Single Nerve Cells Research Articles

Single gene cricket mutations: effects on behavior, sensilla, sensory neurons, and identified interneurons.

Crickets are suitable for studying the effects of single gene mutations on single nerve cells. In one mutant, three classes of sensilla are lost sequentially. The absence of one class of mechanoreceptors throughout postembryonic development deprives certain sensory neurons of normal stimulation and results in abnormal physiological and structural development of an identified interneuron.

THE EFFECT OF DIMETHYL SULFOXIDE ON THE NEURONAL EXCITABILITY AND CHOLINERGIC TRANSMISSION IN APLYSIA GANGLION CELLS*

The effects of DMSO on single nerve cells of Aplysia were investigated by various electrophysiological methods. 1. Although the increase in permeability of the biological membranes produced by DMSO has been well documented, we found that DMSO at concentration of less than 20% actually decreases the permeability of the neuronal membranes, probably toward potassium and chloride ions. This change in ionic permeability reversibly depolarizes the resting membranes and makes the neurons more excitable. 2. The falling phase of the spike is prolonged by 8% DMSO, because it blocks the active increase in potassium permeability. This change suppresses the high frequency discharge, because the refractory period of each spike is increased. Neither the rising phase nor the absolute firing level is appreciably altered by DMSO when these are examined after the depolarization is cancelled. 3. Dilute DMSO (less than 1%) facilitates cholinergic trasmission because it blocks ACh-esterase activity. DMSO at concentrations of more than 10% ultimately blocks cholinergic transmission entirely, because it also depresses cholinoceptive receptor activity (probably by allosteric interaction). The action of 1-10% DMSO is complicated, because both facilitatory and inhibitory effects take place at the same time. 4. In cholinergic synapses, excitatory transmission is more susceptible to DMSO than inhibitory transmission. This is because the activity of the excitatory receptor is blocked more readily than that of the inhibitory receptor. The depressing effects of DMSO are not specific to the cholinergic system, however, since the activities of GABA and glutamate receptors are similarly depressed.

Microspectrophotometric determination of nerve cell respiration at high potassium concentration

The oxygen uptake of free-hand dissected single nerve cells from the lateral vestibular nucleus of the rabbit was studied in the presence of 4 and 50 mM KCl, by use of a recently developed microspectrophotometric procedure, using hemoglobin as an indicator of oxygen tension as well as donor of oxygen. An approximately two-fold increase in respiratory rate was found in the presence of increased potassium concentration, where the oxygen consumption per cell was 4.61 × 10 −4μl O 2/h as compared with the “basal” rate of 2.45 × 10 −4μl O 2/h. A detailed description of the methodological procedure is given.

Specific protein metabolism in identifiable neurons of Aplysia californica.

AbstractThe patterns of protein metabolism of identified cholinergic (R2, L10, and L11) and neurosecretory (R3–13, R14, and Bag cells) cells were analyzed with the use of SDS‐polyacrylamide gel electrophoresis and isoelectric focusing. L11 was unique amongst the three cholinergic neurons in its relatively high rate of incorporation of labeled leucine into proteins at 12,000 daltons. All the neurosecretory cells incorporated relatively large quantities of 3H‐leucine into small proteins (<12,000 daltons), which were concentrated in putative neurosecretory granule fractions of these cells. R3–13 and R14 synthesized a distinct basic protein which appeared specifically in the branchial nerve which contains the axons of these cells. The combination of these two analytical electrophoretic techniques allowed for the characterization of protein specificity in single nerve cells.

Chemical sensitivity of Limnaea stagnalis neurons and their responses to synaptic stimulation

Responses of nerve cells to puncture, to touching the surface of the mollusk leg, osmotic stimulation, and extracellular microiontophoretic injection of acetylcholine, noradrenalin, serotonin, atropine, and propranolol were recorded intracellularly in the right parietal, left pedal, and visceral ganglia of the unisolated circumpharyngeal ring ofLimnaea stagnalis. Selective sensitivity of the neurons to the biologically active substances was observed. Results indicative of the functional differences between the various ganglia and of their neurochemical organization were obtained. Selective blocking of the unit responses to puncture of the surface of the mollusk leg by atropine or propranolol suggests that different forms of excitation reaching the central neurons evoked different and specific neurochemical processes on their subsynaptic membranes which can retain the essential informativeness of the widely different afferent volleys converging on a single nerve cell.

