The Contextual Modulation of Conditioned Taste Aversions by the Physical Environment and Time of Day Is Similar

Abstract

In a pair of experiments, we have compared the ability of changes of place (Exp. 1) and changes of time of day (Exp. 2) to separately modulate learned saline-aversion memory phenomena in rats. Neither a spatial nor a temporal change disrupted latent inhibition using the present behavioral procedure. However, pre-exposure to the taste increased the contextual control of the learned aversion expression. The aversion reappeared in the place or at the time of conditioning after extinction in a different context. The results indicate that environmental and temporal contexts can independently, but similarly modulate taste aversion learning.Context is an often loosely defined term, which in neuroscience is becoming more common, especially with the current interest to investigate the neural bases of episodic memory in humans (Nadel et al 1985;Schacter and Tulving 1994) and to search for equivalent memory phenomena in nonhuman animals (Clayton and Dickinson 1998;Aggleton and Brown 1999). Whereas rats readily associate tastes of substances with their visceral consequences (García and Koelling 1966;García et al. 1968;Bures et al. 1998;Bernstein 1999), contextual cues also modulate conditioned taste aversions (CTA), because the context specificity, both of the expression (Boakes et al. 1997;Archer et al. 1979Archer et al. , 1980Jarbe et al. 1986;Puente et al. 1988;Bonardi et al. 1990;Loy et al. 1993) and extinction (Rosas and Bouton 1997;Archer et al. 1979) of a learned aversion, and of the latent inhibition (LI) of CTA (Rudy et al. 1977;Hall and Channell 1986) has been reported. In CTA studies, context frequently refers to a particular place that may combine a variety of external environmental cues. However, a broad definition of context may include not only external, but also internal, background cues and a sense of time (Bouton 1993;Pearce and Bouton 2001). Very few of the above-cited studies reporting context modulation of CTA have included the time of day as part of the context, either purposely (Rosas and Bouton 1997) or as the outcome of applying two daily drinking sessions (Hall and Channell 1986;Bonardi et al. 1990). Moreover, although the possibility that the time of day may itself form a context is supported by a recent report showing a time-of-day-dependent expression of the behavioral sensitization to amphetamine (Arvanitogiannis et al. 2000), to our knowledge, no study has explored the ability of the time of day to modulate CTA independently of the spatial context.In the present experiments, we specifically examine whether spatial (Exp. 1) and temporal (Exp. 2) contextual cues separately modulate learned saline-aversion memory phenomema. In Experiment 1, two different sized and shaped cages were used as contexts (Fig. 1). The environments differed in location, geometry, visual, auditory, and tactile cues. In Experiment 2, two different times during the illumination cycle were used as temporal contexts. To differentiate them as much as possible, morning (10:00) and evening (20:00) drinking sessions were used. E...

Circadian-temporal context and latent inhibition of conditioned taste aversion: Effect of restriction in the intake of the conditioned taste stimulus

“…In this experiment, we used 4 days of habituation to the temporal context. Temporal specificity of latent inhibition of CTA under long periods of contextual habituation has been described (Molero-Chamizo, 2013), but a short period seems to be a factor that hinders the contextual effect on taste aversion (Morón et al, 2002). The results of this study complement our knowledge of this phenomenon because they show that an exposure without restriction to the taste stimulus under a long period of contextual habituation facilitates the temporal specificity of the latent inhibition of CTA.…”

“…The magnitude of a conditioned taste aversion (CTA) can be modulated by a change in the time of day between conditioning and test (Manrique, Gámiz, Morón, Ballesteros, & Gallo, 2009;Morón et al, 2002). This procedure shows that animals tested in temporal contexts different from that of the conditioning acquire less aversion, which is similar to what has been consistently described by changing the spatial context (Boakes, Elliot, Swinbourne, & Westbrook, 1997;Bonardi, Honey, & Hall, 1990;Bouton, 1993;Bouton, Westbrook, Corcoran, & Maren, 2006;González, Garcia-Burgos, & Hall, 2012;Pearce & Bouton, 2001;Rosas & Bouton 1997).…”

“…As a result, a reduced processing of the taste stimulus during conditioning would prevent the effect of temporal specificity. For example, Morón et al (2002) applied a restriction in the intake of the taste stimulus during conditioning, resulting in a modulation of the taste aversion when tested in a different time of day from that of the conditioning. However, by 4 days of habituation to the temporal context, Molero-Chamizo (2013) found temporal specificity of the latent inhibition of CTA without considering any restriction in the amount of taste stimulus during conditioning.…”

Amygdala and Taste Learning

“…However, the influence of temporal context in associative processes is also a good model for understanding the mechanisms of learning and memory [133]. Regarding the modulating effect of time of day, we have shown in our laboratory that the time of day in the sleep/wake cycle acts as a contextual cue and modulates latent inhibition of taste aversion learning [134] and CTA retrieval [135].…”

“…Temporal context dependency also seems to be mediated by the hippocampus in the paradigm of latent inhibition of taste aversion learning [147], as well as in CTA [14]. However, no studies have reported the role of the amygdala in the temporal modulation of taste learning [134,135]. It is possible that the amygdala is involved in CTA selectively but not in the phenomenon of latent inhibition in this paradigm, nor in the contextual dependency of this phenomenon.…”