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| Olfaction in Behavioral Research: Studies of Equivalence and Social Reinforcement in Rats |
| Sunday, May 26, 2024 |
| 10:00 AM–10:50 AM |
| Convention Center, 200 Level, 204 AB |
| Area: EAB/VBC; Domain: Basic Research |
| Chair: Katherine Ely Bruce (University of North Carolina Wilmington) |
| Abstract: Because rodents' dominant sense is olfaction, those stimuli can be effectively used in behavioral research. In this symposium, the presenters will share some recent research on rats using olfactory stimuli to examine complex behavioral patterns. First, Dr. Jay Hinnenkamp will present experiments in which olfactory stimuli were used 1) as reinforcers to maintain responding in socially-deprived rats and 2) in a probabilistic choice procedure. The next two talks focus on stimulus equivalence using olfactory stimuli as class members and have implications for nonhuman models of concept learning. Eli Richardson will describe procedures to test for class expansion after training initial olfactory classes with a repeated reversals procedure. Madeleine Mason will present experiments on transfer of function of newly-trained discriminative and avoidance functions within established class members. Both transfer of function and class expansion are features of equivalence classes in human research. All three presentations contribute to our understanding of behavioral control by olfactory stimuli. |
| Instruction Level: Advanced |
| Keyword(s): concept learning, equivalence, olfaction, social reinforcement |
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| Investigating the Effects of Olfactory Stimuli on Rats’ Choices |
| JAY HINNENKAMP (Middle Tennessee State University), Jubal Neal (Middle Tennessee State University), Jordan Latham (Middle Tennessee State University), Annie Galizio (Middle Tennessee State University) |
| Abstract: This talk will present data from two ongoing research projects in our lab that make use of olfactory stimuli. The first study investigated the effects of social isolation on rats’ preference for social scents. In this study individual rats were isolated from the colony of rats for 23 h and then given the option to respond across two olfactory ports. The first port produced scents from other rats, the second produced a control scent. All rats demonstrated a preference for social scents, but isolation only impacted some of the rats responding. The second study investigated the effects of using olfactory stimuli in a probabilistic choice procedure. In this procedure rats chose between an option that delivered food 50% of the time and an option that delivered food 25% of the time. The delay to food on both options was 50 s, but the 25% option had stimuli, which followed the rats’ choices, that predicted when food would occur while the 50% option did not. The percentage of choices that animals made and the implications of these findings will be discussed. |
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| Expansion of Functional Classes Using Olfactory Stimuli in Rats |
| ELIJAH RICHARDSON (University of North Carolina Wilmington) |
| Abstract: This study was conducted as part of the ongoing effort to develop a rodent model of equivalence relations. Rats were tested for evidence of functional equivalence and class expansion using olfactory stimuli. Initially, four olfactory stimuli were assigned to two arbitrary sets of two and rats were trained on a go no-go task to respond to members of only one set at a time. Reinforcement contingences for each set were reversed following accurate responding. After repeated reversals, probe sessions revealed that after encountering the reversed contingency with one member of each class, rats then responded at above chance accuracy to the other class members, which demonstrated transfer of function across functional classes in rodents. Next, researchers tested whether rats could show evidence for class expansion. Two new scents were trained alongside one member of each of the original sets using the same repeated reversal procedures. Next, probe sessions were conducted with the new scents and the other original set members to assess whether they had become class members. Expansion training and testing was replicated until set size reached a maximum of six stimuli. Results were consistent with predictions of class expansion. |
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| Functional Equivalence in Rats: Transfer of Discriminative and Avoidance Functions Across Class Members |
| MADELEINE MASON (University of North Carolina - Wilmington ) |
| Abstract: A recent demonstration of functional equivalence classes in rats has raised questions regarding the nature of these classes, specifically whether a novel function trained to one class member will transfer to remaining members as is observed in humans. Rats were trained on concurrent olfactory discriminations, with one set of odors arbitrarily designated as positive (Set X) and the other negative (Set Y). Contingencies (i.e., which set was positive) were repeatedly reversed each time subjects met mastery criteria. Accuracy on the first presentation of odors following a reversal was considered evidence for functional class formation. In Experiment 1, a new discriminative function (responding in a left- or right side-port) was trained to mastery for only one member or a subset of members of each class. Non-reinforced probe trials were then administered to test for transfer of the differential response to remaining class members. Partial evidence of transfer was found in some subjects. In Experiment 2, rats received mild foot shocks in the presence of one member of Set X but not Set Y. Transfer of avoidance responding across class members was then assessed using an active avoidance paradigm. Subjects avoided Set X odors on most but not all transfer tests. |
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