Difference in distribution of central terminals between visceral and somatic unmyelinated (C) primary afferent fibers

1989 ◽  
Vol 62 (4) ◽  
pp. 834-840 ◽  
Author(s):  
Y. Sugiura ◽  
N. Terui ◽  
Y. Hosoya
Keyword(s):  
Electrical Stimulation ◽  
Conduction Velocity ◽  
Nerve Conduction Velocity ◽  
Substantia Gelatinosa ◽  
Afferent Neurons ◽  
Celiac Ganglion ◽  
Afferent Fibers ◽  
Primary Afferent Fibers ◽  
Phaseolus Vulgaris Leucoagglutinin ◽  
Stimulation Of

1. In the guinea pig, the central projections of somatic and visceral C-afferent fibers were compared by tracing arborizations labeled through injection of Phaseolus vulgaris leucoagglutinin (PHA-L) intracellularly into single neurons of the 13th thoracic dorsal root ganglia (DRG). 2. Two of 27 somatic C-afferent neurons that responded to electrical stimulation of the 13th thoracic (subcostal) nerve (conduction velocity: 0.69 +/- 0.14 m/s, mean +/- SD) were well enough marked to allow delineation of their central processes. In both cases, the entering axon ran rostrally, giving off branches that converged on a single terminal field located in the substantia gelatinosa (lamina II) with some extension in lamina I. The terminal field in each case extended approximately 400 microns rostrocaudally and 100 microns mediolaterally. 3. Intracellular recordings were obtained from 31 afferent units that responded to electrical stimulation of the celiac ganglion. Units with onset latencies of greater than 15 ms were classified as having visceral C-afferent fibers because the shortest course from the celiac ganglion stimulation electrodes to the DRG was greater than 7 mm (i.e., a conduction velocity of less than 0.5 m/s). 4. Seven visceral C-afferent fibers were labeled well enough to follow their central trajectories. Each had a main ascending and a descending central branch. Each main branch in turn issued several collaterals that terminated in the superficial dorsal horn (laminae I and II), laminae IV, V, and X, and occasionally in the dorsal and lateral funiculi. A few collaterals reached the contralateral laminae V and X.(ABSTRACT TRUNCATED AT 250 WORDS)

c-Fos expression in rat brain stem and spinal cord in response to activation of cardiac ischemia-sensitive afferent neurons and electrostimulatory modulation

2004 ◽  
Vol 287 (6) ◽  
pp. H2728-H2738 ◽  
Author(s):  
Fang Hua ◽  
Theresa Harrison ◽  
Chao Qin ◽  
Angela Reifsteck ◽  
Brian Ricketts ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Electrical Stimulation ◽  
Brain Stem ◽  
Nucleus Tractus Solitarius ◽  
Cardiac Ischemia ◽  
Afferent Neurons ◽  
Thoracic Spinal Cord ◽  
Thoracic Spinal ◽  
Afferent Fibers ◽  
Stimulation Of

The purpose of this study was to identify central neuronal sites activated by stimulation of cardiac ischemia-sensitive afferent neurons and determine whether electrical stimulation of left vagal afferent fibers modified the pattern of neuronal activation. Fos-like immunoreactivity (Fos-LI) was used as an index of neuronal activation in selected levels of cervical and thoracic spinal cord and brain stem. Adult Sprague-Dawley rats were anesthetized with urethane and underwent intrapericardial infusion of an “inflammatory exudate solution” (IES) containing algogenic substances that are released during ischemia (10 mM adenosine, bradykinin, prostaglandin E2, and 5-hydroxytryptamine) or occlusion of the left anterior descending coronary artery (CoAO) to activate cardiac ischemia-sensitive (nociceptive) afferent fibers. IES and CoAO increased Fos-LI above resting levels in dorsal horns in laminae I–V at C2 and T4 and in the caudal nucleus tractus solitarius. Dorsal rhizotomy virtually eliminated Fos-LI in the spinal cord as well as the brain stem. Neuromodulation of the ischemic signal by electrical stimulation of the central end of the left thoracic vagus excited neurons at the cervical and brain stem level but inhibited neurons at the thoracic spinal cord during IES or CoAO. These results suggest that stimulation of the left thoracic vagus excites descending inhibitory pathways. Inhibition at the thoracic spinal level that suppresses the ischemic (nociceptive) input signal may occur by a short-loop descending pathway via signals from cervical propriospinal circuits and/or a longer-loop descending pathway via signals from the nucleus tractus solitarius.

