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Strength-duration curves of the ascending and descending conductive spinal cord potentials (SCEPs) in cats were obtained using constant current stimuli. For the formulation of numeric indices of excitability, the rheobase is defined as the minimal current strength below which response cannot occur even if the current continues, and the chronaxie is defined as the minimal duration of a current required to evoke the potential at twice the rheobase strength. The chronaxies and rheobases were calculated from the constructed strength-duration curves. The purpose of this study is to produce strength-duration curves and to evaluate the utility of chronaxies and rheobases for SCEPs. This study showed the following results: (1) there was a hyperbolic relationship between stimulus strength and stimulus duration at threshold values, similar to that seen in peripheral nerves; (2) the ascending and descending tracts of SCEP were mediated through the same pathway (based on the similar chronaxies and rheobases); (3) following spinal cord compression the chronaxie and rheobase increased significantly (P < 0.05), which is similar to peripheral nerve disturbance. However, the rheobase decreased significantly following slight spinal cord compression (P < 0.05) and systemic cooling (P < 0.01), and the strength-duration curve shifted showing a tendency towards decrease of the galvanic threshold, therefore, amplitude augmentation with slight compression and with decrease in temperature seems to contribute to the reduction of the threshold. The strength-duration curve, the chronaxie and the rheobase may be useful in assessing spinal cord function.
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N Yamaguchi, and
M Takase, and
H Bertalanffy, and
T Kawase, and
S Toya
January 1989,
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M Ishikawa, and
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H Bertalanffy, and
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Nihon Seikeigeka Gakkai zasshi,
M Ishikawa, and
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M Ishikawa, and
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N Yamaguchi, and
M Takase, and
H Bertalanffy, and
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March 2019,
Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society,
M Ishikawa, and
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M Takase, and
H Bertalanffy, and
T Kawase, and
S Toya
November 2002,
Zhongguo ying yong sheng li xue za zhi = Zhongguo yingyong shenglixue zazhi = Chinese journal of applied physiology,
M Ishikawa, and
T Ohira, and
N Yamaguchi, and
M Takase, and
H Bertalanffy, and
T Kawase, and
S Toya
April 1989,
American journal of veterinary research,
