Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Efferent Pathways”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45Linked to original sources
PubMed1999

[Modification of cochlear active micromechanism by auditory cortex].

OBJECTIVE: To investigate the modification of active micromechanism of outer hair cells by auditory cortex. METHODS: 1. Effects of selective attention on distortion product otoacoustic emissions (DPOAE) were analyzed in 9 human subjects with normal hearing. Visual tasks, two letters, O and Q, were alternatively displayed on a computer screen. Letter Q was target stimulus flashing randomly (probability was 20%), and letter O was non-target stimulus occurring regularly (probability was 80%). 2. In 13 guinea pigs, DPOAEs were measured before and after decerebration. RESULTS: 1. Visual tasks suppressed DPOAE significantly in both 1 kHz and 2 kHz (P < 0.05). 2. DPOAE reduced significantly in decerebrated guinea pigs. CONCLUSION: The study further demonstrates that the efferents from the auditory cortex do innervate the cochlea, and the efferent pathway passes from the auditory cortex, the super olive complex to the cochlea. Through this pathway the auditory cortex modulates the cochlear active micromechanism. The underlying mechanism was discussed.

Acoustic Impedance Tests↗
PubMed1992

Immunolocalization of epidermal growth factor (EGF) in human salivary glands detected with the new monoclonal antibody.

Epidermal growth factor (EGF) is biologically active peptide commonly seen in many human tissues and organs. Its high concentration has been found in the salivary glands. The purpose of the present study was to determine EGF immunolocalization in normal human major salivary glands using a new monoclonal antibody anti-EGF. The results were compared with EGF location determined by using two human antibodies (Oncogene, USA and ICI from dr Gregory, UK). Immunohistochemical studies were performed by the PAP method. All antibodies demonstrated EGF expression in the efferent pathways of the salivary glands, especially in their proximal segments.

Antibodies, Monoclonal↗
PubMed1992

[Effect of ketanserin on arterial baroreflex-blood pressure control in conscious hypertensive rats].

The effect of ketanserin on arterial baroreflex-blood pressure control (ABR-BP) were studied in conscious freely-moving spontaneously hypertensive rats (SHR) and renovascular hypertensive rats (RVHR). The ABR-BP was measured by using a new method comparing with the pressor responses (in area) to angiotensin II before and after blocking the baroreflex efferent pathway by guanethidine and methyl atropine. It was found that ketanserin enhanced markedly the ABR-BP in both groups of hypertensive rats (SHR: 51% to 74%; RVHR: 59% to 77%). This suggests that the enhancement of ABR-BP may be involved in the anti-hypertensive effects of ketanserin.

Animals↗
PubMed1992

Neurophysiological evaluation of disorders and procedures affecting the spinal cord and the cauda equina.

Neurophysiological tests that asses afferent or efferent pathways of the spinal cord and of nerve roots are used for clinical diagnosis, intraoperative monitoring, and judgement of prognosis. Most tests can readily be performed in awake subjects, whereas many difficulties arise in anesthetized patients in whom neurophysiological testing is the only way of monitoring functional integrity of neural tissue. The research, therefore, that has been carried out in this field during the past year is of special interest.

Cauda Equina↗
PubMed1992

[Methods of investigating orthostatic hypotension].

Orthostatic hypotension, which is common mainly in the elderly, is in many cases related to hypovolemia and/or vasodilators intake. However, when an impairment of the autonomic nervous system is suspected, orthostatic hypotension severity and mechanism may be investigated. The most common tests are the head upright tilt-test and the Valsalva manoeuvre. Both of them examine the baroreflex system as a whole, and become non invasive tests with the development of finger arterial blood pressure continuous measurement. Each part of the baroreflex system may be investigated separately. So, cardiac vagal responses to ocular compression, to carotid sinus massage, to respiratory change or to atropine infusion, may be tested. On the other hand, sympathetic efferent pathways may be stimulated in a variety of ways, such as isometric exercise, cutaneous cold, mental arithmetic, norepinephrine infusion, or tiltest. None of these tests should be applied systematically, but according to the clinical features.

