Pre-exposure Schedule Effects on Generalization of Taste Aversion and Palatability for Thirsty and Not Thirsty Rats

Abstract

The study reported four experiments aiming to test the effects of the pre-exposure schedule and water deprivation on the generalization of a conditioned taste aversion in rats, with a particular focus on testing whether or not the concurrent schedule might enhance generalization. In two experiments, non-water-deprived rats received concurrent, intermixed, or blocked exposure to a sweet-acid solution and a salty-acid solution before conditioning of one of these compounds and testing of both flavors. During pre-exposure, the rats consumed a greater amount of the sweet-acid solution than the salty-acid solution (Experiments 1 and 2), consumption of the former increasing during pre-exposure while consumption of the latter decreased (Experiment 1). Furthermore, consumption of the salty-acid solution was lower during concurrent than intermixed or blocked pre-exposure (Experiment 1 and 2) while consumption of the sweet-acid solution was greater during intermixed than concurrent or blocked pre-exposure (Experiment 1). It is discussed whether the pre-exposure schedule might modify stimulus perception beyond the mere enhancement of stimulus differentiation, by, for instance, affecting the palatability of gustatory stimuli. Evidence for enhanced generalization after concurrent pre-exposure was not found for either deprived (Experiments 1, 2, and 3) or non-deprived rats (Experiments 3 and 4), with deprivation leading to a general increase in consumption of both the conditioned and test flavors. This then raised the question of whether or not concurrent pre-exposure to flavors always increases generalization between them. The present study highlights the importance of this issue for various accounts of perceptual learning.

Strong Aversive Conditioning Triggers a Long-Lasting Generalized Aversion

“…Using this approach, we found that after a single conditioning trial, animals can form a long-lasting generalized aversion that persists up to 2 weeks post-CTA training. This persistence, to our knowledge, is longer than any reported thus far in the CTA literature on generalization ( Domjan, 1975 ; Parker and Revusky, 1982 ; Richardson et al, 1984 ; Smith and Theodore, 1984 ; Frank and Nowlis, 1989 ; Chotro and Alonso, 1999 ; Heyer et al, 2003 ; Baird et al, 2005 ; Smith et al, 2012 ; Angulo, 2018 ). The ethological significance of this behavior and the mechanism by which this generalization is occurring remain to be worked out.…”

“…This feature of CTA learning makes it an ideal paradigm to explore how differences in conditioning strength might alter the temporal dynamics of memory generalization. The generalized aversion resulting from CTA conditioning is a well-documented phenomenon ( Domjan, 1975 ; Parker and Revusky, 1982 ; Richardson et al, 1984 ; Smith and Theodore, 1984 ; Frank and Nowlis, 1989 ; Chotro and Alonso, 1999 ; Heyer et al, 2003 ; Baird et al, 2005 ; Smith et al, 2012 ; Angulo, 2018 ; Wu et al, 2021 ), but it is unclear how long this generalization can persist, which factors impact its duration, and the cellular basis of this persistence.…”

Strong Aversive Conditioning Triggers a Long-Lasting Generalized Aversion

“…Using this approach, we found that after a single conditioning trial, animals can form a long-lasting generalized aversion that persists up to two weeks post-CTA training. This persistence, to our knowledge, is longer than any reported thus far in the CTA literature on generalization (Domjan, 1975;Parker & Revusky, 1982;Richardson, Williams, & Riccio, 1984;Smith & Theodore, 1984;Frank & Nowlis, 1989;Chotro & Alonso, 1999;Heyer et al, 2003;Baird, St. John, & Nguyen, 2005;Smith et al, 2012;Angulo, 2018). The ethological significance of this behavior and the mechanism by which this generalization is occurring remain to be worked out.…”

“…This feature of CTA learning makes it an ideal paradigm to explore how differences in conditioning strength might alter the temporal dynamics of memory generalization. The generalized aversion resulting from CTA conditioning is a well-documented phenomenon (Domjan, 1975; Parker & Revusky, 1982; Richardson, Williams, & Riccio, 1984; Smith & Theodore, 1984; Frank & Nowlis, 1989; Chotro & Alonso, 1999; Heyer et al, 2003; Baird, St. John, & Nguyen, 2005; Smith et al, 2012; Angulo, 2018; Wu, Ramos, et al, 2021), but it is unclear how long this generalization can persist, which factors impact its duration, and the cellular basis of this persistence.…”

El efecto de la preexposición alternada y en bloques a los estímulos en una tarea de identificación de estímulos visuales

“…Por ejemplo, a diferencia de lo encontrado en humanos, la generalización de una respuesta condicionada entre estímulos similares en ratas parece ser mayor tras una preexposición concurrente que alterna o en bloques (e.g, Alonso & Hall, 1999;Rodríguez & Alonso, 2008;Rodríguez, Blair, & Hall, 2008;véase también Bennett & Mackintosh, 1999;Honey & Bateson, 1996) o al menos, no menor (e.g, Angulo, 2018). En tanto que el grado de generalización entre estímulos y su diferenciación guardarían entre sí una relación inversamente proporcional (a menor diferenciación, mayor generalización), estos resultados estarían indicando justo lo contrario a lo observado en humanos: una menor diferenciación de los estímulos después de una preexposición concurrente que alterna o en bloques.…”