Characteristics of Slow Bursting Activities Recorded in Cervical Ventral Roots in the In Vitro Brainstem—Spinal Cord Preparation of the Neonatal Rat

1994 ◽  
Vol 11 (1) ◽  
pp. 57-64 ◽  
Author(s):  
L. Perségo ◽  
D. Viala
Keyword(s):  
Spinal Cord ◽  
Neonatal Rat ◽  
Ventral Roots

The in vitro neonatal rat spinal cord preparation: a new insight into mammalian locomotor mechanisms

2004 ◽  
Vol 190 (5) ◽  
pp. 343-357 ◽  
Author(s):  
F. Clarac ◽  
E. Pearlstein ◽  
J. F. Pflieger ◽  
L. Vinay
Keyword(s):  
Spinal Cord ◽  
Neonatal Rat ◽  
Rat Spinal Cord ◽  
Insight Into

Small-caliber afferent inputs produce a heterosynaptic facilitation of the synaptic responses evoked by primary afferent A-fibers in the neonatal rat spinal cord in vitro

1993 ◽  
Vol 69 (6) ◽  
pp. 2116-2128 ◽  
Author(s):  
S. W. Thompson ◽  
C. J. Woolf ◽  
L. G. Sivilotti
Keyword(s):  
Spinal Cord ◽  
Dorsal Root ◽  
Fiber Strength ◽  
Conditioning Stimulus ◽  
Neonatal Rat ◽  
Primary Afferent ◽  
Synaptic Potentials ◽  
C Fiber ◽  
Afferent Inputs

1. The effect of brief primary afferent inputs on the amplitude and duration of the synaptic potentials evoked in ventral horn (VH) neurons by the activation of other unconditioned primary afferents was studied by current-clamp intracellular recording in the neonatal rat hemisected spinal cord in vitro. Low-frequency (1 Hz) trains of stimulation were applied to a lumbar dorsal root (Conditioning root) for 20-30 s. Test excitatory synaptic potentials (EPSPs) were evoked by single electrical shocks applied to an adjacent Test dorsal root. 2. Test and Conditioning inputs were generated at stimulation strengths sufficient to activate A beta-, A delta- and C-afferent fibers successively. At A delta- and C-fiber strength the EPSPs lasted for 4-6 s, and, during the repetitive Conditioning inputs, these summated to produce a progressively incrementing cumulative depolarization that slowly decayed back to the control Vm over tens of seconds. 3. Dorsal root conditioning produced heterosynaptic facilitation, defined as an enhancement of Test EPSPs above their DC matched controls, in 7 out of 20 neurons. To facilitate the unconditioned afferent input, the intensity of conditioning stimulation had to exceed the threshold for the activation of thin myelinated (A delta) afferents: conditioning at A beta-fiber strength had no effect, whereas A delta- and C-fiber strength conditioning were equally effective. 4. Heterosynaptic facilitation of only A beta- or A delta-fiber-evoked Test EPSPs was observed, no enhancement of C-fiber strength Test EPSPs could be demonstrated. The facilitation manifested as increases in the EPSP peak amplitude, area or the number of action potentials evoked. 5. Conditioning trials that produced heterosynaptic facilitation generated cumulative depolarizations larger than those produced by ineffective conditioning trials (9.1 +/- 3.1 vs. 3.3 +/- 0.5 mV after 20 s conditioning at resting Vm, mean +/- SE, n = 6 and 13, respectively; P < 0.05). The slope of the Vm trajectory during the summation of the conditioning EPSPs was higher in trials resulting in heterosynaptic facilitation, at 0.31 +/- 0.10 mV/s in neurons with heterosynaptic facilitation and 0.06 +/- 0.02 mV/s in cells without heterosynaptic facilitation (P < 0.05). 5. Four of the 20 VH neurons in our sample responded to A delta/C-fiber conditioning with action-potential windup: all 4 also displayed heterosynaptic facilitation. 6. Heterosynaptic facilitation decayed after the completion of the conditioning stimulus with a time course that was parallel to but not superimposable on that of the slow Vm depolarization evoked by the conditioning.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Fictive Rhythmic Motor Patterns Induced by NMDA in an In Vitro Brain Stem–Spinal Cord Preparation From an Adult Urodele

