Structural and functional properties of the evoked potentials in the human motor system.
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Evoked Potentials↗
Biomedical subjects
J Vajda
Publications and source records attributed to J Vajda.
Evidence of sensory neurons in the wall of the small intestine revealed by horseradish peroxidase technique.
Sensory neurons in the wall of the small intestine were studied by means of retrograde transport of horseradish peroxidase (HRP). After HRP injection into the mesenteric nerve trunks, peroxidase positive nerve cells were observed in the myenteric and submucous plexuses. Labeled cells of different shape and size were compared with neurones impregnated by silver nitrate. On the basis of HRP-labeled neurons it is concluded that some of the myenteric and submucous nerve cells send processes towards the celiac ganglia; these may correspond to afferent neurons in the wall of the small intestine.
Animals↗
Effect of capsaicin on the nerve elements of the small intestine.
The effect of capsaicin treatment on the nerve elements of the small intestine has been investigated in newborn cats. Degeneration of numerous nerve processes could be observed after capsaicin treatment. Some of these nerve fibres were found in pre- and in postsynaptic situation. A few cell somata were also severely damaged after capsaicin treatment. No such degeneration was observed in the control animals. On the basis of the capsaicin effect is assumed that some of the degenerated nerve terminals might be responsible for the intrinsic sensory innervation of the small intestine.
Animals↗
Distribution of primary sensory nerve terminals in the cat urinary bladder wall.
Distribution of the primary sensory nerve terminals has been investigated in the cat urinary bladder wall in the normal state and after extirpation of certain spinal ganglia. In the normal state the adventitia of the bladder base contained simple sensory corpuscles, Pacinian corpuscles and free nerve endings. In the bladder wall the afferent nerve endings appeared to be free nerve endings without terminal modification. After extirpation of spinal ganglia, some of the nerve fibres degenerated and were located mostly in the trigone and the ventral neck regions of the bladder. After 7 days neither Pacinian nor simple sensory nerve corpuscles could be observed in the wall.
Animals↗
Retrograde phlebography of the internal spermatic vein in varicocele.
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Adolescent↗
Possibilities of CSF pressure diagnosis --a review--.
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Brain Diseases↗
Sympathetic innervation of the urinary bladder.
The sympathetic innervation of the urinary bladder was studied by fluorescence microscopy using glyoxylic methods, and by electron microscopy, in the normal state, after extirpation of hypogastric ganglia and administration of 6-hydroxydopamine. In the normal state adrenergic fibres could be found along the blood and lymph vessels, within the muscle layers and synaptizing on the surface of the local nerve cells or with other, probably local nerve processes. After extirpation of the hypogastric ganglia, degenerated axons could be observed in the local ganglia and in the connective tissue of the vessels. Many fluorescent fibres could be observed in the muscle layers, too. Four to six weeks after the operation, the animals were treated with 6-hydroxydopamine and no fluorescence was observed. In the muscle layer several degenerated fibres could be found, occasionally in close relation to the smooth muscle cells. It was therefore supposed that part of the sympathetic nerves originates from the hypogastric ganglia and is responsible for the modulation of the local ganglia and the blood supply of the urinary bladder. The other part emanates from the "short adrenergic neurons" and may effect directly the smooth muscle cells.
Animals↗
Quantitative analysis of the cells of the cat's trigeminal ganglion.
The volume and structure of the perikarya of nerve cells in the trigeminal ganglia of adult cats were studied light and electron microscopically. According to their volume and eccentricity, the cells could be classified into three groups. Group I. Small cells. Their volume ranges up to 11,400 micrometer 3. Several of them stain light and are spherical in shape. Group II. Medium cells. Their volume ranges up to 40,00 micrometer 3. Several light-stained cells are seen among them. Group III. Large cells. Their volume is the range of 60,000 to 100,000 micrometer 3, and they are spherical in shape. Electron microscopically, the cytoplasm contains a well-developed rough-surfaced endoplasmic reticulum, numerous mitochondria, Golgi complexes, pigment granules, and interspersed neurofibrils and microtubules. The cells exhibit an ultrastructure varying in size and cytoplasmic density. In some cases, nerve fibres were in close contact with the cell body, but neither pre- nor post-synaptic thickenings could be observed.
