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At least 19 recordsLinked to original sources
PubMed1977

Cells of origin and terminal distribution of descending projections of the rat somatic sensory cortex.

The retrograde, horseradish peroxidase technique has been used to demonstrate the cells of origin of corticofugal fiber systems arising in the rat somatic sensory cortex and projecting to the striatum, diencephalon, brainstem, and spinal cord. Correlative experiments conducted with the anterograde, autoradiographic method have been used to confirm the terminal distribution of many of these fiber systems. Corticofugal pathways directed to subcortical structures arise in the first and second somatic sensory areas exclusively from pyramidal cells of the infragranular layers, V and VI. Fibers which descend to the midbrain, pons, medulla and spinal cord arise exclusively from the largest pyramidal cells, the somata of which are found in the deep part of layer V (layer VB). There is some evidence for a sublaminar organization of the different classes of efferent cells within this layer. Fibers projecting to the diencephalon arise from somata situated throughout layer VI and to a lesser extent in layer V. Corticostriatal fibers arise only from cells with somata in layer V, but the somata are more superficially situated than those of the other classes of corticofugal neurons. The laminar distribution of the somata of corticofugal neurons differs considerably from that of commissural and ipsilateral corticocortical neurons.

Animals↗
PubMed1978

Topographic projections between the nucleus isthmi and the tectum of the frog Rana pipiens.

The connections between the nucleus isthmi and the tectum in the frog have been determined by several anatomical techniques: iontophoresis of horseradish peroxidase into the tectum, iontophoresis of 3H-porline into the nucleus isthmi and the tectum, and Fink-Heimer degeneration staining after lesions of the nucleus isthmi. The results show that the nucleus isthmi projects bilaterally to the tectal lobes. The ipsilateral isthmio-tectal fibers are distributed in the superficial layers of the tectum, coincident with the retionotectal terminals. The contralateral isthmio-tectal fibers travel anteriorly adjacent to the lateral optic tract and cross the midline in the supraoptic ventral decussation, where they turn dorsally and caudally; upon reaching the tectum, the fibers end in two discrete layers, layers 8 and A of Potter. The tectum projects to the ipsilateral nucleus isthmi and there is a reciprocal topographic relationship between the two structures. Thus, a retino-tecto-isthmio-tectal route exists which may contribute to the indirect ipsilateral retinotectal projection which is observed electrophysiologically. The connections between the nucleus isthmi and the tectum in the frog are strinkingly similar to the connections between the parabigeminal nucleus and the superior colliculus of mammals.

Animals↗
PubMed1975

An adrenergic mechanism for visual neuroregulation.

Studies of the diffuse electroretinogram (ERG) and evoked reponses in the optic lobe in the baby chick have shown that epinephrine produces changes in both. Epinephrine produces enhancement of the a-wave and depression of the b- and d-waves in both intact and isolated eyes. In the optic lobe it produces enhancement of both components of the evoked response. The presence of epinephrine in the vertebrate retina and the optic lobe of chicks suggests that these changes may reflect the involvement of epinephrine in synaptic transmission.

Animals↗
PubMed1978

Systems-matching by degeneration. II. Interpretation of the generation and degeneration of retinal ganglion cells in the chicken by a mathematical model.

Quantitative data on generation and degeneration of retinal ganglion cells during development (Rager and Rager, 1978) are interpreted in terms of a mathematical model which consists of a system of differential equations. By these equations we attempt to describe the formation of retinal ganglion cells and their termination domains in the tectum. Since ganglion cells seem not to degenerate before their axons have arrived at their termination site and start branching, from the arrival time on they may become competent either to continue to mature or to die. Therefore, to find the actual number of competent cells the extension of the fiber pathway between the retina and the optic tectum had also to be measured and computed. The differential equations are united by the principle that at any given time cells in excess of the number of termination domains have to die. By this model the mathematical function was determined. Several parameter values of this function were optimized with the Gauss-Newton method by which the curve was fitted to the measured values. The high correlation obtained by this method allows to conclude that, to a first approximation, the model may be satisfactory. The evidence of competition for termination sites and of systems-matching by cell death is discussed.

Age Factors↗
PubMed1975

[Histochemical investigations on sialic acid containing compounds in the CNS of teleosts (author's transl)].

By means of histochemical experiments the qualitative (microphotographs) and quantitative (cytophotometry) distribution of sialic acid containing compounds was investigated in the mesencephalon and cerebellum of Carassius carassius. 1. The perikarya of nerve cells are especially stained by means of Azur A. 2. Nerve fibres, on the other hand, showed positive reactions with colloidal ironhydroxyd (CIH). 3. In different structures of the CNS the intensity of CIH-staining is decreased up to about 55% following treatment with neuraminidase. 4. There are no differences in the reactions of 7 degrees C as compared to 20 degrees C adapted animals.

Animals↗
PubMed1977

Putative neurotransmitters of the avian visual pathway.

