Observations on reflex responses to rhythmical stimulation in the frog

The primary object of this investigation was the study of the relation between the frequency and intensity of stimulation, and the resulting reflex reactions. I first studied the effect of alteration of frequency at a given intensity of stimulation and found that under these conditions the frequency has an optimal value. With moderate and rapid frequency stimuli there is also an optimal intensity value, though with those of low frequency this is not the case. It was also hoped that some light might be thrown on the mechanism of the spinal reflex centre by the comparison of the isometrically recorded reflex tetanus, with the tetanus obtained directly by stimulation of the efferent nerve at varying intensity and frequency of stimulation. In particular, an attempt was made to settle the question as to whether stimulation of a nerve can set into action the whole of the reflex centre to which it is afferent. Camis (4) concluded that the cells of a spinal motor centre can be regarded from a functional point of view, as divided into several independent groups, though this division is not absolute. On the other hand, Dreyer and Sherrington’s (5) observations point rather to the physiological unity of the spinal motor centre; since they showed that the maximal mechanical power of tetanic contraction, obtainable from a muscle under spinal reflex action, is sometimes as great as that which can be evoked from it by direct faradisation of the motor nerve itself.

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Inhibition of Spontaneous Lateral-Line Activity by Efferent Nerve Stimulation

Journal of Experimental Biology ◽

10.1242/jeb.57.1.77 ◽

1972 ◽

Vol 57 (1) ◽

pp. 77-82

Author(s):

I. J. RUSSELL ◽

B. L. ROBERTS

Keyword(s):

Lateral Line ◽

Low Frequency ◽

Inhibitory Effect ◽

Afferent Activity ◽

Sense Organs ◽

Nerve Fibres ◽

Impulse Frequency ◽

Efferent Nerve ◽

Visible Effect ◽

Stimulation Of

1. Efferent nerve fibres innervating the lateral-line sense organs of the dogfish Scyliorhinus were stimulated with trains of stimuli while spontaneous afferent activity was monitored. 2. Significant changes in spontaneous impulse frequency could be produced when the efferent nerves were stimulated by trains of pulses at frequencies between 20-100 sec-1 lower stimulus frequencies had no visible effect. The impulse frequency decreased or was totally inhibited during the stimulus period and for 150-200 msec following it. The inhibitory effect was very variable and declined with repetitive stimulation. 3. Stimulation of the efferent nerves to inactive afferent units was followed after 500 msec by a brief low-frequency discharge.

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Nerve-induced nonadrenergic vasoconstriction and vasodilatation in skeletal muscle

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1990.258.5.h1334 ◽

1990 ◽

Vol 258 (5) ◽

pp. H1334-H1338 ◽

Cited By ~ 2

Author(s):

A. Ohlen ◽

M. G. Persson ◽

L. Lindbom ◽

L. E. Gustafsson ◽

P. Hedqvist

Keyword(s):

High Frequency ◽

Motor Nerve ◽

Low Frequency ◽

High Frequency Stimulation ◽

Alpha Adrenoceptor ◽

Adrenoceptor Antagonist ◽

Stimulation Parameters ◽

Low Frequency Stimulation ◽

Frequency Stimulation ◽

Stimulation Of

Intravital microscopy was used to study the effect of motor nerve stimulation on microvessel diameters in the rabbit tenuissimus muscle. Stimulation of the motor nerve (0.5-5 ms, 2-20 Hz, 5-15 V) evoked pulse duration- and frequency-dependent constriction of transverse and terminal arterioles. The vasoconstriction induced by low-frequency stimulation (2 Hz) was abolished by the alpha-adrenoceptor antagonist phentolamine, whereas high-frequency stimulation (10-20 Hz) resulted in a response that was only partially inhibited by phentolamine. However, desensitization of the tissue to the vasoconstrictor effects of neuropeptide Y (NPY) changed the response remaining after phentolamine into vasodilatation. Independent of stimulation parameters, pretreatment of the tissue with the adrenergic neuron blocker guanethidine reversed the constriction into dilatation that was resistant to propranolol, atropine, and indomethacin. The results document the functional presence of both vasoconstrictor and vasodilator fibers in the rabbit tenuissimus muscle motor nerve, and they suggest that part of the nerve-induced vasoconstriction at higher stimulation frequencies is caused by neuronally released NPY.

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Reflex fractionation of a muscle

Proceedings of the Royal Society of London. Series B, Containing Papers of a Biological Character ◽

10.1098/rspb.1926.0067 ◽

1926 ◽

Vol 100 (705) ◽

pp. 448-462 ◽

Cited By ~ 12

Keyword(s):