Aged↗
PubMed1992

[A case of acute idiopathic pandysautonomia--a histochemical study of sural nerve by acetylcholinesterase staining].

A 30-year-old man had an acute onset of orthostatic lightheadedness, sweating disturbance, paroxysmal cough and loss of potency. These symptoms reached the peak in two weeks, and then remitted very slowly. He was admitted to our hospital for further evaluation when he was 39 years old. Neurological examinations revealed right Horner's syndrome, dry skin and impotence, but neither motor nor sensory system was impaired. No abnormalities were found on routine examinations of the blood and cerebrospinal fluid, motor and sensory nerve velocities, computed tomography and electroencephalography. On sural nerve biopsy, the density of unmyelinated fibers was mildly decreased (13,857/mm2), whereas that of myelinated fibers was normal (7,220/mm2). Autonomic function tests disclosed orthostatic hypotension (-31 mmHg) on tilting, reduced levels of serum noradrenaline and vanillyl mandelic acid, supersensitive responses to noradrenaline infusion and adrenaline eye-dripping, severe sweating impairment and complete absence of sympathetic skin response. On the other hand, Aschner's test, Czermak's test and coefficient variation of R-R intervals were all normal. These results suggested that the chief lesion was located in the postganglionic fiber of sympathetic efferent pathway. We (Hayashi et al, 1990) quantified acetylcholinesterase (AchE)-positive fibers in the specimens of sural nerve biopsy, and reported that the density of AchE-positive fibers was correlated to the function of sympathetic postganglionic fibers. The density of AchE-positive fibers in the present case of acute idiopathic pandysautonomia (AIPD) was severely decreased to 225/mm2 by optical microscopy (control: 5,703 +/- 1,289/mm2), and to 2,996/mm2 by electron microscopy (control: 14,112 +/- 3,987/mm2).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholinesterase↗
PubMed1992

Epidermal growth factor (EGF) expression in human salivary glands. An immunohistochemical study.

Epidermal growth factor (EGF) is a biologically active peptide involved in differentiation, growth, regeneration and repair of human and animal tissues. Quantitative biochemical studies showed in man the highest concentration of EGF in the parotid gland. The aim of the present study was to define EGF immunolocalization in the individual segments of the human major salivary glands (salivon). The material consisted of sections obtained from the surgically removed salivary glands: parotid, submaxillary and sublingual. Immunohistochemical studies were performed by PAP method using monoclonal antibody against human epidermal growth factor. EGF expression was found almost exclusively in the efferent pathways of the salivary glands, mostly in the intercalated ducts and Pflüger salivary tubules. These segments of the salivon are most developed in the parotid gland in which the staining was stronger than in other salivary glands.

Epidermal Growth Factor↗
PubMedDate not supplied

[Palliative surgical treatment of spastic paralysis in the upper extremity].

AIMS: In this paper we review the main studies conducted on therapy applied to the bony and soft parts in spastic paralysis of the upper extremity. DEVELOPMENT: Spasticity presents muscular hypertonia and hyperexcitability of the stretch reflex, which are typical of upper motoneuron syndrome. Physiopathologically, spasticity is due to the medullar and supramedullar alteration of the afferent and efferent pathways. Treatment is multidisciplinary and involves the collaboration of rehabilitators, neurophysiologists, neurologists, paediatricians, orthopaedic surgeons and psychologists, who all contribute with their different therapeutic aspects and characteristics (which can be pharmacological, peripheral neurological blockages, surgical, etc.). The characteristic posture of the upper extremities in spastic cerebral palsy is the inward rotation of the shoulder, flexion of the elbow and pronated forearm, and the deformity of the fingers (swan-neck and thumbs-in-palm). The primary objectives in these patients will be to improve communication with their surroundings, perform activities of daily living, increase mobility and walking. CONCLUSIONS: The surgical treatment applied by orthopaedic surgeons in the upper extremities are aimed at achieving an enhanced adaptive functionality rather than morphological normality. Factors to be taken into account include age, voluntary control over muscles and joints, level of severity of the spasticity (Ashworth scale) and stereognostic sensitivity. In general, on soft parts we will use procedures such as dehiscence or lengthening of the flexor muscles of the shoulder and elbow or of the adductor of the thumb; transfer of the pronators in order to adopt the supinating function or of the flexors so as to reinforce the extensors of the forearm, and capsulodesis or tenodesis in the hand. The bony procedures will consist in derotational osteotomies of the humerus and radius and arthrodesis in the wrist or in the metacarpophalangeal joints of the thumb, depending on whether there is greater rigidity or age in the former cases or instability in the latter.

