Spinal

Location of Renshaw Cells

Nature ◽  
1964 ◽  
Vol 204 (4964) ◽  
pp. 1214-1215 ◽  
Author(s):  
W. D. WILLIS ◽  
JEAN C. WILLIS
Keyword(s):  
Renshaw Cells

The coactivation of antagonist muscles

1981 ◽  
Vol 59 (7) ◽  
pp. 733-747 ◽  
Author(s):  
Allan M. Smith
Keyword(s):  
Purkinje Cells ◽  
Cerebellar Cortex ◽  
Precision Grip ◽  
Reciprocal Inhibition ◽  
Inhibitory Neurons ◽  
Voluntary Movements ◽  
Renshaw Cells ◽  
Power Grip ◽  
Antagonist Muscles ◽  
Antagonist Coactivation

Since Sherrington's convincing demonstration of the reciprocal innervation of opposing muscles, it has generally been thought that antagonist muscles are inactive during most voluntary movements. However, more recent evidence suggests that excitation of Renshaw cells may facilitate antagonist coactivation whereas excitation of Ia inhibitory neurons can induce reciprocal inhibition. A body of evidence has accumulated to indicate some of the circumstances which particularly favour the co-contraction of antagonist muscles. Isometric prehension, either in the precision grip or the power grip, can be shown to be one of the most important examples of antagonist coactivation. Studies of the discharge of single Purkinje cells of the intermediate cerebellar cortex in awake monkeys during performance of a maintained grip revealed that the majority of these neurons are deactivated during antagonist co-contraction. In contrast, other, unidentified neurons of the cerebellar cortex were as a group activated during grasping. It is suggested that the Purkinje cells act to inhibit antagonist muscles during reciprocal inhibition but are themselves inhibited during antagonist coactivation. These results support a suggestion made by Tilney and Pike in 1925 that the cerebellum plays an important role in switching between the coactivation and reciprocal inhibition of antagonist muscles.

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