Partitioning of monosynaptic Ia excitatory postsynaptic potentials in the motor nucleus of the cat lateral gastrocnemius muscle

1986 ◽  
Vol 55 (3) ◽  
pp. 569-586 ◽  
Author(s):  
S. Vanden Noven ◽  
T. M. Hamm ◽  
D. G. Stuart
Keyword(s):  
Species Specificity ◽  
Motor Nucleus ◽  
Excitatory Postsynaptic Potentials ◽  
Cell Type ◽  
Nerve Branch ◽  
Lateral Gastrocnemius ◽  
Postsynaptic Potentials ◽  
Group I ◽  
Cell Groups ◽  
Stimulation Of

Experiments were conducted to test the hypothesis that a partitioning of Ia monosynaptic excitatory postsynaptic potentials (Ia EPSPs) is present in motor nuclei supplying muscles with regions capable of different mechanical actions. Intracellular recordings of synaptic potentials were made in lateral gastrocnemius (LG) motoneurons in anesthetized low-spinal cats. The effects were tested of stimuli (group I range) to the four primary nerve branches of the LG nerve supplying muscle compartments LGm, LG1, LG2, and LG3 (terminology of English, Ref. 26) and the nerve to a heteronymous muscle, soleus. Stimulation of a given LG nerve branch produced monosynaptic Ia EPSPs of greater amplitude in "own-branch" motoneurons than "other-branch" cells. A significant partitioning of mean Ia EPSPs was found in three (LG1, LG2, LG3) out of the four homonymous pathways studied. An EPSP normalization (7) was performed to eliminate potential differences in cell type that might affect the amplitudes of the EPSPs between these four cell groups (e.g., differences in the number of cells supplying FF, FR, and S muscle units). This normalization confirmed that the partitioning of monosynaptic Ia inputs upon stimulation of LG1, LG2, and LG3 could not be attributed to differences in cell type. In addition, the effects of LGm stimulation were found to be significantly greater in the LGm motoneurons compared with the other cell groups. Heteronymous input (from soleus) to the LG motor nucleus showed some partitioned effects. Motoneurons innervating compartment LG2 received larger EPSPs from soleus than did the cells supplying compartments LG1, LG3, and LGm. The contributions of location specificity and species specificity (terminology of Scott and Mendell, Ref. 55) in the establishment of these Ia-afferent-motoneuronal connections were examined. Cell location sites within the spinal cord were consistent with location specificity making some contribution to the observed pattern of homonymous Ia connections. A more prominent role for species specificity was indicated by species-dependent differences in EPSP amplitude in pairs of LG motoneurons (e.g., LGm vs. LG2) at similar rostrocaudal locations upon stimulation of a given homonymous or heteronymous nerve/branch.

Connexions Between a Movement-Detecting Visual Interneurone and Flight Motoneurones of a Locust

1980 ◽  
Vol 86 (1) ◽  
pp. 87-97
Author(s):  
PETER SIMMONS
Keyword(s):  
Movement Detector ◽  
Excitatory Postsynaptic Potentials ◽  
Schistocerca Americana ◽  
Postsynaptic Potentials ◽  
Contralateral Movement ◽  
Contralateral Eye ◽  
Stimulation Of

Both of the descending contralateral movement detector (DCMD) neurones of Schistocerca americana gregaria, which respond to stimulation of the contralateral eye or to loud noises, mediate excitatory postsynaptic potentials in most ipsilateral flight motoneurones.

scholarly journals Properties and Interconnections of Trigeminal Interneurons of the Lateral Pontine Reticular Formation in the Rat

2001 ◽  
Vol 86 (5) ◽  
pp. 2583-2596 ◽  
Author(s):  
M.-J. Bourque ◽  
A. Kolta
Keyword(s):  
Electrical Stimulation ◽  
Reticular Formation ◽  
Motor Pattern ◽  
High Frequency Stimulation ◽  
Motor Nucleus ◽  
Trigeminal Motor Nucleus ◽  
Postsynaptic Potentials ◽  
Frequency Stimulation ◽  
Stimulation Of