Animals↗
Innervation of the cat ureter. An experimental study.
Innervation of the ureter was studied by fluorescent microscopy using glyoxylic methods and by electron microscopy in the normal state and after extirpation of hypogastric ganglia. According to the morphology of the vesicle population, four groups of nerve processes could be distinguished: Type a with a dominant population of small agranular vesicles; Type b with a large number of small granular vesicles; Type c with 80 to 120 nm granulated vesicles; Type d with large 150 to 250 nm neurosecretory vesicles. After extirpation of the hypogastric ganglia, degenerated nerve terminals could be found in all the layers of the ureter, but a few fluorescent fibres could be observed in the muscle layers, too. It is assumed that most of the fluorescent fibres originate from the hypogastric ganglia and the others from the local neurons of from the spinal ganglia. These nerve processes act directly on the smooth muscle cells.
Animals↗
Evoked responses by physiological sensory inputs in human central motor structures.
In human with chronic implanted electrodes physiological evoked responses could be detected from those structures they were thought to be parts mainly of central motor system. Investigating the functional changes of evoked responses to motor states and attention the results have suggested the responses do not sign the centres to treat as directly the sensory inputs i.e. auditory, visual, somatosensory stimuli as motor stimuli.
Attention↗
Quantitative analysis for innervation of smooth muscle cells in the wall of the urinary bladder.
The distribution of nerve terminals to different parts of the urinary bladder was studied by electron microscopy with the aid of 6-hydroxydopamine treatment. A quantitative analysis was made for each region. In the sphincter and trigone areas nerve terminals were found to be much more numerous (3 times more) than in sections from the body and the apex of the bladder. In much of the bladder there were 6--7 smooth muscle cells for each nerve fiber, however in the trigone area 1--2 muscle cells were supplied by terminal nerve fiber. The narrowest gap between nerve terminals and smooth muscle cells was found to be 150--250 nm. It was commonly seen that Desmosome-like attachments, called nexuses, connected adjacent smooth muscle cells. After 6-hydroxydopamine treatment degenerated terminals could be found mostly in the fine periarterial plexuses but some were also observed that were not related to blood vessels, especially in the trigone area. Summation of our figures and results for terminal density suggests to us that contractions of the urinary bladder are initiated or controlled in the trigone region and that other parts of the wall are activated by local nerve processes and the numerous nexal contacts.
Animals↗
The function of the human cerebellum studied by evoked potentials and motor reactions.
The authors investigated the cerebellar function of patients with chronic implanted electrodes. The investigations were carried out using elicited compulsion events--evoked potentials and motor reactions--in different functional motor states, i.e., rest and contraction. The compulsion events are the result of motor control processes which eliminate the transient effect of stimuli. In connection with the cerebellum, these motor control processes in some ways mirror the function of the cerebellum. The evoked potentials recorded in the cerebellum have specific features and specific functional dependence as well. On stimulation of the cerebellum, the first effect on motor activity is always inhibitory. Altering the cerebellar function by high frequency stimulation appears to cause cerebellar symptoms such as hypotonia and ataxia.
Cerebellum↗
Multitarget technique in Parkinson surgery.
In the past 10 years, experience has been gained with combined VL-thalamotomy, pallidotomy and dentatomy using chronically implanted electrodes in Parkinson's disease. In the vast majority of cases, symptoms ceased surprisingly for 10-14 days just after stereotactic exploration of these motor centers. Clinical neurophysiological investigations (evoked responses, motor effects) show where consecutive lesions will be permanently effective at definitive coagulation. The physiological basis of these findings are discussed and a sophisticated therapeutic protocol is advised.
Electrodes, Implanted↗
Transoral surgery for basilar impression.
A patient with basilar impression presented with a progressive myelopathy due to odontoid invagination. It was thought that a posterior decompression would be hazardous; therefore, the inferior clivus, odontoid process, and anterior arch of the atlas were removed transorally. We have found that, even with symptoms of long duration, marked improvement can be expected when the operation is targeted to the actual abnormality. In such cases, analysis of craniocervical tomograms will show the direction of medullary compression and thus indicate the correct surgical approach.