Thorotrast uptake and transit in embryonic glia, heart fibroblasts and neurons in vitro

Thorotrast (colloidal ThO 2) is incorporated into coated vesicles, various agranular vesicles and sacs, and a surface-associated system of membranous channels in times as short as 1 min by single cultured glial and heart cells. Thorotrast appears in ‘C’-shaped bodies and in small, dense bodies of the lysosomal series within ca. 25 min. With longer chase periods, thorotrast ‘clears’ from all cytoplasmic organelles except the lysosomal series. The technique of applying thorotrast and using varying chase periods fails to distinguish a class of membranous organelles, located close to the cell periphery, that might serve as a source of new cell surface during locomotory activity. Similarly, thorotrast (colloidal ThO 2) is incorporated into almost all classes of membrane-bounded organelles of growth cones and axons of single nerve cells in vitro in times as short as 1 min. This includes elements of the smooth endoplasmic reticulum. No thorotrast enters the lysosomal granules in this short time. During various chase periods, the tracer disappears from the initial sites of incorporation and accumulates in dense bodies of the lysosome series within growth cones and axons. ‘C’-shaped bodies may be an intermediate in that process. No unique sites of endocytotic activity or of a complete absence of endocytosis were observed that could be correlated with growth cone function and axonal elongation, though the presence of the tracer in agranular sacs of the smooth endoplasmic reticulum in growth cones could reflect hypothesized cycling of cell surface (Bray, 1973).

Electrophysiological evidence for existence of neurones sensitive to direction of depth movement.

RECENT psychophysical evidence suggests that there are movement detectors in the human visual pathway selectively sensitive to different directions of motion in three-dimensional space1–5. In animals (such as the cat) there are single nerve cells with properties which suggest that they signal when an object is moving in depth away from the plane of binocular fixation6.

Mechanical factors in the design of chronic recording intracortical microelectrodes.

To obtain chronic recordings from single nerve cells in the cerebral cortex it is necessary to prevent motion of the microelectrode tip with respect to the adjacent neural tissue. This paper presents an engineering analysis to estimate these motions in terms of the geometry and material properties of the electrode, its lead wire, and the cortex. The results are used to gain an understanding of a recently reported successful recording system, and to thereby provide a design guide for future systems. In addition, a buckling analysis is presented for a class of microelectrodes to enable a minimum size to be achieved with an adequate safety margin.

Fluorimetric determination of creatine kinase activity in isolated single neurons.

A quantitative fluorimetric method for determination of creatine kinase activity in isolated single nerve cells (2-10 ng dry weight) has been developed. Enzyme activity was measured in the direction of adenosine triphosphate and creatine formation. The creatine generated was measured by the fluorescent compound formed with ninhydrin in alkali. The coefficient of variation for the assay of enzyme activity in brain homogenate (47 ng wet tissue/sample) was 3.17%. The coefficient of variation for single neurons of the lateral vestibular nucleus (nucleus Deitersi) in rabbit was about 15%. The creatine kinase activity in these cell bodies was 342.0 ± 14.2 moles/kg dry tissue/hr, at 38°C.

