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At least 19 recordsLinked to original sources
PubMed1979

The laminar and size distribution of commissural efferent neurons in the cat visual cortex.

The laminar and size distribution of commissural efferent neurons were studied in the cat visual cortex including area 17, 18, 19 and the lateral suprasylvian cortex (the lateral wall of the middle suprasylvian gyrus) by means of retrograde transport of horseradish peroxidase. Single or multiple injections of the enzyme were made unilaterally along the medial part of the lateral gyrus (the adjoining parts of area 17 and 18) or along the lateral wall of the middle suprasylvian gyrus. In the contralateral cerebral cortex (area 17, 18, 19 and lateral suprasylvian cortex) the majority of peroxidase labeled commissural efferent neurons was identified in layer III with a smaller population in other layers except layer I. The size distribution of labeled cells of layer III showed that all sizes of neurons contribute to interhemispheric connections, ranging from small cells which are comparable to those predominating in layer III of the acommissural medial area 17 to the characteristic large pyramides of layer III at the area 17/18 boundary. There was a certain difference in the pattern of size distribution of commissural efferent neurons of layer III between area 17, 18, 19 and the lateral suprasylvian cortex. Labeled neurons in area 17, 18, 19 showed a dominant peak in the histograms of cell size, while in the lateral suprasylvian cortex they were more evenly distributed in a wide size range.

Animals↗
PubMed1976

Mechanisms of efferent neuronal control of the reflex nicitating membrane response in rabbit (Oryctolagus cuniculus)

Efferent mechanisms controlling the nicitating membrane (NM) reflex response to air puff in the albino rabbit were analyzed using stimulation, lesions, and recording techniques. In brief, stimulation of the sixth nerve (abducens) yields short-latency NM extension. Stimulation of the fourth and seventh nerves and the superior cervical ganglion has essentially no effect on the NM. Stimulation of the third nerve causes short-latency retraction of the NM. Lesions and recording data are consistent with this result - the sole efferent neuronal control of NM extension is the sixth cranial nerve and of NM retraction is the third cranial nerve. The NM extension response appears to be mediated by mechanical actions via retraction of the eyeball by the retractor bulbi muscle, and NM retraction appears to result from direct activation of muscle fibers in the NM by the third nerve. The superior cervical ganglion appears to play no role in reflex NM retraction in the rabbit, in contrast to its action in the cat.

Abducens Nerve↗
PubMed1975

Olivocochlear and vestibular efferent neurons of the feline brain stem: their location, morphology and number determined by retrograde axonal transport and acetylcholinesterase histochemistry.

Anterograde degeneration studies have shown that the cochlear and vestibular receptor organs receive an efferent innervation from neurons in the brain stem. This pathway may provide a mechanism by which the CNS could modulate its own afferent input. The neurons which provide this innervation have so far escaped positive identification with methods which depend on retrograde cell changes after axotomy. In the present study, horseradish peroxidase (HRP) was injected into the labryinths of kittens and after allowing 24 hours for the retrograde axonal transport of this tracer, its presence in neurons of the brain stem was demonstrated histochemically. Because there is evidence that the efferent innervation of the labyrinth is cholinergic, acetylcholinesterase (AChE) was also demonstrated histochemically in the same or in adjacent tissue sections. Neurons labelled with HRP were found bilaterally in most periolivary cell groups of the superior olivary complex (cochlear efferents) and in the parvocellular reticular nucleus lateral to the abducens nucleus (vestibular efferents). Counts of labelled neurons yielded estimated totals of 1,700-1,800 cochlear and 400-500 vestibular efferent neurons. Approximately 60% of the neurons in each total were located on the side ipsilateral to the injection. The distribution of HRP-labelled neurons was virtually identical to that of AChE-positive neurons found in adjacent sections, and in those regions with predominantly ipsilateral or contralateral projections, there was an approximate correspondence in number of HRP- and AChE-positive neurons. In tissue sections processed successively for demonstration of HRP and AChE, virtually all HRP-labelled neurons were found to be AChE-positive. These findings suggest that a number of current conceptions regarding labyrinthine efferent systems may need revision.

Acetylcholinesterase↗
PubMed1977

Organization of the facial nerve nucleus in the cat.

The location of efferent neurons in the brain stem of newborn kittens supplying the facial muscles was studied by means of horseradish peroxidase (HRP) used as a tracer of retrograde protein transport. Three to 15 microliters containing 0.3 to 1.5 mg of HRP was injected into the orbicularis oris and orbicularis oculi muscles of six kittens and in the seventh kitten, the ventral ramus of the facial nerve was transected and HRP was instilled on the cut end of the nerve. After a survival time of 24 hours, the animals were anesthetized, perfused by intracardic perfusion technique, and then they were fixed and the brain stems sectioned. Stains for peroxidase demonstrated the labelled neurons in the lateral division of facial nuclei in the ipsilateral side. The orbicularis oculi muscles were represented in the rostral pole of the lateral division of the facial nucleus dorsally while the orbicularis oris muscles were represented in the caudal pole of the lateral division of the facial nucleus ventrally. No labelled neurons were found in the nuclei of the Vth or any other brain stem nuclei. According to my knowledge, this method of localizing the neurons supplying the facial muscles has not been reported previously.

