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1
Yu, Zhou, J. Michael McIntosh, Soroush G. Sadeghi e Elisabeth Glowatzki. "Efferent synaptic transmission at the vestibular type II hair cell synapse". Journal of Neurophysiology 124, n. 2 (1 agosto 2020): 360–74. http://dx.doi.org/10.1152/jn.00143.2020.
Testo completoAbstract (sommario):
Type II vestibular hair cells (HCs) receive inputs from efferent neurons in the brain stem. We used in vitro optogenetic and electrical stimulation of vestibular efferent fibers to study their synaptic inputs to type II HCs. Stimulation of efferents inhibited type II HCs, similar to efferent effects on cochlear HCs. We propose that efferent inputs adjust the contribution of signals from type I and II HCs to vestibular nerve fibers.
2
Mishra, Srikanta K. "The role of efferents in human auditory development: efferent inhibition predicts frequency discrimination in noise for children". Journal of Neurophysiology 123, n. 6 (1 giugno 2020): 2437–48. http://dx.doi.org/10.1152/jn.00136.2020.
Testo completoAbstract (sommario):
Despite several decades of research, the functional role of medial olivocochlear efferents in humans remains controversial and is thought to be insignificant. Here it is shown that medial efferent inhibition strongly predicts frequency discrimination in noise for younger children but not for older children and adults. Young children are relatively more dependent on the efferent system for listening-in-noise. This study highlights the role of the efferent system in hearing-in-noise during childhood development.
3
Kaiser, A., e G. A. Manley. "Physiology of single putative cochlear efferents in the chicken". Journal of Neurophysiology 72, n. 6 (1 dicembre 1994): 2966–79. http://dx.doi.org/10.1152/jn.1994.72.6.2966.
Testo completoAbstract (sommario):
1. An experimental approach was developed that allowed recording of neurophysiological activity from single putative cochlear efferents in the auditory brain stem of anesthetized chickens with the use of glass micropipettes. The aim of this study was to study spontaneous and tone-evoked activity from single efferent neurons in the chick and to compare their properties with those of other vertebrate hair cell organs. Because the birds, like mammals, have a complex hearing organ with different hair cell types and different afferent and efferent innervation, the purpose of this study was also to determine whether different types of efferents exist. 2. In the same electrode penetrations, putative trapezoid fibers were also isolated. In addition, the penetration angle permitted recordings from units in both cochlear nuclei, nucleus magnocellularis and nucleus angularis (probably mostly cochlear afferents), in the same animal. This allowed monitoring of the auditory sensitivity of the individual animal during the experiment. With the use of physiological criteria, it was possible to distinguish between trapezoid fibers and putative cochlear efferents. Possible alternative origins of the responses described are discussed. 3. Tuning curve characteristics of putative efferents were determined. They were as sensitive as ascending auditory neurons. Q10 dB values of efferent tuning curves were < 2.5 and thus showed poorer frequency selectivity than ascending fibers; in some cases they covered the entire hearing range of the chicken. 4. Latencies to tone pips were different for ascending neurons and putative efferent units. For trapezoid fibers and neurons from the cochlear nuclei, latencies usually did not exceed 5 ms, whereas latencies of efferents were always longer. 5. Because of the interaural canal that connects both middle ear cavities in birds, the measurement of the lateralization of the efferents was difficult. In any case, the majority of putative cochlear efferents responded more sensitively to sound stimulation of the contralateral side. 6. Of the efferent units, 28% showed no spontaneous activity. The others either showed regular spontaneous activity, or their time-interval histograms showed longer modes than ascending fibers. In general, mean spontaneous activity was lower than in ascending fibers, being < 30 spikes/s. 7. In contrast to reports from mammalian studies, in which efferents only showed on peristimulus time (PST) response pattern to tonal stimuli (chopper), two different response types were found in this study: two excitation types (chopper and primary-like) and one suppression type.(ABSTRACT TRUNCATED AT 400 WORDS)
4
WILLIAMSON, R. "Efferent Influences on the Afferent Activity from the Octopus Angular Acceleration Receptor System". Journal of Experimental Biology 119, n. 1 (1 novembre 1985): 251–64. http://dx.doi.org/10.1242/jeb.119.1.251.
Testo completoAbstract (sommario):
Electrophysiological recordings were made from afferent units of the octopus angular acceleration receptor system during the electrical stimulation of efferent axons to this system. Of the afferent units examined, 93% changed their activity in response to stimulation of the efferent axons. During efferent stimulation 77% of the afferent units decreased their activity. The magnitude of the inhibition and the time to maximum response were frequency dependent, with most units showing an increase in inhibition with increase in efferent stimulation frequency. The poststimulus recovery from inhibition was of two types: either a gradual increase in activity to the pre-stimulus resting level of activity (Fig. 3) or a rapid increase in activity to a level above the pre-stimulus level, i.e. a postinhibitory rebound or facilitation, and then a gradual decline to the resting level of activity (Fig. 4). During long periods of efferent stimulation (<40 s) the inhibition was not maintained. During stimulation of the efferent axons 16% of the afferent units increased their activity. The post-stimulus response consisted of either a gradual decrease in activity to the pre-stimulus level of resting activity or a rapid increase in activity followed by a gradual decrease to the resting level of activity (Fig. 6). During long periods of efferent stimulation the excitation increased to a plateau level which was maintained for the duration of the stimulus period (Fig. 7). Sinusoidal oscillations of the statocyst evoked bursts of afferent activity in time with the movement. The magnitude of these bursts could be decreased or increased by stimulation of the efferent axons (Fig. 8). It is proposed that two populations of efferents are present in the octopus statocyst, one inhibitory and the other excitatory, and that both types of efferent affect single afferent units.
5
Highstein, S. M., e R. Baker. "Action of the efferent vestibular system on primary afferents in the toadfish, Opsanus tau". Journal of Neurophysiology 54, n. 2 (1 agosto 1985): 370–84. http://dx.doi.org/10.1152/jn.1985.54.2.370.
Testo completoAbstract (sommario):
Spinalized toadfish were held in a lucite chamber and perfused through the mouth with running seawater. Primary vestibular afferents and vestibular efferent axons and somas were studied with glass microelectrodes. Vestibular semicircular canal afferent and efferent axons were visually identified and penetrated with glass microelectrodes. Afferents responded to pulses of injected current with trains of action potentials, whereas efferents responded with only a single spike. This differential response to injected current served to further distinguish these two classes of nerve fibers that share the same canal nerve for part of their course. When current pulses were injected into efferent somadendritic recording sites, cells responded with trains of action potentials similar to those seen in other central nervous system neurons. Semicircular canal afferents were spontaneously active and occupied the same spectrum of regularity as vestibular afferents recorded in other species. Behavioral arousal evoked by lightly touching the fish on the snout or over the eye resembled spontaneous arousal observed in the field and consisted of eye withdrawal, fin erection, and attempted swimming. Efferent vestibular neurons were spontaneously active and increased their frequency of discharge when the fish was behaviorally aroused. Most efferents were briskly activated by behavioral arousal, but the time constant of the decay of their responses was variable ranging from 100 to 600 ms. Not only touch, but multimodal stimuli were capable of increasing the level of spontaneous activity of efferent vestibular neurons. The shortest latency to behavioral activation was 160 ms. Vestibular primary afferents also manifested increase in neuronal activity with behavioral activation. Irregularly discharging afferents were much more responsive than regularly discharging afferents. One rare case of transient inhibition in a regularly discharging afferent is illustrated. Severing the efferent vestibular nerve blocked behavioral activation in vestibular primary afferents. Electrical stimulation of the efferent vestibular nerve produced excitatory postsynaptic potentials (EPSPs) at latencies within the monosynaptic range in vestibular primary afferents. These monosynaptic EPSPs could produce action potentials in primary afferents or could sum with subthreshold depolarizations produced by current passed through the microelectrode to initiate impulses.(ABSTRACT TRUNCATED AT 400 WORDS)
6
Liberman, M. C. "Response properties of cochlear efferent neurons: monaural vs. binaural stimulation and the effects of noise". Journal of Neurophysiology 60, n. 5 (1 novembre 1988): 1779–98. http://dx.doi.org/10.1152/jn.1988.60.5.1779.
