scholarly journals Cellular Properties of Lateral Spinal Nucleus Neurons in the Rat L6–S1 Spinal Cord

1999 ◽  
Vol 81 (6) ◽  
pp. 3078-3086 ◽  
Author(s):  
M. C. Jiang ◽  
L. Liu ◽  
G. F. Gebhart
Keyword(s):  
Spinal Cord ◽  
Steady State ◽  
Action Potentials ◽  
Dorsal Root ◽  
High Amplitude ◽  
Repetitive Firing ◽  
Intrinsic Properties ◽  
Bath Application ◽  
Spinal Nucleus ◽  
Lateral Spinal Nucleus

Cellular properties of lateral spinal nucleus neurons in the rat L6–S1 spinal cord. Conventional intracellular recordings were made from 26 lateral spinal nucleus (LSN) neurons in slices of L6–S1 spinal cord from 10- to 15-day-old rats. At rest, LSN neurons did not fire spontaneous action potentials. With injection of a positive current pulse, action potentials had an amplitude of 72 ± 7 (SD) mV and duration at half-peak height of 0.75 ± 0.22 ms. Action potentials were followed by an afterpotential. Most LSN neurons (13/17) exhibited only an afterhyperpolarization (AHP); four neurons exhibited both a fast and a slow AHP separated by an afterdepolarization (ADP). For LSN neurons that exhibited only an AHP, a slow ADP could be identified during bath application of apamin (100 nM). Four of 11 LSN neurons showed a postinhibitory rebound (PIR). Two types of PIR were noted, one with high threshold and low amplitude and the other with low threshold and high amplitude. The PIR with high amplitude was partially blocked in 0 mM Ca2+/high Mg2+ (10 mM) recording solution. Repetitive firing properties were examined in 17 LSN neurons. On the basis of the ratio of the slopes between initial instantaneous firing and steady-state firing frequencies, neurons with low spike frequency adaptation (SFA, 8/17) and high SFA (4/17) were identified. In addition, 2/17 LSN neurons exhibited biphasic repetitive firing patterns, which were composed of a fast SFA, delayed excitation, and low SFA; another two neurons showed only delayed excitation. Plateau potentials also were found in two LSN neurons. Dorsal root stimulation revealed that most LSN neurons (12/13) had polysynaptic postsynaptic potentials (PSP); only one neuron exhibited a monosynaptic PSP. Electrical stimulation of the dorsal root evoked prolonged discharges in low SFA neurons and a short discharge in high SFA neurons. Intrinsic properties were modulated by bath application of substance P (SP). Membrane potentials were depolarized in all eight LSN neurons tested, and membrane resistance was either increased ( n = 3) or decreased ( n = 2). Both instantaneous firing and steady-state firing were facilitated by SP. In addition, oscillation of membrane potentials were induced in three LSN neurons. These results demonstrate that LSN neurons exhibit a variety of intrinsic properties, which may significantly contribute to sensory processing, including nociceptive processing.

Spatiotemporal Patterns of Dorsal Root–Evoked Network Activity in the Neonatal Rat Spinal Cord: Optical and Intracellular Recordings

2005 ◽  
Vol 94 (3) ◽  
pp. 1952-1961 ◽  
Author(s):  
Lea Ziskind-Conhaim ◽  
Stephen Redman
Keyword(s):  
Spinal Cord ◽  
Action Potentials ◽  
Dorsal Root ◽  
Spatiotemporal Patterns ◽  
Neonatal Rat ◽  
Network Activity ◽  
Rat Spinal Cord ◽  
Optical Signals ◽  
Postsynaptic Potentials ◽  
Neuronal Ensembles

Spatiotemporal patterns of dorsal root–evoked potentials were studied in transverse slices of the rat spinal cord by monitoring optical signals from a voltage-sensitive dye with multiple-photodiode optic camera. Typically, dorsal root stimulation generated two basic waveforms of voltage images: dual-component images consisting of fast, spike-like signal followed by a slow signal in the dorsal horn, and small, slow signals in the ventral horn. To qualitatively relate the optical signals to membrane potentials, whole cell recordings were combined with measurements of light absorption in the area around the soma. The slow optical signals correlated closely with subthreshold postsynaptic potentials in all regions of the cord. The spike-like component was not associated with postsynaptic action potentials, suggesting that the fast signal was generated by presynaptic action potentials. Firing in a single neuron could not be detected optically, implying that local voltage images originated from synchronously activated neuronal ensembles. Blocking glutamatergic synaptic transmission inhibited excitatory postsynaptic potentials (EPSPs) and significantly reduced the slow optical signals, indicating that they were mediated by glutamatergic synapses. Suppressing glycine-mediated inhibition increased the amplitude of both optical signals and EPSPs, while blocking GABAA receptor–mediated synapses, increased the amplitude and time course of EPSPs and prolonged the duration of voltage images in larger areas of the slice. The close correlation between evoked EPSPs and their respective local voltage images shows the advantage of the high temporal resolution optical system in measuring both the spatiotemporal dynamics of segmental network excitation and integrated potentials of neuronal ensembles at identified sites.

