Stimulus intensity versus firing frequency

The association between stimulus intensity and response for static sensory neurons can be linear, as for illustration in skin thermoreceptor afferents. Frequently, though, the relationship is more complicated. Generally, for illustration, the firing rate increases with the logarithm (log10) of the intensity. Most of the skin mechanoreceptors and all photoreceptors fall into this class. This permits a very wide range of stimulus intensities to be accommodated in the dynamic variety of neurons, which is, the maximum difference in firing frequency a neuron is capable of. It has the drawback that for high intensities the capability to discriminate intensity differences is decreased.