Testo completoAbstract (sommario):
1. Discharge properties of olivocochlear efferent neurons were measured in anesthetized cats. Previous studies of these neurons concentrated on monaural stimulation with tones and found sound-evoked discharge rates rarely exceeded 60 spikes/s (16, 20). In the present study, rates as high as 140 spikes/s were achieved by binaural stimulation and/or the addition of noise. Based on studies on the known effects of electrically stimulating the efferents such high rates of sound-evoked efferent activity probably have significant feedback effects on the auditory periphery. 2. Spontaneous discharge rate (SR) was weakly correlated with threshold among efferent neurons: those with SRs greater than 1 spikes/s were generally more sensitive than spontaneously inactive fibers. The discharge rate measured in the absence of acoustic stimulation was shown to be dependent on stimulation history: some units with zero SR became spontaneously active after several minutes of continuous noise stimulation. 3. For stimulation with monaural tones, efferent excitability varied with characteristic frequency (CF): units with CF less than 10 kHz tended to have lower thresholds, higher discharge rates, and shorter latencies than higher CF units. These differences could be minimized by the addition of broadband noise (see below). 4. When tones were presented to one ear at a time, most efferent units appeared monaural (91%), with roughly two-thirds excited by ipsilateral stimuli and one-third by contralateral stimuli. However, the effects of simultaneous stimulation of the two ears suggested that the great majority of efferent units have binaural inputs: the addition of opposite-ear noise or tones, which presented alone were not excitatory, typically enhanced the response to main-ear stimulation. This type of binaural facilitation was strongest among low-CF efferents when the opposite-ear stimuli were tones, and strongest among high-CF units when the opposite-ear stimulus was broadband noise. 5. The binaural facilitation seen using opposite-ear noise both lowered the threshold (by as much as 40 dB) and increased the discharge rate (by as much as 80%) to tones presented in the main ear. Significant facilitation was seen with noise levels as low as 25 dB SPL or tone levels as low as 30 dB SPL. In general, the weaker the response to monaural stimuli, the stronger the binaural facilitation. 6. The facilitatory effects of stimulation with continuous noise could outlast the stimulus. Persistent increases in efferent sensitivity were documented following 10-min exposures to broadband noise at 85-115 dB SPL.
7
Yoshioka, Takashi, Jonathan B. Levitt e Jennifer S. Lund. "Independence and merger of thalamocortical channels within macaque monkey primary visual cortex: Anatomy of interlaminar projections". Visual Neuroscience 11, n. 3 (maggio 1994): 467–89. http://dx.doi.org/10.1017/s0952523800002406.
Testo completoAbstract (sommario):
AbstractAn important issue in understanding the function of primary visual cortex in the macaque monkey is how the several efferent neuron groups projecting to extrastriate cortex acquire their different response properties. To assist our understanding of this issue, we have compared the anatomical distribution of VI intrinsic relays that carry information derived from magno- (M) and parvocellular (P) divisions of the dorsal lateral geniculate nucleus between thalamic recipient neurons and interareal efferent neuron groups within area VI. We used small, iontophoretic injections of biocytin placed in individual cortical laminae of area VI to trace orthograde and retrograde inter- and intralaminar projections. In either the same or adjacent sections, the tissue was reacted for cytochrome oxidase (CO), which provides important landmarks for different efferent neuron populations located in CO rich blobs and CO poor interblobs in laminae ⅔, as well as defining clear boundaries for the populations of efferent neurons in laminae 4A and 4B. This study shows that the interblobs, but not the blobs, receive direct input from thalamic recipient 4C neurons; the interblobs receive relays from mid 4C neurons (believed to receive convergent M and P inputs), while blobs receive indirect inputs from either M or P (or both) pathways through layers 4B (which receives M relays from layer 4Cα) and 4A (which receives P relays directly from the thalamus as well as from layer 4Cβ). The property of orientation selectivity, most prominent in the interblob regions and in layer 4B, may have a common origin from oriented lateral projections made by mid 4C spiny stellate neurons. While layer 4B efferents may emphasize M characteristics and layer 4A efferents emphasize P characteristics, the dendrites of their constituent pyramidal neurons may provide anatomical access to the other channel since both blob and interblob regions in layers ⅔ have anatomical access to M and P driven relays, despite functional differences in the way these properties may be expressed in the two compartments.
8
KHADILKAR, RASHMI V., JOHN R. MYTINGER, LAURA E. THOMASON, SCOTT L. RUNYON, KEVIN J. WASHICOSKY e ROBERT N. JINKS. "Central regulation of photosensitive membrane turnover in the lateral eye of Limulus. I. Octopamine primes the retina for daily transient rhabdom shedding". Visual Neuroscience 19, n. 3 (maggio 2002): 283–97. http://dx.doi.org/10.1017/s0952523802192066.
Testo completoAbstract (sommario):
Limulus lateral eyes shed and renew a portion of their photosensitive membrane (rhabdom) daily. Shedding, in many species including Limulus, is regulated by complex interactions between circadian rhythms and light. Little is known about how circadian clocks and photoreceptors communicate to regulate shedding. Limulus photoreceptors do not contain an endogenous circadian oscillator, but rely upon efferent outflow from a central clock for circadian timing. To investigate whether the putative efferent neurotransmitter octopamine (OA) communicates circadian rhythms that prime the lateral eye for transient rhabdom shedding, we decoupled photoreceptors from the clock by transecting the lateral optic nerve (contains the retinal efferent fibers). Overnight (6 h) intraretinal injections of 40 μM OA restored transient shedding to lateral eyes with transected nerves to levels comparable to those of intact internal control eyes. To determine whether OA acts alone in communicating circadian rhythms that prime the lateral eye for transient shedding, we “primed” eyes with intact nerves for transient shedding with exogenous OA during subjective day. In nature, lateral eyes shed their rhabdoms only once a day at dawn following overnight efferent priming. Eyes in animals placed in darkness during subjective day, when the retinal efferents are quiescent, and injected for 6 h with 40 μM OA shed their rhabdoms in response to a second introduction to light. Untreated control eyes of the same animals did not. The same results were observed in vitro in lateral eyes treated similarly. Octopamine is the only efferent neurotransmitter/messenger required to make lateral eyes competent for transient shedding. Phentolamine, an OA receptor antagonist, reduced the number of photoreceptors primed for transient shedding and the amount of rhabdom shed in those photoreceptors suggesting that OA acts via a specific OA receptor.
9
Rucker, Janet C., e Paul H. Phillips. "Efferent Vision Therapy". Journal of Neuro-Ophthalmology 38, n. 2 (giugno 2018): 230–36. http://dx.doi.org/10.1097/wno.0000000000000480.
Testo completo
10
Norgren, R., e G. P. Smith. "A method for selective section of vagal afferent or efferent axons in the rat". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 267, n. 4 (1 ottobre 1994): R1136—R1141. http://dx.doi.org/10.1152/ajpregu.1994.267.4.r1136.
Testo completoAbstract (sommario):
Although normally a mixed nerve, intracranially the vagus separates into dorsal rootlets that contain afferent axons and ventral rootlets that contain efferents. Surgical procedures are described for exposing the ventral surface of the occipital bone at the level where the vagus passes through the posterior lacerated foramen. When the foramen is expanded medially and the dura lanced, the intracranial course of the vagus can be observed by use of an operating microscope. Under these conditions, either the efferent or the afferent rootlets can be severed selectively. When the dorsal rootlets are divided and the contralateral trunk is cut below the diaphragm, a selective bilateral subdiaphragmatic afferent vagotomy is produced with unilateral sparing of the efferents. Cutting the efferents intracranially has the converse effect.
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Montgomery, J. C., e D. Bodznick. "HINDBRAIN CIRCUITRY MEDIATING COMMON MODE SUPPRESSION OF VENTILATORY REAFFERENCE IN THE ELECTROSENSORY SYSTEM OF THE LITTLE SKATE RAJA ERINACEA". Journal of Experimental Biology 183, n. 1 (1 ottobre 1993): 203–16. http://dx.doi.org/10.1242/jeb.183.1.203.
