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PubMed1989

The effects of cryogenic blockade of the centrifugal, bulbopetal pathways on the dynamic and static response characteristics of goldfish olfactory bulb mitral cells.

The responses of single goldfish olfactory bulb mitral cells were studied by extracellular recordings before and during cryogenic blockade of the efferent, centrifugal pathways in the ipsilateral olfactory tract. In each experiment the same odour was presented 40 times before and then 40 times during cooling. Each stimulus period (at least 30 s) was preceded by a stimulus-free interval (at least 30 s), during which a steady stream of tap water was applied. These procedures allow the investigation of activity changes of single neurons and of cell ensembles using statistical methods. i) In comparison with the pre-cooling activity, cooling of the efferent pathways did not cause a generalized disinhibition in mitral cell responses. Significant disinhibitory, significant inhibitory and indifferent effects occurred in about the same proportion during repetitive water and odour applications. ii) Abrupt or slow changes of single mitral cell discharge patterns during the 40 water and odour applications were observed before and during blocking of the efferent fibre systems: These pattern changes are therefore not necessarily a consequence of the efferent signals, and may thus have been a result of intrabulbar plasticity. iii) The most notable effect of efferent fibre blockade across all experiments was a significant (Wilcoxon-rank-test, P = 0.01) decrease of the signal to noise ratio i.e., the ratio between the activity during the "spontaneous" (water) and the stimulus (odour) phase, which could be demonstrated for both the phasic (immediately after stimulus onset) and tonic (during long term stimulation) components of the mitral cell responses.

Action Potentials↗
PubMed1997

The mechanism of action of botulinum toxin type A in focal dystonia is most probably through its dual effect on efferent (motor) and afferent pathways at the injected site.

OBJECTIVE: To highlight some clinical and physiological features related to treatment with botulinum toxin type A (BTX-A) injections for focal dystonia that may suggest an effect through efferent (alpha motoneuron) and afferent pathways. DATA SOURCES: This review is based on published clinical and physiological studies as well as personal experience regarding the effect of BTX-A in focal dystonia. DATA SYNTHESIS: Long or short lag period between BTX-A injections and clinical improvement, remote effect, an effect on the basic physiological characteristics of dystonia, poor correlation between the local weakness and the clinical improvement and alleviation of pain are clinical observations which are difficult to explain on the basis of the known effect of BTX-A on the neuromuscular junction of the alpha motoneuron. These observations as well as recent scientific reports are used to discuss a hypothesis that in addition to its effect as local muscle relaxant, BTX-A acts at the level of the central nervous system (CNS) for 'reorganization'. Such an effect on CNS activity can be mediated through afferent pathways coming from the injected site--possibly originated in muscle spindles. Its effect through afferent pathways on the CNS may be considered as a long-term 'sensory trick'.

Afferent Pathways↗
PubMedDate not supplied

[A neuroanatomical study of the vestibular efferent system, III: the origin and pathway of the axons].

We have studied the vestibular efferent fibers pathway, after scratching the peripheral vestibular receptors and horseradish peroxidase injection, and TMB or DAB processing. We have proved the existence of a differentiated bundle in the main vestibular pathway, this bundle crosses the areas where the efferent somas have been situated, some of this fibers have been seen crossing the midline. It has not been possible to connect the efferent somas with the fibers.

Animals↗
PubMed1978

Autoradiographic evidence for pathways from the medial preoptic area to the midbrain involved in the drinking response to angiotensin II.

The 3H-amino acid autoradiographic method was used to localize intracerebral sites from which angiotensin II (AII) elicits drinking and to identify their efferent neural pathways. Small injections (0.02-0.1 mul) of AII and 3H-amino acid mixtures were injected together or separately into widespread regions of the forebrain of adult rats in normal food and water balance. From an analysis of 39 positive and negative injection sites it was concluded that the caudal half of the medial preoptic area and the adjacent rostral part of the anterior hypothalamic area are sensitive to AII. Two anatomically defined pathways arising from neurons within this region were identified. One descends through the medial forebrain bundle and appears to terminate in the lateral hypothalamic area, the ventromedial nucleus, the mammillary body, and the ventral tegmental area. The other descends through the periventricular region and posterior hypothalamic area to end in the midbrain central gray. Additional widespread connections with the amygdala, septum, habenula, and pons appear to arise in the lateral preoptic area (Swanson, '76). Combined AII-3H-amino acid injections centered in the subfornical organ only elicited drinking in those cases in which injected label diffuse through the third ventricle to the medial preoptic area. No efferent pathways were identified in experiments in which a small injection (0.02 mul) heavily labeled cells strictly confined to the subfornical organ and there was no ventricular spread of label.