Animals↗
PubMed1978

Characteristics of interhemispheric impulse conduction between prelunate gyri of the rhesus monkey.

Cells of origin of the corpus callosum (callosal efferent neurons) in prelunate gyrus (area OA) of the rhesus monkey were studied using electrophysiological techniques. Monkeys were chronically prepared and callosal efferent neurons were identified by their antidromic activation following electrical stimulation of the contralateral prelunate gyrus and/or the splenium of the corpus callosum. Interhemispheric antidromic latencies ranged from 2.6--18.0 ms (median = 7.0 ms) while the conduction velocity along the length of the axon ranged from 2.8 to 22.5 M/s (median = 7.4 M/s) while the conduction velocity along the length of the axon ranged from 2.8 to 22.5 M/s (median = 7.4 M/s. Following the relative refractory period of a single prior impulse, all but one of 61 callosal efferent neurons studied showed a supernormal period of increased axonal conduction velocity and excitability. Following several prior impulses, the supernormal period was followed by a subnormal period of decreased axonal conduction velocity and excitability, which, depending on the number of prior impulses, lasted from several hundred ms to nearly 2 min.

Animals↗
PubMed1978

The morphology of the spinal cord efferent and afferent neurons contributing to the ventral roots of the cat.

Horseradish peroxidase was applied to proximal ventral roots of the coccygeal and sacral spinal cord of cats. Subsequent histochemical reaction resulted in extensive staining of spinal cord neurons that had processes in the ventral roots. This procedure was used to study four issues concerning ventral root neurons. (1) Extensive transverse dendritic arborizations were revealed for large and small neurons presumed to be alpha and gamma motoneurons respectively. Dendrites from these neurons were found to project heavily into the ipsilateral white matter, both laterally and ventrally. Dendrites also projected extensively through the anterior commissure, attaining the contralateral grey and white matter. (2) Medially-located efferent neurons were found to contribute the contralateral dendrites as well as some dorsally-directed dendrites. Laterally-located neurons projected dendrites extensively into the lateral and ventral white matter. (3) Stained neurons were found in the intermediolateral cell column, and were presumed to be preganglionic efferent neurons. Some of these neurons projected dendrites into the marginal zone of the dorsal horn, while others sent dendrites medially toward the central canal. (4) Stained fibers, presumed to be primary afferents, were found to enter from the ventral roots and course to the dorsal horn. Most of these fibers were small in diameter and distributed boutons predominantly to the substantia gelatinosa. A few large ventral root afferent fibers were observed that distributed boutons mostly to the nucleus proprius.

Animals↗
PubMed1976

[Development of the neuronal structure of the hippocampus during pre- and post-natal ontogenesis in the albino rat. I. Neurohistological demonstration of the development of lung-axonal neurons in the CA3 and CA4 regions].

In this paper qualitative investigations by means of light microscopy (Golgi impregnation) considering the ontogenesis of efferent neurons of the CA3, CA4a, CA4b regions in the rat hippocampus are presented following the already described development of CA1 pyramids (MINKWITZ and HOLZ 1975). After the migration of neuroblasts the types of projective neurons can be distinguished in the mentioned regions at the end of the prenatal period. During the first postnatal time particularly the basal dendritic tree develops expressing more distinctly the typical forms of pyramids (CA3, CA4a) and the of the multipolare neurons of CA4b. No distinct qualitative jumps at the transition of the regions in contrast to the CA3--CA1 boundary can be observed. Temporal retardations in the appearance of postsynaptic structures (microdendrites, excrescenses, spines) at pyramidal neurons from CA4 to CA3 and CA1 are regarded as signs of earlier development of the phylogenetic older pool of cells. During the early postnatal developmental period (until stage P10) proceedings of the growth are predominant. Later on, during the late postnatal period, the maturation of the neurons takes place with a considerable multiplication of spines distributed in similar ways as known from other pyramids. At stage P20 neurons of all hippocampal regions cannot be distinguished from adult ones without using morphometric procedures. The development of parts of the intrahippocampal network including mossy fibre system and SCHAFFER collaterals is discussed with regard to in this way appearing boundaries between fascia dentata and regio inferior CA4, CA3) and regio superior (CA1). These fibre systems establish by their stepwise construction one of the basic elements to hippocampal functioning.

Age Factors↗