The ability of homogenates of the chick optic lobe to accumulate a series of possible neurotransmitters has been studied. High affinity uptake of several possible neurotransmitters was examined in optic lobes of 21-day-old embryos that had a single eye removed on the third day of incubation and in 23-day-old chicks that had an eye removed at hatch. Embryonic enucleation resulted in severe reduction of development of the ability of the contralateral optic lobe to take up tritiated GABA, dopamine, choline, serotonin and glutamate from solutions around 10(-8)M. Unilateral eye removal of new-hatched chicks caused failure of the denervated optic lobe to grow, but only the uptake capacity for glutamate was significantly recuced. This deficit was apparent as early as 4 days after enucleation. The transport of other compounds was unimpaired. The uptake of glutamate by homogenates of the optic tract was 43% of that or the optic lobe. This was a much greater fraction than the corresponding value for other postulated neurotransmitters. These data suggest that glutamate may be the primary neurotransmitter of the fibers of the optic tract originating in the retinal ganglion cells.

Age Factors↗
PubMed1977

Progesterone metabolism in the pineal, brain stem, thalamus and corpus callosum of the female rat.

Specific brain regions, namely, thalamus, tectum, tegmentum, cerebellum, medulla and pineal, from five proestrous rats were incubated for 30 min with [3H]progesterone. After reverse isotopic dilution analysis, the following metabolites were identified in all incubations by purification to constant specific activity, derivative formation and/or gas liquid chromatography trapping: [3H]5alpha-pregnane-3, 20-dione (10-20% of the starting substrate except pineal -- 0.7%), [3H]3alpha-hydroxy-5alpha-pregnan-20-one (1.6-3.8% except for pineal -- 0.5%) and [3H]20alpha-hydroxy-4-pregnen-3-one (0.05-0.11%). Preliminary results from the corpus collosum incubation indicated the presence of the same metabolites. Although some apparent constant specific activities were obtained for 20alpha-hydroxy-5alpha-pregnan-3-one and 5beta-pregnane-3, 20-dione, the low levels of 3H associated with these steroids did not permit a definitive identification. The results indicate the presence of at least delta1-steroid 5alpha-reductase, 3alpha-hydroxysteroid dehydrogenase and 20alpha-hydroxysteroid dehydrogenase activities with progesterone as substrate in the brain regions examined.

Animals↗
PubMed1975

Axoplasmic transport of a brain-specific soluble protein.

The rate and extent of axoplasmic transport of the brain-specific soluble protein (14-3-2 protein) has been investigated in the avian visual system. 1-day-old chicks were injected monocularly with tritiated proline, Incorporation of the isotope into the 14-3-2 protein synthesized within the retina of the injected eye, as well as the appearance of the labeled protein in the optic lobes was determined at 6 h and 6 days. These time periods were chosen to distinguish between the rapid and slow phases of axophlasmic flowmfollowing preparation of high-speed supernatant fractions, dialysis, chromatography on Sephadex G-150 and immunoprecipitation with specific antiserum, identification of the labeled 14-3-2 protein was carried out by sodium dodecylsulfate-polyacrylamide gel analysis of the radioactive immunoprecipitates; 6 days after isotope administration, approxo% of the 14-3-2 protein synthesized in the chick retina had been transported to the contralateral optic lobe. By contrast, at 6 h no labeled 14-3-2 protein was detectablemthus, transport of this neuronal protein appears to be relatively slow process with little or no rapid component.

Animals↗
PubMed1979

Utilization in vivo of glucose carbon in the optic lobes and the cerebellum of the chick during postnatal growth.

1. The incorporation of glucose carbon in vivo into amino acids was studied in the chick optic lobes and cerebellum during postnatal growth after subcutaneous injection of [U-14C]glucose. 2. The rapid incorporation of glucose carbon into free amino acids appears between the 1st and the 2nd day of postnatal growth in the optic lobes and between the 1st and the 4th day after hatching in the cerebellum. 3. The period during which the properties of mature brain metabolism are obtained is characterized in both structures during the first 48 hr of postnatal growth by changes in the specific radioactivity of some amino acids such as aspartate and alpha-alanine, and also by transient increases of glucose and glutamine concentrations. 4. The gamma-aminobutyrate content in the optic lobes is very high; the cerebellum on the contrary is characterized by its low gamma-aminobutyrate concentration linked to a very fast metabolism of this amino acid.

Aging↗
PubMed1978

Mesencephalic participation in the control of sexual behavior in the female rat.

Electric stimuli applied to both pudendal nerves evoked field potentials, unit responses, and multiunit responses in the ventrolateral midbrain, in and around the peripeduncular nucleus. Bilateral lesions placed in this region suppressed sexual behavioral responses (lordosis and courting behavior) of ovariectomized rats primed with 5, 10, 100, and 1,000 microgram of estradiol benzoate and 2 mg of progesterone per kilogram of body weight. It is proposed that the region in question represents a relay station for the integration of sensory and endocrine information concerned in the control of receptive sexual behavior in the female rat.

Action Potentials↗