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PubMed1987

Remote electrodermic response to an algogenic stimulus. Pathway and spinal integration.

The pathway of a non-segmental sudomotor reflex was studied in rabbits (New Zealand white). By means of thermic stimulation (45 degrees during 30") at the lateral border of the foot, a sudoral response was evoked in a circumscribed area of the pinna. By sequential sections of different nerves and the nervous network around the saphenous and femoral vessels, it was possible to establish the following afferent pathways to the spinal cord: lateral plantar nerve, tibial nerve up to the tuber calcanei, saphenous perivascular network, femoral perivascular network and femoral nerve. The fibres responsible for the podo-auricular sudomotor reflex penetrate into the spinal cord above L4, because the spinal transection at this level does not alter the auricular response. Since the hemisection of the spinal cord at T6 suppresses this reflex in the pinna of the same side, it must be concluded that the spinal pathway is ipsilateral. The efferent pathway abandons the spinal cord beneath segment C6: in fact, the spinal transection at C6 does not alter the auricular response to plantar stimulation. Finally, the sudomotor impulses reach the pinna sweat glands with the auricular vessels.

Afferent Pathways↗
PubMed2003

Nicotinic receptors on local circuit neurons in dentate gyrus: a potential role in regulation of granule cell excitability.

Although the dentate gyrus is one of the primary targets of septo-hippocampal cholinergic afferents, relatively little is known about the cholinergic physiology of neurons in the area. By combining whole cell patch-clamp recording with brief local application of exogenous agonists in horizontal slices, we found that there is robust expression of functional somatic alpha 7-containing nicotinic acetylcholine receptors (nAChRs) on molecular layer interneurons, hilar interneurons, and the glutamatergic mossy cells of the dentate hilus. In contrast, the principal neurons of the dentate gyrus, the granule cells, are generally unresponsive to focal somatic or dendritic application of ACh in the presence of atropine. We also demonstrate that cholinergic activation of alpha 7-containing nAChRs on the subgranular interneurons of the hilus can produce methyllycaconitine-sensitive GABAergic inhibitory postsynaptic currents (IPSCs) in nearby granule cells and enhance the amplitude of an electrically evoked monosynaptic IPSC. Further, activation of alpha 7-containing nAChRs on subgranular interneurons that is timed to coincide with synaptic release of glutamate onto these cells will enhance the functional inhibition of granule cells. These findings suggest that a complex interplay between glutamatergic afferents from the entorhinal cortex and cholinergic afferents from the medial septum could be involved in the normal regulation of granule cell function. Such a relationship between these two afferent pathways could be highly relevant to the study of both age-related memory dysfunction and disorders involving regulation of excitability, such as temporal lobe epilepsy.

Acetylcholine↗
PubMed1999

Physiological pathways regulating the activity of magnocellular neurosecretory cells.

Magnocellular oxytocin and vasopressin cells are among the most extensively studied neurons in the brain; their large size and high synthetic capacity, their discrete, homogeneous distribution and the anatomical separation of their terminals from their cell bodies, and the ability to determine their neuronal output readily by measurements of hormone concentration in the plasma, combine to make these systems amenable to a wide range of fundamental investigations. While vasopressin cells have intrinsic burst-generating properties, oxytocin cells are organized within local pattern-generating networks. In this review we consider the rôle played by particular afferent pathways in the regulation of the activity of oxytocin and vasopressin cells. For both cell types, the effects of changes in the activity of synaptic input can be complex.

Afferent Pathways↗
PubMed1998

Commissural and lemniscal synaptic input to the gerbil inferior colliculus.