Angiotensin II↗
PubMed1990

Investigation on the effect of 30-min tourniquet ischemia on the so-called sympathetic skin response.

The effect of ischemia on the sympathetic skin response has been evaluated in a group of healthy volunteers. Sympathetic skin response elicited by an electro-tactile stimulation has an afferent A beta fibre pathway and an efferent sympathetic postganglionic C fibre pathway. Even if 30' ischemia was able to block tactile sensory afferent (A beta fibres) the sympathetic skin response was still present, suggesting a concomitant activation of other levels of integration in the genesis of the sympathetic skin response.

Adult↗
PubMedDate not supplied

Brainstem myoclonus.

In brainstem myoclonus, muscle jerks arise from activity in neuronal centres within the lower brainstem. The most common forms probably use the same circuitry as used by the normal startle reflex, which may be related to that described in animal experiments as the spino-bulbo-spinal reflex. In man, the jerks are generalized with long-lasting electromyographic bursts (greater than 100 ms), and may be provoked by many different types of sensory stimuli, although cutaneous taps around the nose and face are particularly effective. The neural activity spreads down from the brainstem via a relatively slowly conducting spinal efferent motor pathway. The cranial nerve nuclei are activated by rapid spread up the brainstem. Other forms of brainstem myoclonus may also exist, and these are characterized by more rapid conduction in spinal efferent pathways and greater sensitivity to muscle stretch rather than cutaneous input.

Animals↗
PubMed1992

Gastric mucosal hyperemia due to acid backdiffusion depends on splanchnic nerve activity.

Acid backdiffusion through a disrupted gastric mucosal barrier leads to an increase in gastric mucosal blood flow (MBF). This response involves afferent neurons that pass through the celiac ganglion. The present study examined the neural pathways that underlie the rise in MBF caused by gastric perfusion with 15% ethanol in 0.15 N HCl. MBF was measured by the hydrogen gas clearance technique in urethan-anesthetized rats. Mucosal hyperemia due to acid backdiffusion was not changed by acute bilateral subdiaphragmatic vagotomy but was blocked by acute removal of the celiac-superior mesenteric ganglion complex or acute bilateral transection of the greater splanchnic nerves. Hexamethonium (85 mumol/kg iv) also attenuated the rise in MBF due to acid backdiffusion, whereas guanethidine (0.225 mmol/kg sc) had no effect. None of the procedures and drug treatments altered basal MBF to a significant extent. Transection of the splanchnic nerves, hexamethonium, and guanethidine lowered mean arterial blood pressure, but hypotension as such did not significantly influence the hyperemic response under study. Taken together, the previous and present data indicate that the rise in MBF caused by acid backdiffusion depends on the integrity of afferent and efferent neural pathways that run in the splanchnic nerves and through the celiac ganglion. The efferent pathway involves ganglionic transmission through nicotinic acetylcholine receptors but is independent of noradrenergic neurons.

Animals↗
PubMed2005

Motor evoked potentials (MEP) and evoked pressure curves (EPC) from the urethral compressive musculature (UCM) by functional magnetic stimulation in healthy volunteers and patients with neurogenic incontinence.

