Discrete and continuous prepulses have differential effects on startle prepulse inhibition and skin conductance orienting

The effectiveness of different types of auditory prepulses in eliciting ski n conductance orienting and in producing prepulse inhibition (PPI) of the a coustic startle eyeblink was studied in two experiments. A discrete white n oise prepulse produced greater PPI than either a continuous white noise, a discrete tone, or a continuous tone, The discrete white noise advantage was not due to similarity in bandwidth to the startle pulse or to a refractory effect of the prepulse. Moreover, a dissociation between PPI and skin cond uctance orienting was seen in both experiments. PPI using auditory prepulse s appears to be dependent primarily on the acoustic characteristics of the transient portion of the prepulse, whereas skin conductance orienting is mo re dependent on the sustained portions of the stimulus.