Optimal control principles for sensory transducers

Sensory transduction in physiological systems faces the double dilemma of maximizing both sensitivity and dynamic range despite limitations inherent in the transmission of information via all-or-none action potentials. The thresholds for detection in senses such as vision and hearing are close to the theoretical physical limits of uncertainty whereas these same senses frequently must discriminate well among stimuli having five or six orders of magnitude greater amplitude. All of this information must be transmitted via digital pulse-rate encoding with a maximum dynamic range of 0–500 pps. Among the mechanisms known to assist in solving this encoding problem are logarithmic response curves in the transducers themselves, accomodative processes intrinsic to the transducers, gain control systems under efferent neural control, and mechanical gates (e.g. iris of the eye, tensor tympani muscle of the ear).