AIMS: The aim of this study is to assess neurogenic lesions of the somatomotor efferent nervous pathway to the urethral compressive musculature (UCM) by means of motor evoked potentials (MEP) and simultaneously recorded evoked pressure curves (EPC). METHODS: Nine healthy subjects and 33 patients (15 spinal cord injury, 14 cauda equina lesion, and 4 multiple sclerosis (MS)) with neurogenic urinary incontinence were prospectively examined by means of urodynamics and electrophysiology. MEP responses from the UCM were evoked after transcranial (tc) and lumbosacral (ls) single pulse magnetic stimulation. A ratio out of tx/ls latencies was calculated to distinguish between central (i.e., spinal) and peripheral lesions. The mechanical UCM pressure responses (=EPC) were recorded simultaneously with electromyographic (EMG) recordings using a microtip pressure transducer catheter with integrated bipolar surface electrodes. RESULTS: In nine healthy subjects the central latency was 19.0 msec, the peripheral latency was 4.25 msec, and the ratio was 4.4. In patients with incomplete spinal cord lesion the central latency was significantly delayed (22.7 msec), whereas the peripheral responses were normal. The ratio (5.5) was increased. Thirteen of these 15 patients suffered from neurogenic incontinence. Patients with a complete spinal lesion showed no UCM reaction after tc stimulation, whereas peripheral responses were normal. Patients with MS showed significantly prolonged central latencies (25.5 msec). The increased ratio of 6.0 indicated a spinal lesion. Ten patients with incomplete cauda equina lesions and urinary incontinence had normal central latencies but prolonged peripheral latencies of 6.7 msec. The ratio of 3.4 indicated a lesion of the sacral caudal roots. In patients with complete cauda injury neither central nor peripheral responses could be evoked. Tc evoked mechanical pressure responses (i.e., contractions) from the UCM could only be recorded in intact or incompletely injured spinal and peripheral motor nervous pathways, whereas they could be evoked after ls stimulation only in cases with partially preserved sacral caudal roots independent of a spinal lesion. CONCLUSIONS: MEP and EPC from the UCM proved to be a well tolerated disgnostic tool in patients with neurogenic incontinence that distinguished central and peripheral lesions of the motor efferent pathways to the UCM.

Adult↗
PubMed2006

Expression of multiple P2X receptors by glossopharyngeal neurons projecting to rat carotid body O2-chemoreceptors: role in nitric oxide-mediated efferent inhibition.

In mammals, ventilation is peripherally controlled by the carotid body (CB), which receives afferent innervation from the petrosal ganglion and efferent innervation from neurons located along the glossopharyngeal nerve (GPN). GPN neurons give rise to the "efferent inhibitory" pathway via a plexus of neuronal nitric oxide (NO) synthase-positive fibers, believed to be responsible for CB chemoreceptor inhibition via NO release. Although NO is elevated during natural CB stimulation by hypoxia, the underlying mechanisms are unclear. We hypothesized that ATP, released by rat CB chemoreceptors (type 1 cells) and/or red blood cells during hypoxia, may directly activate GPN neurons and contribute to NO-mediated inhibition. Using combined electrophysiological, molecular, and confocal immunofluorescence techniques, we detected the expression of multiple P2X receptors in GPN neurons. These receptors involve at least four different purinergic subunits: P2X2 [and the splice variant P2X2(b)], P2X3, P2X4, and P2X7. Using a novel coculture preparation of CB type I cell clusters and GPN neurons, we tested the role of P2X signaling on CB function. In cocultures, fast application of ATP, or its synthetic analog 2',3'-O-(4 benzoylbenzoyl)-ATP, caused type I cell hyperpolarization that was prevented in the presence of the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide potassium. These data suggest that ATP released during hypoxic stress from CB chemoreceptors (and/or red blood cells) will cause GPN neuron depolarization mediated by multiple P2X receptors. Activation of this pathway will lead to calcium influx and efferent inhibition of CB chemoreceptors via NO synthesis and consequent release.

Adenosine Triphosphate↗
PubMed1985

Indirect hypothalamo-cerebellar pathway? Demonstration of hypothalamic efferents to the lateral reticular nucleus.

Hypothalamic efferents to the lateral reticular nucleus (NRL) have been demonstrated in the cat by means of anterograde and retrograde axonal transport of the wheat germ agglutinin-horseradish peroxidase (WGA-HRP) complex. Pressure injections of the WGA-HRP complex into the hypothalamus resulted in anterograde labelling of branching terminal axons both in the NRL and in an adjacent X area, presumably the ventrolateral catecholaminergic cell group (A1). After microiontophoretical ejections of the WGA-HRP complex into the NRL from a ventral approach, retrogradely labelled neurons were found in the lateral, dorsal, posterior and anterior hypothalamic areas and in the tubero-mammillary, dorsomedial and periventricular nuclei. The projection is bilateral with a clear ipsilateral predominance and has its main origin in the lateral hypothalamic area. The locations of hypothalamic cells projecting to the NRL are somewhat different from those giving rise to hypothalamo-cerebellar and hypothalamo-spinal connections. The present demonstration of a hypothalamic input to one of the major precerebellar relay nuclei introduces a new possible indirect route through which the cerebellum may be influenced by the hypothalamus. The different indirect and direct hypothalamo-cerebellar pathways and their potential functional importance are discussed.