Intrinsic properties of deep dorsal horn neurons in the L6-S1 spinal cord of the intact rat

1995 ◽  
Vol 74 (5) ◽  
pp. 1819-1827 ◽  
Author(s):  
M. C. Jiang ◽  
C. L. Cleland ◽  
G. F. Gebhart
Keyword(s):  
Spinal Cord ◽  
Steady State ◽  
Membrane Potential ◽  
Dorsal Horn ◽  
Action Potentials ◽  
Time Course ◽  
Inward Rectification ◽  
Current Voltage ◽  
Steady State Current ◽  
Current Passage

1. Stable intracellular recordings were obtained from neurons (n = 62) in the L6-S1 deep dorsal horn of the spinal cord in pentobarbital-sodium-anesthetized, intact rats (n = 26). All neurons responded to natural mechanical stimuli and/or electrical stimulation of peripheral afferents. 2. Intracellular penetrations were maintained for 30 min-2 h. Action potentials occurred spontaneously in most neurons (n = 50) and could be evoked in the remainder (n = 12) by depolarizing current passage. Mean resting membrane potential was -60.9 mV, mean action potential height amplitude was 75.2 mV, mean half-width of the action potentials was 0.33 ms, mean input resistance was 38 M omega, and mean time constant was 9.1 ms. 3. Action potentials were followed by afterpotentials made up of at least three components; a fast afterhyperpolarization (fAHP), a slow afterhyperpolarization (sAHP), and an afterdepolarization (ADP). Most neurons (n = 40) exhibited all three afterpotentials, although some displayed only a fAHP and an ADP (n = 10) or a fAHP and a sAHP (n = 12). The durations and magnitudes of the afterpotentials varied widely among neurons. 4. Steady-state current-voltage relations were investigated in 14 neurons with depolarizing and hyperpolarizing current pulses. Of these 14 neurons, 5 exhibited inward rectification, 3 had outward rectification, and the remaining 6 showed a predominantly linear change of membrane potential to current injection. In addition, several neurons (n = 9) exhibited a postinhibitory rebound that was sometimes (n = 4) accompanied by a "sag" in voltage during the preceding hyperpolarizing current step. 5. Four patterns of spike frequency adaptation occurred during step depolarizing current passage. The firing of most neurons gradually decreased with a simple, approximately exponential time course (n = 21), in some neurons it decreased with both a fast and a slow time course (n = 8), in several it incremented in rate (n = 3), and one neuron showed a complex combination of multiple decrementing and incrementing adaptations. Time constants, magnitude of adaptation, and the slopes of the steady-state current-voltage relation varied widely. 6. Oscillations in membrane potential and firing rate occurred in three neurons. The oscillations arose from endogenous mechanisms in at least one neuron because manipulation of membrane potentials altered the frequency of oscillation; a depolarizing current increased the period of oscillation and eventually produced tonic firing, and a hyperpolarizing current increased the frequency of oscillation and eventually terminated firing. 7. The results demonstrate that neurons in the L6-S1 region of the dorsal horn exhibit a diversity of cellular mechanisms that may significantly modulate normal somatosensory and visceral input.

scholarly journals Neonatal Mice Spinal Cord Interneurons Sending Axons in Dorsal Roots

2020 ◽  
Author(s):  
Laura Paulina Osuna-Carrasco ◽  
Sergio Horacio Duenas-Jimenez ◽  
Carmen Toro-Castillo ◽  
Braniff De la Torre ◽  
Irene Aguilar-Garcia ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Action Potentials ◽  
Dorsal Root ◽  
Staining Technique ◽  
Spinal Cord Dorsal Horn ◽  
Monosynaptic Reflex ◽  
Primary Afferent Depolarization ◽  
Dorsal Roots ◽  
Dorsal Root Reflex

Abstract Background: Spinal cord interneurons send their axons in the dorsal root. Their antidromic fire could modulate peripheral receptors. Thus, it could control pain, other sensorial modality, or muscle spindle activity. In this study, we assessed a staining technique to analyze whether interneurons send axons in the neonate mouse’s dorsal roots. We conducted experiments in 10 Swiss-Webster mice, which ranged in age from 2 to 13 postnatal days. We dissected the spinal cord and studied it in vitro. Results: We observed interneurons in the spinal cord dorsal horn sending axons through dorsal roots. A mix of fluorochromes applied in dorsal roots marked these interneurons. They have a different morphology than motoneurons. Primary afferent depolarization in afferent terminals produces antidromic action potentials (dorsal root reflex; DRR). These reflexes appeared by stimulation of adjacent dorsal roots. We found that in the presence of bicuculline, DRR recorded in the L4 dorsal root evoked by L5 dorsal root stimulation was reduced. Simultaneously, the monosynaptic reflex (MR) in the L5 ventral root was not affected; nevertheless, a long-lasting after discharge appeared. The addition of 2-amino-5 phosphonovalric acid (AP5), an antagonist of NMDA receptors, abolished the MR without changing the after discharge. Action potentials persisted in dorsal roots even in low Ca2+ concentration. Conclusions: Thus, firing interneurons could send their axons by dorsal roots. Antidromic potentials may be characteristics of the neonatal mouse, probably disappearing in adulthood.

Dorsal Root Crush in Adult Mice to Study Spinal Cord Regeneration

BIO-PROTOCOL ◽  
2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Hyukmin Kim ◽  
Harun Noristani ◽  
Seung Han ◽  
Young-Jin Son
Keyword(s):  
Spinal Cord ◽  
Dorsal Root ◽  
Spinal Cord Regeneration ◽  
Adult Mice

Microanatomy of the Origin of the Cervical Plexus at the Spinal Cord, Nerve Root Cuffs, and Dorsal Root Ganglia Levels

2022 ◽  
pp. 93-125
Author(s):  
Irene Riquelme ◽  
Miguel Angel Reina ◽  
André P. Boezaart ◽  
Francisco Reina ◽  
Virginia García-García ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Dorsal Root Ganglia ◽  
Nerve Root ◽  
Dorsal Root ◽  
Cervical Plexus
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