ABSOLUTE REFRACTORY PERIODS OF SELF-STIMULATION NEURONS

A new method is described for measuring the separate contributions of absolute refractory periods (ARPs), relative refractory periods (RRPs) and supernormal periods (SNPs) of the directly stimulated neurons mediating rewarding brain stimulation, to behaviorally measured excitability estimates. If pulse pairs are presented in which the first pulse in each pair is either higher, lower or equal in current to the second pulse in each pair, then ARPs, RRPs and SNPs contribute differentially. ARPs were found to make contributions at intrapair intervals between 0.4 and 1.2 msec, but were largest between 0.6 and 1.0 msec. RRPs made inappreciable contributions at all intrapair intervals. SNPs were found to make large contributions, particularly at intrapair intervals of 3.0 and 5.0 msec. Results for a dorsal pons placement were similar to those for two medial forebrain bundle placements. © 1979.