Sinuslichtreizung der rezeptiven Felder einzelner Retinaneurone

Summary The action potentials of optic nerve fibres in cats were stereotactically recorded (light pentobarbital anaesthesia, Curarin-immobilization). The activation of retinal neurons stimulated by light spots within the receptive field centre was a non-linear function of the sinusoidal intensity modulation of the stimuli.     

Der Nachweis des Barbiturateffektes an der isolierten Warmblüternetzhaut

Summary Barbiturates cause an increase of the ERG amplitude in the isolated perfused retina of the rabbit as well as in the eye of the intact animal. Therefore, this effect cannot be transmitted by centrifugal fibres in the optic nerve.     

Zum Vorkommen von RNS im Nervenfaserbereich

Summary The incorporation of 3H-uridine into the RNA of the perikaryal and fibrous region of the optic tectum of the fish brain was investigated by means of radioautography after incubation times of 11 min to 96 h. There is no transport of RNA from the cell body to the nerve fibres. After RNase-treatment 90% of perikaryal RNA-labelling is washed out, but only a very small amount of the previous very few labelling of the nerve fibres.     

Der elektrophysiologische Nachweis der propriozeptiven Muskelafferenz und des monosynaptischen Reflexbogens der inneren Kehlkopfmuskeln

Summary On excitation of the superior laryngeal nerve and the recurrent nerve with single square wave shocks in patients undergoing total exstirpation of the larynx for cancer, a reflex potential can be recorded from the vocal muscle. This potential shows the criteria characteristic of the reflex potential arising on excitation of muscle spindles or the afferents of muscle spindles (la-fibres) in limb muscles. The pathway of afferent fibres is for the main part via the sup. lar. nerve but there seems to be an indication of a small part of afferents in the recurrent nerve also.     

The possibility of centrifugal projections to the retina in the rat

In rats, glutamic acid decarboxylase activity increased in the proximal portion of the optic nerve after its ligation, whereas the activities of choline acetyltransferase and tyrosine hydroxylase remained constant. Possible centrifugal neurons to the retina are GABAergic.     

Antidromic responses evoked in the central end of the phrenic nerve by stimulation of the ipsilateral dorsal column in the cat]

In 15 adult cats under nembutal anaesthesia the dorsal columns have been stimulated at the level of the first and the second cervical segments. Under these conditions antidromically evoked responses appear both on the ipsilateral radial and phrenic nerves. Some of the afferent phrenic fibres thus activated may be related to the diaphragm muscle receptors. In some experiments a group of thin fibres (conduction velocity comprised between 16-20 m/sec) were also activated.     

The possibility of centrifugal to the retina in the rat

Summary In rats, glutamic acid decarboxylase activity increased in the proximal portion of the optic nerve after its ligation, whereas the activities of choline acetyltransferase and tyrosine hydroxylase remained constant. Possible centrifugal neurons to the retina are GABAergic.     

Sekretomotorische Fasern und Endigungen in der Adenohypophyse

Summary We demonstrated, in the pituitary of the animals examined, fibres which emerge from the Tr. hypothalamo-hypophyseal system and enter partly into the Pars intermedia and partlyvia the Pars tubularis into the Pars distalis and take their course directly towards the glandular cells. In the Pars distalis the nerve fibres end around the glandular cells in a special pericellular net.     

An analysis of the distribution of the myelinated nerve fibers in the optic fascicle of a Beagle dog

Summary The composition of both optic fascicles of a Beagle dog was studied in topographically oriented, semithin transections of whole nerve stained with toluidine blue. About 165,000 myelinated fibers were present in each nerve, their maximum caliber reaching 11 m; large, less densely arranged fibers occurred especially in the dorso-temporal region.We are grateful to Dr D.C. Naylor, Mrs K. Schnider, Mr F. da Silva and Mr K. Traber for their aid.     

Nachweis einer physiologischen Spontanaktivität in Einzelfasern des N. opticus der Katze

Summary Spike potentials were recorded with metal micro-electrodes from single fibers in the intracranial part of the cat's optic nerve with the retina left completely intact. All units studied as yet showed a marked spontaneous activity irrespective of differences in their response to light stimuli. The spontaneous activity in the intracranial part of the optic nerve could be suppressed reversibly by increasing the intraocular pressure up to 200 mm Hg. Thus spontaneous activity has been verified as a normal feature of the retina. A spontaneous firing rate of 22±11/s after 1 h dark adaptation was found in altogether 12 well-isolated fiber units.     

