Interactions among lumbar motoneurons on opposite sides of the frog spinal cord: Morphological and electrophysiological studies

Erulkar, S. D.; Soller, R. William

doi:10.1002/cne.901920307

Cited by 39 publications

(18 citation statements)

References 19 publications

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“…Since motoneurones in the spinal cord of the frog are electrically coupled (Erulkar & Soller, 1980;, it is important to distinguish sensory-motor synaptic potentials from 496 PROJECTIONS OF FOREIGN SENSORY NEURONES motoneurone coupling potentials. In normal animals only homonymous triceps motoneurones are coupled to each other and we also observed normal motoneuronal coupling after dorsal root section in the experimental animals.…”

Section: Methodsmentioning

confidence: 99%

The formation of appropriate central and peripheral connexions by foreign sensory neurones of the bullfrog

Frank

Westerfield

1982

The Journal of Physiology

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SUMMARY1. The ability of foreign sensory neurones to form novel reflex pathways was studied in bullfrogs by removing, during early larval stages of development, the dorsal root ganglion (d.r.g. 2) that normally provides the entire sensory innervation of the front limb.2. After the operation these tadpoles metamorphosed into frogs that responded to sensory stimuli and had nearly normal use of the limb. Sensation in the limb was mediated by sensory neurones located in an adjacent ganglion (d.r.g. 3); these neurones normally never grow into the arm.3. These neurones were shown, by labelling with horseradish peroxidase, to project into the arm and into the region of the brachial spinal cord occupied by motoneurones innervating muscles in the arm. These projections do not occur at any time during normal development.4. Intracellular recordings from identified motoneurones demonstrated that when the operations were done before developmental stage 9 appropriate monosynaptic sensory-motor pathways were established. The relative strengths of synergistic and antagonistic sensory projections onto motoneurones were normal, although the latencies of the synaptic potentials were somewhat longer.5. When the operation was performed after stage 9 but before metamorphosis, d.r.g. 3 sensory afferents grew into the arm and into the brachial spinal cord but did not make monosynaptic connexions onto motoneurones.6. Removal of d.r.g. 2 from adult bullfrogs failed to produce either central or peripheral changes in the projections of d.r.g. 3 sensory neurones.7. Many d.r.g. 3 neurones still innervated their normal sensory targets in the thorax. These neurones never formed monosynaptic connexions onto brachial motoneurones in either normal or experimental animals. In experimental animals, the polysynaptic projections of these third nerve sensory neurones to brachial motoneurones were stronger than in normal animals independent of when d.r.g. 2 was removed during development.8. Thus foreign sensory cells can form specific, functionally appropriate connexions between peripheral targets and motoneurones if the sensory cells that normally mediate this reflex pathway are removed sufficiently early during development.

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Section: Methodsmentioning

confidence: 99%

The formation of appropriate central and peripheral connexions by foreign sensory neurones of the bullfrog

Frank

Westerfield

1982

The Journal of Physiology

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“…la, b). Only the medial motoneuron has dendrites which cross the midline [Grinnell, 1966;Stensaas and Stensaas, 1971;Erulkar and Soller, 1982], The medial motoneuron appears to have a greater dendritic range both rostrocaudally and mediolaterally.…”

Section: Resultsmentioning

confidence: 99%

“…Spinal motoneurons in frogs have been the subject of numerous physiological studies, particularly because of the separa tion of specific inputs onto their somata and their dendrites [Cruce, 1974], Many of these studies have concentrated on the re lationship between primary afferent fibers and dendrites of lateral motoneurons [Grantyn et al, 1982;Jhaveri and Frank, 1983;Lichtman et al, 1984], Lateral mo toneuron dendrites are of interest because they are contacted by primary afferent fib ers from spindles in limb musculature in nervated by the same motoneuron [Gran tyn et al, 1982;Jhaveri and Frank, 1983;Lichtman et al, 1984], Unlike lateral mo-toneurons, medial motoneurons innervate axial musculature and have dendrites which cross the midline [Grinnell, 1966;Erulkar and Soller, 1982], There is little quantitative information on motoneuron dendrite morphology such as length, surface area, volume, and peak branching. These data are useful in the analysis of synaptic input, since the re gion where dendrites are most highly branched may represent a site of abundant synaptic contacts.…”

