Development of intersensory function: Age-related differences in stimulus selection of multimodal compounds in rats as revealed by Pavlovian conditioning.

Abstract

Preweanling and adult rats were exposed to Pavlovian stimulus pairings with lights, tones, and light-tone compounds as conditional stimuli (CSs). Tone intensity was varied. As was found in previous studies using flavor CSs, odor CSs, or both, in which significant overshadowing or potentiation occurred to an element of a compound, overshadowing was less likely and potentiation more likely for preweanlings than for adults. Several experiments supported the view that these effects reflect an age-related difference in the controlling properties of stimuli: Young rats are more disposed to encode multimodal compounds on the basis of amodal intensity, whereas their elders are more likely to encode modality-specific properties of light and sound. Differential reinforcement in the presence of lights, tones, and light-tone compounds made preweanlings' stimulus selection appear more adultlike and may be a cause of development of intersensory function.

Contextual fear conditioning differs for infant, adolescent, and adult rats

“…In summary, neither extinction of the training context, nor that of the CS, altered expression of conditioning to the CS-context compound, in consonance with previous data gathered on infant rats (e.g., Lariviere et al, 1990;Mellon, Kraemer, & Spear, 1991).…”

“…Obviously, and unfortunately, effects of the extinction treatments on expression of contextual fear conditioning could not be determined fully for adults, because their contextual fear conditioning occurred only in the unpaired condition. Similar age-related differences in responding to components of a compound stimulus previously have been reported for analogous circumstances (e.g., Lariviere et al, 1990;Mellon et al, 1991).…”

“…A two-way ANOVA, 5 (Group) × 2 (Sex), showed an effect of the Group factor [F (4, 57) = 7.01], but no effect of either Sex, or the Group × Sex interaction. So data were clustered across Group and LSD tests conducted.In accord with visual inspection of Figure 2, they showed that the difference between NOEXT and UNPAIRED (and CXTCTL) was significant, and that neither CSEXT nor CXTEXT differed from NOEXT, but both differed from UNPAIRED (and CXTCTL).In summary, neither extinction of the training context, nor that of the CS, altered expression of conditioning to the CS-context compound, in consonance with previous data gathered on infant rats (e.g., Lariviere et al, 1990;Mellon, Kraemer, & Spear, 1991).It should be noted that responding to the CS-context compound after CS exposure might simply reflect the failure of such exposure as an effective extinction treatment. However, because the CS extinction treatment led to a diminished fear response to the context alone, it seems reasonable to assume that this extinction treatment was, somehow, able to weaken some underlying association with the US.…”

“…For infants, fear to the CS-context compound was unaffected by extinction of either context alone or the CS alone, implying the same strong differentiation between a compound and its individual components observed for infants in other paradigms (e.g., Lariviere et al, 1990;Mellon et al, 1991;Spear & Kucharski, 1984). Responding to the CS-context compound by adolescent males and females also was unaffected by context extinction, and the females were unaffected by CS extinction, as occurred for infants.…”

Intersensory redundancy accelerates preverbal numerical competence

“…When given information that is redundant across multiple senses, nonhuman animals and humans tested on a wide variety of non-numerical dimensions have been shown to improve in accuracy and/or reaction time, relative to performance with unisensory stimuli (e.g., Bahrick and Lickliter, 2000;Gogate and Bahrick, 1998;Lewkowicz and Kraebel, 2004;Lickliter et al, 2002;Lovelace et al, 2003;Mellon et al, 1991;Meredith and Stein, 1983). For example, multimodal cues occurring together in time and space enhance responses of multisensory neurons in the superior colliculus of cats to a level above the responses evoked by unisensory cues; multisensory cues also produce behaviorally evident increases in cats' effectiveness at detecting, orienting towards, and approaching the cue as compared with responses to unimodal sensory cues (e.g., Meredith and Stein, 1983;Stein, Huneycutt, and Meredith, 1988).…”