Effects of variations in temperature on impulse conduction along nonmyelinated axons in the mammalian brain

The effects of changes in brain temperature on conduction velocity and minimal interspike interval were examined in nonmyelinated callosal axons in awake and in barbiturate-anesthetized rabbits. These two parameters exhibited different sensitivities to brain temperature. For a range of 4.0°C, increases in brain temperature resulted in a decrease of approximately 2.5%/°C in antidromic latency and in a decrease of approximately 10%/°C in minimal interspike interval. Significant variations in conduction velocity and interspike interval can therefore be expected to occur with normally occurring changes in brain temperature. These variations may have implications for mechanisms of neural coding.