Distribution of Enzymes between Nucleus and Cytoplasm of Single Nerve Cell Bodies

The activities of nine enzymes (hexokinase, P-fructokinase, glucose-6-P dehydrogenase, 6-P-gluconic dehydrogenase, TPN-linked isocitric dehydrogenase, malic dehydrogenase, lactic dehydrogenase, glutamic dehydrogenase, and ATP: NMN adenylyltransferase) and the concentration of DPN+ were determined in nuclei, cytoplasm, and cell bodies (nucleus + cytoplasm) of single dorsal root ganglion cells of the rabbit. The structures were dissected from 8- to 10-µ frozen dried tissue sections. In each case, the nucleus (0.2 to 1.2 ng) and two or three pieces of cytoplasm were obtained from the same cell body. The samples were weighed on quartz fiber balances sensitive to as little as 1.2 pg. The specific enzyme reactions were carried out in small volumes (1 nl to 5 µl) under mineral oil (oil well technique), and the DPN+, DPNH, or TPNH formed was amplified 800- to 1,000,000-fold by enzymatic cycling or double enzymatic cycling. Of the seven enzymes from major energy-yielding systems, three were higher in concentration in the nucleus than in the cytoplasm (hexokinase, 6-P-gluconic dehydrogenase, TPN-linked isocitric dehydrogenase) and two were higher in the cytoplasm (P-fructokinase, glucose-6-P dehydrogenase). Unexpectedly, glutamic dehydrogenase was found in the nucleus as well as in the cytoplasm (at 60% of the cytoplasmic level). ATP:NMN adenylyltransferase was found to be localized almost exclusively in the cytoplasm, in complete contrast to findings of others who examined nucleiisolated in bulk.

Monoamines in the liquor-contacting nerve cells in the hypothalamus of the lamprey, Lampetra fluviatilis L.

The hypothalamus of adult lampreys (Lampetra fluviatilis L.) was studied by means of light and fluorescence microscopy (Falck's technique). Some single liquorcontacting nerve cells (LCNC) showing a weak green fluorescence were demonstrated in the ventral part of the third ventricle, above the preoptic recess. Caudally numerous fluorescent LCNC occur in the ventral part of the third ventricle, in the infundibular and in the posterior recess. The LCNC are to be observed between or below the ependymal cells lining the ventricular wall. These cells appear to be of the bipolar type. One process with a club-like protrusion is directed into the ventricular lumen, the other one into the opposite direction. Two types of fluorescent LCNC were distinguished: yellowish green cells, containing catecholamines, and yellowish orange cells, containing 5-hydroxytryptamine. Some similarity between the hypothalamic monoaminergic LCNC in lampreys and LCNC of the paraventricular organ of the other vertebrates was found. The localization, structure and monoaminergic nature of the hypothalamic LCNC in lampreys suggest the possibility, that their monoamines are released into the cerebrospinal fluid.

Orientational preferences shown by microspikes of growing nerve cells in vitro

The shapes of microspikes on single neurones cultured in vitro have been analysed with respect to angles of bending and branching. Characteristic frequency distributions were found in all of the four categories of angles. Certain `preferred' orientations of bending and branching were seen to center about 60°, 90°, and 120°. The possible cellular basis for such behavior is discussed, as well as the similarity of bending and branching in the axonal-microspike system of the single nerve cell to the analogous branching in the vertebrate blood vascular system.

Evoked Potentials in Psychology, Sensory Physiology and Clinical Medicine

Only quite recently has it become technically possible to record, from elec trodes attached to the scalp, the human brain's electrical responses to sensory stimulation. The core of this book is a critical survey of endeavours to use these electrical responses (called evoked potentials) as tools in attempts to discover the ways in which the brain first processes incoming sensory information and then forms internal representations of features ofthe external world. Buttressed by quantities of undeniably sloppy evoked potential research there are some who would dismiss out of hand the recording of evoked potentials as being comparable to 'holding an oscilloscope probe 6 feet in diameter up to a computer and pronouncing from the resultant waveform on the underlying structure and function'; many would contrast the scientific value of recording the activities of single nerve cells with microelectrodes. However, although it is certainly true that the brain may indeed function in a way which would not be susceptible to the approaches of the evoked potential researcher it might equally well resist the stratagems of the single-cell man. If, for example, the neural correlate of some sensation were the state of some large population of nerve cells, then the present-day researcher who records in great detail the activity of one single cell or of a very few cells would be faced with a major problem in trying to see the forest for the trees.