Testo completoAbstract (sommario):
Elasmobranch fish have an electrosensory system which they use for prey detection and for orientation. Sensory inputs to this system are corrupted by a form of reafference generated by the animal's own ventilation, but this noise is reduced by sensory processing within the medullary nucleus of the electrosensory system. This noise cancellation is achieved, at least in part, by a common mode rejection mechanism. In this study we have examined characteristics of neurones within the medullary nucleus in an attempt to understand the neural circuitry responsible for common mode suppression. Our results are in accord with previous indications that ascending efferent neurones of the medullary nucleus are monosynaptically activated from the ipsilateral electrosensory nerves and project to the midbrain. We demonstrate that in Raja erinacea, as has been previously shown in one other species (Cephaloscyllium isabella), ascending efferent neurones typically have a discrete focal excitatory receptive field and an inhibitory receptive field which may be discrete or diffuse and which often includes a contralateral component. We identify a group of interneurones within the medullary nucleus which are driven monosynaptically from the electrosensory nerves, have simple discrete excitatory receptive fields and respond vigorously to imposed common mode signals. The simplest model of the circuitry underlying common mode rejection that is consistent with the evidence is that direct afferent input impinges onto the basal dendrites of the ascending efferent neurones and onto interneurones within the nucleus, and the interneurones in turn inhibit the ascending efferents. The pattern of this projection, including commissural inputs, determines the nature and extent of ascending efferents' inhibitory surrounds and mediates the suppression of common mode signals.
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Latash, Mark L. "Efference copy in kinesthetic perception: a copy of what is it?" Journal of Neurophysiology 125, n. 4 (1 aprile 2021): 1079–94. http://dx.doi.org/10.1152/jn.00545.2020.
Testo completoAbstract (sommario):
A number of notions in the fields of motor control and kinesthetic perception have been used without clear definitions. In this review, we consider definitions for efference copy, percept, and sense of effort based on recent studies within the physical approach, which assumes that the neural control of movement is based on principles of parametric control and involves defining time-varying profiles of spatial referent coordinates for the effectors. The apparent redundancy in both motor and perceptual processes is reconsidered based on the principle of abundance. Abundance of efferent and afferent signals is viewed as the means of stabilizing both salient action characteristics and salient percepts formalized as stable manifolds in high-dimensional spaces of relevant elemental variables. This theoretical scheme has led recently to a number of novel predictions and findings. These include, in particular, lower accuracy in perception of variables produced by elements involved in a multielement task compared with the same elements in single-element tasks, dissociation between motor and perceptual effects of muscle coactivation, force illusions induced by muscle vibration, and errors in perception of unintentional drifts in performance. Taken together, these results suggest that participation of efferent signals in perception frequently involves distorted copies of actual neural commands, particularly those to antagonist muscles. Sense of effort is associated with such distorted efferent signals. Distortions in efference copy happen spontaneously and can also be caused by changes in sensory signals, e.g., those produced by muscle vibration.
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Cowie, R. J., M. K. Smith e D. L. Robinson. "Subcortical contributions to head movements in macaques. II. Connections of a medial pontomedullary head-movement region". Journal of Neurophysiology 72, n. 6 (1 dicembre 1994): 2665–82. http://dx.doi.org/10.1152/jn.1994.72.6.2665.
Testo completoAbstract (sommario):
1. In the companion article, a variety of head movements were elicited by stimulation in, and adjacent to, the gigantocellular reticular nucleus (Cowie and Robinson 1994). We refer to this area, caudal to the abducens nucleus, as the gigantocellular head movement region. In the present paper, the anatomical connections of this region, as determined by injections of wheat-germ agglutinin conjugated horseradish peroxidase (WGA-HRP), are reported. The majority of efferent and afferent connections were with areas related to head movements. 2. Efferent fibers from the region projected via two paths to the caudal medulla and upper cervical spinal cord. Labeled fibers descended in the anterolateral funiculus of the ipsilateral spinal cord to terminate in lateral parts of the ventral horn. A second pathway descended bilaterally in the medial longitudinal fasciculus to the anterior funiculi and medial portions of the ventral gray. These efferents paralleled the head-movement topography demonstrated physiologically. Other projections included efferents to the interstitial nucleus of Cajal, caudal field H of Forel, paramedian pontine reticular formation, and caudal vestibular nuclei. Other efferent fibers projected to the trigeminal, facial, and hypoglossal nuclei, as well as to the parvocellular reticular field, which contains interneurons for these motor groups. However, no efferent or afferent labeling involved the ocular motor nuclei. 3. Afferents to the gigantocellular head movement region arose mainly from head-movement areas. In all animals, labeled cells were found in the intermediate and deep layers of the caudal superior colliculus. Labeled neurons also were found in the caudal field H of Forel, interstitial nucleus of Cajal, pontine medial tegmentum including the pontine paramedian reticular formation, nucleus subcoeruleus, and vestibular nuclear complex. Caudally, filled cells were located in the parvocellular, magnocellular, dorsal, and ventral reticular nuclei, the supraspinal nucleus, and the upper cervical ventral horn. 4. In one animal, the ipsilateral frontal cortex contained retrogradely labeled neurons. These cells were found in layer V of cortical areas 4 and 6. Other afferent cells were found consistently in the periventricular and periaqueductal gray matter. 5. A control injection into the caudal vestibular nuclear complex showed projections to the gigantocellular reticular formation and labeled cells in the vestibular and parvocellular reticular nuclei. These observations show that the connections of the gigantocellular region are not typical of all head movement sites. 6. These data indicate that the gigantocellular head-movement region has the requisite efferent and afferent connections to function in the subcortical control of head, but not eye, movements.(ABSTRACT TRUNCATED AT 400 WORDS)
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Maison, Stéphane F., Douglas E. Vetter e M. Charles Liberman. "A Novel Effect of Cochlear Efferents: In Vivo Response Enhancement Does Not Require α9 Cholinergic Receptors". Journal of Neurophysiology 97, n. 5 (maggio 2007): 3269–78. http://dx.doi.org/10.1152/jn.00067.2007.
Testo completoAbstract (sommario):
Outer hair cells in the mammalian cochlea receive a cholinergic efferent innervation that constitutes the effector arm of a sound-evoked negative feedback loop. The well-studied suppressive effects of acetylcholine (ACh) release from efferent terminals are mediated by α9/α10 ACh receptors and are potently blocked by strychnine. Here, we report a novel, efferent-mediated enhancement of cochlear sound-evoked neural responses and otoacoustic emissions in mice. In controls, a slow enhancement of response amplitude to supranormal levels appears after recovery from the classic suppressive effects seen during a 70-s epoch of efferent shocks. The magnitude of post-shock enhancement can be as great as 10 dB and tends to be greater for high-frequency acoustic stimuli. Systemic strychnine at 10 mg/kg eliminates efferent-induced suppression, revealing a purely enhancing effect of efferent shocks, which peaks within 5 s after efferent-stimulation onset, maintains a constant level through the stimulation epoch, and slowly decays back to baseline with a time constant of ∼100 s. In mice with targeted deletion of the α9 ACh receptor subunit, efferent-evoked effects resemble those in wild types with strychnine blockade, further showing that this novel efferent effect is fundamentally different from all cholinergic effects previously reported.
15
Akita, Shinsuke, Yoshihisa Yamaji, Motone Kuriyama, Hideki Tokumoto, Tatsuya Ishigaki, Takafumi Tezuka, Hideyuki Ogata, Yoshitaka Kubota e Nobuyuki Mitsukawa. "Intraoperative Detection of Efferent Lymphatic Vessels Emerging from Lymph Node during Lymphatic Microsurgery". Journal of Reconstructive Microsurgery 35, n. 05 (21 gennaio 2019): 372–78. http://dx.doi.org/10.1055/s-0038-1677039.
Testo completoAbstract (sommario):
Background Although the usefulness of efferent lymphaticovenular anastomosis (ELVA) in lymphatic microsurgery has been reported, the optimal method to distinguish efferent from afferent lymphatics is not yet established. We propose a novel technique to detect efferent lymphatics appropriate for anastomosis. Methods In total, 62 groin lymph nodes (LNs) of 46 limbs were divided into four groups based on the findings of indocyanine green lymphography: n = 15 in normal, 15 in dermal backflow stage 0, 18 in stage I, and 14 in stage II groups. The target LN and afferent lymphatic connecting it were preoperatively detected using ultrasonography. Intraoperatively, 0.05 mL patent blue dye was slowly manually injected from the afferent lymphatic; the lymphatic(s) subsequently stained was diagnosed as the efferent lymphatic(s) emerging from the node. The success rates of efferent lymphatic detection, sizes of LN, and diameter of efferent lymphatics were compared among the groups. Results Both LN size and diameter of efferent lymphatic were significantly larger in the stage 0 and I groups than the other groups (p < 0.01). Efferent lymphatic could be stained in 13, 13, 18, and 9 LNs in the normal and stage 0, I, and II groups, respectively. A significant difference was observed between the stage I and II groups regarding the success rate of efferent lymphatic detection (p = 0.04). Conclusion Efferent lymphatics could be detected using patent blue dye in 85.5% of the cases. The patients in early-stage lymphostasis might be the most appropriate candidates for ELVA.
