Integration of impulse activity in a peripheral sensory unit.

Abstract When recording from fine strands of dorsal root, receptors of the multiterminal tactile pad units in hairy skin of cat were mechanically stimulated, separately and simultaneously. Upon combined stimulation, no summation of discharges from the several terminals was observed even at low frequencies. Due to the antidromic invasion of the inactive branches of the fiber and to the slow recovery of the mechanically excitable terminals, afferent discharges arise from only one receptor at a time. Since the slow recovery also occurs when a terminal is invaded antidromically, but with a time lag due to interterminal conduction, a stimulus of greater intensity will be required to elicit a discharge at a sister terminal than at the receptor originally stimulated, and in doing so, will shut off discharge from the remaining terminals.