Chronaxie calculated from current–duration and voltage–duration data

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Holsheimer, Jan and Dijkstra, Emiel A. and Demeulemeester, Hilde and Nuttin, Bart (2000) Chronaxie calculated from current–duration and voltage–duration data. Journal of Neuroscience Methods, 97 (1). pp. 45-50. ISSN 0165-0270

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Abstract:To determine the rheobase and the chronaxie of excitable cells from strength–duration curves both constant-current pulses and constant-voltage pulses are applied. Since the complex impedance of the electrode-tissue interface varies with both the pulsewidth and the stimulation voltage, chronaxie values estimated from voltage–duration measurements will differ from the proper values as determined from current–duration measurements. To allow a comparison of chronaxie values obtained by the two stimulation methods, voltage–duration curves were measured in human subjects with a deep brain stimulation electrode implanted, while the current and the load impedance of the stimulation circuit were determined in vitro as a function of both stimulation voltage and pulsewidth. Chronaxie values calculated from voltage–duration data were shown to be 30–40% below those estimated from current–duration data. It was also shown that in the normal range of stimulation amplitudes (up to 7 V) the load impedance increases almost linearly with the pulsewidth. This result led us to present a simple method to convert voltage–duration data into current–duration data, thereby reducing the error in the calculated chronaxie values to ≈6%. For this purpose voltage–duration data have to be measured for pulses up to 10–20 times the expected chronaxie.
Item Type:Article
Copyright:© 2000 Elsevier
Faculty:
Electrical Engineering, Mathematics and Computer Science (EEMCS)
Research Group:
Link to this item:http://purl.utwente.nl/publications/74311
Official URL:http://dx.doi.org/10.1016/S0165-0270(00)00163-1
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