16
Poppi, L. A., J. C. Holt, R. Lim e A. M. Brichta. "A review of efferent cholinergic synaptic transmission in the vestibular periphery and its functional implications". Journal of Neurophysiology 123, n. 2 (1 febbraio 2020): 608–29. http://dx.doi.org/10.1152/jn.00053.2019.
Testo completoAbstract (sommario):
It has been over 60 years since peripheral efferent vestibular terminals were first identified in mammals, and yet the function of the efferent vestibular system remains obscure. One reason for the lack of progress may be due to our deficient understanding of the peripheral efferent synapse. Although vestibular efferent terminals were identified as cholinergic less than a decade after their anatomical characterization, the cellular mechanisms that underlie the properties of these synapses have had to be inferred. In this review we examine how recent mammalian studies have begun to reveal both nicotinic and muscarinic effects at these terminals and therefore provide a context for fast and slow responses observed in classic electrophysiological studies of the mammalian efferent vestibular system, nearly 40 years ago. Although incomplete, these new results together with those of recent behavioral studies are helping to unravel the mysterious and perplexing action of the efferent vestibular system. Armed with this information, we may finally appreciate the behavioral framework in which the efferent vestibular system operates.
17
Tomchik, Seth M., e Zhongmin Lu. "Modulation of Auditory Signal-to-Noise Ratios by Efferent Stimulation". Journal of Neurophysiology 95, n. 6 (giugno 2006): 3562–70. http://dx.doi.org/10.1152/jn.00063.2006.
Testo completoAbstract (sommario):
One of the primary challenges that sensory systems face is extracting relevant information from background noise. In the auditory system, the ear receives efferent feedback, which may help it extract signals from noise. Here we directly test the hypothesis that efferent activity increases the signal-to-noise ratio (SNR) of the ear, using the relatively simple teleost ear. Tone-evoked saccular potentials were recorded before and after efferent stimulation, and the SNR of the responses was calculated. In quiet conditions, efferent stimulation suppressed saccular responses to a tone, reducing the SNR. However, when masking noise was added, efferent stimulation increased the SNR of the saccular responses within a range of stimulus combinations. These data demonstrate that auditory efferent feedback can increase SNR in conditions where a signal is masked by noise, thereby enhancing the encoding of signals in noise. Efferent feedback thus performs a fundamental signal processing function, helping the animal to hear sounds in difficult listening conditions.
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NICHANI, A. K., B. H. THORP, C. G. D. BROWN, J. D. M. CAMPBELL, D. J. BROWN, M. RITCHIE e R. L. SPOONER. "In vivo development of Theileria annulata: major changes in efferent lymph following infection with sporozoites or allogeneic schizont-infected mononuclear cells". Parasitology 118, n. 4 (aprile 1999): 327–33. http://dx.doi.org/10.1017/s0031182098003904.
Testo completoAbstract (sommario):
The object of these experiments was to study the pathogenesis and kinetics of Theileria annulata infection in the efferent lymph of the draining lymph nodes of calves. Efferent lymphatics of calves were cannulated prior to infection with T. annulata sporozoite or an allogeneic schizont cell line. Potentially lethal sporozoite challenge induced cell shut-down from days 4–6 and then a massive increase in output of blasting cells (both infected and non-infected) in the efferent lymph. The rate of lymph flow and total cell output increased to 5 to 10-fold from day 6 onwards. Sporozoites were never isolated from the efferent lymph. However, large numbers of parasite-infected cells were seen in efferent lymph from the sixth day of infection. The animals inoculated with an allogeneic T. annulata-infected cell line exhibited only a small increase in flow rate and cell output. Parasite-infected cells of recipient origin were seen in efferent lymph from day 11 onwards. However, cells of donor origin were never isolated either from efferent lymph or peripheral blood. Thus the parasite transferred from the inoculated donor cell line to the cells of the recipient before schizonts appeared in efferent lymph.
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Horii, Y., Y. Nakakita, Y. Misonou, T. Nakamura e K. Nagai. "The serotonin receptor mediates changes in autonomic neurotransmission and gastrointestinal transit induced by heat-killed Lactobacillus brevis SBC8803". Beneficial Microbes 6, n. 6 (1 dicembre 2015): 817–22. http://dx.doi.org/10.3920/bm2015.0031.
Testo completoAbstract (sommario):
Lactobacilli exhibit several health benefits in mammals, including humans. Our previous reports established that heat-killed Lactobacillus brevis SBC8803 (SBC8803) increased both efferent gastric vagal nerve activity and afferent intestinal vagal nerve activity in rats. We speculated that this strain could be useful for the treatment of gastrointestinal (GI) disorders. In this study, we examined the effects of SBC8803 on peristalsis and the activity of the efferent celiac vagal nerve innervating the intestine in rats. First, we examined the effects of intraduodenal (ID) administration of SBC8803 on efferent celiac vagal nerve activity (efferent CVNA) in urethane-anesthetised rats using electrophysiological studies. The effects of intravenous injection of the serotonin 5-HT3 receptor antagonist granisetron on changes in efferent CVNA due to ID administration of SBC8803 were also investigated. Finally, the effects of oral gavage of SBC8803 on GI transit were analysed using the charcoal propulsion method in conscious rats treated with or without granisetron. ID administration of SBC8803 increased efferent CVNA. Pretreatment with granisetron eliminated SBC8803-dependent changes in efferent CVNA. Furthermore, oral gavage of SBC8803 significantly accelerated GI transit, while pretreatment with granisetron inhibited GI transit. Our findings suggested that SBC8803 increased efferent CVNA and GI transit of charcoal meal via 5-HT3 receptors. Moreover, SBC8803 enhanced the activity of efferent vagal nerve innervating the intestine and promoted peristalsis via 5-HT3 receptors.
20
Guinan, John J. "Olivocochlear Efferents: Anatomy, Physiology, Function, and the Measurement of Efferent Effects in Humans". Ear and Hearing 27, n. 6 (dicembre 2006): 589–607. http://dx.doi.org/10.1097/01.aud.0000240507.83072.e7.
Testo completo
21
Bokhari, Malak B., Stephen D. Fitzgerald, Anthony M. Vernava e Walter E. Longo. "Hemorrhagic Efferent Limb Diverticulosis". Journal of Clinical Gastroenterology 18, n. 2 (marzo 1994): 174. http://dx.doi.org/10.1097/00004836-199403000-00027.
Testo completo
22
Yamamoto, Takumi, Nana Yamamoto, Marie Yamashita, Megumi Furuya, Akitatsu Hayashi e Isao Koshima. "Efferent Lymphatic Vessel Anastomosis". Annals of Plastic Surgery 76, n. 4 (aprile 2016): 424–27. http://dx.doi.org/10.1097/sap.0000000000000381.
Testo completo
23
Szolcsanyi, J. "Efferent function of nociceptors". Pain 30 (1987): S221. http://dx.doi.org/10.1016/0304-3959(87)91508-9.
Testo completo
24
Loughlin, S. E., S. L. Foote e R. Grzanna. "Efferent projections of nucleus locus coeruleus: Morphologic subpopulations have different efferent targets". Neuroscience 18, n. 2 (giugno 1986): 307–19. http://dx.doi.org/10.1016/0306-4522(86)90156-9.
Testo completo
25
WELLER, CYNTHIA, SARAH H. LINDSTROM, WILLEM J. DE GRIP e MARTIN WILSON. "The area centralis in the chicken retina contains efferent target amacrine cells". Visual Neuroscience 26, n. 2 (marzo 2009): 249–54. http://dx.doi.org/10.1017/s0952523808080917.
Testo completoAbstract (sommario):
AbstractThe retinas of birds receive a substantial efferent, or centrifugal, input from a midbrain nucleus. The function of this input is presently unclear, but previous work in the pigeon has shown that efferent input is excluded from the area centralis, suggesting that the functions of the area centralis and the efferent system are incompatible. Using an antibody specific to rods, we have identified the area centralis in another species, the chicken, and mapped the distribution of the unique amacrine cells that are the postsynaptic partners of efferent fibers. Efferent target amacrine cells are found within the chicken area centralis and their density is continuous across the border of the area centralis. In contrast to the pigeon retina then, we conclude that the chicken area centralis receives efferent input. We suggest that the difference between the two species is attributable to the presence of a fovea within the area centralis of the pigeon and its absence from that of the chicken.
