A quantitative analysis of the responses of certain dorsal horn neurones to mechanical stimulation of the large foot pad in cats.

1. Responses of single units in the dorsal horns of the spinal cords of cats to mechanical stimulation of the large foot pad have been recorded.2. The observations made with different single stimuli belonging to the set under different conditions of excitability have included: the numbers of impulses per response, their means and variation; the frequency distributions of impulse numbers; the time distribution of activity during a response and in particular the probability of an impulse occurring in each successive time interval.3. The observations with two stimuli were designed to measure the [ill] of the whole response contributed by the second stimulus and [ill] relate the size of this contribution to the interval between the stimuli and their distance apart.4. The results are discussed and it is concluded that the observed transformations allow representations of successive events to exist at the same time and that the purpose of the transformation may therefore be to allow particular types of interaction between successive events. A model of mechanism which is consistent with many of the observations is also discussed.