Numerous evidence suggests that interneurons located in the lateral tegmentum at the level of the trigeminal motor nucleus contribute importantly to the circuitry involved in mastication. However, the question of whether these neurons participate actively to genesis of the rhythmic motor pattern or simply relay it to trigeminal motoneurons remains open. To answer this question, intracellular recordings were performed in an in vitro slice preparation comprising interneurons of the peritrigeminal area (PeriV) surrounding the trigeminal motor nucleus (NVmt) and the parvocellular reticular formation ventral and caudal to it (PCRt). Intracellular and extracellular injections of anterograde tracers were also used to examine the local connections established by these neurons. In 97% of recordings, electrical stimulation of adjacent areas evoked a postsynaptic potential (PSP). These PSPs were primarily excitatory, but inhibitory and biphasic responses were also induced. Most occurred at latencies longer than those required for monosynaptic transmission and were considered to involve oligosynaptic pathways. Both the anatomical and physiological findings show that all divisions of PeriV and PCRt are extensively interconnected. Most responses followed high-frequency stimulation (50 Hz) and showed little variability in latency indicating that the network reliably distributes inputs across all areas. In all neurons but one, excitatory postsynaptic potentials (EPSPs) or inhibitory postsynaptic potentials (IPSPs) were also elicited by stimulation of NVmt, suggesting the existence of excitatory and inhibitory interneurons within the motor nucleus. In a number of cases, these PSPs were reproduced by local injection of glutamate in lieu of the electrical stimulation. All EPSPs induced by stimulation of PeriV, PCRt, or NVmt were sensitive to ionotropic glutamate receptor antagonists 6-cyano-7-dinitroquinoxaline and d,l-2-amino-5-phosphonovaleric acid, while IPSPs were blocked by bicuculline and strychnine, antagonists of GABAA and glycine receptors. Examination of PeriV and PCRt intrinsic properties indicate that they form a fairly uniform network. Three types of neurons were identified on the basis of their firing adaptation properties. These types were not associated with particular regions. Only 5% of all neurons showed bursting behavior. Our results do not support the hypothesis that neurons of PeriV and PCRt participate actively to rhythm generation, but suggest instead that they are driven by rhythmical synaptic inputs. The organization of the network allows for rapid distribution of this rhythmic input across premotoneuron groups.

Excitatory postsynaptic potentials evoked by ventral root stimulation in neonate rat motoneurons in vitro

1991 ◽  
Vol 65 (1) ◽  
pp. 57-66 ◽  
Author(s):  
Z. G. Jiang ◽  
E. Shen ◽  
M. Y. Wang ◽  
N. J. Dun
Keyword(s):  
Receptor Antagonist ◽  
Response Latency ◽  
Ventral Root ◽  
Synaptic Delay ◽  
Excitatory Postsynaptic Potentials ◽  
Related Substance ◽  
Postsynaptic Potentials ◽  
Axon Collaterals ◽  
Hyperpolarizing Response ◽  
Stimulation Of

1. Intracellular recordings were made from antidromically identified motoneurons in transverse (500 microns) lumbar spinal cord slices of neonatal (12-20 day) rats. 2. Electrical stimulation of ventral rootlets evoked, with or without an antidromic spike or initial segment potential, a depolarizing response (latency, 1-4.2 ms), a hyperpolarizing response (latency, 1.5-3.5 ms), or a combination of two preceding responses in 38, 6, and 8% of motoneurons investigated. 3. The hyperpolarizing response was reversibly eliminated by low Ca2+ (0.25 mM), d-tubocurarine (d-Tc; 10 microM) or strychnine (1 microM), suggesting that this response represents an inhibitory post-synaptic potential (IPSP) mediated by glycine or a related substance release from inhibitory interneurons subsequent to their activation by axon collaterals in a manner analogous to the Renshaw cell circuitry described for the cat motoneurons. 4. The depolarizing responses were excitatory postsynaptic potentials (EPSPs), because they could be graded by varying the stimulus intensity and were reversibly abolished in low Ca2+ solution. 5. Membrane hyperpolarization increased the amplitude of EPSPs, and the mean extrapolated reversal potential was -4 mV. 6. EPSPs were augmented, rather than diminished, by dihydro-beta-erythroidine (1 microM) or d-Tc, arguing against a role of recurrent motor axon collaterals in initiating the responses. 7. The conduction velocity of the fibers initiating the EPSPs ranged from 0.35 to 0.96 m/s, indicating that these fibers were unmyelinated. Furthermore, the EPSP exhibited a constant delay when the stimulus frequency was varied from 1 to 5 Hz, and the synaptic delay estimated by extrapolation was less than 1 ms, suggesting that it was a monosynaptic event. 8. After complete separation of the ventral and dorsal horns by a knife cut, stimulation of ventral rootlets could still evoke an EPSP in motoneurons. 9. Superfusion of the slices with the nonselective glutamate receptor antagonist kynurenic acid (0.2-1 mM) or the selective quisqualate/kainate receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX) (0.5-1 microM) reversibly diminished the EPSPs. 10. EPSPs evoked by stimulation of dorsal and ventral rootlets exhibited different latency and waveform in the same motoneurons. 11. The results provide evidence that activation of ventral root afferents evoked an EPSP mediated by glutamate or a related substance in a population of motoneurons. Furthermore, the afferent pathway mediating the EPSP appears to be monosynaptic and confined to the ventral horn.

