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doi: 10.1002/cne.901240102pmid: 14304271
Electroencephalographic studies were carried out on chickens to determine the normal electroencephalogram (EEC) patterns from wakefulness to sleep and the effect of anesthesia. Sixteen electrodes were fixed to the frontal and parietal bones. EEC was recorded under unstressed condition.
doi: 10.1002/cne.901240103pmid: 14304270
The anterior cochlear nucleus was examined with a view to describing its subdivisions. The brains of 29 adult rats were paraffin embedded, sliced at 16 μ and impregnated according to the protargol method of Bodian. From examination of this material the nucleus was divided into three major regions.
doi: 10.1002/cne.901240104pmid: 14304272
Midline cross‐sections of the posterior commissures of five adult males were used for a determination of their cross‐sectional area and fiber‐density. Due to non‐uniform fiber‐size distribution a stratified sample involving from 12–20 areas was collected from each case. A mean cross‐sectional area of 3,587 mm2 with a standard variation of ±0.820 mm2 was measured for the five cases. Fiber density was found to vary in the different strata between 86,400 to 432,000 ± 10% per mm2 on axon counts taken from sections stained by Häggqvist's method. Counting myelin sheaths on sections stained by Weigert's method fiber density varied from 40,000 to 158,400 fibers per mm2 ± 30%. Using these values for calculating a total fiber number estimate, based on the axon count, fiber number varies from 504,566 to 887,849 fibers. Comparing this total fiber estimate with a similar estimate taken from the anterior commissure, the figure appears low. This difference is due to the presence of a great number of large diameter fibers in the posterior commissures, not found in either the anterior commissure or the corpus callosum. Attaching a probability level of t0.05 to this sample of five cases, a hypothetical posterior commissure may be expected to have a cross‐sectional area of 3.587 ± 0.942 mm2 and from 497,404 to 1,090,270 fibers. In one case the habenular commissure was also studied and found to contain 112,706 fibers (cross‐sectional area 0.697 mm2).
doi: 10.1002/cne.901240105pmid: 14304273
Gliogenesis in the spinal cord was studied in chick embryos ranging in age from 3 to 14 days of incubation using H3‐thymidine autoradiography. It has been reported by the author that the neuron production of the spinal cord begins on the third day and ends at the eighth day of incubation. At eight days of incubation glioblasts with small dark round nuclei first appear in the sub‐pial region. Using the selective labeling technique with H3‐thymidine the author demonstrated that no transition exists from pial cells to sub‐pial glioblasts. The glioblasts are produced from the matrix cells by their migration and transformation. These glioblasts mature into neuroglia (oligodendroglia and astrocytes), as development proceeds. The suggestion that the stage of neuroglia differentiation follows that of neuron production in development of the central nervous system has been reconfirmed.
doi: 10.1002/cne.901240106pmid: 14304274
Cerebellar collaterals of the mesencephalic trigeminal root have been studied by the use of various histologic techniques in adult and fetal brains of rat and mouse. In addition, brains of rats with lesions in the mesencephalic trigeminal system were studied.
doi: 10.1002/cne.901240107pmid: 14304275
Following lesions in the brain stem reticular formation in 20 cats the ensuing degeneration within the spinal cord has been studied with silver impregnation methods with special reference to the laminar organization of the gray matter described by Rexed ('52, '54).
Heric, Thomas M.; Kruger, Lawrence
doi: 10.1002/cne.901240108pmid: 14304266
Electrical responses were recorded from the optic tectum of the alligator with steel microelectrodes, and the receptive field for each of a series of systematically spaced recording sites was delineated on a transparent plastic hemisphere positioned in front of the contralateral eye. A precise retinotopic relationship was determined with the inferior portion of the retina projecting onto the dorsal surface of the tectum, and the superior portion of the retina represented on the lateral and ventral aspects of the tectum. The equatorial line of the hemisphere is situated laterally and runs obliquely across the tectum from the rostrolateral pole to the caudomedial corner. The center of the visual field occupies a disproportionate amount of tectal space providing for functional magnification. Receptive field size and spacing diminish for the representation of the central region implying a retinal area for increased visual acuity. It is suggested that this alinearity between the visual field and the tectum is expressed in its fiber architecture and is probably a consequence of specialization of the eye rather than an evolutionary modification within the reptilian central nervous system.
Schwassmann, Horst O.; Kruger, Lawrence
doi: 10.1002/cne.901240109pmid: 14304267
In four species of freshwater fish, bass, carp, bluegill and goldfish, the topographical relations of the visual field with the contralateral optic tectum were investigated, using a small light as stimulus in the visual field and recording the electrical response of the tectum with a metal microelectrode. The results show a precisely organized visual projection onto the contralateral tectum in which the anterior visual field lies anteriorly on the tectum, the temporal field posteriorly, the dorsal field medio‐dorsally, and the ventral field in the latero‐ventral part of the tectum. The projection was found to be essentially linear and uniform with no indication of a specialized area in the visual field in those species investigated. Some receptive fields extended into the anterior binocular visual field.
doi: 10.1002/cne.901240110pmid: 14304268
The nerves innervating the tongue were stimulated electrically and multineuron responses were recorded in the nucleus of the solitary tract. Stimulation of the chorda tympani and the IXth nerves evoked responses in the lateral and medial ipsilateral solitary nucleus in a rostral‐caudal order. Responses to lingual nerve stimulation were found only in the lateral, larger‐celled portion of the ipsilateral solitary nucleus overlapping the chorda tympani and the IXth nerve areas. Stimulation of the above three nerves also evoked somewhat longer latency responses in the ambiguus nucleus. Responses to lingual nerve stimulation were found in the XIIth nerve motor nucleus and the solitary nucleus at the level of the obex using high voltage levels of stimulation. The results were discussed in terms of the anatomical discreteness of the relays of the gustatory and the other tongue modalities in the solitary nucleus. These results were obtained in the white rats.
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