The central nucleus of the inferior colliculus (ICC) receives direct inputs, bilaterally, from all auditory brain stem nuclear groups. To evaluate the contribution made to gerbil ICC neuron physiology by two major afferent pathways, we examined the synaptic responses evoked by direct stimulation of the commissure of the inferior colliculus (CIC) and the ipsilateral lateral lemniscus (LL). Frontal midbrain slices were obtained from postnatal day (P) 9-P19 gerbils, and whole cell recordings were made under current- (n = 22) or voltage-clamp (n = 52) conditions. Excitatory and inhibitory synaptic responses were characterized by sequentially exposing the slice to ionotropic glutamate receptor antagonists [6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) + aminophosphonpentanoic acid (AP-5), or kynurenic acid)], a gamma-aminobutryic acid type A receptor antagonist (bicuculline), and a glycine receptor antagonist (strychnine). In current clamp, LL stimulation typically produced a short latency depolarization followed by a longer duration hyperpolarization. The depolarization was abolished by AP-5 + CNQX, and the remaining inhibitory potential displayed either bicuculline or strychnine sensitivity. In voltage clamp, 79% of ICC neurons displayed synaptic currents after stimulation of each pathway. The synaptic currents were typically complex waveforms, and ionotropic glutamate receptor antagonists reduced inward currents at a holding potential of -80 mV in the majority of neurons. In addition, this treatment reduced outward synaptic currents at a holding potential of -20 mV, indicating that inhibitory interneuronal input was often activated by LL or CIC afferents. A minority of neurons had synaptic currents that were unaffected by glutamate receptor antagonists, but it was more common for CIC-evoked currents to be unaffected (38%) rather than LL-evoked currents (22%). The CIC provided a strong inhibitory input that was almost exclusively GABAergic, whereas the LL inhibition often included a glycinergic component. These experiments have shown that the CIC provides a major glutamatergic and GABAergic input to most ICC neurons. However, much of the inhibitory input from both the CIC and the LL appears to be mediated by interneuronal connections.

Afferent Pathways↗
PubMed2003

Uncontrollable high-frequency tachypnea in a case of unilateral medial medullary infarct.

BACKGROUND: Medullary infarcts can be associated with breathing disorders that usually consist in central hypoventilation. PATIENT: We describe the case of a 54-year-old man, fully conscious, presenting with an uncontrollable high frequency and shallow tachypnea (95/min) at the onset of a unilateral medial medullary infarct. This disorder disappeared under inspiratory pressure support mechanical ventilation. MEASUREMENTS AND RESULTS: Respiratory drive (respiratory rate, occlusion pressure, and mean inspiratory flow), efferent pathway (transcranial and cervical magnetic stimulation), and afferent pathway (response to CO(2) and to lung inflation) were investigated. The respiratory drive was increased. The phrenic nerve conduction time was normal. The sensitivity of the central pattern generator to lung inflation and to CO(2) was preserved. The territory of the infarct was supplied by the spinal anterior artery. CONCLUSIONS: An extremely rapid and shallow tachypnea due to the increase in respiratory drive can be associated with unilateral medullary infarction.

Cerebral Infarction↗
PubMed1985

High frequency oscillation of the lungs alone lengthens expiration in dogs.

High frequency (15 Hz), low volume (approximately 40 ml) oscillation of the respiratory system lengthens expiration in anesthetized dogs even in the absence of changes in mean expiratory lung volume or blood gases (Banzett et al., 1983). Although vagotomy abolishes this response, we felt it might mask the reflex rather than interrupt the afferent pathway. To ascertain whether pulmonary and airway afferents alone are capable of evoking this reflex, we confined the oscillatory stimulus to the lung by widely opening the chest. The dogs were paralyzed but breathed 'spontaneously' by means of a solenoid valve opened and closed by the phrenic neurogram. End-expiratory lung volume and PCO2 were held constant. All eight dogs that were tested after thoracotomy lengthened expiration during oscillation. Although quantitative comparisons of responses before and after thoracotomy are not entirely reliable, we could see no consistent change in the strength of response with paralysis or with thoracotomy. We conclude that the principal afferent limb of the ventilatory reflex response to oscillation arises in the lungs and intrathoracic airways.

Animals↗
PubMed1978

The strength of the reflex response to sinusoidal stretch of monkey jaw closing muscles during voluntary contraction.