Isonicotinic acid hydrazide: early effects on peripheral nerve conduction velocity

This report describes the effects of short treatments with isonicotinic acid hydrazide (isoniazid), 300 mg/kg/day, on conduction velocity in the rat tail dorsal nerve trunk. After 6 days of continuous treatment, conduction velocity falls significantly for measurements made at 35 degrees C. After 10 days it falls significantly at both 25 degrees C and 35 degrees C. This appears to be the first electrophysiological corroboration of the early neuropathological changes recently observed in isoniazid treated rats and seems to provide evidence that the temperature at which the experiments are made is important in determining conduction velocity changes.     

The conduction velocity, number, and diameter of unmyelinated fibers in Remak's nerve

Remak's nerve in the chicken was examined ultrastructurally and electrophysiologically to determine the characteristics of fibers in the nerve trunk. The ration of unmyelinated fibers to myelinated ones was 111:1. The mean number of unmyelinated fibers was 3555 plus/minus 232 (SEM, n=5) and they had a mean diameter of 0.502 plus/minus 0.034 (SEM) micron. The compound action potential consisted almost entirely of a large diphasic waveform which had a mean peak conduction velocity of 0.62 plus/minus 0.031 (SEM, n=5) m.s-1 at 37 degrees C.     

Elektrophysiologische Untersuchungen an der Seitenlinie vonXenopus laevis

Summary Electrophysiological recording of the spontaneous activity from a single group of lateral sense organs on the abdomen ofXenopus laevis results in a more or less regular series of large spikes, either all of the same height or of two different sizes (each group is innervated by two large lateralis fibres). Mechanical stimulation of such a group may cause a rise or a fall of spontaneous impulse frequency. There is evidence for a two-directional sensitivity of the same unit (nerve fibre) from a single group, out of the middle as well as out of the dorsal lateral line.     

Zur Histochemie der Gliafaser

Summary Histochemical investigations (periodate-Schiff reaction, lead-tetra-acetate-Schiff reaction, chromic acid-Schiff reaction, acetylation-, deacetylation-, and bromination-test) of neuroglial fibres from human brain and spinal cord indicate, that these proteinic fibres contain a small amount of prosthetic carbohydrate. The weak periodate reactivity of the glial fibres is due to -glycol groups and not to -oxy-amino-acids.     

Impulsantworten des Nervus opticus auf Reizung der Netzhaut mit Acetylcholin

Summary Application of ACh on the isolated perfused retina of the frog elicited spikes of the optic nerve. The extent of this spike activity depended on the amount of ACh applied. The retinal response to ACh was varied by prostigmine and atropine as expected by their pharmacological properties. From these experiments it cannot be concluded that ACh is acting on the synapses of the firing ganglion cells directly.     

Variation in the number and size of myelinated nerve fibers regenerated after repeated localized freezing of the sciatic nerve of rats]

The number and size of myelinated fibres have been determined in the nerve to medial head of the gastrocnemius muscle of Rats in which the sciatic nerve had been frozen locally 1 to 5 times at monthly intervals. The contralateral nerve was used as a control. When the measurements were made one month after the last freezing, the number of fibres increased progressively until the 3rd freezing, reaching about 220% of the normal value. No higher values were observed after 4 or 5 freezings. The mean diameter of fibres decreased with the number of operations. When the measurements were made 3, 6, 12 or 18 months after the 3rd freezing, the number of fibres decreased by about 30% between the 1st and the 3rd month and then stabilized. The mean diameter of fibres increased progressively. However, at the 18th month, the size of the myelinated fibres had not reached the normal value.     

Pathways for excitatory and inhibitory innervation to the guinea-pig tracheal smooth muscle.

The trachea receives excitatory cholinergic innervation from the vagus nerve and the stellate ganglion. Inhibitory adrenergic fibres have the same sources. Those in the vagus nerve probably derive from high vagosympathetic anastomoses. Nonadrenergic inhibitory fibres have a preganglionic vagal supply.     

Coordinated activation of muscle fibres by different conduction velocities in branches of a crustacean motor axon

Summary Higher conduction velocities in branches of the fast excitor axon to distal muscle fibres ensure that these fibres are activated almost simultaneously with proximal fibres in the claw closer muscle of lobsters, producing a contraction of maximal force.Supported by Muscular Dystrophy Association and National Research Council of Canada.Supported by National Institute of Health and Muscular Dystrophy Association of America.     

Endothelial nerve fibres in the cornea of the frogRana ridibunda

Summary The ultrastructural study of the frog cornea revealed the existence of intraendothelial nerve fibres. These nerve fibres are unmyelinated elements but surrounded by cytoplasmic lamellae of Schwann cells.Supported by D.C.I.N.P. Grant 78-77.     

Degeneration of unmyelinated axons in the dental root canal induced by 6-OH-dopamine

Summary The pulpal nerve fibres of feline incisors were examined ultrastructurally after i.v. administration of 6-OH-dopamine. The presence of degenerating unmyelinated fibres at this site provides conclusive morphological evidence that sympathetic fibres enter the dental pulp.