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. 1972 Mar;221(3):715–730. doi: 10.1113/jphysiol.1972.sp009778

Excitation and inhibition of motoneurones in the tortoise

M E Rosenberg
PMCID: PMC1331362  PMID: 5016368

Abstract

1. Intracellularly recorded responses of lumbosacral motoneurones in the tortoise are described. The preparation was decerebrate and unanaesthetized. Cells were tested by stimulation of the main branches of the ipsilateral sciatic nerve.

2. The distribution of cells according to resting membrane potential is given; highest recorded values were around 70 mV.

3. The action potential has a step on the rising phase and has a total duration in the region of 4 msec.

4. The motoneurone input resistance, measured by the spike height method, was 5-8 MΩ.

5. Orthodromic excitation of motoneurones occurred after a central latency of 2 msec.

6. Inhibition, and inhibitory (hyperpolarizing) potentials were demonstrated. Peak amplitude of maximum response was frequently greater than 10 mV. The potentials were influenced by injected currents in a manner resembling IPSPs in mammalian motoneurones. Minimum central latency for inhibitory potentials was about 3 msec.

7. Membrane potentials and dimensions of action potentials for motoneurones in the cat are given for purposes of comparison with the tortoise.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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