Excitatory and inhibitory processes which result in the generation of output impulses were analyzed in single crayfish interneurons by using intracellular recording and membrane polarizing techniques. Individual spikes which are initiated orthodromically in axon branches summate temporally and spatially to generate a main axon spike; temporally dispersed branch spikes often pace repetitive discharge of the main axon. Hyperpolarizing IPSP's sometimes suppress axonal discharge to most of these inputs, but in other cases may interact selectively with some of them. The IPSP's reverse their polarity at a hyperpolarized level of membrane potential; they sometimes exhibit two discrete time courses indicating two different input sources. Outward direct current at the main axon near branches causes repetitive discharges which may last, with optimal current intensities, for 1 to 15 seconds. The relation of discharge frequency to current intensity is linear for an early spike interval, but above 100 to 200 impulses/sec. it begins to show saturation. In one unit the current-frequency curve exhibited two linear portions, suggesting the presence of two spike-generating sites in the axon. Current threshold measurements, using test stimuli of different durations, showed that both accommodation and "early" or "residual" refractoriness contribute to the determination of discharge rate at different frequencies.
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1 January 1965
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January 01 1965
The Mechanism of Discharge Pattern Formation in Crayfish Interneurons
Kimihisa Takeda,
Kimihisa Takeda
From the Department of Biological Sciences, Stanford University, Stanford.
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Donald Kennedy
Donald Kennedy
From the Department of Biological Sciences, Stanford University, Stanford.
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Kimihisa Takeda
From the Department of Biological Sciences, Stanford University, Stanford.
Donald Kennedy
From the Department of Biological Sciences, Stanford University, Stanford.
Dr. Takeda is on leave from the Department of Physiology, Tokyo Medical and Dental University, Tokyo, Japan
Received:
June 01 1964
Online ISSN: 1540-7748
Print ISSN: 0022-1295
Copyright © 1965 by The Rockefeller Institute Press
1965
J Gen Physiol (1965) 48 (3): 435–453.
Article history
Received:
June 01 1964
Citation
Kimihisa Takeda, Donald Kennedy; The Mechanism of Discharge Pattern Formation in Crayfish Interneurons . J Gen Physiol 1 January 1965; 48 (3): 435–453. doi: https://doi.org/10.1085/jgp.48.3.435
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