Primary Afferent Fibers That Contribute to Increased Substance P Receptor Internalization in the Spinal Cord After Injury

1999 ◽  
Vol 81 (3) ◽  
pp. 1379-1390 ◽  
Author(s):  
Brian J. Allen ◽  
Jun Li ◽  
Patrick M. Menning ◽  
Scott D. Rogers ◽  
Joseph Ghilardi ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Electrical Stimulation ◽  
Dorsal Horn ◽  
Nerve Transection ◽  
Primary Afferent ◽  
Lamina I ◽  
C Fibers ◽  
Afferent Fibers ◽  
Primary Afferent Fibers ◽  
Stimulation Of

Primary afferent fibers that contribute to increased substance P receptor internalization in the spinal cord after injury. Upon noxious stimulation, substance P (SP) is released from primary afferent fibers into the spinal cord where it interacts with the SP receptor (SPR). The SPR is located throughout the dorsal horn and undergoes endocytosis after agonist binding, which provides a spatial image of SPR-containing neurons that undergo agonist interaction. Under normal conditions, SPR internalization occurs only in SPR+ cell bodies and dendrites in the superficial dorsal horn after noxious stimulation. After nerve transection and inflammation, SPR immunoreactivity increases, and both noxious as well as nonnoxious stimulation produces SPR internalization in the superficial and deep dorsal horn. We investigated the primary afferent fibers that contribute to enhanced SPR internalization in the spinal cord after nerve transection and inflammation. Internalization evoked by electrical stimulation of the sciatic nerve was examined in untreated animals, at 14 days after sciatic nerve transection or sham surgery and at 3 days after hindpaw inflammation. Electrical stimulation was delivered at intensities to excite Aβ fibers only, Aβ and Aδ fibers or A and C fibers as determined by the compound action potential recorded from the tibial nerve. Electrical stimuli were delivered at a constant rate of 10 Hz for a duration of 5 min. Transection of the sciatic nerve and inflammation produced a 33.7 and 32.5% increase in SPR and immunoreactivity in lamina I, respectively. Under normal conditions, stimulation of Aδ or C fibers evoked internalization that was confined to the superficial dorsal horn. After transection or inflammation, there was a 20–24% increase in the proportion of SPR+ lamina I neurons that exhibited internalization evoked by stimulation of Aδ fibers. The proportion of lamina I SPR+ neurons that exhibited internalization after stimulation of C-fibers was not altered by transection or inflammation because this was nearly maximal under normal conditions. Moreover, electrical stimulation sufficient to excite C fibers evoked SPR internalization in 22% of SPR+ lamina III neurons after nerve transection and in 32–36% of SPR+ neurons in lamina III and IV after inflammation. Stimulation of Aβ fibers alone never evoked internalization in the superficial or deep dorsal horn. These results indicate that activation of small-caliber afferent fibers contributes to the enhanced SPR internalization in the spinal cord after nerve transection and inflammation and suggest that recruitment of neurons that possess the SPR contributes to hyperalgesia.

Electronmicroscopic and electrophysiological studies of the teat branch of the XIII thoracic nerve: relationship with lactation in the rat

1988 ◽  
Vol 118 (3) ◽  
pp. 471-483 ◽  
Author(s):  
L. M. Voloschin ◽  
E. Décima ◽  
J. H. Tramezzani
Keyword(s):  
Electrical Stimulation ◽  
Conduction Velocity ◽  
Action Potentials ◽  
Silent Period ◽  
High Amplitude ◽  
Milk Ejection ◽  
Nerve Activity ◽  
Thoracic Nerve ◽  
Myelinated Fibres ◽  
Stimulation Of