26
Kass, Leonard, e Robert B. Barlow. "A circadian clock in the Limulus brain transmits synchronous efferent signals to all eyes". Visual Neuroscience 9, n. 5 (novembre 1992): 493–504. http://dx.doi.org/10.1017/s0952523800011299.
Testo completoAbstract (sommario):
AbstractA circadian clock in the brain of the horseshoe crab, Limulus polyphemus, has an important role in the function of the peripheral visual system. At night, the clock transmits neural activity to the lateral, ventral, and median eyes via efferent optic nerve fibers. The activity occurs in synchronous bursts (maximum rate of 2 bursts/s) with individual efferent fibers contributing a single spike in each burst. The circadian efferent activity originates in the protocerebrum. Lateral connections synchronize the efferent activity recorded from the two halves of the protocerebrum, suggesting the existence of bilateral circadian oscillators. Circadian efferent activity survives excision of the brain and isolation of the protocerebrum. We conclude that circadian clock and its complex neural circuitry are fundamental components of the Limulus visual system.
27
LINDSTROM, S. H., N. NACSA, T. BLANKENSHIP, P. G. FITZGERALD, C. WELLER, D. I. VANEY e MARTIN WILSON. "Distribution and structure of efferent synapses in the chicken retina". Visual Neuroscience 26, n. 2 (marzo 2009): 215–26. http://dx.doi.org/10.1017/s0952523809090063.
Testo completoAbstract (sommario):
AbstractThe visual system of birds includes an efferent projection from a visual area, the isthmo-optic nucleus in the midbrain, back to the retina. Using a combination of anterograde labeling of efferent fibers, reconstruction of dye-filled neurons, NADPH-diaphorase staining, and transmission electron microscopy, we have examined the distribution of efferent fibers and their synaptic structures in the chicken retina. We show that efferent fibers terminate strictly within the ventral retina. In two completely mapped retinas, only 2 fibers from a total of 15,359 terminated in the dorsal retina. The major synapse made by each efferent fiber is with a single efferent target amacrine cell (TC). This synapse consists of 5–25 boutons of 2 μm diameter, each with multiple active zones, pressed into the TC soma or synapsing with a basketwork of rudimentary TC dendrites in the inner nuclear layer (INL). This basketwork, which is sheathed by Muller cell processes, defines a private neuropil in the INL within which TCs were also seen to receive input from retinal neurons. In addition to the major synapse, efferent fibers typically produce several very thin processes that terminate nearby in single small boutons and for which the soma of a local amacrine cell is one of the likely postsynaptic partners. A minority of efferent fibers also give rise to a thicker process, terminating in a strongly diaphorase-positive ball about 5 μm in diameter.
28
Calman, B. G., e B. A. Battelle. "Central origin of the efferent neurons projecting to the eyes of Limulus polyphemus". Visual Neuroscience 6, n. 5 (maggio 1991): 481–95. http://dx.doi.org/10.1017/s0952523800001334.
Testo completoAbstract (sommario):
AbstractCircadian rhythms affect the anatomy, physiology, and biochemistry of the visual cells in the eyes of the horseshoe crab (Limulus polyphemus). These rhythms are mediated by the activity of efferent neurons that project from the central nervous system to all of the eyes. In this study, the optic nerves of Limulus were backfilled with Neurobiotin revealing the location of efferent cell bodies and their projections through the central nervous system. We propose that this efferent system mediates the circadian changes in visual functions in Limulus. Whether these cells are the circadian pacemaker neurons is unknown.The cell bodies of the efferent neurons are ovoid and have a diameter of 40−80 μm. They lie within the cheliceral ganglion of the tritocerebrum, just posterior to the protocerebrum. This ganglion is on the lateral edge of the circumesophageal ring, near the middle of the dorsal-ventral axis of the ring. Each optic nerve contains axons from both ipsilateral and contralateral efferent cells, and some, possibly all, of them project bilaterally and to more than one type of optic nerve.The efferent axons form a tract that projects anteriorly from the cell bodies to the protocerebrum, and bifurcates just lateral to the protocerebral bridge. One branch crosses the midline and projects anteriorly to the optic tract and medulla on the side contralateral to the cell of origin; the other branch follows a symmetric pathway on the ipsilateral side. Small branches arising from the major efferent axons in the optic tract project through the ocellar ganglia to the median optic nerves. The efferent axons branch again in the medulla, and some of these branches innervate the ventral optic nerves. The major branches of the efferent axons continue through the lamina and enter the lateral optic nerve.
29
Nishiyama, Akira, Edward W. Inscho e L. Gabriel Navar. "Interactions of adenosine A1 and A2areceptors on renal microvascular reactivity". American Journal of Physiology-Renal Physiology 280, n. 3 (1 marzo 2001): F406—F414. http://dx.doi.org/10.1152/ajprenal.2001.280.3.f406.
Testo completoAbstract (sommario):
Adenosine vasoconstricts preglomerular arterioles via adenosine A1receptors. Because adenosine also activates adenosine A2receptors, its overall renal vascular actions are complex and not fully understood. The present study was performed to determine the relative contributions of adenosine A1 and A2a receptors to the responsiveness of the renal microvasculature to adenosine. Afferent and efferent arteriolar diameters were monitored in vitro using the blood-perfused rat juxtamedullary nephron preparation. Basal afferent and efferent arteriolar diameters averaged 17.1 ± 0.5 ( n = 35) and 17.8 ± 0.5 ( n = 20) μm, respectively. Superfusion with 0.1 and 1 μmol/l adenosine did not significantly alter afferent and efferent arteriolar diameters; however, 10 μmol/l adenosine significantly reduced afferent and efferent arteriolar diameters (−8.2 ± 0.8 and −5.7 ± 0.6%, respectively). The afferent and efferent arteriolar vasoconstrictor responses to adenosine waned at a dose of 100 μmol/l, such that diameters returned to values not significantly different from control within 2 min. During adenosine A1 receptor blockade with 8-noradamantan-3-yl-1,3-dipropylxanthine (KW-3902: 10 μmol/l), 10 and 100 μmol/l adenosine significantly increased afferent diameter by, respectively, 8.1 ± 1.2 and 13.7 ± 1.3% ( n = 14) and efferent arteriolar diameter by 6.4 ± 1.3 and 9.3 ± 1.2% ( n = 8). The afferent and efferent arteriolar vasodilatory responses to adenosine in the presence of KW-3902 were significantly attenuated by addition of the adenosine A2a receptor antagonist 1,3-dipropyl-7-methyl-8-(3,4-dimethoxystyryl)xanthine (KF-17837: 15 μmol/l, n = 7 and 6, respectively). The addition of KF-17837 alone significantly enhanced afferent ( n = 15) and efferent ( n = 6) arteriolar vasoconstrictor responses to 1, 10, and 100 μmol/l adenosine. These results indicate the presence of adenosine A1 and A2a receptors on afferent and efferent arterioles of juxtamedullary nephrons, such that adenosine A2a receptor-mediated vasodilation partially buffers adenosine-induced vasoconstriction in both pre- and postglomerular segments of the renal microvasculature.
30
Le Feber, J., E. Van Asselt e R. Van Mastrigt. "Neurophysiological modeling of voiding in rats: bladder pressure and postganglionic bladder nerve activity". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 272, n. 1 (1 gennaio 1997): R413—R421. http://dx.doi.org/10.1152/ajpregu.1997.272.1.r413.
Testo completoAbstract (sommario):
A model was developed that describes the relations between bladder pressure and both efferent and afferent nerve activity in postganglionic bladder nerves in urethan-anesthetized rats. Nerve activity was calculated as the 100-ms time integral of the rectified nerve signal. Afferent and efferent nerve signals were measured separately by crushing the nerve proximally or distally. A linear relation was found between bladder pressure and afferent nerve activity (fit error < 7%), and the relation between bladder pressure and efferent nerve activity was described by a low-pass filter (fit error < 90%). In most experiments, combined (efferent and afferent) nerve activity was measured. Absence of efferent nerve activity was assumed during the pressure decrease immediately after voiding. From this episode, the afferent nerve activity was estimated for the entire measurement. Efferent nerve activity was then estimated assuming linear addition in the bidirectionally conducting nerves. The model described the measured data very well (fit error < 7%), and the model parameters showed a good reproducibility in each rat (SD was approximately 30% of the mean).
