The effects of temperature on mechanotransduction in the cockroach tactile spine

1. The dynamic behaviour of the cockroach femoral tactile spine can be characterised as fractional differentiation. In the frequency domain this corresponds to a frequency response function which can be completely represented by two parameters: the gain at a frequency of 1 radian/s and an exponent of frequency. 2. Frequency response functions for mechanotransduction in the tactile spine have been measured at temperatures in the range of 10-40 °C. Sensory transduction fails at temperatures a few degrees Celsius outside this range. 3. The effect of temperature upon sensory transduction is to multiply the entire response by a constant factor, independent of frequency, at each temperature. The multiplication factor increases with warming up to about 35 °C and then decreases rapidly. The data up to 35 °C is well fitted by an Arrhenius relationship with an activation energy of 18.6 kcal/ mole. 4. Changing the temperature has no effect upon the exponent of frequency which stays constant at approximately 0.5, corresponding to a system which performs semi-differentiation. 5. The possible sites of temperature sensitivity and sensory transduction in these mechanoreceptors are discussed. Possible origins of the semi-differentiation behaviour are reviewed and a visco-elastic travelling wave model of the tubular body is suggested. Comparisons are drawn throughout to the behaviour of Pacinian corpuscles, muscle spindle primary afférents and other cuticular mechanoreceptors.