Point Of View ◽

Spinal Reflexes ◽

Primary Circuit ◽

Lumbar Region ◽

Afferent Nerves ◽

Functional Point ◽

Deep Anaesthesia ◽

Hip Flexor ◽

A Current ◽

Motor Centre

Studying spinal reflexes Camis (1) (1910) from observations on M. semitendinosus (cat) reached the conclusions that “ the cells of a spinal motor centre ca be regarded from a functional point of view as divided into several independent groups,” but that “such independence is however not absolute.” The present experiments pursue a like inquiry. That in a reflex evoked by weak excitation of the afferent nerve the resulting contraction of the muscle may involve a portion only of the muscle has common acceptance. Camis’s observations, however, employed maximal stimuli and yet the muscle evidenced fractional responses ; whereas later (3) Dreyer and one of us found, contrary to previous (4) experience, that reflex tetani in some instances activated the sum-total of the muscle. Both of these observations are confirmed by the present experiments. Method . The sample muscles taken have been a hip-flexor, tensor fasciœ femoris , a knee flexor, semitendinosus , and an ankle flexor, tibialis anticus . The preparation (cat) has been spinal, with cord transection, performed under deep anæsthesia, in the anterior lumbar region, prior to intereollicular decerebration, the anæsthesia being later relaxed. All other muscles of the limb except that one attached to the myograph have been paralysed by resection or nervesection. The limb has been securely fixed by steel drills clamped to the table. For exciting reflex contraction various afferent nerves, as cited below, of the ipsilateral limb have been stimulated by faradisation. The inductorium has been coreless and its primary circuit fed by a current of less than 0·2 amp. An optically recording myograph with isometric registration and of the pattern described in a previous paper (2) has been used.

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Dental Inclusion of Canine and Wisdom Tooth in Orthodontics Chemical Necroses

Revista de Chimie ◽

10.37358/rc.18.8.6497 ◽

2018 ◽

Vol 69 (8) ◽

pp. 2191-2196

Author(s):

Cristian Constantin Budacu ◽

Nicoleta Ioanid ◽

Cristian Romanec ◽

Mihail Balan ◽

Liliana Lacramioara Pavel ◽

...

Keyword(s):

Third Molar ◽

Point Of View ◽

Separate Entity ◽

Wisdom Tooth ◽

Facial Aesthetics ◽

The Third ◽

Edentulous Mandible ◽

Canine Guidance ◽

Upper Jaw ◽

Functional Point

Canine plays an important role in the dento-maxillary system. From a functional point of view, it provides the canine guidance, by positioning it in the frontal area, has a role in facial aesthetics. It plays an important prosthetic role by having the longest root and one of the longest arcade teeth. Three molars represent the last teeth that erupt in the arches both in the jaw and in the mandible, which is why they remain the most frequently included.Canine incidence is quite common following the wisdom tooth. It can be unilateral or bilateral and is more common in the upper jaw. The canine may remain included at the vestibular, palatal or between the two bones. A separate entity is the incision of the canine in the edentulous mandible or jaw. The study included 213 cases with dento-alveolar pathology, of which 128 patients were selected with dental inclusion. Our study reports that the first three molars are frequent, followed by the canine as opposed to other studies conducted by Guzduz K in 2011 and Fardi A of the same year bringing the canines first (Fardi, Guzduz). Some studies attribute the first place to the superior canine in terms of frequency, but they are abstracted from the molar three inclusion that they consider as most frequently (Compoy). The most common tooth in inclusion is the third molar (lower and upper) followed by the upper canine; the most commonly affected are women for both canine and molar.

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Deep Brain Stimulation of the Posterior Insula in Chronic Pain: A Theoretical Framework

Brain Sciences ◽

10.3390/brainsci11050639 ◽

2021 ◽

Vol 11 (5) ◽

pp. 639

Author(s):

David Bergeron ◽

Sami Obaid ◽

Marie-Pierre Fournier-Gosselin ◽

Alain Bouthillier ◽

Dang Khoa Nguyen

Keyword(s):

Chronic Pain ◽

Electrical Stimulation ◽

Deep Brain Stimulation ◽

Brain Stimulation ◽

High Frequency ◽

Brain Lesion ◽

Low Frequency ◽

Posterior Insula ◽

Deep Brain ◽

Stimulation Of

Introduction: To date, clinical trials of deep brain stimulation (DBS) for refractory chronic pain have yielded unsatisfying results. Recent evidence suggests that the posterior insula may represent a promising DBS target for this indication. Methods: We present a narrative review highlighting the theoretical basis of posterior insula DBS in patients with chronic pain. Results: Neuroanatomical studies identified the posterior insula as an important cortical relay center for pain and interoception. Intracranial neuronal recordings showed that the earliest response to painful laser stimulation occurs in the posterior insula. The posterior insula is one of the only regions in the brain whose low-frequency electrical stimulation can elicit painful sensations. Most chronic pain syndromes, such as fibromyalgia, had abnormal functional connectivity of the posterior insula on functional imaging. Finally, preliminary results indicated that high-frequency electrical stimulation of the posterior insula can acutely increase pain thresholds. Conclusion: In light of the converging evidence from neuroanatomical, brain lesion, neuroimaging, and intracranial recording and stimulation as well as non-invasive stimulation studies, it appears that the insula is a critical hub for central integration and processing of painful stimuli, whose high-frequency electrical stimulation has the potential to relieve patients from the sensory and affective burden of chronic pain.