31
Purcell, I. M., e A. A. Perachio. "Three-Dimensional Analysis of Vestibular Efferent Neurons Innervating Semicircular Canals of the Gerbil". Journal of Neurophysiology 78, n. 6 (1 dicembre 1997): 3234–48. http://dx.doi.org/10.1152/jn.1997.78.6.3234.
Testo completoAbstract (sommario):
Purcell, I. M. and A. A. Perachio. Three-dimensional analysis of vestibular efferent neurons innervating semicircular canals of the gerbil. J. Neurophysiol. 78: 3234–3248, 1997. Anterograde labeling techniques were used to examine peripheral innervation patterns of vestibular efferent neurons in the crista ampullares of the gerbil. Vestibular efferent neurons were labeled by extracellular injections of biocytin or biotinylated dextran amine into the contralateral or ipsilateral dorsal subgroup of efferent cell bodies (group e) located dorsolateral to the facial nerve genu. Anterogradely labeled efferent terminal field varicosities consist mainly of boutons en passant with fewer of the terminal type. The bouton swellings are located predominately in apposition to the basolateral borders of the afferent calyces and type II hair cells, but several boutons were identified close to the hair cell apical border on both types. Three-dimensional reconstruction and morphological analysis of the terminal fields from these cells located in the sensory neuroepithelium of the anterior, horizontal, and posterior cristae were performed. We show that efferent neurons densely innervate each end organ in widespread terminal fields. Subepithelial bifurcations of parent axons were minimal, with extensive collateralization occurring after the axons penetrated the basement membrane of the neuroepithelium. Axonal branching ranged between the 6th and 27th orders and terminal field collecting area far exceeds that of the peripheral terminals of primary afferent neurons. The terminal fields of the efferent neurons display three morphologically heterogeneous types: central, peripheral, and planum. All cell types possess terminal fields displaying a high degree of anisotropy with orientations typically parallel to or within ±45° of the longitudinal axis if the crista. Terminal fields of the central and planum zones predominately project medially toward the transverse axis from the more laterally located penetration of the basement membrane by the parent axon. Peripheral zone terminal fields extend predominately toward the planum semilunatum. The innervation areas of efferent terminal fields display a trend from smallest to largest for the central, peripheral, and planum types, respectively. Neurons that innervate the central zone of the crista do not extend into the peripheral or planum regions. Conversely, those neurons with terminal fields in the peripheral or planum regions do not innervate the central zone of the sensory neuroepithelium. The central zone of the crista is innervated preferentially by efferent neurons with cell bodies located in the ipsilateral group e. The peripheral and planum zones of the crista are innervated preferentially by efferent neurons with cell bodies located in the contralateral group e. A model incorporating our anatomic observations is presented describing an ipsilateral closed-loop feedback between ipsilateral efferent neurons and the periphery and an open-loop feed-forward innervation from contralateral efferent neurons. A possible role for the vestibular efferent neurons in the modulation of semicircular canal afferent response dynamics is proposed.
32
Lev-Tov, A., I. Delvolvé e E. Kremer. "Sacrocaudal Afferents Induce Rhythmic Efferent Bursting in Isolated Spinal Cords of Neonatal Rats". Journal of Neurophysiology 83, n. 2 (1 febbraio 2000): 888–94. http://dx.doi.org/10.1152/jn.2000.83.2.888.
Testo completoAbstract (sommario):
The ability of mammalian spinal cords to generate rhythmic motor behavior in nonlimb moving segments was examined in isolated spinal cords of neonatal rats. Stimulation of sacrocaudal afferents (SCA) induced alternating left-right bursts in lumbosacral efferents and in tail muscles. On each side of the tail, flexors, extensors, and abductors were coactive during each cycle of activity. This rhythm originated mainly in the sacrocaudal region because it persisted in sacrocaudal segments after surgical removal of the thoracolumbar cord. Sacrocaudal commissural pathways were sufficient to maintain the left-right alternation of lumbar efferent bursts, because their timing was unaltered after a complete thoracolumbar hemisection. The lumbar rhythm originated in part from sacrocaudal activity ascending in lateral and ventrolateral funiculi, because efferent bursts in rostral lumbar segments were nearly abolished on a particular side by lesions of the lateral quadrant of the cord at the L4–L5 junction. Intracellular recordings from S2–S3 motoneurons, obtained during the rhythm, revealed the presence of phasic oscillations of membrane potential superimposed on a tonic depolarization. Bursts of spikes occurred on the depolarizing phases of the oscillation. Between these bursts the membrane input conductance increased, and hyperpolarizing drive potentials were revealed. The inhibitory drive and the decreased input resistance coincided with contralateral efferent bursts, suggesting that crossed pathways controlled it. Our studies indicate that pattern generators are not restricted to limb-moving spinal segments and suggest that regional specializations of pattern-generating circuitry and their associated interneurons are responsible for the different motor patterns produced by the mammalian spinal cord.
33
Myers, S. F., H. H. Salem e J. A. Kaltenbach. "Efferent Neurons and Vestibular Cross Talk in the Frog". Journal of Neurophysiology 77, n. 4 (1 aprile 1997): 2061–70. http://dx.doi.org/10.1152/jn.1997.77.4.2061.
Testo completoAbstract (sommario):
Myers, S. F., H. H. Salem, and J. A. Kaltenbach. Efferent neurons and vestibular cross talk in the frog. J. Neurophysiol. 77: 2061–2070, 1997. A galvanic stimulus (30- to 120-s, 0.3-mA constant current pulse) was used to depolarize the spike-generating region of horizontal and anterior canal afferent neurons. The galvanically induced spike activity from these neurons served as a driving input to the efferent vestibular system in the bullfrog. Efferent-mediated effects were assessed by intracellular recordings of posterior canal afferent spike activity, either ipsilateral or contralateral to the driving stimulus. Ipsilateral to the driving stimulus, efferent-mediated spike rate changes occurred in 62 (39%) of 158 posterior canal afferent neurons. Ipsilateral efferent-mediated effects were overwhelmingly excitatory (92%). Of responding units, 3% were inhibited during stimulus application and 5% showed mixed responses involving 3–20 s of inhibition followed by facilitation. Contralateral to the driving stimulus, efferent-mediated spike rate changes occurred in 18 (23%) of 77 posterior canal afferent neurons. Contralateral efferent-mediated effects were overwhelmingly inhibitory (95%). Only one unit was facilitated during stimulation and no mixed responses to contralateral stimulation were observed. Analysis of the coefficient of variation in interspike intervals (CV) before and during stimulation showed no significant efferent-mediated effects on spike train noise. Comparisons of resting spike rates between units showing efferent-mediated effects and those that did not were in general agreement with previous studies. Responding units had a lower mean spike rate (6.8 ± 0.70 spikes/s, mean ± SE) than did nonresponding units (10.7 ± 0.42 spikes/s, mean ± SE; P < 0.001; 2-tailed t-test of log-normalized data). Comparison between groups in the regularity of their resting spike rates, as quantified by CV, showed considerable overlap. When responding and nonresponding units with similar resting spike rates were compared, responding units had more irregular resting spike rates than did nonresponding units ( P < 0.004; 2-tailed, paired t-test). In most cases (77%) the temporal pattern and general shapes of efferent-mediated responses mirrored the driving input of the galvanically activated afferent neurons. The other 23% of efferent-mediated responses exhibited a marked adaptation of the response. Adapting and nonadapting units were not significantly different in their mean resting spike rates or in the regularity of their resting spike rates.
34
Gjedde, Albert, Sean Marrett e Manouchehr Vafaee. "Oxidative and Nonoxidative Metabolism of Excited Neurons and Astrocytes". Journal of Cerebral Blood Flow & Metabolism 22, n. 1 (gennaio 2002): 1–14. http://dx.doi.org/10.1097/00004647-200201000-00001.