Animals↗
PubMed1999

Differential subcellular localization of forward and feedback interareal inputs to parvalbumin expressing GABAergic neurons in rat visual cortex.

In rat visual cortex, forward and feedback interareal pathways innervate both pyramidal and gamma-aminobutyric acid (GABA)ergic (Johnson and Burkhalter [1996] J. Comp. Neurol. 368:383-398). GABAergic neurons consist of different cell types of which the largest group expresses parvalbumin (PV; Gonchar and Burkhalter [1997] Cereb. Cortex 4:347-358). Here, we report that PV neurons in layers 2/3 are synaptic targets of forward and feedback projections between area 17 and the lateromedial area (LM) of rat visual cortex. In both forward and feedback pathways, approximately 90% of axon terminals in layer 2/3 labeled by tracing with biotinylated dextran amine formed synapses with PV-negative profiles. In both pathways, most of these profiles resembled dendritic spines. Although there were no differences in the innervation of PV-negative targets, the two pathways differed in the innervation of PV-positive neurons. In each pathway, approximately 10% of terminals formed synapses with PV-positive profiles. However, in the forward pathway, the size of the contacted PV-positive profiles was larger than in the feedback pathway. Moreover, in the forward pathway, axon terminals on PV-positive profiles were larger, contained more mitochondria and docked synaptic vesicles than feedback synapses on PV neurons. Our results show that PV neurons provide a major target for area 17 <-> LM forward and feedback pathways terminating in upper layers. In each pathway, the proportion of axons contacting PV neurons is similar. However, both pathways differ in the subcellular localization and morphology of synapses on PV neurons. These asymmetries may contribute to the inequality in the strength of disynaptic inhibition evoked by forward and feedback inputs (Shao and Burkhalter [1996] J. Neurosci. 16:7353-7365).

Afferent Pathways↗
PubMed2000

Afferent sources to the ganglion of the terminal nerve in teleosts.

Afferent sources to the ganglion (ggl) of the terminal nerve (TN) were studied in percomorph teleosts the tilapia and dwarf gourami. After tracer applications to the TN-ggl and the surrounding bulbus olfactorius, retrogradely labeled neurons were present in the area dorsalis telencephali pars posterior (Dp), area ventralis telencephali pars ventralis et supracommissuralis (Vv and Vs), nucleus tegmento-olfactorius of Prasada Rao and Finger (1984), and locus coeruleus. In the contralateral bulbus olfactorius labeled cells were observed, and terminals were seen in the TN-ggl. Tracer injection experiments to the possible sources of origin to the TN-ggl were then performed. Tracer applications to the nucleus tegmento-olfactorius labeled abundant terminals in the TN-ggl but labeled very few in the bulbus olfactorius proper. Retrogradely labeled neurons were present in the nucleus ventromedialis thalami, nucleus commissurae posterioris, area pretectalis pars dorsalis et ventralis, nucleus sensorius nervi trigemini, and formatio reticularis pars superius et medius. Tracer applications to the Dp or Vs/Vv labeled terminals mainly in the bulbus olfactorius proper. However, terminals to the TN-ggl were supplied from labeled axons on their way to the bulbus olfactorius. Tracer injections to the locus coeruleus labeled only a few fibers around the TN-ggl. These results suggest that the TN-ggl receives somatosensory and visual inputs from the nucleus tegmento-olfactorius and olfactory inputs from the bulbus olfactorius and telencephalic subdivisions, which receive secondary olfactory projections. The locus coeruleus may also send fibers to the TN-ggl.

Afferent Pathways↗
PubMed2000

Physiological patterns in the hippocampo-entorhinal cortex system.

