Synaptic potentials produced in jaw-closer and jaw-opener motoneurons by palatal stimulation

1992 ◽  
Vol 90 (2) ◽  
Author(s):  
M. Takata ◽  
S. Tomioka ◽  
N. Tomomune
Keyword(s):  
Synaptic Potentials ◽  
Palatal Stimulation

scholarly journals Accuracy Evaluation of Additively and Subtractively Fabricated Palatal Plate Orthodontic Appliances for Newborns and Infants–An In Vitro Study

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4103
Author(s):  
Maite Aretxabaleta ◽  
Alexey Unkovskiy ◽  
Bernd Koos ◽  
Sebastian Spintzyk ◽  
Alexander B. Xepapadeas
Keyword(s):  
Layer Thickness ◽  
In Vitro Study ◽  
Orthodontic Appliances ◽  
Accuracy Evaluation ◽  
Palatal Plate ◽  
Cad Cam ◽  
Subtractive Manufacturing ◽  
Palatal Stimulation ◽  
Manufacturing Time

Different approaches for digital workflows have already been presented for their use in palatal plates for newborns and infants. However, there is no evidence on the accuracy of CAD/CAM manufactured orthodontic appliances for this kind of application. This study evaluates trueness and precision provided by different CAM technologies and materials for these appliances. Samples of a standard palatal stimulation plate were manufactured using stereolithography (SLA), direct light processing (DLP) and subtractive manufacturing (SM). The effect of material (for SM) and layer thickness (for DLP) were also investigated. Specimens were digitized with a laboratory scanner (D2000, 3Shape) and analyzed with a 3D inspection software (Geomagic Control X, 3D systems). For quantitative analysis, differences between 3D datasets were measured using root mean square (RMS) error values for trueness and precision. For qualitative analysis, color maps were generated to detect locations of deviations within each sample. SM showed higher trueness and precision than AM technologies. Reducing layer thickness in DLP did not significantly increase accuracy, but prolonged manufacturing time. All materials and technologies met the clinically acceptable range and are appropriate for their use. DLP with 100 µm layer thickness showed the highest efficiency, obtaining high trueness and precision within the lowest manufacturing time.

N-cholinergic facilitation of glutamate release from an individual retinotectal fiber in frog

2001 ◽  
Vol 18 (4) ◽  
pp. 549-558 ◽  
Author(s):  
A. KURAS ◽  
N. GUTMANIENĖ
Keyword(s):  
Nicotinic Acetylcholine Receptors ◽  
Action Potentials ◽  
Acetylcholine Receptors ◽  
Kynurenic Acid ◽  
Glutamate Release ◽  
Synaptic Potentials ◽  
Lower Vertebrates ◽  
Optic Fibers ◽  
Retinotectal Transmission

Nicotinic acetylcholine receptors are localized on retinotectal axons' terminals in lower vertebrates. The effects of activation of these receptors by endogenous acetylcholine were observed under stimulation of mass optic fibers. This study was designed to determine whether endogenous acetylcholine facilitates frog retinotectal transmission, provided only the synapses of an individual optic axon are activated, and to evaluate the feasible extent of nicotinic facilitation in these synapses by applied agonist. To this end, the effects of cholinergic drugs on the extracellular action and synaptic potentials recorded from the terminal arborization of a separate retinotectal fiber (in layer F of the tectum) were investigated in vivo. Glutamatergic nature of retinotectal synapses was reexamined by treatment with kynurenic acid. Both kynurenic acid (0.25–1 mM) and d-tubocurarine chloride (10–15 μM) significantly depressed the synaptic potentials. Carbamylcholine chloride (50–150 μM) evoked a large augmentation of the synaptic potentials and a slight but statistically significant decrease of the action potentials. D-tubocurarine reduced the effect of carbamylcholine. Pilocarpine hydrochloride (50 μM) had only a weak effect. The paired-pulse facilitation of the synaptic potentials changed significantly under the action of carbamylcholine and d-tubocurarine. The obtained results suggest that the glutamate release from activated synapses of individual retinotectal axons is facilitated by endogenous acetylcholine via presynaptic nicotinic receptors. Under used stimulation conditions, this modulation mechanism was employed only partially since its activation by applied carbamylcholine could enhance synaptic transmission up to 2.8 times.

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)

The synaptic organization of optic afferents in the amphibian tectum

1974 ◽  
Vol 187 (1089) ◽  
pp. 421-447 ◽  
Keyword(s):  
Optic Nerve ◽  
Cell Layer ◽  
Maximum Amplitude ◽  
Synaptic Organization ◽  
Nerve Fibres ◽  
Synaptic Potentials ◽  
Postsynaptic Cell ◽  
Optic Fibre ◽  
Stimulation Of

Potentials in the amphibian tectum, evoked by stimulation of the optic nerve, were recorded extracellularly. Four discrete potentials, referred to as the m 1 , m 2 , u 1 and u 2 waves, occur at different latencies after stimulation. We have shown that these waves represent summed post-synaptic potentials generated by synchronous activation of four different groups of optic nerve fibres. The m 1 and m 2 waves are generated by two classes of myelinated optic nerve fibres, previously characterized as ‘dimming’ and ‘event’ fibres. The maximum amplitude of the m 2 wave occurs just below, and of the m 2 wave just above, cell layer 8 of P. Ramón. The u 1 and u 2 waves are generated by ‘edge’ and ‘convexity’ fibres, respectively. The maximum amplitude of the u 1 wave occurs near the surface of the tectum, and of the u 2 wave some 100 μm below it. Postsynaptic cell bodies for all four classes of optic fibre are located in layer 8.