Testo completoAbstract (sommario):
There is evidence that the metabolic responses to afferent and efferent nervous activity are dissociated at sites of neuronal excitation in brain. Whether efferent activity follows afferent activity depends on the responsiveness of postsynaptic neurons, which in turn depends on the summation of excitatory and inhibitory postsynaptic potentials. The afferent activity excites the presynaptic terminals and astrocytes, whereas the efferent activity arises from excitation of the dendrites of projection neurons. Measurements in vivo indicate that primary stimulation, elicited by simple stimuli, gives rise to limited increases of energy metabolism associated with afferent activity. Reports show that a major consequence of afferent activity, in addition to the release of excitatory neurotransmitters from presynaptic terminals and the import of glutamate by astrocytes, is the establishment of rates of blood flow commensurate with increased rates of oxidative energy metabolism associated with efferent activity projecting from the site of activation. Increased flow rates overcome the inherent diffusion limitation of oxygen delivery, while increased rates of glycolysis elevate tissue pyruvate contents, to which oxygen consumption rates are matched. In vivo, neurons in the baseline condition sustain no net import of pyruvate or lactate, and the reported changes of metabolism subserving afferent and efferent activity are additive rather than linked by significant additional transfer of pyruvate or lactate from astrocytes. The dissociation of blood flow changes from efferent activity weakens the identification of functional states by changes of blood flow alone. It raises the possibility that uncoupling of flow from oxidative metabolism occurs at sites of low efferent activity, such that dissociations of flow and glycolysis from oxygen consumption signify imbalances of afferent and efferent activity.
35
Johnson, Stuart L., Carolina Wedemeyer, Douglas E. Vetter, Roberto Adachi, Matthew C. Holley, Ana Belén Elgoyhen e Walter Marcotti. "Cholinergic efferent synaptic transmission regulates the maturation of auditory hair cell ribbon synapses". Open Biology 3, n. 11 (novembre 2013): 130163. http://dx.doi.org/10.1098/rsob.130163.
Testo completoAbstract (sommario):
Spontaneous electrical activity generated by developing sensory cells and neurons is crucial for the maturation of neural circuits. The full maturation of mammalian auditory inner hair cells (IHCs) depends on patterns of spontaneous action potentials during a ‘critical period’ of development. The intrinsic spiking activity of IHCs can be modulated by inhibitory input from cholinergic efferent fibres descending from the brainstem, which transiently innervate immature IHCs. However, it remains unknown whether this transient efferent input to developing IHCs is required for their functional maturation. We used a mouse model that lacks the α9-nicotinic acetylcholine receptor subunit (α9nAChR) in IHCs and another lacking synaptotagmin-2 in the efferent terminals to remove or reduce efferent input to IHCs, respectively. We found that the efferent system is required for the developmental linearization of the Ca 2+ -sensitivity of vesicle fusion at IHC ribbon synapses, without affecting their general cell development. This provides the first direct evidence that the efferent system, by modulating IHC electrical activity, is required for the maturation of the IHC synaptic machinery. The central control of sensory cell development is unique among sensory systems.
36
KMENT, PETR, e JITKA VILÍMOVÁ. "Thoracic scent efferent system of Pentatomoidea (Hemiptera: Heteroptera): a review of terminology". Zootaxa 2706, n. 1 (22 gennaio 2019): 1. http://dx.doi.org/10.11646/zootaxa.2706.1.1.
Testo completoAbstract (sommario):
The terminology used for structures constituing the thoracic scent efferent system is reviewed and discussed, with the emphasis on the Pentatomoidea. The most suitable terms are selected and suggested for a general use, i.e., scent gland system, metathoracic scent apparatus, thoracic scent efferent system, internal scent efferent system, internal orifice, vestibule, vestibular furrows, external scent efferent system, ostiolar plate, metepimeral pseudosuture, ostiole, ostiolar groove, periostiolar depression, vestibular scar, peritreme, supporting projection, median furrow, auricle, spout, (peritremal) groove, (peritremal) ruga, (peritremal) disc, peritremal lobes, terminal lobe, pseudoperitremal structures, pseudoperitreme, evaporatorium, evaporatory channel, gyrification, mycoid microsculpture, mycoid surface, mushroom body, stem, cap, bridge, alveole, trabeculae, peritremal microsculpture, peritremal surface. The traditional terminology describing the external scent efferent system (especially peritreme) in Cydnidae is discussed and reinterpreted. All the suggested terms are illustrated by scanning electron micrographs and an extensive synonymic list is given for most of them.
37
Egger, Gunter F., e Kirsti Witter. "Peritubular Contractile Cells in Testis and Epididymis of the Dog, Canis lupus familiaris". Acta Veterinaria Brno 78, n. 1 (2009): 3–11. http://dx.doi.org/10.2754/avb200978010003.
Testo completoAbstract (sommario):
Contractile cells surrounding the tubular system of the mammalian testis and epididymis are supposed to contribute to the initial transport of spermatozoa from the testis to epididymis. Testicular peritubular smooth muscle cells have been characterised in detail especially in rodents and humans. The aim of our study was to assess the distribution of peritubular contractile cells of the canine tubuli seminiferi, rete testis channels, ductuli efferentes, and ductus epididymidis by immunohistochemistry and transmission electron microscopy and to classify these cells with respect to their possible physiological function. The entire tubular system of the canine testis and epididymis is surrounded by contractile cells expressing smooth muscle actin, smooth muscle myosin and desmin, which are enveloped, at least partly, by a basal lamina. Some contractile cells of the tubuli seminiferi, rete channels, and efferent ducts and sometimes also single peritubular cells of the ductus epididymidis express vimentin. Contractile cells of seminiferous tubules and efferent ducts represent an intermediate cell type exhibiting characteristics of both smooth muscle cells (SMC) and myofibroblasts, those of rete channels stellate myofibroblasts, and those of the ductus epididymidis SMC. Differences in structure and arrangement of the contractile cells between seminiferous tubules, rete channels, efferent ducts, and ductus epididymidis suggest different functions. Myofibroblasts and contractile cells similar to them could be mainly responsible for the maintenance of an appropriate tissue turgor, whereas contraction of SMC of the ductus epididymidis might cause propulsion of spermatozoa by peristaltic waves.
38
Sarker, Ashok Kumar. "An Unusual Cause of Efferent Loop Obstruction". Journal of Enam Medical College 10, n. 2 (22 maggio 2021): 118–21. http://dx.doi.org/10.3329/jemc.v10i2.53538.
Testo completoAbstract (sommario):
Efferent loop obstruction is a very rare post-gastrectomy obstruction that can occur following Billroth-II or Roux-en-Y reconstruction. Here we report a case who underwent gastrojejunostomy for gastric outlet obstruction 30 years back and now developed efferent loop obstruction due to phytobezoar. The efferent loop obstruction was successfully resolved by laparotomy.
J Enam Med Col 2020; 10(2): 118-121
39
Fallet, Rachel W., Hideki Ikenaga, Joseph P. Bast e Pamela K. Carmines. "Relative contributions of Ca2+ mobilization and influx in renal arteriolar contractile responses to arginine vasopressin". American Journal of Physiology-Renal Physiology 288, n. 3 (marzo 2005): F545—F551. http://dx.doi.org/10.1152/ajprenal.00150.2002.
Testo completoAbstract (sommario):
Experiments addressed the hypothesis that afferent and efferent arterioles differentially rely on Ca2+ influx and/or release from intracellular stores in generating contractile responses to AVP. The effect of Ca2+ store depletion or voltage-gated Ca2+ channel (VGCC) blockade on contractile responsiveness to AVP (0.01–1.0 nM) was assessed in blood-perfused juxtamedullary nephrons from rat kidney. Depletion of intracellular Ca2+ stores by 100 μM cyclopiazonic acid (CPA) or 1 μM thapsigargin treatment increased afferent arteriolar baseline diameter by 14 and 21%, respectively, but did not significantly alter efferent arteriolar diameter. CPA attenuated the contractile response to 1.0 nM AVP by 34 and 55% in afferent and efferent arterioles, respectively ( P = 0.013). The impact of thapsigargin on AVP-induced afferent arteriolar contraction (52% inhibition) was also less than its effect on the efferent arteriolar response (88% inhibition; P = 0.046). In experiments probing the role of the Ca2+ influx through VGCCs, 10 μM diltiazem evoked a 34% increase in baseline afferent arteriolar diameter and attenuated the contractile response to 1.0 nM AVP by 45%, without significantly altering efferent arteriolar baseline diameter or responsiveness to AVP. Combined treatment with both diltiazem and thapsigargin prevented AVP-induced contraction of both vascular segments. We conclude that Ca2+ release from the intracellular stores contributes to the contractile response to AVP in both afferent and efferent arterioles but is more prominent in the efferent arteriole. Moreover, the VGCC contribution to AVP-induced renal arteriolar contraction resides primarily in the afferent arteriole.