Axis, Cervical Vertebra↗
Intrinsic innervation of the urinary bladder.
The intrinsic innervation of the urinary bladder of the cat was studied with the aid of total extrinsic denervation (L7, S1, S2, S3 and the first coccygeal spinal nerves were transected and the hypogastric ganglia were extirpated on both sides); the materials were studied by electron microscopy. Several synapses could be observed between nerve processes and perikarya and between two adjacent nerve processes. The terminals could be classified into four groups according to the existence of a dense core and according to the size of the synaptic vesicles; the first group is made up of small clear vesicles; the second group of terminals contains some large granulated vesicles in addition to a few small clear vesicles; the third group of terminals contains small granulated vesicles and in the fourth type of terminals, large, 150- to 250-nm 'peptiderg' vesicles could be observed. The latter type of terminals was always observed in postsynaptic situation. Spine synapses could also be found in the ureterovesical ganglia. Several desmosome-liek attachments also could be observed between the nerve processes and perikaraya and between two nerve fibers. Up to three different types of nerve fibers have been observed on the same neuron. These morphological results suggest that the ureterovesical junction should be considered a single functional unit which plays an important role in coordinating the function of the bladder; further local circuits might exist in the urinary bladder wall.
Animals↗
Degeneration analysis of the efferent nerves to the urinary bladder in the cat.
The extrinsic efferent nerve fibres to the urinary bladder in the cat were studied by secondary degeneration after transection of the seventh lumbar, all three sacral and the first coccygeal ventral roots of spinal nerves and after extirpation of both hypogastric ganglia. Under the electron microscope, degenerated nerve fibres of spinal origin could be observed in the trigone region among the ganglion cells and all layers and in the different areas of the urinary bladder wall. These degenerated nerve fibres containing mainly clear vesicles, 30-60 nm in diameter, and a few 80- to 120-nm granular vesicles were situated in synapsing contacts on the surface of the local nerve cells and in synapsing with other probably local nerve processes. After extirpation of the hypogastric ganglia several degenerated nerve fibres could be found along the blood vessels and lymph vessels in all layers. However, occasionally on the surface of the local nerve cells degeneratd nerve fibres could also be found. 2 months after both interferences most of the nerve fibres and synapses remained unaffected. According to these observations the extrinsic efferent nerve fibres and synapse seem to have a modulatory effect on the local ganglia. The large amount of the local intact synapses suggests that the micturition reflex is not a spinal but a local peripheral reflex.
Animals↗
Distribution and fine structure of the interstitial cells of Cajal.
Distribution and fine structure of the interstitial cells of Cajal were studied in the cat's small intestine. They were only found in the circular muscle layer. They had a slender structure with numerous mitochondria, rough endoplasmic reticulum and granular or secretory vesicles 100 to 300 nm in diameter. The closest distance between the membrane of smooth muscle cells and interstitial cells was 40 to 60 nm. Some nerve bundles were found in close relation to their processes, but neither pre- nor postsynaptic differentiation could be observed. After nialamide treatment the quantity of secretory vesicles increased and therefore it is suggested that these cells have a secretory function producing some kind of peptide and so they may act directly on the smooth muscle cells.
Animals↗
Innervation of the small intestine.
It was shown in acute and chronic degeneration studies that the nerve elements of the cat small intestine belong to two according to whether they are extrinsic or intrinsic in origin. Part of the extrinsic nerve fibres originate from the vagus nerve and can be found on both intestinal plexuses, the other fibres are processes of the coeliac ganglion and occur in the first place in the vascular tunica adventitia. The intrinsic nerve cells may be classified into three groups on grounds their ultrastructure the number of synapses and processes on their surface. The synaptic connections between the different nerve cells of the internal plexuses were confirmed on chronic isolated of intestinal loops. The local reflexes provided by these connections are held responsible for peristalsis, the functional modifications of the mucosal pattern and the movements of the villi.
Animals↗