1. Rhesus monkeys were trained to exert steady biting forces of 3--60 N for 1--2 sec. This behaviour was well maintained while sinusoidal or step opening and closing movements were imposed on the jaw. 2. The amplitude of the force modulation during sinusoidal stretching was divided by the amplitude of movement to obtain the magnitude of stiffness. This estimate was made at frequencies from 2 to 50 Hz at amplitudes of 100 and 500 micrometer (half the peak-to-peak movement at the incisors). 3. Peak magnitudes of stiffness were seen with frequencies of 8--15 Hz when the amplitude of movement was small; there was a great deal of variation between individual animals. This variation was most striking with mean forces of 25--35 N. The stiffness was greatest in animals that showed considerable spontaneous tremor, and the highest levels of stiffness were often recorded with frequencies near which tremor amplitude was large. A marked phase lag in the force response was often seen during small amplitude stretching at 8--30 Hz. 4. Estimates of stiffness for larger amplitude (500 micrometer) stretching showed less variation; the magnitude of stiffness showed maximum values below 10 Hz and a minimum at 15--30 Hz. Force always showed a phase lead on position although this lead became small in the frequency range where with smaller movement there had been phase lags. The magnitude of stiffness increased with increasing mean force. 5. Bilateral electrolytic lesions were made in the brain stems of three animals; they reduced by over 95% the expected number of cells in the mesencephalic nucleus of the fifth cranial nerve on either side. These lesions interrupted the afferent pathway for the stretch reflex and so abolished excitatory electromyogram (e.m.g.) responses to step stretches of the jaw closing muscles. 6. Such reflex responses as persisted after the lesions were small and inhibitory. E.m.g. silences followed both step stretch and release; the response to release was a 'load compensation' that could not be attributed to spindle afferents. 7. After the lesions the responses to movements of 100 micrometer showed neither negative values for the phase nor marked peaks in the stiffness magnitude at low frequencies; these features therefore take origin in the action of the stretch reflex. The stiffness that was measured after the lesions may be attributed to the non-reflex components resisting stretch, particularly to the properties of the contracting muscles. Thus, the phase of the force response was markedly advanced at all frequencies and the stiffness seen for 100 micrometer was similar to that for 500 micrometer. Stiffness increased with increasing mean force, as before surgery. 8. Vector subtraction of the stiffness seen at each frequency after interrupting the stretch reflex from that seen before doing so gave a quantitative estimate of the strength of the stretch reflex. The reflex activity calculated in this way showed attenuation and progressive phase lag as the frequency increased above 10 Hz...

Afferent Pathways↗
PubMed1997

Interactions between sympathetic and vagal cardiac afferents in nucleus tractus solitarii.

Epicardial application of hydrogen peroxide (H2O2) reflexly elicits a sympathetically mediated pressor response. This pressor response is augmented by vagotomy and abolished by sympathectomy, suggesting an occlusive interaction between the afferents in the central nervous system (CNS). To support this observation we recorded sympathetic efferent responses from the sympathetic chain (T1-T2) before and after epicardial application of H2O2 in six cats before and after vagotomy. Cardiac sympathetic efferent responses to H2O2 were increased by vagotomy. Thus there exists an occlusive interaction between the two afferent pathways in the CNS. Because cardiopulmonary vagal afferents make their first central synapse in the nucleus tractus solitarii (NTS), we further hypothesized that cells in the NTS receive convergent inputs from sympathetic and vagal afferents and that the inputs would interact in an occlusive manner. In alpha-chloralose-anesthetized sinoaortic-denervated cats, cardiac sympathetic and vagal branches were stimulated electrically at 1 Hz, either separately or in combination. Extracellular single-unit activity was recorded in the NTS. Vagal stimuli most frequently (38%) diminished sympathetically evoked unit activity (-46.6 +/- 6.0%) versus control (1.4 +/- 1.5%). However, a few (21%) vagal and sympathetic afferent inputs were found to be additive or facilitative. We conclude that interactions occur between cardiac sympathetic and vagal afferents in the NTS. It is possible that this occlusive interaction explains the alteration in cardiac sympathetic outflow after epicardial stimulation with H2O2.

Animals↗
PubMed1977

[The action of acupuncture on pain. Physiological basis].

A review of experimental studies concerning acupuncture gives a current indication as to the neurophysiological mechanisms of its hypoalgesic effects. In man, these effects are demonstrated by study of the nociceptive flexion reflex. Other methods for the study of pain threshold have revealed a hypoalgesic action in man and in the animal. The authors analyse the pathways and structures necessary to analgesia: peripheral afferent pathway, ascending pathways, suprasegmental controls. The inhibitory mechanisms activated by acupuncture appear to be identical to those involved in analgesia by morphine and by central stimulation.

Acupuncture Therapy↗
PubMed1987

Role of peripheral afferents and spinal reflexes in normal and impaired human locomotion.