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Induction of long-term potentiation without participation of N-methyl-D-aspartate receptors in kitten visual cortex

Journal of Neurophysiology ◽

10.1152/jn.1991.65.1.20 ◽

1991 ◽

Vol 65 (1) ◽

pp. 20-32 ◽

Cited By ~ 47

Author(s):

Y. Komatsu ◽

S. Nakajima ◽

K. Toyama

Keyword(s):

Nmda Receptors ◽

Stimulus Frequency ◽

Low Frequency ◽

Nmda Antagonist ◽

Long Term Potentiation ◽

Conditioning Stimulation ◽

Postsynaptic Potential ◽

Term Potentiation ◽

Stimulation Of

1. Intracellular recording was made from layer II-III cells in slice preparations of kitten (30-40 days old) visual cortex. Low-frequency (0.1 Hz) stimulation of white matter (WM) usually evoked an excitatory postsynaptic potential (EPSP) followed by an inhibitory postsynaptic potential (IPSP). The postsynaptic potentials (PSPs) showed strong dependence on stimulus frequency. Early component of EPSP and IPSP evoked by weak stimulation both decreased monotonically at frequencies greater than 0.5-1 Hz. Strong stimulation similarly depressed the early EPSP at higher frequencies (greater than 2 Hz) and replaced the IPSP with a late EPSP, which had a maximum amplitude in the stimulus frequency range of 2-5 Hz. 2. Very weak WM stimulation sometimes evoked EPSPs in isolation from IPSPs. The falling phase of the EPSP revealed voltage dependence characteristic to the responses mediated by N-methyl-D-aspartate (NMDA) receptors and was depressed by application of an NMDA antagonist DL-2-amino-5-phosphonovalerate (APV), whereas the rising phase of the EPSP was insensitive to APV. 3. The early EPSPs followed by IPSPs were insensitive to APV but were replaced with a slow depolarizing potential by application of a non-NMDA antagonist 6,7-dinitro-quinoxaline-2,3-dione (DNQX), indicating that the early EPSP is mediated by non-NMDA receptors. The slow depolarization was mediated by NMDA receptors because it was depressed by membrane hyperpolarization or addition of APV. 4. The late EPSP evoked by higher-frequency stimulation was abolished by APV, indicating that it is mediated by NMDA receptors, which are located either on the recorded cell or on presynaptic cells to the recorded cells. 5. Long-term potentiation (LTP) of EPSPs was examined in cells perfused with solutions containing 1 microM bicuculline methiodide (BIM), a gamma-aminobutyric acid (GABA) antagonist. WM was stimulated at 2 Hz for 15 min as a conditioning stimulus to induce LTP, and the resultant changes were tested by low-frequency (0.1 Hz) stimulation of WM. 6. LTP of early EPSPs occurred in more than one-half of the cells (8/13) after strong conditioning stimulation. The rising slope of the EPSP was increased 1.6 times on average. 7. To test involvement of NMDA receptors in the induction of LTP in the early EPSP, the effect of conditioning stimulation was studied in a solution containing 100 microM APV, which was sufficient to block completely synaptic transmission mediated by NMDA receptors. LTP occurred in the same frequency and magnitude as in control solution.

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Effects of low-frequency stimulation of the superior colliculus on spontaneous and visually guided saccades

Journal of Neurophysiology ◽

10.1152/jn.1993.69.3.953 ◽

1993 ◽

Vol 69 (3) ◽

pp. 953-964 ◽

Cited By ~ 43

Author(s):

P. W. Glimcher ◽

D. L. Sparks

Keyword(s):

Superior Colliculus ◽

Time Course ◽

Low Frequency ◽

Arbitrary Point ◽

Visually Guided ◽

Spontaneous Movements ◽

Low Frequency Stimulation ◽

Frequency Stimulation ◽

Stimulation Current ◽

Stimulation Of

1. The first experiment of this study determined the effects of low-frequency stimulation of the monkey superior colliculus on spontaneous saccades in the dark. Stimulation trains, subthreshold for eliciting short-latency fixed-vector saccades, were highly effective at biasing the metrics (direction and amplitude) of spontaneous movements. During low-frequency stimulation, the distribution of saccade metrics was biased toward the direction and amplitude of movements induced by suprathreshold stimulation of the same collicular location. 2. Low-frequency stimulation biased the distribution of saccade metrics but did not initiate movements. The distribution of intervals between stimulation onset and the onset of the next saccade did not differ significantly from the distribution of intervals between an arbitrary point in time and the onset of the next saccade under unstimulated conditions. 3. Results of our second experiment indicate that low-frequency stimulation also influenced the metrics of visually guided saccades. The magnitude of the stimulation-induced bias increased as stimulation current or frequency was increased. 4. The time course of these effects was analyzed by terminating stimulation immediately before, during, or after visually guided saccades. Stimulation trains terminated at the onset of a movement were as effective as stimulation trains that continued throughout the movement. No effects were observed if stimulation ended 40–60 ms before the movement began. 5. These results show that low-frequency collicular stimulation can influence the direction and amplitude of spontaneous or visually guided saccades without initiating a movement. These data are compatible with the hypothesis that the collicular activity responsible for specifying the horizontal and vertical amplitude of a saccade differs from the type of collicular activity that initiates a saccade.

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