Response decrement of the flexion reflex in the acute spinal cat and transient restoration by strong stimuli.

Abstract

The Prosser and Hunter paradigm (1936) has been adapted to the acute spinal cat and to the use of single shock stimuli rather than the brief stimulus trains which they employed. In our acute experiments, the effects of varying stimulus strength were found to be similar to those described by Prosser and Hunter in their studies on chronic spinal animals. In addition, it was found that there was some generalization across input channels when adjacent branches of a cutaneous nerve were stimulated. Several lines of evidence were presented which are incompatible with the idea that the phenomenon of "disinhibition" represents a removal of the process responsible for response decrement. The basic phenomena of response decrement to repetitive cutaneous stimulation and restoration by a strong extrastimulus are also elicitable after interruption of the gamma loop by either deefferentation (using dorsal root stimuli in the latter case). The paradigm described has been compared to the earliest descriptions of behavioral "habituation" and "dishabituation" and the application of these terms to the processes we have described is justified on the basis of historical usage.