For many years, electrophysiological investigations of locomotion were restricted to animals, largely the cat. They concentrated on and emphasized the role of spinal interneuronal networks responsible for the generation of the locomotor pattern. Following the introduction of perturbation impulses and electrical nerve stimulation during stance and gait, information became increasingly available concerning the role of the reflex systems involved in the regulation of gait, their afferent pathways and their control by supraspinal motor centres. During gait monosynaptic stretch reflexes are inhibited. From a knowledge of the behaviour of the cerebral potentials evoked during stance and gait, it can be deduced that during gait the signals of group I afferents are blocked at both segmental and supraspinal levels. Polysynaptic reflex responses are mainly responsible for the compensation of perturbations introduced during gait. They are most probably mediated by group II afferents via a spinal pathway closely connected with the spinal locomotor centres. The functioning of these responses depends on an intact supraspinal control. They are suggested to be incorporated in a more complex e.m.g. pattern mainly determined by central mechanisms. In contrast to the gait condition, segmental stretch reflex activity does contribute to activation of extensor muscles of the leg during fast movements, such as running and hopping. In children at an early stage in the development of gait (around 1 to 2 years of age), as well as in patients with spastic paresis, the polysynaptic reflex responses are reduced or absent, and isolated monosynaptic reflex potentials are present. This suggests a reciprocal modulation of mono- and polysynaptic reflex mechanisms, both being dependant on supraspinal control. When this control is either not yet matured (small children) or impaired (spastic paresis), inhibition of monosynaptic stretch reflexes is absent and associated with a reduced facilitation of polysynaptic spinal reflexes. In spastic muscle hypertonia, the tension developed at the Achilles tendon during gait cannot be explained by gastrocnemius activation alone. In patients with spastic hemiparesis gastrocnemius e.m.g. activity is reduced in the spastic leg as compared to the unaffected one. It can be concluded that the paretic muscle undergoes changes in its mechanical properties, secondary to the supraspinal lesion, which results in the development of spastic muscle hypertonia.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1993

The paraventricular nucleus and corticotrophin-releasing hormone are not critical in suppressing pulsatile LH secretion in ovariectomized lactating rats.

Various types of hypothalamic roof deafferentation (RD) (i.e. large anterior (LARD), large posterior (LPRD), small anterior (SARD) or middle (MRD)), electrolytic lesions of the paraventricular nucleus (PVN) or intracerebroventricular (i.c.v.) injection of alpha-helical corticotrophin-releasing factor(9-41) (alpha-helical CRF(9-41)) were performed in ovariectomized lactating rats in order to determine the afferent pathway of the suckling stimulus and whether the PVN and corticotrophin-releasing hormone (CRH) are involved in suppressing pulsatile LH secretion during lactation. Animals were ovariectomized on day 2 of lactation (day 0 = the day of parturition). Deafferentations and electrolytic lesions were made on day 7. On the following day, blood samples were taken via an indwelling atrial cannula every 6 min for 3 h. Pulsatile LH secretion with high frequency and amplitude was present in rats with LARD or LPRD despite the suckling. In rats with MRD, LH pulses with a small amplitude were observed when the cut was on or under the ventral margin of the PVN, but there were few LH pulses when the cut passed through the PVN. Electrolytic lesioning of the PVN, however, did not affect the suppression of pulsatile LH secretion during lactation. In addition, i.c.v. injection of alpha-helical CRF(9-41) (26.1 nmol/10 microliters) into the third ventricle on day 8 of lactation did not reverse the suppression of LH secretion by the suckling stimulus. These results suggest that the pathway associated with this inhibition may be rather diffuse and that the PVN region and CRH are not critical in conveying the inhibitory inputs of the suckling stimulus.

Afferent Pathways↗
PubMed2005

Mapping the rat somatosensory pathway from the anterior cruciate ligament nerve endings to the cerebrum.

The anterior cruciate ligament (ACL) serves as the primary restraint to anterior tibial translation. In addition to this biomechanical function, the ACL appears to have a function in neuromuscular control. This hypothesis was formulated after the discovery of mechanoreceptors within the ACL. The full somatosensory pathway from the ACL to the cerebrum has yet to be elucidated. In order to map this sensory pathway, we conducted a viral trans-synaptic tracing experiment using the neurotropic pseudorabies virus (PRV). The pseudorabies virus was injected into the ACL of rats and allowed to replicate and spread trans-synaptically for 6-7 days. The brain and spinal cord of each sacrificed rat was then removed and processed immunohistochemically to detect the presence of PRV. PRV-immunoreactive neurons were found to be localized in several different regions from the spinal cord to the cerebrum. Four nuclei in the reticular formation of the brain stem demonstrated strong positive labeling: the mesencephalic reticular nucleus, magnocellular reticular nucleus, paragigantocellular reticular nucleus, and gigantocellular reticular nucleus. This finding suggests that the nerve endings of the rat ACL project into the cerebrum and that the reticular formation may play an important role in the afferent pathway of those nerve endings.

