Either stimulation of the mesencephalic reticular formation or a flashing light increases latent inhibition to a tone-conditioned stimulus

Presentation of a flashing light following one-trial fear conditioning enhances retention

“…We find it interesting, as well as somewhat disconcerting when one considers cost, time, and talent, that we can obtain very similar effects on retention performance by stimulating the MRF and by simply flashing the houselight (cf. DeVietti et al, 1981; the present experiments). To date, the only discrepancy in the effects of these two treatments appears to be in the length of the enhancement gradient, a fact which may simply reflect a parametric problem.…”

“…Other rats did acquire a discrimination when either stimulus was differentially reinforced. Moreover, we recently reported (DeVietti et al, 1981) that presentation of a flashing light after each preexposure trial to a tone in a latent inhibition paradigm resulted in increased latent inhibition (decreased drink latencies) in the presence 01 the tone following fear conditioning in which the tone was paired with footshock. If the flashing light had been aversive, decreased latent inhibition (in.…”

“…None of these tests gave any indication that the MRF stimulation was aversive. However, the data from these tests were less than compelling, because the evidence supporting the conclusion that MRF stimulation was not aversive rested on failures to obtain a significant effect of the stimulation.We recently used another test for aversiveness of MRF stimulation: a latent inhibition paradigm (DeVietti, Wittman, Emmerson, & Thatcher, 1981). In that study, the to-be-conditioned stimulus, a tone, was presented to rats on several occasions prior to fear conditioning in which the tone was paired with footshock; the fear conditioning resulted in attenuated retention performance relative to that of controls not given the preexposure experience.…”

“…We recently used another test for aversiveness of MRF stimulation: a latent inhibition paradigm (DeVietti, Wittman, Emmerson, & Thatcher, 1981). In that study, the to-be-conditioned stimulus, a tone, was presented to rats on several occasions prior to fear conditioning in which the tone was paired with footshock; the fear conditioning resulted in attenuated retention performance relative to that of controls not given the preexposure experience.…”

Latent inhibition: No effect of intertrial interval of the preexposure trials

“…This phenomenon, termed latent inhibition (LI; Lubow & Moore, 1959), has been demonstrated in a variety of species and tasks, and seldom occurs if fewer than 18 preexposure (PE) trials to the to-he-conditioned stimulus are administered (see Lubow, 1973, for a review). However, we have consistently obtained LI with six PE trials in a one-trial fear conditioning task (DeVietti, Emmerson, & Wittman, 1982;DeVietti, Wittman, & Comfort, 1980;DeVietti, Wittman, Emmerson, & Thacher, 1981). We are currently investigating the factor(s) responsible for our finding of the rapid development of LI.…”