Incubation of passive avoidance in rats: Shock intensity and pretraining.

Abstract

Rats were given .5-, 1.0-, or 2.0-ma. footshock after entry of a dark chamber from a lighted chamber on the 1st, 2nd, 4th, or 8th training trial and then tested at one of five postconditioning intervals (10 N see., n -1, 5). Latency to reenter the dark chamber was linearly increasing functions of the conditioning-test interval and shock intensity and a linearly decreasing function of amount of preexposure to the apparatus. A second study using a single set of parameters (1 ma., 4 training trials), larger numbers of & and a wider range of test intervals yielded response latencies that were an inverted U-shaped function of the conditioning-test interval.A number of recent studies have shown that a variety of passive-avoidance responses acquired in one conditioning trial incubate, that is, change as a function of time following aversive conditioning (e.g., Irwin & Benuazizi, 1966;McGaugh, 1966). The majority of the studies which investigated the conditioning-test interval used only a few intervals and thus have been relatively uninformative with respect to the form of the incubation function. Irwin and Benuazizi reported two experiments in which a fairly large range of conditioning-test intervals was used. In both experiments response latency was an inverted U-shaped function of the conditioning-test interval with maximum latency at 90 min. Clark (1967) also included a large number of conditioning-test intervals, although his shortest interval was J/2 h r -I n contrast to most other studies, Clark found that passive-avoidance responding decreased monotonically across conditioning-test intervals. Most studies have found monotonically increasing passive-avoidance responding up to the longest interval tested, generally either 1 or 24 hr., with very few

Appetitive context conditioning proactively, but transiently, interferes with expression of counterconditioned context fear

“…One explanation for the increase in expression of contextconditioned fear across the retention interval among rats shocked in the appetitively conditioned context is so-called fear incubation (e.g., McMichael 1966;Zammit-Montebello et al 1969;Pinel and Mucha 1973;Houston et al 1999;Balogh et al 2002;Pickens et al 2009aPickens et al ,b, 2010Pickens et al , 2013. This incubation could be due to better consolidation, and hence, better retrieval of the CS-shock association with time, or to recovery from a hypothesized inhibitory effect of recent conditioning (Pickens et al 2009a(Pickens et al ,b, 2010(Pickens et al , 2013; see also Bouton et al 2008).…”

Time-dependent variations in aversively motivated behaviors: Nonassociative effects of cholinergic and catecholaminergic activity.

“…In experiments involving specific response-shock contingencies, such as conditioned emotional response (CER) and passive avoidance tasks, it was observed that at short periods after initial shock there is a phase of hypermotility, which results in a weak CER and poor avoidance performance. Between the brief and intermediate interval there is an increased CER and improved passive avoidance performance (Anisman & Waller, 1973b;Irwin, Banuazizi, Kalsner, & Curtis, 1968;Kumar, 1970;McMichael, 1966;Tarpy, 1966;Zammit-Montebello, Black, Marquis, & Suboski, 1969). Evidently, although the pairing of a stressor with an explicit cue has profound associative consequences, the initial shock-induced excitation and subsequent response suppression may modify performance.…”

Long-Lasting Incubation of Conditioned Fear in Rats

“…Fear incubation over the course of 24 h has also been well documented in rodents (10-12), but it is unclear whether fear in rodents reliably incubates over longer periods. Long-term fear incubation to environmental contexts associated with shock has been demonstrated over 60 days in rats (13) or over 14 days in mice (14; 15).…”