Moving Movement Detectors

Single nerve cells readily recordable in the ventral nerve cord of locusts and crickets respond to moving targets but not to the forced movement of the eye. This asymmetry of response is shown to be due to an inhibition generated whenever large areas of the hemispheric receptive fields of these units are stimulated. Dimming of a large, stationary target movement of a large field of vertical bars, or movement of the eye while viewing a large pattern are all potent inhibitory stimuli which can prevent the cell's otherwise vigoious response to a small target or arrest a response which is already under way. These properties of single insect neurons are phenomenologically similai to human sensations described by psychophysicists as saccadic suppression and backward masking, as well as to the properties of some vertebrate visual neurons. It is argued that the spatial and dynamic characteristics of neurons in visual input pathways may well acount for some psychophysical findings generally interpreted in terms of central mechanisms such as “efference copy,” and must be incorporated inmodels seeking to explain perceptual stability during eye movement.

Another tungsten microelectrode.

A technique is described for fitting a sharpened tungsten wire and a glass micropipette together so that a precisely controlled amount of bare wire is exposed at the tip. The method is tedious and demanding but produces very reliable electrodes yielding isolated extracellular recordings from single nerve cells and their axons.

Visual system's view of acoustic space.

SINGLE nerve cells of the visual cortex of the cat can respond to stimuli in other modalities1–11, but the physiological role of such excitation is not understood. Many investigators consider that this activation reflects generalized arousal12–15. In this report I present evidence of a rigorous spatial specificity in the acoustical projection to visual neurones.

Electrophysiological Equipment for Measuring the Activity of Single Olfactory Nerve Cells on the Antennae of Mosquitoes13

Electrophysiological Equipment for Measuring the Activity of Single Olfactory Nerve Cells on the Antennae of Mosquitoes13

Determination of amino acids in single identifiable nerve cells of Helix pomatia.

Microchromatography of dansylated compounds was used to study the distribution of free amino acids, GABA, serotonin and 5-hydroxyindole in the metacerebral serotonergic cell and one of the giant cells in the buccal ganglia of Helix pomaiia. The distribution of some of the substances in each of the cell types varied depending upon the isolation procedure. Metacerebral cells dissected in the presence of nialamide contained large amounts of serotonin. The same neurons isolated in the absence of nialamide, but dissected with methylene blue contained no serotonin. The distribution of ornithine, glycine, alanine, arginine, e-lysine, α-amino-histidine and cystine in each cell type varied depending upon the method of isolation.Generally the distribution of dansylated substances is similar; GABA is present in each cell type but in low concentrations. However, there are some exceptions. The serotonergic cell contains less ornithine and more glycine than do the buccal cells. In addition the metacerebral cells have h...

Vestibular nerve response to pressure changes in the external auditory meatus of the guinea pig.

Increases and decreases of action potential (pulse) rate were observed in some single vestibular ganglion nerve cells of the guinea pig in response to pressure changes in the external auditory meatus. Minimum stimulus intensities necessary to elicit clear responses were in the range of 1-2 cm Hg. These results (1) support an hypothesis regarding mechanisms of vestibular activation by intense infra- and audiofrequency sound, and (2) suggest a new stimulus technique for neurophysiological investigations of the vestibular pathway and central sensory integration.

Effect of hemicerebellectomy upon the cytochemistry of neurons in the lateral vestibular nucleus. I. Effects on RNA content and succinoxidase activity in Deiters' neurons at different post-operative intervals.

RNA content and succinoxidase activity was measured in single Deiters' giant nerve cells from the lateral vestibular nucleus in rabbits subjected to hemicerebellectomy. Postoperatively there was a decreased RNA content bilaterally after 1–2 weeks and almost restored values after 6 weeks. The succinoxidase activity showed asymmetrical changes with initially higher values on the operated side and with a rise on the contralateral side after 1 week. The succinoxidase activity and RNA content later returned to approximately preoperative values.