The anatomical connectivity and intrinsic properties of entorhinal cortical neurons give rise to ordered patterns of ensemble activity. How entorhinal ensembles form, interact, and accomplish emergent processes such as memory formation is not well-understood. We lack sufficient understanding of how neuronal ensembles in general can function transiently and distinctively from other neuronal ensembles. Ensemble interactions are bound, foremost, by anatomical connectivity and temporal constraints on neuronal discharge. We present an overview of the structure of neuronal interactions within the entorhinal cortex and the rest of the hippocampal formation. We wish to highlight two principle features of entorhinal-hippocampal interactions. First, large numbers of entorhinal neurons are organized into at least two distinct high-frequency population patterns: gamma (40-100 Hz) frequency volleys and ripple (140-200 Hz) frequency volleys. These patterns occur coincident with other well-defined electrophysiological patterns. Gamma frequency volleys are modulated by the theta cycle. Ripple frequency volleys occur on each sharp wave event. Second, these patterns occur dominantly in specific layers of the entorhinal cortex. Theta/gamma frequency volleys are the principle pattern observed in layers I-III, in the neurons that receive cortical inputs and project to the hippocampus. Ripple frequency volleys are the principle population pattern observed in layers V-VI, in the neurons that receive hippocampal output and project primarily to the neocortex. Further, we will highlight how these ensemble patterns organize interactions within distributed forebrain structures and support memory formation.

Afferent Pathways↗
PubMed1977

The organization of the pulvinar in the grey squirrel (Sciurus carolinensis). I. Cytoarchitecture and connections.

The posterior neocortex in the grey squirrel, Sciurus carolinensis, includes an extensive region which receives projections from the pulvinar. Previous studies have demonstrated that this cortical region can be subdivided on the basis of differences in cytoarchitecture and electrophysiologically defined representations of the visual field. The main purpose of the present paper was to determine whether these cortical subdivisions could be related to corresponding subdivisions in the pulvinar. The methods used to trace connections included anterograde degeneration, anterograde axonal transport of tritiated amino acids and the retrograde axonal transport of horseradish peroxidase. The results indicate that the pulvinar in this species contains at least three main subdivisions which can be distinguished by their cytoarchitecture and their patterns of connections. A caudal subdivision contains large, evenly-spaced neurons and receives bilateral input from the superficial, retinal-recipient layers of the superior colliculus. This caudal subdivision has reciprocal interconnections with a cytoarchitectonically distinct area in the temporal cortex. A rostro-lateral subdivision contains smaller, more lightly stained neurons which tend to form clusters. This subdivision receives only ipsilateral tectal input and projects to occipital area 18. This subdivision does not receive input from areas 17, 18, and 19, or from the temporal cortex. Finally, a rostro-medial subdivision is cytoarchitectonically similar to the rostro-lateral subdivision but receives little, if any, input from the superior colliculus. This rostro-medial area does, however, receive corticofugal projections from occipital areas 17, 18, and 19, and projects to area 19. These patterns of connections suggest that each of these subdivisions has close associations with the visual system. The question of whether similar subdivision are present in the visual thalamus of other species is discussed.

Afferent Pathways↗
PubMed1986

The organization of the pudendal nerve in the male and female rat.

Mature male and female Sprague-Dawley rats were used in this study to compare the organization of the pudendal nerve in the two sexes. Experiments included incubating the cut pudendal nerve in diamidino-2-phenylindole HCl (DAPI), fast blue (FB), or horseradish peroxidase (HRP) and injecting individual perineal muscles with these substances. In both sexes, incubation of the pudendal nerve labelled two motoneuron nuclei in the L5-L6 segments of the spinal cord. These nuclei are the dorsomedial (DM) and dorsolateral (DL) cell columns described by Schrøder (J. Comp. Neurol. 192:567-587, 1980). In agreement with previous studies, there were significantly more neurons in both nuclei in the male than in the female and the neurons were larger in the male. In both sexes, the DL and DM nuclei were characterized by a longitudinal dendritic structure. The DM nucleus also had numerous dendritic bundles extending across the midline, linking the DM nuclei bilaterally. Pudendal nerve afferent neurons were located in the L6 and S1 dorsal root ganglia. In the male, the afferent neurons were larger and more numerous. In both sexes, labelled pudendal afferent fibers in the spinal cord were located in the dorsal columns, the medial half of Lissauer's tract, the extreme medial edge of the dorsal horn, both ipsilaterally and contralaterally, and in a large terminal field in the dorsal gray commissure. No labelled afferents were seen in the intermediate or ventral gray. Perineal muscle injections established that there was no difference between males and females in the number of motoneurons innervating the external anal or urethral sphincters. In the female, urethral sphincter motoneurons accounted for almost all the DL motoneurons, and anal sphincter motoneurons accounted for almost all the DM motoneurons. The ischiocavernosus and bulbospongiosus muscles are vestigial in the female rat. In the male, neurons innervating the anal sphincter and bulbospongiosus muscles were intermingled in the DM nucleus. In contrast, in the DL nucleus, the urethral sphincter neurons were located in the lateral portion of the nucleus and the ischiocavernosus neurons were located in the medial portion.