Humans↗
PubMed1992

Single unit activity in the guinea-pig cochlear nucleus during sleep and wakefulness.

The effects of waking and sleep on the response properties of auditory units in the ventral cochlear nucleus (CN) were explored by using extracellular recordings in chronic guinea-pigs. Significant increases and decreases in firing rate were detected in two neuronal groups, a) the "sound-responding" and b) the "spontaneous" (units that do not show responses to any acoustic stimuli controlled by the experimenter). The "spontaneous" may be considered as belonging to the auditory system because the corresponding units showed a suppression of their discharge when the receptor was destroyed. The auditory CN units were characterized by their PSTH in response to tones at their characteristic frequency and also by the changes in firing rate and probability of discharge evaluated during periods of waking, slow wave and paradoxical sleep. The CNS performs functions dependent on sensory inputs during wakefulness and sleep phases. By studying the auditory input at the level of the ventral CN with constant sound stimuli, it was shown that, in addition to the firing rate shifts, some units presented changes in the temporal probability of discharge, implying central actions on the corresponding neurons. The mean latency of the responses, however, did not show significant changes throughout the sleep-waking cycle. The auditory efferent pathways are postulated to modulate the auditory input at CN level during different animal states. The probability of firing and the changes in the temporal pattern, as shown by the PSTH, are thus dependent on both the auditory input and the functional brain state related to the sleep-waking cycle.

Acoustic Stimulation↗
PubMed2004

The human hypothalamus: a morpho-functional perspective.

Historical investigation suggests that the role of the hypothalamus as a site of integration for endocrine with autonomic and behavioral responses in man rises from ideas and observations first appearing between the 14th and 18th centuries. Research on human, post-mortem brains and by in vivo magnetic resonance techniques reveal that the functional morphology of the hypothalamus in man is very similar to that in Rodents and Primates. As such, the adult human hypothalamus can be subdivided in three longitudinal zones, representing the source and target of neural informations traveling back and forth the brain stem, thalamus, limbic system, basal ganglia and neocortex. In addition, the human hypothalamus can be further partitioned in three anterior-posterior regions, of which the rostral one exerts a prominent regulation in predictive homeostasis, as opposed to the two caudal ones, primarily involved in reactive homeostasis. Finally, nuclear distribution in the human hypothalamus largely coincides with that in higher Mammals. Nevertheless, it is still unclear how the hypothalamus may give rise to specific homeostatic behaviors like hunger, thirst, reproductive and parental attitude, thermoregulation, aggressive-defensive performance, affective-motivational tone, circadian rhythmicity, sleep-wake cycle and immune regulation. The recent advent of new theories for nervous communication, like volume transmission and neural Darwinism, is progressively enlightening our understanding of the role played by the hypothalamic architecture in homeostatic responses, both in Mammals and man.

Afferent Pathways↗
PubMed2004

[Neurogenic bladder: pathophysiology of the disorder of compliance].