Afferent Pathways↗
PubMed1987

Facilitatory effect of oxytocin on oxytocin cell background activity in the rat is suckling-dependent.

The injection of oxytocin into the third ventricle during suckling in lactating rats not only enhances neurosecretory bursts but also the background activity of oxytocin cells. However, removing the young rats 10 min after the oxytocin injection is immediately followed by a decrease in background activity, while injecting oxytocin alone (i.e. without suckling) or suckling alone (i.e. without oxytocin injection) has no effect. These results, which show that the facilitatory effect of oxytocin on oxytocin cell background activity is suckling-dependent, suggest that oxytocin could act either on the afferent pathways for milk ejection or on oxytocin cells themselves, but only if they received inputs from mammary glands. Various hypotheses on the site and mode of action of oxytocin are discussed.

Afferent Pathways↗
PubMed1992

Mechanisms of vasopressin secretion.

The magnocellular vasopressin system of the rat has been studied intensively in recent years. This review outlines the electrophysiological characteristics of vasopressin neurons, the characteristics of stimulus-secretion coupling in the neural lobe, and describes some of the major features of the neural regulation of this system which underlie physiological regulation of vasopressin release by osmoregulatory stimuli. The major afferent pathways to the magnocellular system are now well characterised. Those involved in osmoregulation have been mapped using expression of the primary response gene c-fos as a marker for neuronal activation.

Afferent Pathways↗
PubMed1986

Afferent projections to the thalamic mediodorsal nucleus in the cat studied by retrograde and anterograde axonal transport of horseradish peroxidase.

The afferent pathways to the thalamic mediodorsal nucleus (MD) in the cat were studied using the methods of anterograde and retrograde axonal transport of horseradish peroxidase (HRP) and wheat germ agglutinin conjugated to HRP (WGA-HRP). The MD receives fibers from the prefrontal cortex in a topically organized manner in accordance with the thalamocortical projections. The medial or ventral portion of the MD receives afferents from the islands of Calleja of the olfactory tubercle, the nucleus of the diagonal band, the amygdala and the claustrum. The lateral hypothalamic nucleus sends a moderate number of fibers to the medial MD, but other hypothalamic nuclei send only a few fibers to the MD. The lateral or dorsal portion of the MD receives fibers from the nucleus of the diagonal band, the ventral pallidum and the entopeduncular nucleus, but only few from the olfactory tubercle and the amygdala. The thalamic reticular nucleus sends many fibers to the MD without showing any topography. The MD, particularly its lateral part, receives afferents from brainstem structures, such as the substantia nigra, superior colliculus, reticular formation, raphe nuclei and nucleus loci coerulei. Only the interpeduncular nucleus sends fibers mainly to the medial part of the MD. The cerebellar nuclei send only a few fibers to the lateral part of the MD at posterior levels.

Afferent Pathways↗
PubMed1995

Influence of VPM afferents on putative inhibitory interneurons in S1 of the awake rabbit: evidence from cross-correlation, microstimulation, and latencies to peripheral sensory stimulation.