40
Neahring, J. C., S. Y. Jones e G. F. DiBona. "Cardiopulmonary baroreflex function in nephrotic rats." Journal of the American Society of Nephrology 5, n. 12 (giugno 1995): 2082–86. http://dx.doi.org/10.1681/asn.v5122082.
Testo completoAbstract (sommario):
Efferent renal sympathetic nerve activity is increased in experimental nephrotic syndrome and exhibits attenuated cardiopulmonary baroreflex inhibition during volume expansion in anesthetized rats. Additional studies were performed in conscious rats to avoid the potentially confounding influences of anesthesia; these studies used another more specific standardized stimulus for cardiopulmonary baroreflex activation. Sprague Dawley rats were studied 3 to 4 wk after adriamycin injection (3.5 mg/kg iv); all rats developed proteinuria. In sinoaortic denervated rats (anesthetized), graded frequency stimulation of the central end of the cut right vagus nerve produced frequency-dependent decreases in mean arterial pressure, heart rate, and efferent renal sympathetic nerve activity. The decreases in mean arterial pressure and heart rate were similar in control and nephrotic rats, but efferent renal sympathetic nerve activity decreased significantly less in nephrotic than control rats over the entire frequency range (P < 0.02). In sinoaortic denervated rats (conscious), 10% body weight isotonic saline volume expansion decreased mean arterial pressure, heart rate, and efferent renal sympathetic nerve activity. The decreases in mean arterial pressure and heart rate were similar in control and nephrotic rats, but efferent renal sympathetic nerve activity decreased significantly less in nephrotic than control rats over the entire period of volume expansion (P < 0.04). In nephrotic syndrome, the cardiopulmonary baroreflex inhibition of efferent renal sympathetic nerve activity is decreased; the defect lies in the central portion of the reflex. This may contribute to the observed increase in efferent renal sympathetic nerve activity in nephrotic syndrome.
41
Feng, Ming-Guo, Ming Li e L. Gabriel Navar. "T-type calcium channels in the regulation of afferent and efferent arterioles in rats". American Journal of Physiology-Renal Physiology 286, n. 2 (febbraio 2004): F331—F337. http://dx.doi.org/10.1152/ajprenal.00251.2003.
Testo completoAbstract (sommario):
L-type Ca2+ channels predominantly influence preglomerular arterioles, but there is less information regarding the role of T-type Ca2+ channels in regulating the renal microvasculature. We compared the effects of T- and L-type channel blockade on afferent and efferent arterioles using the in vitro blood-perfused juxtamedullary nephron preparation. Single afferent or efferent arterioles of Sprague-Dawley rats were visualized and superfused with solutions containing Ca2+ channel blockers. We confirmed that L-type channel blockade with diltiazem dilates afferent arterioles but has no significant effects on efferent arterioles. In contrast, T-type channel blockade with pimozide (10 μmol/l) or mibefradil (1 μmol/l) dilated both afferent (26.8 ± 3.4 and 24.6 ± 1.9%) and efferent (19.2 ± 2.9 and 19.1 ± 4.8%) arterioles. Adding diltiazem did not significantly augment the dilation of afferent arterioles elicited by pimozide and mibefradil, and adding pimozide after diltiazem likewise did not elicit further vasodilation. Diltiazem blocked the depolarization-induced afferent arteriolar constriction elicited by 55 mM KCl; however, the constrictor response to KCl remained intact during treatment with 10 μM pimozide. Pimozide also prevented the afferent arterioles from exhibiting autoregulatory-mediated constrictor responses to increases in perfusion pressure. We conclude that T-type channel blockers dilate efferent arterioles as well as afferent arterioles and diminish afferent arteriolar autoregulatory responses to changes in perfusion pressure. To the extent that these agents exert their effects primarily on T-type Ca2+ channels in our experimental setting, these results indicate that T-type channels are functionally expressed in juxtamedullary afferent and efferent arterioles and may act cooperatively with L-type channels to regulate afferent arteriolar resistance. Because L-type channels are not functionally expressed in efferent arterioles, T-type channels may be particularly significant in the regulation of efferent arteriolar function.
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ICHIHARA, ATSUHIRO, MATSUHIKO HAYASHI, L. GABRIEL NAVAR e TAKAO SARUTA. "Inducible Nitric Oxide Synthase Attenuates Endothelium-Dependent Renal Microvascular Vasodilation". Journal of the American Society of Nephrology 11, n. 10 (ottobre 2000): 1807–12. http://dx.doi.org/10.1681/asn.v11101807.
Testo completoAbstract (sommario):
Abstract. Previous studies have demonstrated that inducible nitric oxide synthase (iNOS) plays a key pathophysiologic role during sepsis. The present study was designed to delineate the consequences of iNOS activation on renal microvascular function. Male Sprague-Dawley rats were given intraperitoneal injections of lipopolysaccharide (LPS; 4 mg/kg) at 16 h and 4 h before experimentation. Afferent and efferent arteriolar diameters from LPS-treated and control rats were assessed in vitro with the use of the blood perfused juxtamedullary nephron technique. Basal afferent and efferent arteriolar diameters of LPS-treated rats averaged 19.7 ± 0.9 (n = 7) and 18.3 ± 1.0 μm (n = 5), respectively, and were similar to those of control rats (20.8 ± 0.3 [n = 6] and 18.4 ± 0.6 μm [n = 6], respectively). Superfusion with the selective iNOS inhibitor S,S′-(1,3-phenylenebis[1,2-ethanediyl]) bisisothiourea (PBIT), at the doses of 0.01, 0.1, and 1 μM, significantly decreased afferent and efferent arteriolar diameters in a dose-dependent manner, whereas afferent or efferent arteriolar diameters of control rats were not altered in response to the same doses of PBIT. In the second series of experiments, superfusion with 10 μM acetylcholine (ACh) significantly increased afferent and efferent arteriolar diameters of LPS-treated rats by 14.9 ± 1.6% (n = 9) and 6.6 ± 1.1% (n = 6), respectively. The ACh-induced afferent and efferent arteriolar dilator responses were inhibited by superfusion with the nonselective NOS inhibitor Nω-nitro-L-arginine (100 μM). However, afferent and efferent arteriolar dilator responses to ACh were significantly enhanced during selective iNOS inhibition with 1 μM PBIT (40.1 ± 0.7% and 25.2 ± 1.3%, respectively). These results suggest that activation of iNOS by LPS increases the influence of nitric oxide on afferent and efferent arteriolar tone and impairs endothelium-dependent nitric oxide effects.
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Khoroshilov, S. E., e A. V. Nikulin. "Efferent Treatment for Critical Conditions". General Reanimatology 8, n. 4 (20 agosto 2012): 30. http://dx.doi.org/10.15360/1813-9779-2012-4-30.
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Heller, Jiři, e Vladislav Horáčcek. "Angiotensin II: Preferential Efferent Constriction?" Kidney and Blood Pressure Research 9, n. 6 (1986): 357–65. http://dx.doi.org/10.1159/000173101.
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Fuchs, Paul Albert, e Amanda M. Lauer. "Efferent Inhibition of the Cochlea". Cold Spring Harbor Perspectives in Medicine 9, n. 5 (6 agosto 2018): a033530. http://dx.doi.org/10.1101/cshperspect.a033530.
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Menendez, Pablo, Carlos Leon, Alberto Garcia e Jesus Martin. "Effectiveness of Efferent Loop Stimulation". Diseases of the Colon & Rectum 58, n. 4 (aprile 2015): e54-e55. http://dx.doi.org/10.1097/dcr.0000000000000344.
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Persson, Pontus B., e John Andrew Armour. "Dual vagal cardiac efferent pathways". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 286, n. 4 (aprile 2004): R624. http://dx.doi.org/10.1152/ajpregu.00665.2003.
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Guinan, John J. "Cochlear efferent innervation and function". Current Opinion in Otolaryngology & Head and Neck Surgery 18, n. 5 (ottobre 2010): 447–53. http://dx.doi.org/10.1097/moo.0b013e32833e05d6.
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McCuskey, Robert S. "Anatomy of efferent hepatic nerves". Anatomical Record 280A, n. 1 (2004): 821–26. http://dx.doi.org/10.1002/ar.a.20087.
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Subei, Adnan M., e Eric Eggenberger. "Efferent manifestations of multiple sclerosis". Current Opinion in Ophthalmology 23, n. 6 (novembre 2012): 506–9. http://dx.doi.org/10.1097/icu.0b013e328358e0e5.
Testo completo