Bladder compliance is defined by the ratio of the increase of intravesical pressures to the increase of volume (_V/_P). The pathophysiology of disorders of compliance in neurogenic bladder is still poorly elucidated. It can be evaluated in terms of three elements: 1) The natural history of the appearance of these disorders in neurogenic bladders. Clinical experience shows the existence of prognostic factors that determine the development of these disorders, such as the voiding mode adopted (self-catheterization/hetero-catheterization versus indwelling catheter), the level of the spinal cord lesion (suprasacral versus sacral, incomplete versus complete, and cauda equina lesions), and the presence of meningomyelocele. 2). Data derived from conservative management of these disorders in neurogenic bladders: urethral dilatation, various sphincterotomies, bladder disafferentation, alpha-blockers, vanilloids (resiniferatoxin and capsaicin), intra-detrusor botulinum toxin and intrathecal baclofen, have demonstrated a marked improvement of disorders of compliance associated with neurogenic bladder 3). Data derived from experimentations. Morphometric studies on animal or human bladder strips have demonstrated an increased expression of proteolytic enzymes and endogenous tissue inhibitors of metalloproteinases (MMP-1) and type III collagen mRNA in hypocompliant neurogenic bladders. Reduction of bladder wall blood flow, bilateral section of hypogastric nerves in rats, study of the bladders of spinalized rats, and reduction of oestrogenic hormone impregnation, show that these conditions induce loss of the viscoelastic properties of the bladder With the arrival of new treatments, active on afferent and/or efferent pathways or even on the central nervous system, it is very important to further our understanding of the pathophysiology of disorders of compliance in neurogenic bladders. Reversibility of these disorders constitutes a major therapeutic challenge and its functional consequences make it a critical prognostic factor for the outcome of neurogenic bladder

Animals↗
PubMed1992

Common aspects of the cerebral regulation of thirst and renal sodium excretion.

It has been shown that several mammalian species increase the excretion of sodium in urine as they become dehydrated. This dehydration-induced natriuresis occurs despite simultaneous hypovolemia, and it can be blocked by an experimentally-induced reduction in the sodium concentration of CSF, or by ablation of the periventricular tissue in the vicinity of the lamina terminalis. These two experimental procedures also disrupt thirst and vasopressin secretion. There may therefore be common features involved in the central control of osmoregulatory thirst, vasopressin secretion and sodium excretion. Experimental evidence in sheep suggests that whenever the tonicity of body fluids increases, a centrally mediated natriuretic mechanism is engaged. This cerebral natriuretic mechanism may contribute along with other influences such as the extracellular fluid volume, aldosterone and atrial natriuretic peptide, to determine the rate of sodium excretion by kidneys. The efferent pathway from brain to kidney mediating osmoregulatory natriuresis is not known. It is probably hormonal, because renal denervation does not disrupt such natriuresis.

Animals↗
PubMed2005

Hereditary ataxia and behavior.

Recognizing cognitive deficits and psychiatric disorders in patients with autosomal dominant ataxias is relatively new. At this time, the percentage of patients with these disorders who experience changes in cognition or psychiatric symptoms is unknown. Cognitive impairment, when seen, is often found on tests of executive function, probably reflecting disruption of afferent and efferent pathways of the prefrontal cortex and subcortical structures, including the cerebellum. Widespread global dysfunction does occur in some cases, especially later in the disease course. Psychiatric symptoms including depression, aggression, irritability, and psychosis have all been reported. As these behavioral changes receive further study, one hopes that guidelines for treating these symptoms will emerge. Clinicians should be mindful of the psychosocial effects that genetic testing for the hereditary ataxias may have, especially in cases of predictive testing for those who are asymptomatic but at risk because of family history. Guidelines established for genetic testing in HD may be helpful when approaching these cases.

Behavior↗
PubMed2006

An unusual case of split cord malformation.

We present a variant of a split cord malformation with coexisting segmental spinal dysgenesis. CT myelography showed the left hemicord with a small remnant of subarachnoid space running through an intravertebral cleft in a spine anomaly. The left hemicord had no apparent intradual connection to the upper cord on any radiologic examination, though functional electrical stimulation studies revealed an intact efferent pathway that connected the left hemicord to the main spinal cord.

Child, Preschool↗
PubMed2005

Neuroanatomy and physiology of ejaculation.

Ejaculation is the final stage of coitus in the mammalian male and results in the expulsion of sperm out of the urethral meatus. Two successive phases, emission and expulsion, can be distinguished during ejaculatory response. Normal anterograde ejaculation requires close coordination of sympathetic, parasympathetic, and somatic components commanding the different peripheral anatomical structures (accessory sexual glands, ducti, and striated muscles) involved in ejaculation. The efferent pathways innervating these anatomical structures drive motor outputs originating from spinal thoracolumbar and lumbosacral nuclei. These spinal ejaculatory centers, the synchronized activation of which is likely carried out by a group of spinal cells, are under the control of both peripheral sensory afferents coming from genital areas and supraspinal information arising from specific brain regions.

