| | 1 | Author
| K. Kirschfeld | Requires cookie* | | | Title
| The Effect of Volatile Anesthetics on Giant Neurons in the Lobula Plate in the Fly  | | | | Abstract
| Movement sensitive giant neurons in the lobula plate of the fly (H,-neurons, V-neurons) are affected by low con centrations of volatile anesthetics (halothane, N20): the spike frequency generated by motion in the preferred di rection decreases, that in the opposite direction increases. This means that the response to the motion stimulus de fined as the spike frequency modulation decreases. Higher concentrations of the anesthetics lead to an increasing spike frequency which is unaffected by the motion stimulus, until eventually no spikes are generated any longer. The results are in agreement with the assumption that the anesthetics increase the membrane permeability of these neurons. | | | |
Reference
| Z. Naturforsch. 41c, 1137—1138 (1986); received September 17 1986 | | | |
Published
| 1986 | | | |
Keywords
| Insect, Central Nervous System, Halothane, Nitrous Oxide | | | |
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| default:Reihe_C/41/ZNC-1986-41c-1137_n.pdf | | | | Identifier
| ZNC-1986-41c-1137_n | | | | Volume
| 41 | |
| 2 | Author
| H. Endrick, E. A. Eckert, K. Urt, H. Am Dorf | Requires cookie* | | | Title
| Action Potentials in "Non-Spiking" Visual Interneurones | | | | Abstract
| The response o f the homolateral "horizontal cells" (H-cells) o f the third visual neuropile o f the blowfly, Phoenicia sericata, has been investigated by intracellular recordings coupled with dye injections (Procion Yellow, cobaltous chloride). Responses were obtained from their terminal axon endings in the central protocerebrum. Under natural conditions, the horizontal cells respond not with graded potentials as reported previously, but with action potentials upon stimulation by regressive pattern motion within the contralateral receptive field. The stimulus-induced responses change from action potentials to graded signals within a few minutes after opening the head capsule. The possible causes o f this change, namely hypoxic conditions and a consequent depletion of the ATP-supply, are consistent with the experimental data: a change in the resting potential as well a reduction o f the spike amplitude. Furthermore, the possibility of two functionally different output regions o f the H-cells is discussed, namely, (1) the terminal axon endings appear to conduct action potentials induced by the contralateral input (to the H-cells). Thus, these endings provide a solely contralateral, i.e. "monocular output". Whereas (2) the axonal arborisation appears to conduct graded signals elicited by the ipsilateral input onto which the contralateral input is superimposed, thus providing a "binocular output". | | | |
Reference
| Z. Naturforsch. 36c, 470—4 (1981); received August 7 1980/January 21 1981 | | | |
Published
| 1981 | | | |
Keywords
| Vision, Diptera, Central Nervous System, Identified Neurones, Graded Signal Transmission | | | |
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| default:Reihe_C/36/ZNC-1981-36c-0470.pdf | | | | Identifier
| ZNC-1981-36c-0470 | | | | Volume
| 36 | |
| 3 | Author
| J. Bernhardt | Requires cookie* | | | Title
| Biologische Wirkungen elektromagnetischer Felder Biological Effects of Electromagnetic Fields | | | | Abstract
| This resume deals with thermal and nonthermal effects o f electromagnetic fields on man. In consideration o f two aspects a limitation is necessary. Firstly, there will be discussed only direct and im m ediate influences on biological cells and tissues, secondly, the treatment is limited to such phenom ena, for which biophysical aproxim ations, based on experimental data, could be develop ed. Hazards for the human being may occur only by thermal effects within the microwave range. Regarding frequencies below approxim ately 30 kHz, excitation processes cannot be excluded in exceptional cases. Thermal effects are predom inant, between 30 kH z and 100 kHz, before excita tions can appear. Furthermore, by com paring the electrically and m agnetically induced currents with the natural ly flowing currents in man caused by the brain's and heart's electrical activity, a "lower boundary-line" was estimated. Regarding electric or magnetic field strengths undercutting this boundary-line, direct effects on the central nervous system may be excluded; other m echanism s should be re sponsible for demonstrated biological effects. The paper closes referring to som e reports — presently discussed — on experimental findings o f biological effects, which were observed as a result o f the influence o f electromagnetic fields o f small field strengths. | | | |
Reference
| Z. Naturforsch. 34c, 616 (1979); eingegangen am 18. April 1979 | | | |
Published
| 1979 | | | |
Keywords
| Electromagnetic Fields, Thermal Effects, Nontherm al Effects, Central Nervous System, Current Densities | | | |
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| default:Reihe_C/34/ZNC-1979-34c-0616.pdf | | | | Identifier
| ZNC-1979-34c-0616 | | | | Volume
| 34 | |
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