ABSTRACT Electrical stimulation of the XIII thoracic nerve (the 'mammary nerve') causes milk ejection and the release of prolactin and other hormones. We have analysed the route of the suckling stimulus at the level of different subgroups of fibres of the teat branch of the XIII thoracic nerve (TBTN), which innervates the nipple and surrounding skin, and assessed the micromorphology of the TBTN in relation to lactation. There were 844 ± 63 and 868 ± 141 (s.e.m.) nerve fibres in the TBTN (85% non-myelinated) in virgin and lactating rats respectively. Non-myelinated fibres were enlarged in lactating rats; the modal value being 0·3–0·4 μm2 for virgin and 0·4–0·5 μm2 for lactating rats (P > 0·001; Kolmogorov–Smirnov test). The modal value for myelinated fibres was 3–6 μm2 in both groups. The compound action potential of the TBTN in response to electrical stimulation showed two early volleys produced by the Aα- and Aδ-subgroups of myelinated fibres (conduction velocity rate of 60 and 14 m/s respectively), and a late third volley originated in non-myelinated fibres ('C') group; conduction velocity rate 1·4 m/s). Before milk ejection the suckling pups caused 'double bursts' of fibre activity in the Aδ fibres of the TBTN. Each 'double burst' consisted of low amplitude action potentials and comprised two multiple discharges (33–37 ms each) separated by a silent period of around 35 ms. The 'double bursts' occurred at a frequency of 3–4/s, were triggered by the stimulation of the nipple and were related to fast cheek movements visible only by watching the pups closely. In contrast, the Aα fibres of the TBTN showed brief bursts of high amplitude potentials before milk ejection. These were triggered by the stimulation of cutaneous receptors during gross slow sucking motions of the pup (jaw movements). Immediately before the triggering of milk ejection the mother was always asleep and a low nerve activity was recorded in the TBTN at this time. When reflex milk ejection occurred, the mother woke and a brisk increase in nerve activity was detected; this decreased when milk ejection was accomplished. In conscious rats the double-burst type of discharges in Aδ fibres was not observed, possibly because this activity cannot be detected by the recording methods currently employed in conscious animals. During milk ejection, action potentials of high amplitude were conveyed in the Aα fibres of the TBTN. During the treading time of the stretch reaction (SR), a brisk increase in activity occurred in larger fibres; during the stretching periods of the SR a burst-type discharge was again observed in slow-conducting afferents; when the pups changed nipple an abrupt increase in activity occurred in larger fibres. In summary, the non-myelinated fibres of the TBTN are increased in diameter during lactation, and the pattern of suckling-evoked nerve activity in myelinated fibres showed that (a) the double burst of Aδ fibres, produced by individual sucks before milk ejection, could be one of the conditions required for the triggering of the reflex, and (b) the nerve activity displayed during milk-ejection action may result, at least in part, from 'non-specific' stimulation of cutaneous receptors. J. Endocr. (1988) 118, 471–483

Connections between thoraco-coxal proprioceptive afferents and motor neurons in the locust

2000 ◽  
Vol 203 (3) ◽  
pp. 435-445
Author(s):  
M. Wildman
Keyword(s):  
Electrical Stimulation ◽  
Sensory Neurons ◽  
Motor Neurons ◽  
Chordotonal Organ ◽  
Synaptic Connections ◽  
Afferent Neurons ◽  
Postsynaptic Potentials ◽  
The Common ◽  
Proprioceptive Afferents ◽  
Stimulation Of

The position of the coxal segment of the locust hind leg relative to the thorax is monitored by a variety of proprioceptors, including three chordotonal organs and a myochordotonal organ. The sensory neurons of two of these proprioceptors, the posterior joint chordotonal organ (pjCO) and the myochordotonal organ (MCO), have axons in the purely sensory metathoracic nerve 2C (N2C). The connections made by these afferents with metathoracic motor neurons innervating thoraco-coxal and wing muscles were investigated by electrical stimulation of N2C and by matching postsynaptic potentials in motor neurons with afferent spikes in N2C. Stretch applied to the anterior rotator muscle of the coxa (M121), with which the MCO is associated, evoked sensory spikes in N2C. Some of the MCO afferent neurons make direct excitatory chemical synaptic connections with motor neurons innervating the thoraco-coxal muscles M121, M126 and M125. Parallel polysynaptic pathways via unidentified interneurons also exist between MCO afferents and these motor neurons. Connections with the common inhibitor 1 neuron and motor neurons innervating the thoraco-coxal muscles M123/4 and wing muscles M113 and M127 are polysynaptic. Afferents of the pjCO also make polysynaptic connections with motor neurons innervating thoraco-coxal and wing muscles, but no evidence for monosynaptic pathways was found.