The Physiology and Morphology of Median Nerve Motor Neurones in the Thoracic Ganglia of the Locust

1982 ◽  
Vol 96 (1) ◽  
pp. 325-341
Author(s):  
MALCOLM BURROWS
Keyword(s):  
Synaptic Input ◽  
Motor Neurone ◽  
Abdominal Muscles ◽  
Thoracic Ganglia ◽  
Synaptic Potentials ◽  
Metathoracic Ganglion ◽  
Inspiratory Motor ◽  
Motor Neurones ◽  
Chemical Synapses ◽  
The Right

Simultaneous intracellular recordings have been made from the two expiratory, and from the two inspiratory motor neurones which have their axons in the unpaired median nerves of the thoracic ganglia. Each motor neurone has an axon that branches to innervate muscles on the left and on the right side of one segment. The expiratory neurones studied were those in the meso- and meta-thoracic ganglia which innervate spiracular closer muscles. The depolarizing synaptic potentials underlying the spikes during expiration are common to the two closer motor neurones in a particular segment. Similarly, during inspiration when there are usually no spikes, the hyperpolarizing, inhibitory potentials are also common to both motor neurones. The synaptic input to the neurones can be derived from four interneurones; two responsible for the depolarizing potentials during expiration and two for the inhibitory potentials during inspiration. The inspiratory neurones studied were those in the abdominal ganglia fused to the metathoracic ganglion which innervate dorso-ventral abdominal muscles. During inspiration the two motor neurones of one segment spike at a similar and steady frequency. The underlying synaptic input to the two is common. During expiration, when there are usually no spikes, the hyperpolarizing synaptic potentials are also common to both neurones. In addition they match exactly the depolarizing potentials occurring at the same time in the closer motor neurones. The same set of interneurones could be responsible. No evidence has been revealed to indicate that the two closer, or the two inspiratory motor neurones of one segment are directly coupled by electrical or chemical synapses. The morphology of both types of motor neurone is distinct from that of other motor neurones in these ganglia. Both types branch extensively in both the left and in the right areas of the neuropile.

Mormyromast electroreceptor organs and their afferent fibers in mormyrid fish. II. Intra-axonal recordings show initial stages of central processing

1990 ◽  
Vol 63 (2) ◽  
pp. 303-318 ◽  
Author(s):  
C. C. Bell
Keyword(s):  
Lateral Line ◽  
Electric Organ Discharge ◽  
Electric Organ ◽  
Direct Stimulation ◽  
Postsynaptic Potentials ◽  
Central Processing ◽  
Refractory Periods ◽  
Synaptic Potentials ◽  
Afferent Fibers ◽  
Stimulation Of

1. Physiologically and morphologically identified primary afferent fibers from mormyromast electroreceptor organs were recorded intracellularly. The fiber recordings were made from the nerve root of the posterior lateral line nerve, where the fibers enter the brain, and from the electrosensory lateral line lobe (ELL), near the central terminals of the fibers. 2. The intracellular recordings reveal a variety of potentials, synaptic and nonsynaptic, in addition to the large orthodromic action potentials from the periphery. The goal of the present study was to describe and interpret these various potentials in mormyromast afferent fibers as a first step in understanding the processing of electrosensory information in ELL. 3. Three types of synaptic potentials were recorded inside mormyromast afferent fibers: 1) electric organ corollary discharge (EOCD) excitatory postsynaptic potentials (EPSPs), driven by the motor command that elicits the electric organ discharge (EOD); 2) EPSPs evoked by electrosensory stimulation of electroreceptors in the skin near the electroreceptor from which the recorded fiber originates or by direct stimulation of an electrosensory nerve; and 3) inhibitory postsynaptic potentials (IPSPs) evoked by electrosensory stimulation of more distant electroreceptors. These synaptic potentials can be attributed to synaptic input to postsynaptic cells in ELL that is observed inside the afferent fibers because of electrical synapses between the fibers and the postsynaptic cells. 4. The peripherally evoked EPSPs could frequently be shown to be unitary. The unitary EPSPs were identical to the orthodromic spikes in originating from a single electroreceptor, in threshold, and in latency shift with increasing stimulus intensity. These similarities suggest that the unitary EPSPs are electrotonic EPSPs caused by impulses in other mormyromast afferent fibers that terminate on some of the same postsynaptic cells as the recorded fiber. The peripherally evoked IPSPs had a longer latency than the EPSPs or orthodromic spikes, requiring the presence of an inhibitory interneuron. 5. The peripherally evoked EPSPs, both unitary and nonunitary, show absolute refractory periods of 3-8 ms, followed by relative refractory periods of approximately 8 ms, when tested with two identical stimuli to a nerve. These refractory periods are interpreted as because of refractoriness in the fine preterminal branches of the axonal arbor. 6. A depolarizing afterpotential is commonly associated with the orthodromic spike and probably results from the successful propagation of the spike into the entire terminal arbor. The depolarizing afterpotential has a refractory period that is similar to that of the peripherally evoked EPSPs and that is also interpreted as refractoriness in the fine preterminal branches.(ABSTRACT TRUNCATED AT 400 WORDS)

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