Quantitative relations between noxious stimulus intensity and magnitude of central afferent evoked responses in rat

Relations between intensities of electrical noxious stimulus applied to the tooth pulp and magnitudes of evoked responses at various relay stations of tooth pulp afferents were investigated with lightly anesthetized rats. The stimulus-response function in each relay station and the cerebral cortex follows the power function only in the range of lower, but noxious, stimulus intensities; however, it deviates from it in the range of higher ones, the exponent of the function becoming smaller. The higher the relay station locates, the smaller the exponent value is.