Modelling compound action potentials of peripheral nerves in situ. II. A study of the influence of temperature

Compound nerve action potentials of sural nerves of healthy volunteers have been measured at different temperatures. In the range from 21 to 39 degrees C a linear temperature dependence of the propagation velocity, related to the fastest fibres, is found (slope 1.9 m/sec/degree C). The causes of amplitude and shape alterations in the compounds action potentials (CAPs) with changing temperature are analysed with the help of a model. It appears that the changes in the measured CAPs are well explained by known temperature effects on the single fibre level. Both the considerable increase in CAP duration after cooling and the relative constancy of the CAP amplitude were reproduced by the model. Close fits to the actually measured CAPs can be obtained when some crucial parameter values are optimized. The results of this procedure are presented.