Afferent Pathways↗
PubMed1987

Effects of fimbria-fornix transection and ganglioside treatments on histochemical staining for glucose-6-phosphate dehydrogenase in the lateral septum.

The present study examined whether ganglioside treatments would affect an enzyme marker (glucose-6-phosphate dehydrogenase; G6PDH) of neural metabolism in an established model system (the hippocamposeptal projection) of deafferentation and sprouting. Rats were subjected to unilateral transections of the fimbria-fornix (FF) in order to (1) interrupt the hippocamposeptal projection, (2) deafferent the lateral septal nucleus (LSN) ipsilaterally, and (3) induce sprouting by the contralateral FF. In untreated rats which were killed at 2-4 days postlesion, histochemical staining for G6PDH was reduced by 35-40% in the deafferented LSN relative to the contralateral side. However, at 6-8 days (i.e., when sprouting begins), staining intensity returned toward contralateral values (i.e., recovered). This pattern of changes in G6PDH staining was not observed in the caudate nucleus adjacent to the LSN. In ganglioside-treated rats which were killed at 4 days, there was a significantly smaller reduction of G6PDH staining in the deafferented LSN (23%; P = .05). This effect was not observed in the LSN of treated rats killed at 2 days, nor in the caudate nucleus at either time point. The present data indicate that (1) FF transection results in a reduction and subsequent recovery of G6PDH staining in the deafferented LSN; and (2) ganglioside treatments may accelerate the onset of the recovery of G6PDH activity. We suggest that gangliosides' effect on G6PDH reflects an acute enhancement of biosynthetic events in deafferented neurons.

Afferent Pathways↗
PubMed1983

Projections to the midbrain tectum in Salamandra salamandra L.

Following unilateral iontophoretic application of HRP into the optic tectum of Salamandra salamandra, retrogradely HRP-filled cells were found bilaterally in the pretectum, tegmentum isthmi, the reticular formation, pars medialis, and in the nucleus vestibularis magnocellularis. The area octavo-lateralis projects only to the caudal part of the tectum. Ipsilateral projections were noted from the dorsal gray columns of the cervical spinal cord, the dorsal tegmentum, the thalamus dorsalis pars medialis, thalamus dorsalis, pars anterior (to the rostral one-third of the tectum), the thalamus ventralis (in its entire rostro-caudal extent), and the preoptico-hypothalamic complex. Retrogradely filled cells were identified in deeper layers of the contralateral tectum. There are two telencephalic nuclei projecting ipsilaterally to the tectum via the lateral forebrain: the ventral part of the lateral pallium, and the posterior strioamygdalar complex.

Afferent Pathways↗
PubMed1987

Neuropeptides in pelvic afferent pathways.

Neurochemical and pharmacological experiments have raised the possibility that several neuropeptides including, vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine amide (PHI), substance P, calcitonin gene-related peptide (CGRP), neurokinin A, cholecystokinin (CCK) and opioid peptides may be transmitters in afferent pathways to the pelvic viscera. These substances are widely distributed in: 1) nerve fibers in the pelvic organs, 2) visceral afferent neurons in the lumbosacral dorsal root ganglia and 3) at sites of afferent termination in the spinal cord. Double staining immunocytochemical techniques have shown that more than one peptide can be localized in individual visceral afferent neurons and that neuronal excitatory (VIP, substance P, CCK) and inhibitory peptides (leucine enkephalin) can coexist in the same afferent cell. Studies with the neurotoxin, capsaicin, indicate that peptidergic afferent pathways are involved in the initiation of central autonomic reflexes as well as peripheral axon reflexes which modulate smooth muscle activity, facilitate transmission in automatic ganglia and trigger local inflammatory responses.

Afferent Pathways↗