Journal of Neuroscience, Vol 4, 2063-2068, Copyright © 1984 by Society for Neuroscience
The receptor potential and adaptation in the cockroach tactile spine
AS French
The receptor potential in the cockroach tactile spine was measured during
mechanotransduction by recording from the afferent axon about 0.5 mm from
the sensory ending. The receptor potential was a linear function of spine
position, but its amplitude and phase varied with the mean position of the
spine. This can be related to the mechanical linkage from the socket of the
spine to the sensory ending. The frequency response for mechanotransduction
was flat over a frequency range of 0.1 to 100 Hz, after accounting for the
cable properties of the axon, and there was no evidence of adaptation. The
length constant and membrane time constant of the axon were estimated to be
130 microns and 1 msec, respectively. The threshold amplitude of movement
required to produce action potentials was also measured as a function of
frequency. It gave a power law relationship which was exactly the inverse
of the frequency response of the receptor during strong stimulation and
rapid firing. This suggests that adaptation of the sensory discharge in
this receptor is produced by the action potential encoding mechanism.