Plasticity of the extensor group I pathway controlling the stance to swing transition in the cat

1995 ◽  
Vol 74 (6) ◽  
pp. 2782-2787 ◽  
Author(s):  
P. J. Whelan ◽  
G. W. Hiebert ◽  
K. G. Pearson
Keyword(s):  
Medial Gastrocnemius ◽  
Lateral Gastrocnemius ◽  
Group I ◽  
Excitatory Pathways ◽  
Extensor Muscles ◽  
Stimulus Train ◽  
Control Response ◽  
Control Limb ◽  
Adult Cats ◽  
Stimulation Of

1. This study examines whether the efficacy of polysynaptic group I excitatory pathways to extensor motoneurons are modified after axotomy of a synergistic nerve. Previously, it has been shown that stimulation of extensor nerves at group I strength can extend the stance phase and delay swing. Stimulation of the lateral gastrocnemius and soleus (LG/S) nerve prolongs stance for the duration of the stimulus train, whereas stimulation of the medial gastrocnemius (MG) nerve moderately increases stance. Our hypothesis was that after axotomy of the LG/S nerve the efficacy of the MG group I input would increase. 2. This idea was tested in 10 adult cats that had their left LG/S nerves axotomized for 3-28 days. On the experimental day the cats were decerebrated and the left (experimental) and right (control) LG/S and MG nerves were stimulated during late stance as the animals were walking on a motorized treadmill. A significant increase in the efficacy of the left MG nerve occurred 5 days after axotomy of the LG/S nerve when compared with the control response. By contrast, the previously cut LG/S nerve showed a reduction in efficacy after 3 days compared with the control limb. 3. Functionally, this plasticity may be an important mechanism by which the strength of the group I pathway is calibrated to different loads on the extensor muscles.

Positive Proprioceptive Feedback Elicited By Isometric Contractions of Ankle Flexors on Pretibial Motoneurons in Cats

2002 ◽  
Vol 88 (5) ◽  
pp. 2207-2214 ◽  
Author(s):  
L. Brizzi ◽  
L. H. Ting ◽  
D. Zytnicki
Keyword(s):  
Electrical Stimulation ◽  
Positive Feedback ◽  
Tibialis Anterior ◽  
Extensor Digitorum Longus ◽  
Motor Units ◽  
Extensor Digitorum ◽  
Isometric Contractions ◽  
Postsynaptic Potentials ◽  
Group I ◽  
Stimulation Of

Pretibial flexor motoneurons were recorded intracellularly in anesthetized cats during unfused isometric contractions of a subpopulation of motor units from either tibialis anterior (TA) or extensor digitorum longus (EDL) muscles. The contractions elicited excitatory postsynaptic potentials in 23 of 28 pretibial flexor motoneurons. No effect was observed in the remaining motoneurons. In control experiments, the effects of electrical stimulation of afferents within the TA nerve were investigated to help identify afferents responsible for the contraction-induced positive feedback. This feedback was ascribed to actions of Ia fibers because the pattern of the contraction-induced excitatory potentials was consistent with the known pattern of Ia discharge; in control experiments, electrical stimulation of group I fibers elicited only monosynaptic excitatory potentials; and the distribution of both the contraction-induced positive feedback among motor nuclei as well as the electrically evoked Ia excitatory monosynaptic potentials were restricted to homonymous and synergic motoneurons. Observation of the Ia contraction-induced positive feedback was facilitated by the absence of Ib autogenic inhibition. This contraction-induced Ia excitatory feedback in ankle flexors might either reinforce Ia-induced reflexes when these muscles are lengthened or help to lift the leg over an obstacle.

