Order in the optic nerve of goldfish

A small amount of horseradish peroxidase, injected into the goldfish optic nerve and transported into the retina, filled an annulus of ganglion cells. Since the retina grew by annular addition of cells, this result shows that axons from cells of similar age clustered together in the nerve.     

Axonal transport of gangliosides in the goldfish optic nerve

Radioactive glucosamine and N-acetylmannosamine injected into the goldfish eye are incorporated into gangliosides that undergo rapid axonal transport to the optic nerve terminals. All ganglioside fractions are labeled. These data provide the first evidence that axonal transport has a role in neuronal ganglioside function and metabolism.     

Multiple temperature-sensitive spots innervated by single nerve fibers

Electrophysiological recordings were made from single nerve fibers which were specifically responsive to temperature changes of the skin of monkeys. Previous reports indicated that the receptive area on the skin of such preparations was a single small spot less than 1 millimeter in diameter. However, we found that the activity in a single thermally sensitive fiber increased when any one of eight individual spots on the skin was cooled. In other preparations two to six spots, each less than 1 millimeter in diameter, appeared to be innervated by a single fiber. The neural activity resulting from the cooling of one or several of these spots summed, and we suggest that this summation may be the neural analog of areal summation of thermal stimuli reported in psychophysical measurements.     

Transported proteins in the regenerating optic nerve: regulation by interactions with the optic tectum

The transport of specific proteins in regenerating optic fibers of goldfish depends on the presence or absence of the optic tectum. When optic fibers were allowed to contact the tectum, amounts of rapidly transported proteins having molecular weights between 120,000 and 160,000 increased, and a species of molecular weight 26,000 reverted to normal levels. When nerves were prevented from contacting the tectum, the amount of the 26,000-molecular weight protein remained high for months. Amounts of other transported proteins, in particular a group of acidic components of molecular weight 44,000 to 49,000 that increase greatly at early stages of regeneration, proved to be independent of the tectum.     

Activation of single lateral geniculate cells by stimulation of either optic nerve

The lateral geniculate nucleus is organized in such a way that, initially at least, information from the one eye is almost exclusively segregated from that from the other eye. Single-unit recording, however, confirms the histological evidence that bilateral integration does take place. A small number of cells (< 8.5 percent) receive afferents directly from both optic nerves and are discharged by stimulating either nerve (direct interaction). More common is delayed interaction, where the cells are discharged independently by either optic nerve but only after a relatively long latency. Indirect interaction effects also occur.     

Acetylcholine receptor synthesis in retina and transport to optic tectum in goldfish

Previous studies have suggested that the retinotectal system of the goldfish contains a nicotinic acetylcholine receptor (nAChR) that is sensitive to alpha-bungarotoxin. Extracellularly recorded field potentials elicited in response to visual stimulation can be blocked by alpha-bungarotoxin, and alpha-bungarotoxin can interfere with the maintenance of retinotectal synaptic connections. Whether the transmission between the retinal ganglion cells and the tectal cells is mediated by acetylcholine and whether nAChR's exist on the dendrites of tectal cells are questions that remain. The experiments described in this report were designed to determine the site of synthesis of the nAChR's associated with the goldfish retinotectal projection. Radioactive (35S-labeled) methionine was injected into either the eye or the tectal ventricle, and the incorporation of radioactivity into the nAChR was measured by immunoprecipitation. The use of this technique provides evidence that an nAChR associated with the goldfish retinotectal projection is synthesized in the retina and transported to the optic tectum, which suggests a presynaptic site of acetylcholine action on retinal terminals.     

Innervation of periosteum and bone by sympathetic vasoactive intestinal peptide-containing nerve fibers

Neural control of bone metabolism and growth has been suggested, although the identity of participating neurons and neurotransmitters effecting this control has not been established. Immunohistochemical studies demonstrated a system of vasoactive intestinal peptide (VIP)-immunoreactive nerve fibers that innervate periosteum and bone in several mammalian species. Thoracic sympathetic chain ganglionectomy resulted in an ipsilateral loss of VIP-immunoreactive fibers in the periosteum of ribs, whereas dorsal root ganglionectomy had no effect. Injection of fast blue into rib periosteum labeled a population of VIP-immunoreactive sympathetic postganglionic neurons. Thus, postganglionic sympathetic neurons may provide an important means by which VIP regulates bone mineralization.     

Unit responses from commissural fibers of optic lobes of fish

The paired optic lobes of teleost fish are connected by two commissures. One of these, the tectal commissure, was studied with metal microelectrodes. Fibers are rhythmically active for prolonged periods in the dark and respond to light by a decrease in the rate of discharge. There is a rebound acceleration when the light is turned of. Each fiber is influenced by light in one eye only, and there is no response when light is projected into the opposite eye. This behavior resembles the "off" response recorded from the optic lobes and the optic nerve of fish. Unlike most units from the visual pathways of lower animals, single commissural fibers do not seem to give any recognizable response to patterned input such as small light or dark objects or small light sources stationary or moving anywhere in the visual field, nor do they respond to a vertical black bar moved over a white background.     

Glial cell diversification in the rat optic nerve

A central challenge in developmental neurobiology is to understand how an apparently homogeneous population of neuroepithelial cells in the early mammalian embryo gives rise to the great diversity of nerve cells (neurons) and supporting cells (glial cells) in the mature central nervous system. Because the optic nerve is one of the several types of glial cells but no intrinsic neurons, it is an attractive place to investigate how neuroepithelial cells diversify. Studies of developing rat optic nerve cells in culture suggest that both cell-cell interactions and intrinsic cellular programs play important parts in glial cell diversification.     