Brain stem responses to electrical stimulation of ventral vagal gastric fibers

1989 ◽  
Vol 257 (1) ◽  
pp. G24-G29
Author(s):  
W. D. Barber ◽  
C. S. Yuan
Keyword(s):  
Electrical Stimulation ◽  
Brain Stem ◽  
Time Of Arrival ◽  
Neuronal Responses ◽  
Proximal Stomach ◽  
Afferent Fibers ◽  
Sensory Modalities ◽  
The Mean ◽  
The Brain ◽  
Stimulation Of

The brain stem neuronal responses to electrical stimulation of gastric branches of the ventral vagal trunk serving the proximal stomach were localized and evaluated in anesthetized cats. The responses were equally distributed bilaterally in the region of nucleus solitarius in the caudal brain stem. The mean latency of the response was 289 +/- 46 (SD) ms, which translated into a conduction velocity of less than 1 m/s based on the distance between the stimulating and recording electrodes. The responses consisted of single and multiple spikes that showed slight variability in the latency, indicating orthodromic activation via a synapse in approximately 98% of the responses recorded. Forty two percent of the units tested showed evidence of convergence of input from vagal afferent fibers in different branches of the ventral vagal trunk that served the proximal stomach. The resultant activity pattern of the unitary response appeared to be the product of 1) the gastric sensory input or modality conveyed by the afferent source and 2) the time of arrival and diversity of modalities served by other gastric afferents impinging on the unit. This provides a mechanism capable of responding on the basis of specific sensory modalities that dynamically reflect ongoing events monitored and conveyed by other gastric afferents in the region.

Reflex vasodilatation in the cat lip elicited by stimulation of nasal mucosa by chemical irritants

1993 ◽  
Vol 265 (4) ◽  
pp. R733-R738 ◽  
Author(s):  
H. Izumi ◽  
K. Karita
Keyword(s):  
Blood Flow ◽  
Electrical Stimulation ◽  
Nasal Mucosa ◽  
Threshold Dose ◽  
Ammonia Vapor ◽  
Autonomic Ganglion ◽  
Afferent Fibers ◽  
Autonomic Reflex ◽  
Chemical Irritants ◽  
Stimulation Of

Local application of capsaicin (threshold dose 150 microM) or nicotine (threshold dose 15 mM) to the nasal mucosa as well as electrical stimulation (threshold intensity 10 V) of the nasal mucosa elicited dose- or intensity-dependent blood flow increases in the ipsilateral lower lips of the anesthetized cats. Pretreatment with 3 mM capsaicin applied locally to the nasal mucosa abolished or reduced the vasodilation in response to capsaicin, nicotine, and ammonia vapor but not to light mechanical or electrical stimulation of the nasal mucosa. The blood flow increases elicited by all above stimuli were greatly reduced by pretreatment with hexamethonium, an autonomic ganglion blocker. These results suggest that stimulation of the nasal mucosa by chemical (capsaicin, nicotine, ammonia), mechanical, or electrical methods elicits the autonomic reflex vasodilatation in the cat lower lips. Furthermore, there seem to be at least two types of afferent fibers in the nasal mucosa of the cats: one type is capsaicin-sensitive fibers, while another type is capsaicin-resistant fibers involved in reflex vasodilatation.

Cerebral-evoked potential responses following direct vagal and esophageal electrical stimulation in humans

1993 ◽  
Vol 264 (3) ◽  
pp. G486-G491 ◽  
Author(s):  
G. Tougas ◽  
P. Hudoba ◽  
D. Fitzpatrick ◽  
R. H. Hunt ◽  
A. R. Upton
Keyword(s):  
Electrical Stimulation ◽  
Evoked Potential ◽  
Vagal Stimulation ◽  
Direct Electrical Stimulation ◽  
Sensory Pathways ◽  
Afferent Fibers ◽  
Health And Disease ◽  
Esophageal Sphincter ◽  
Afferent Response ◽  
Stimulation Of

Cerebral evoked responses following direct electrical stimulation of the vagus and esophagus were compared in 8 epileptic subjects and with those recorded after esophageal stimulation in 12 healthy nonepileptic controls. Direct vagal stimulation was performed using a left cervical vagal pacemaker, which is used in the treatment of epilepsy. Esophageal stimulation was obtained with the use of an esophageal assembly incorporating two electrodes positioned 5 and 20 cm orad to the lower esophageal sphincter. Evoked potential responses were recorded with the use of 20 scalp electrodes. The evoked potential responses consisted of three distinct negative peaks and were similar with the use of either vagal or esophageal stimulation. The measured conduction velocity of the afferent response was 7.5 m/s in epileptic subjects and 10 m/s in healthy controls, suggesting that afferent conduction is through A delta-fibers rather than slower C afferent fibers. We conclude that the cortical-evoked potential responses following esophageal electrical stimulation are comparable to direct electrical stimulation of the vagus nerve and involve mostly A delta-fibers. This approach provides a method for the assessment of vagal afferent gastrointestinal sensory pathways in health and disease.