In Vitro Investigation of Synaptic Relations Between Interneurons Surrounding the Trigeminal Motor Nucleus and Masseteric Motoneurons

1997 ◽  
Vol 78 (3) ◽  
pp. 1720-1725 ◽  
Author(s):  
Arlette Kolta
Keyword(s):  
Motor Nucleus ◽  
Trigeminal Motor Nucleus ◽  
Postsynaptic Potentials ◽  
In Vitro Investigation ◽  
Reciprocal Connections ◽  
Trigeminal Motoneurons ◽  
Inhibitory Components ◽  
Premotor Areas ◽  
Stimulation Of

Kolta, Arlette. In vitro investigation of synaptic relations between interneurons surrounding the trigeminal motor nucleus and masseteric motoneurons. J. Neurophysiol. 78: 1720–1725, 1997. Because of their many inputs and bilateral projections, interneurons surrounding the trigeminal motor nucleus (MotV) are thought to be very important in control of jaw movements and reflexes. However, their interactions with the trigeminal motoneurons are almost unknown. In the present study an in vitro slice preparation was used to investigate this relationship in rat. The zone bordering MotV has been subdivided into four regions: the supra-, juxta-, and intertrigeminal areas (SupV, JuxtV, and IntV, respectively) and the parvocellular reticular formation ventral and caudal to MotV. Stimulation of all areas evoked short-latency excitatory postsynaptic potentials (EPSPs) in masseteric motoneurons. Frequently the EPSPs masked inhibitory postsynaptic potentials (IPSPs) or were followed by long-lasting inhibitory potentials. Only responses obtained from stimulation of JuxtV and IntV seemed devoid of inhibitory components. The EPSPs were mediated through kainate/α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors, whereas the IPSPs appear to be due to γ-aminobutyric acid and glycine. EPSPs and IPSPs were also recorded in SupV premotor interneurons after stimulation of IntV and MotV, respectively, thus suggesting that reciprocal connections exist between premotor areas and also between premotor interneurons of SupV and inhibitory interneurons located within MotV. It is concluded that the preparation used here will doubtless prove useful for further investigation of the circuitry involved in the bilateral coordination of the jaw.

Organization of intrinsic cholinergic neurons projecting within submucosal plexus of guinea pig ileum

1998 ◽  
Vol 275 (3) ◽  
pp. G490-G497 ◽  
Author(s):  
B. A. Moore ◽  
S. Vanner
Keyword(s):  
Guinea Pig ◽  
Pressure Pulse ◽  
Cholinergic Neurons ◽  
Excitatory Postsynaptic Potentials ◽  
Submucosal Plexus ◽  
Guinea Pig Ileum ◽  
Postsynaptic Potentials ◽  
Ics 205 930 ◽  
Stimulation Of

Electrophysiological techniques were employed to examine the organization of the projections of submucosal neurons in the submucosal plexus of guinea pig ileum. These neurons were activated by focal pressure-pulse application of 5-hydroxytryptamine (5-HT) to single ganglia in submucosal preparations in vitro, and resulting fast excitatory postsynaptic potentials (EPSPs) were recorded intracellularly in S-type neurons. 5-HT-evoked fast EPSPs were blocked by TTX, hexamethonium, and ICS-205-930 (tropisetron). 5-HT was applied either directly to the ganglion containing the neuron recorded intracellularly or to adjacent ganglia positioned at increasing distances on either side of the impaled cell in circumferential or longitudinal orientations. All S-type neurons recorded in this study ( n = 103) received nicotinic fast EPSPs from cholinergic neurons when 5-HT was applied directly to the ganglion containing the impaled neuron. Stimulation of adjacent ganglia also evoked nicotinic fast EPSPs, but the number of neurons that received this input decreased as the distance between the stimulus and the impaled cell increased. Maximal projections were 3 mm in the circumferential and orad-to-aborad orientations. There were no significant projections in the aborad-to-orad direction. These findings suggest that S-type neurons in the submucosal plexus are innervated by intrinsic cholinergic neurons that project over relatively short distances and have a distinct orad-to-aborad polarity.

