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| Drug Effects on Conditional Discriminations |
| Sunday, May 25, 2008 |
| 9:00 AM–10:20 AM |
| Inspiration Studio |
| Area: BPH/EAB; Domain: Basic Research |
| Chair: Bryan S. Lovelace (University of North Texas) |
| Discussant: John A. Nevin (University of New Hampshire) |
| Abstract: This symposium will examine experimental findings of drug effects on conditional discrimination performance and offer a discussion of relevant conceptual issues. |
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| Effects of Cocaine Administration on Performance under a Titrating-Delay Matching-to-Sample Procedure. |
| BRIAN D. KANGAS (University of Florida), Marc N. Branch (University of Florida) |
| Abstract: In the current study, four pigeons were exposed to a titrating delay matching-to-sample procedure in which the delay between sample-stimulus offset and comparison-stimuli onset was adjusted as a function of the pigeon’s accuracy. Specifically, every two consecutive correct matches increased the delay by one second, and each incorrect match decreased the delay by one second. Because previous research has shown that increasing the observing response requirement on the sample increases accuracy under TDMTS procedures, multiple responses on the sample key were required prior to sample offset to engender higher titrated delay values to allow for the assessment of drug effects. Once stable daily mean titrated delays were observed, the effects of a range of cocaine doses (1.0-10.0 mg/kg) were studied. Results of acute cocaine administration suggest dose-related decreases in titrated delay relative to baseline performance. Data collected during and after chronic exposure suggests tolerance to the effects of cocaine of moderate doses. |
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| Effects of Nicotine on Temporal Discrimination and Attending to Temporal Samples. |
| SCOTT T. BARRETT (Utah State University), Robert N. Johnson (Delta State University), Ryan D. Ward (Utah State University), Amy Odum (Utah State University) |
| Abstract: Recent research has shown that disruption by drugs and other manipulations is consistent with a decrease in attending to samples. The present study investigated the effects of nicotine, a drug that has been reported to increase attending under a number of experimental procedures, on a temporal discrimination task in pigeons. Four pigeons responded under an interval-bisection procedure, in which presented sample durations were categorized as either shorter or longer than 3 seconds by responding on a key lit a corresponding color. Following stability, we administered nicotine (0.03-3.0 mg/kg). The proportion of responses to the “long” key color was analyzed and the psychophysical function was fit by a cumulative normal function with four parameters (upper and lower asymptotes, mean, and SD) in order to differentiate specific effects of nicotine on temporal discrimination from those on overall stimulus control (attending). Across doses, nicotine had no systematic effects on the mean or SD of the function, but dose-dependently decreased the range of the function. These results suggest that nicotine, like previous drugs and other manipulations studied, reduces the degree of stimulus control under these experimental arrangements, but has no systematic effects on temporal discrimination. |
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| Incrementing Non-Match-to-Sample in Rats: Effects of Drugs. |
| DAVID A. MACQUEEN (University of North Carolina, Wilmington), Laura A. Bullard (University of North Carolina, Wilmington), Theophania Guze (University of North Carolina, Wilmington), Mark Galizio (University of North Carolina, Wilmington) |
| Abstract: The present study developed an incrementing non-match to sample procedure in rats designed to be analogous to memory span tasks used with humans. Rats were placed in a large arena with 18 food locations. In the initial trial of each session, one food cup marked with a distinct olfactory stimulus was present and responding to it was reinforced. Each subsequent trial added a new olfactory stimulus and responding to the new stimulus was always reinforced (non-matching). The dependent measures were number of stimuli that incremented without error (span) and overall percent correct responses. Spans improved with successive testing and frequently exceeded 20 stimuli. Both morphine and NMDA-receptor antagonist, dizocilpine, interfered with performance on this task, but only dizocilpine did so selectively. |
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