1999 ◽  
Vol 82 (2) ◽  
pp. 1074-1077 ◽  
Author(s):  
Isabelle Delvolvé ◽  
Pascal Branchereau ◽  
Réjean Dubuc ◽  
Jean-Marie Cabelguen
Keyword(s):  
Spinal Cord ◽  
Brain Stem ◽  
Rhythm Generation ◽  
Motor Patterns ◽  
Rhythmic Motor ◽  
Bath Application ◽  
The Neural Networks ◽  
Ventral Roots ◽  
Pleurodeles Waltl

An in vitro brain stem–spinal cord preparation from an adult urodele ( Pleurodeles waltl) was developed in which two fictive rhythmic motor patterns were evoked by bath application of N-methyl-d-aspartate (NMDA; 2.5–10 μM) with d-serine (10 μM). Both motor patterns displayed left-right alternation. The first pattern was characterized by cycle periods ranging between 2.4 and 9.0 s (4.9 ± 1.2 s, mean ± SD) and a rostrocaudal propagation of the activity in consecutive ventral roots. The second pattern displayed longer cycle periods (8.1–28.3 s; 14.2 ± 3.6 s) with a caudorostral propagation. The two patterns were inducible after a spinal transection at the first segment. Preliminary experiments on small pieces of spinal cord further suggested that the ability for rhythm generation is distributed along the spinal cord of this preparation. This study shows that the in vitro brain stem–spinal cord preparation from Pleurodeles waltl may be a useful model to study the mechanisms underlying the different axial motor patterns and the flexibility of the neural networks involved.

Neurochemical excitation of propriospinal neurons facilitates locomotor command signal transmission in the lesioned spinal cord

2011 ◽  
Vol 105 (6) ◽  
pp. 2818-2829 ◽  
Author(s):  
Eugene Zaporozhets ◽  
Kristine C. Cowley ◽  
Brian J. Schmidt
Keyword(s):  
Spinal Cord ◽  
Brain Stem ◽  
Signal Transmission ◽  
Cholinergic Receptor ◽  
Neonatal Rat ◽  
Receptor Antagonists ◽  
Ion Removal ◽  
Propriospinal Neurons ◽  
Command Signal

Previous studies of the in vitro neonatal rat brain stem-spinal cord showed that propriospinal relays contribute to descending transmission of a supraspinal command signal that is capable of activating locomotion. Using the same preparation, the present series examines whether enhanced excitation of thoracic propriospinal neurons facilitates propagation of the locomotor command signal in the lesioned spinal cord. First, we identified neurotransmitters contributing to normal endogenous propriospinal transmission of the locomotor command signal by testing the effect of receptor antagonists applied to cervicothoracic segments during brain stem-induced locomotor-like activity. Spinal cords were either intact or contained staggered bilateral hemisections located at right T1/T2 and left T10/T11 junctions designed to abolish direct long-projecting bulbospinal axons. Serotonergic, noradrenergic, dopaminergic, and glutamatergic, but not cholinergic, receptor antagonists blocked locomotor-like activity. Approximately 73% of preparations with staggered bilateral hemisections failed to generate locomotor-like activity in response to electrical stimulation of the brain stem alone; such preparations were used to test the effect of neuroactive substances applied to thoracic segments (bath barriers placed at T3 and T9) during brain stem stimulation. The percentage of preparations developing locomotor-like activity was as follows: 5-HT (43%), 5-HT/ N-methyl-d-aspartate (NMDA; 33%), quipazine (42%), 8-hydroxy-2-(di- n-propylamino)tetralin (20%), methoxamine (45%), and elevated bath K+ concentration (29%). Combined norepinephrine and dopamine increased the success rate (67%) compared with the use of either agent alone (4 and 7%, respectively). NMDA, Mg2+ ion removal, clonidine, and acetylcholine were ineffective. The results provide proof of principle that artificial excitation of thoracic propriospinal neurons can improve supraspinal control over hindlimb locomotor networks in the lesioned spinal cord.

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