Autonomic Nervous System↗
PubMed1991

Pathological changes in dendrites of substantia nigra neurons in Parkinson's disease: a Golgi study.

Neurons of the substantia nigra show severe morphological changes in Parkinson's disease. Pathological alterations of cell bodies have been described, whereas those of neuronal processes have hardly been investigated. Golgi impregnation has been the chosen method for demonstrating neuronal processes and dendritic and somatic spines. We therefore used the Golgi-Braitenberg method to qualitatively and semi-quantitatively study the substantia nigra of eight patients with Parkinson's disease compared with eight control cases. Golgi impregnation of substantia nigra neurons was good in all control cases. In full agreement with the analysis of Braak and Braak (1986) three neuronal types within the substantia nigra were found. In cases of Parkinson's disease, severe pathological changes such as decrease of dendritic length, loss of dendritic spines and several types of dendritic varicosities were found only in the melanin-containing pars compacta neurons. Pars reticulata nerve cells were intact. These findings support the predominant role played by the dopaminergic efferent pathway in the degenerative process. The afferent pathway was not affected. This suggests that the substantia nigra lesion is primary in Parkinson's disease. Loss of neurons found in H & E sections corresponded to a lesser amount of impregnated pars compacta neurons in cases with Parkinson's disease when compared to controls. Evidences exist that the duration of the disease may be related to the extent of pathologically altered Golgi-impregnated pars compacta cells. The amount of Lewy bodies in H & E sections corresponded to the quantity of round varicosities in impregnated pars compacta neurons. These round dendritic varicosities were considered to be Lewy body inclusions.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Group I fibers: pressor reflex and cardiac activity.

Experiments were performed on cats to see whether stimulation of group I afferent fibers from gastrocnemius-soleus muscles induced changes in cardiac activity, in addition to the increase in systemic arterial pressure already established. The results show that the increase in arterial pressure is accompanied by an increase in systolic left ventricular pressure, without any significant changes in cardiac inotropism and chronotropism. It is concluded that the cardiac innervation is not an important efferent pathway of the pressor reflex evoked by stimulating group I afferent fibers, and that the reflex increase in arterial pressure depends mainly on an increase in peripheral vascular resistance.

Afferent Pathways↗
PubMed1991

[Flash-evoked visual potentials in the early diagnosis of optic nerve injury due to craniofacial fractures].

Impairment or loss of vision due to optic nerve injury occurs in about 10% of patients with cranio-facial fractures. The assessment of optic nerve function is important for decisions regarding optic nerve decompression. But examination of vision and pupillary reflexes may be difficult, especially in uncooperative patients with reduced consciousness and primary disturbances of pupillary functions. In these cases, optic nerve function can be monitored by means of flash-evoked visual potentials elicited by use of a LED-goggle stimulator. VEPs were recorded in ten patients with head injuries comprising cranio-facial fractures and cerebral concussion with prolonged alteration of consciousness. Recordings were obtained in the acute phase upon admission. Visual acuity and visual fields were examined after regaining consciousness and the clinical findings correlated to the initial VEPs. Upon clinical examinations, four patients with initially normal VEPs had normal vision on both eyes. One patient initially revealed unilateral reduction of the VEP-amplitude of more than 50% and clinically showed a concentric visual field defect. Three patients with unilateral loss of potentials were amaurotic on this side. Perception of light was preserved in one patient in whom VEPs were absent. One patient with bilateral loss of potentials was blind when consciousness was regained. In general, pupillary light reflexes tested at admission corresponded to the VEP-findings. In two cases, however, pupillary reactivity was lost, but VEPs were still present. These patients had normal vision, but exhibited a lesion of the efferent pathways of pupillary reflexes. In two other patients, examination of pupillary reactivity could not be performed due to extreme edema of the eyelids.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