1. Responses of thalamocortical projection neurons and suspected cortical interneurons (SINs) to very brief peripheral stimuli were examined within the vibrissae, the sinus hair, the lip, and the chin representations of ventroposterior medial thalamus (VPM) and primary somatosensory cortex (S1). VPM thalamocortical neurons (N = 40) were identified by their antidromic activation after electrical stimulation of S1. SINs were identified by a high-frequency (> 600 Hz) burst of three or more spikes elicited by suprathreshold stimulation of one or more afferent pathways. SINs also had spikes of very short duration. 2. Previous work has shown that electrical stimulation of VPM elicits a very early and powerful synaptic response in many S1 SINs. Three experimental strategies were employed to test the hypothesis that such responses reflect a monosynaptic VPM input onto SINs and to examine the effects of such input. 1) After a brief peripheral stimulus, the arrival times of VPM thalamocortical impulses in S1 were determined and compared with the initial response times of S1 SINs. 2) Shift-corrected cross-correlograms (CCGs) were constructed from the spike trains of pairs of VPM neurons and SINs that were in precise topographic alignment. 3) Inferences of connectivity based on such CCGs were supported by applying very low-intensity (1-10 microA) microstimulation pulses to the recording microelectrode in VPM and observing evoked responses in the cortical SIN. 3. VPM thalamocortical neurons responded to a brief air puff stimulus at a median latency of 5.05 ms, and the estimated arrival time of the VPM impulses at S1 had a median value of 5.97 ms. This estimate was obtained by adding the antidromic latency of each VPM neuron to the latency of the peripheral stimulus and was supported by similar values obtained from three VPM thalamocortical axons recorded near their termination site within S1. SINs of S1 were among the first cortical neurons to respond to the peripheral stimulus, responding to the air puff at a median latency of 6.6 ms (range 5.7-13.0 ms). The latency of SINs to the peripheral stimulus was strongly related to the latency to gross electrical stimulation of VPM (median value 1.52 ms, r2 = +0.44, P < 0.0001). Many SINs (23 of 34) showed significant shift-corrected CCGs with VPM neurons that were in precise topographic alignment. Most significant CCGs revealed a very brief increase in SIN spike probability (half-amplitude response of approximately 1 ms) that reached a peak value at intervals of 1.4-2.0 ms after the VPM spike.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗
PubMed2002

Bladder activation: afferent mechanisms.

The major function of the lower urinary tract is to store and periodically evacuate urine from the bladder. This requires coordination of the smooth muscles of the bladder and urethra, and of the striated muscles of the outflow region and pelvic floor by a complex neural control system. Lumbosacral afferent fibers (pelvic afferents), but also afferents in the hypogastric and pudendal nerves, are of major importance for the regulation of the mechanisms for continence and micturition. In the bladder, afferent nerves have been identified suburothelially as well as in the detrusor muscle. Suburothelially, they form a plexus that lies immediately beneath the epithelial lining. This plexus is particularly dense in the bladder neck and the trigone. The most important afferents for the micturition process are myelinated Adelta-fibers and unmyelinated C-fibers. Immunocytochemical and tracing studies have revealed that numerous peptides, including substance P, calcitonin gene-related peptide, vasoactive intestinal polypeptide, enkephalins, and cholecystokinin are localized either alone, or in combination, in afferent pathways of the bladder and urethra. The receptors on these nerves include: vanilloid receptors, purinoceptors, tachykinin, and prostanoid receptors. Extracellular adenosine triphosphate (ATP) has been found to mediate excitation of small-diameter sensory neurons via P2X3 receptors, and it has been proposed that in the bladder, distention causes release of ATP from the urothelium. ATP, in turn, can activate P2X3 receptors on suburothelial afferent nerve terminals to evoke a neural discharge. However, it is most likely that a cascade of inhibitory and stimulatory transmitters/mediators, as well as ATP, are involved in the transduction mechanisms underlying the activation of afferent fibers during bladder filling.

Adenosine Triphosphate↗
PubMed1997

Sigmoid afferent mechanisms in patients with irritable bowel syndrome.

Up to 60% of patients with IBS have lowered perception thresholds in the rectum to balloon distension. The current study sought to test the hypothesis that IBS patients with normal perception thresholds in the rectum show hypersensitivity of afferent pathways in the sigmoid colon. Eleven healthy normal subjects and eight IBS patients with normal rectal perception thresholds underwent a balloon distension protocol in the sigmoid and rectum. Discomfort thresholds, receptive relaxation, compliance, and referral patterns were measured. Although IBS patients had significantly lower discomfort thresholds in the sigmoid when measured as volume, pressure, and wall tension, thresholds were similar to normals. Receptive relaxation and dynamic compliance were significantly decreased in IBS patients in the sigmoid. Referral patterns were similar during sigmoid distention in IBS patients in comparison to normals. Despite normal perception thresholds in rectum and sigmoid, IBS patients show evidence for alterations in rectosigmoid afferent mechanisms. In the sigmoid, this is seen in the form of reduced reflex relaxation and compliance and in the rectum in the form of altered viscerosomatic referral.

Adult↗