Central Connections of Trigeminal Primary Afferent Neurons: Topographical and Functional Considerations

1992 ◽  
Vol 4 (1) ◽  
pp. 1-52 ◽  
Author(s):  
Norman F. Capra ◽  
Dean Dessem
Keyword(s):  
Trigeminal Nerve ◽  
Central Projection ◽  
Afferent Neurons ◽  
Primary Afferent Neurons ◽  
Primary Afferent ◽  
Single Fibers ◽  
Afferent Fibers ◽  
Single Nerve ◽  
Primary Afferent Fibers ◽  
Definition Of

This article reviews literature relating to the central projection of primary afferent neurons of the trigeminal nerve. After a brief description of the major nuclei associated with the trigeminal nerve, the presentation reviews several early issues related to theories of trigeminal organization including modality and somatotopic representation. Recent studies directed toward further definition of central projection patterns of single nerve branches or nerves supplying specific oral and facial tissues are considered together with data from intraaxonal and intracellular studies that define the projection patterns of single fibers. A presentation of recent immunocytochemical data related to primary afferent fibers is described. Finally, several insights that recent studies shed on early theories of trigeminal input are assessed.

Functional specialization of central projections from identified primary afferent fibers

1988 ◽  
Vol 60 (5) ◽  
pp. 1597-1614 ◽  
Author(s):  
H. R. Koerber ◽  
L. M. Mendell
Keyword(s):  
Test Stimulus ◽  
Conditioning Stimulus ◽  
Hair Follicles ◽  
Single Fiber ◽  
High Frequency Stimulation ◽  
High Threshold ◽  
Primary Afferent ◽  
Afferent Fibers ◽  
Primary Afferent Fibers ◽  
Stimulation Of

1. Somata of primary afferent fibers were impaled in the L7 or S1 dorsal root ganglion in cats anesthetized with alpha-chloralose. Individual cells (n = 182) were characterized according to receptive field (RF) and by the peripheral mechanoreceptor they innervated. They were then stimulated intracellularly while recording the evoked cord dorsum potentials (CDPs) simultaneously at four sites. CDPs were recorded in response to single fiber stimulation while varying both the frequency and the numbers of action potentials (APs) evoked per trial. Stimulus parameters included: 1) single APs evoked at both high (18 Hz) and low (0.67 Hz) frequencies, 2) pairs of APs (50-ms ISI) delivered at 0.67 Hz, and 3) trains of four APs (20-ms ISI) also delivered at 0.67 Hz. The properties of the CDPs and their relationship to receptor type innervated by the fiber were determined. 2. CDPs evoked by 18-Hz stimulation consisted of an axon fiber spike followed at a short latency [600 +/- 9.9 (SEM) microseconds] by the onset of a monophasic negative wave. A-beta-afferent fibers innervating slowly adapting type 1 and 2 receptors (SA1 and SA2) evoked the largest amplitude CDPs followed by field and hair follicle afferents while A-delta-fibers rarely produced measurable CDPs at this frequency of stimulation. 3. The magnitude of the CDP varied at the four recording sites with clear evidence in individual experiments that the projections of individual fibers are somatotopically organized. 4. CDPs evoked by 0.67-Hz stimulation had the same onset latency but were larger in amplitude and had longer time-to-peak and durations than those elicited by high frequency stimulation. Under these conditions A-beta-fibers innervating hair follicles produced the largest CDPs followed by field receptors and SA1s and SA2s. A-beta- and A-delta-fibers innervating high threshold mechanoreceptors (HTMRs) and A-delta-fibers innervating down hair follicles (D-hairs) produced CDPs of amplitude and duration similar to those evoked by slower A-beta-fibers. 5. The response to a test stimulus delivered 50 ms after a conditioning stimulus to the same single fiber was always depressed in the case of A-beta-fibers supplying rapidly adapting receptors. The conditioning stimulus exerted relatively little effect on the response to the test stimulus for A-beta- fibers innervating slowly adapting receptors. The test response to stimulation of A-beta- and A-delta- fibers innervating HTMRs was consistently facilitated while stimulation of A-delta- D-hairs evoked either marked facilitation or slight depression.(ABSTRACT TRUNCATED AT 400 WORDS)

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