Stimulation of adenosine A1 and A2A receptors by AMP in the submucosal plexus of guinea pig small intestine

2007 ◽  
Vol 292 (2) ◽  
pp. G492-G500 ◽  
Author(s):  
Na Gao ◽  
Hong-Zhen Hu ◽  
Sumei Liu ◽  
Chuanyun Gao ◽  
Yun Xia ◽  
...  
Keyword(s):  
Small Intestine ◽  
Guinea Pig ◽  
Receptor Antagonist ◽  
Pyridoxal Phosphate ◽  
Disulfonic Acid ◽  
Receptor Subtype ◽  
Excitatory Postsynaptic Potentials ◽  
Submucosal Plexus ◽  
Postsynaptic Potentials ◽  
Stimulation Of

Actions of adenosine 5′-monophosphate (AMP) on electrical and synaptic behavior of submucosal neurons in guinea pig small intestine were studied with “sharp” intracellular microelectrodes. Application of AMP (0.3–100 μM) evoked slowly activating depolarizing responses associated with increased excitability in 80.5% of the neurons. The responses were concentration dependent with an EC50 of 3.5 ± 0.5 μM. They were abolished by the adenosine A2A receptor antagonist ZM-241385 but not by pyridoxal-phosphate-6-azophenyl-2,4-disulfonic acid, trinitrophenyl-ATP, 8-cyclopentyl-1,3-dimethylxanthine, suramin, or MRS-12201220. The AMP-evoked responses were insensitive to AACOCF3 or ryanodine. They were reduced significantly by 1) U-73122, which is a phospholipase C inhibitor; 2) cyclopiazonic acid, which blocks the Ca2+ pump in intraneuronal membranes; and 3) 2-aminoethoxy-diphenylborane, which is an inositol ( 1 , 4 , 5 )-trisphosphate receptor antagonist. Inhibitors of PKC or calmodulin-dependent protein kinase also suppressed the AMP-evoked excitatory responses. Exposure to AMP suppressed fast nicotinic ionotropic postsynaptic potentials, slow metabotropic excitatory postsynaptic potentials, and slow noradrenergic inhibitory postsynaptic potentials in the submucosal plexus. Inhibition of each form of synaptic transmission reflected action at presynaptic inhibitory adenosine A1 receptors. Slow excitatory postsynaptic potentials, which were mediated by the release of ATP and stimulation of P2Y1 purinergic receptors in the submucosal plexus, were not suppressed by AMP. The results suggest an excitatory action of AMP at adenosine A2A receptors on neuronal cell bodies and presynaptic inhibitory actions mediated by adenosine A1 receptors for most forms of neurotransmission in the submucosal plexus, with the exception of slow excitatory purinergic transmission mediated by the P2Y1 receptor subtype.

Reflex increase in ventilation by muscle receptors with nonmedullated fibers (C fibers)

1972 ◽  
Vol 32 (2) ◽  
pp. 189-193 ◽  
Author(s):  
Madhu Kalia ◽  
J. M. Senapati ◽  
B. Parida ◽  
A. Panda
Keyword(s):  
Gastrocnemius Muscle ◽  
Medial Gastrocnemius ◽  
Lateral Gastrocnemius ◽  
Group Iii ◽  
C Fibers ◽  
Group I ◽  
Natural Stimulation ◽  
Antidromic Stimulation ◽  
Sensory Endings ◽  
Stimulation Of

The reflex increase in ventilation (Ve) produced by natural stimulation of certain sensory receptors in gastrocnemius muscle was studied in dogs anesthetized with Na pentobarbital. Reflex increase in Ve occurred when the endings of group III fibers and nonmedullated fibers were stimulated (by stretching, pressing, or squeezing the muscle locally), whereas the endings of group I and group II fibers were blocked by repetitive antidromic stimulation. Stimulation of endings of nonmedullated fibers alone also increased Ve after all the medullated fibers were blocked either by cooling the medial gastrocnemius nerve to 5 C or by stimulating lateral gastrocnemius nerve repetitively. It was concluded that there were sensory endings of nonmedullated fibers in muscles which are stimulated by stretching, pressing, or squeezing the muscle locally; these endings produce reflex hyperventilation. antidromic stimulation; gastrocnemius muscle

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