Section: Introductionmentioning

confidence: 99%

The Dendritic Extent of Motoneurons in Frog Brachial Spinal Cord: A Computer Reconstruction of HRP-Filled Cells

Rosenthal¹,

Cruce²

1985

Brain Behav Evol

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A lateral and a medial motoneuron in the brachial spinal cord of the leopard frog, Rana pipiens, were labeled by horseradish peroxidase applied to the ventral root. Their dendritic trees were traced, analyzed, and plotted using a computer-microscope system. Some dendrites of the medial motoneuron crossed the midline of the spinal cord, but no dendrites of the lateral motoneuron crossed the midline. Nevertheless, the total dendritic length of the lateral motoneuron exceeded that of the medial motoneuron. The peak number of dendritic branch segments of the medial motoneuron was located at a greater distance from its soma than that of the lateral motoneuron. Three-dimensional reconstruction and rotation of the dendritic trees revealed that the dendrites of the medial motoneuron had a greater rostrocaudal extent than those of the lateral motoneuron. When compared to reports of Golgi-impregnated motoneurons our results suggest that the HRP technique labels dendrites more completely. However, use of the HRP technique may introduce greater errors in the subsequent measurement of dendritic segments due to nonuniform tissue shrinkage.

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“…The role of dendrodendritic interactions in the coactivation and synchronization of contra-and ipsilateral motoneurons was observed in various parts of the central nervous system [Grinnell, 1966;Stensaas and Stensaas, 1971;Erulkar and Soller, 1980;Bácskai et al, 2008;Campbell et al, 2009]. Our previous studies suggested a similar morphological organization of the XII motoneurons as their dendrites cross the midline and arborize within the confines of the contralateral XII nucleus [Matesz and Székely, 1977;Birinyi et al, 2004].…”

Section: Morphological Background Of XII Motor Activities During the mentioning

confidence: 91%

Brainstem Circuits Underlying the Prey-Catching Behavior of the Frog

Matesz¹,

Kecskes²,

Bácskai³

et al. 2014

Brain Behav Evol

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Prey-catching behavior (PCB) of the frog consists of a sequence of movements as a stimulus-response chain of the behavioral pattern in which each action presents a signal for the subsequent event. The transformation of visual information into appropriate spatiotemporal patterns of motor activity is carried out by the motor pattern generators located in the brainstem reticular formation. The motor pattern generators provide input to the motoneurons either directly or via the last-order premotor interneurons (LOPI). Although the feeding program is predetermined in this way, various sensory mechanisms control the motor activity. By using neuronal labeling methods, we have studied the morphological details of sensorimotor integration related to the hypoglossal motoneurons to provide further insight into the neuronal circuits underlying the PCB in ranid frogs. Our major findings are as follows. (1) Dendrodendritic and dendrosomatic contacts established by the crossing dendrites of hypoglossal (XII) motoneurons may serve as a morphological option for co-activation, synchronization and proper timing of the bilateral activity of tongue muscles. The crossing dendrites may also provide a feedforward amplification of various signals to the XII motoneurons. The overlapping dendritic territories of the motoneurons innervating protractor and retractor muscles may facilitate the coordinated activities of the agonistic and antagonistic muscles. (2) The musculotopic organization of the XII motoneurons is reflected in the distribution of LOPI for the protractor and retractor muscles of the tongue. (3) Direct sensory inputs from the trigeminal, vestibular, glossopharyngeal-vagal, hypoglossal and spinal afferent fibers to the XII motoneurons may modulate the basic motor pattern and contribute to the plasticity of neuronal circuits. (4) The electrical couplings observed in the vestibulocerebellar neuronal circuits may synchronize and amplify the afferent signals. The combination of chemical and electrical impulse transmission provides a mechanism by which motoneurons can be activated sequentially.

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Interactions among lumbar motoneurons on opposite sides of the frog spinal cord: Morphological and electrophysiological studies

Cited by 39 publications

References 19 publications

The formation of appropriate central and peripheral connexions by foreign sensory neurones of the bullfrog

The formation of appropriate central and peripheral connexions by foreign sensory neurones of the bullfrog

The Dendritic Extent of Motoneurons in Frog Brachial Spinal Cord: A Computer Reconstruction of HRP-Filled Cells

Brainstem Circuits Underlying the Prey-Catching Behavior of the Frog

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