Fast transport system of materials in mammalian nerve fibers

A fast transport system of materials is shown in cat sensory fibers of sciatic nerve. After injection of tritiated leucine into the lumbar seventh ganglia, the distribution of activity was measured in the sciatic nerves from 2 to 8 hours afterward. The distribution showed a crest of activity advancing down the fibers at a rate of approximately 410 millimeters per day. An intraaxonic locus of the activity was indicated by a block of the downflow induced by local freezing which causes the fibers to close off. Some of the activity in the nerve was due to free tritiated leucine, with most of it incorporated into polypeptide, soluble protein, and subcellular particulates.     

Radioautography of the optic tectum of the goldfish after intraocular injection of ( 3 H)proline

Radioautography of the optic tectum of the goldfish, performed after injection of [(3)H]proline into the contralateral eye, effectively resolves several distinct layers of retinal synapses. Silver grains are found unilaterally over nerve tracts containing efferent fibers from the tectum, a result that suggests intercellular migration of labeled molecules. The low background and high specific grain density obtained with [(3)H]proline radioautography indicate the usefulness of this technique for the elucidation of neuroanatomical connections in the visual system.     

Transport of dsRNA into cells by the transmembrane protein SID-1

RNA interference (RNAi) spreads systemically in plants and nematodes to silence gene expression distant from the site of initiation. We previously identified a gene, sid-1, essential for systemic but not cell-autonomous RNAi in Caenorhabditis elegans. Here, we demonstrate that SID-1 is a multispan transmembrane protein that sensitizes Drosophila cells to soaking RNAi with a potency that is dependent on double-stranded RNA (dsRNA) length. Further analyses revealed that SID-1 enables passive cellular uptake of dsRNA. These data indicate that systemic RNAi in C. elegans involves SID-1-mediated intercellular transport of dsRNA.     

9 -Tetrahydrocannabinol: effects on mammalian nonmyelinated nerve fibers

Delta(9)-Tetrahydrocannabinol can be applied to tissue in vitro by dissolving it in Pluronic F68 and ethanol. It causes a decrease in size of the compound action potential of the nonmnyelinated fibers of the vagus nerve of the rabbit. This effect appears to be dose-related and chloride-dependent. Effects on other measurable parameters of nerve function seem to be minimal. Although the amounts required seem to be higher than those required to produce hallucinogenic effects in man, this effect is consistent with other work on Delta(9)-tetrahydrocannabinol and may ultimately account for a significant portion of the pharmacological activity of this drug.     

Electrical responses of the retinal nerve and optic ganglion of the squid

Recordings were obtained from the retinal nerves and optic ganglia of intact squid, which were maintained in good condition by perfusing their mantles with sea water. Only "on" discharges were found in the nerves, whereas "on" and "off" discharges as well as spontaneous activity and tactile responses were obtained from the ganglia.     

Dorsal spinocerebellar tract: response pattern of nerve fibers to muscle stretch

The response to muscle stretch of second-order neurons of the dorsal spinocerebellar tract was studied in anesthetized cats. Three different types of neurons are defined; the response of each type is remarkably similar to that of the corresponding stretch-receptors of the muscle. Accordingly, the cerebellum receives information on the mechanical situation in muscle from three qualitatively different channels: one has a high degree of sensitivity to dynamic stretch (Ia units) and provides a mixed signal of muscle length and speed of movement; another provides information mainly on muscle length (group-Il units); and the third signals information on the degree of contraction of the muscle (Ib units).     

Taste nerve fibers: a random distribution of sensitivities to four tastes

The numbers of rat glossopharyngeal and chorda tympani fibers responding to one, two, three, or four taste stimuli of different quality (sodium chloride, hydrochloric acid, quinine, and sucrose) and to each of the six possible pairs of these stimuli can be predicted if there are four independent sensitivities randomly distributed among innervating fibers.     

扬子鳄心脏神经肽Y免疫反应纤维和细胞的分布

应用免疫组织化学(ABC)法和间接免疫荧光法对扬子鳄心脏内神经肽Y(NPY)免疫反应物质进行了观察.结果显示NPY免疫反应(IR)纤维和细胞主要见于心室及静脉窦.心房和主动脉瓣处可见少量IR纤维.IR纤维呈有膨体的点线状或"串珠状"和无膨体的线状,多分布于外膜层和肌层.IR神经节呈椭圆形,内见数十个阳性细胞,胞体有突起伸出节外,提示扬子鳄作为两栖爬行类动物鳄纲的代表,其心脏内含有NPY-IR物质,表明其体内具备肽能神经,该结果丰富了比较神经解剖学的内容,同时也为研究NPY在心血管系统中的生理和病理作用提供了形态学依据.     

Receptive fields of opponent color units in the optic nerve of the ground squirrel

When mapped with white light, each receptive field consisted either of an excitatory ("on") center and a concentric inhibitory ("off") surround, or of the reverse arrangement. Monochromatic stimuli revealed that each receptive field was composed of two mutually antagonistic components (one excitatory, one inhibitory) which had different spectral sensitivities and different spatial distributions. For some units the two chromatic components had identical spatial distributions.