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| Mouse Operant: Measurements and Analyses |
| Saturday, May 26, 2007 |
| 3:30 PM–4:50 PM |
| Madeleine AB |
| Area: EAB; Domain: Basic Research |
| Chair: Troy J. Zarcone (University of Rochester Medical Center) |
| Abstract: There is growing interest in the use of genetically defined mice to model functional behavioral endpoints. To achieve this goal, neuroscientists are looking to the behavior of mice to determine if their biological manipulations have meaningful effects on the behavioral model of interest. To date, operant techniques have played a minor role in the advancement of genetics and neuroscience. Neuroscientists and genetisists have relied heavily on simple behavioral preparations that appear to be easy to replicate. However, there is growing demand for more sophisticated preparations that operant techniques can fulfill. The present symposia present examples of operant procedures and analyses that address these issues. |
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| Matching in the Mouse: Is it Innate? |
| DAN GOTTLIEB (Rutgers University), Charles Gallistel (Rutgers University), A. King (Rutgers University), Fuat Balci (Rutgers University), Efstathios Papachristos (Rutgers University), M Szalecki (Rutgers University), K Carbone (Rutgers University) |
| Abstract: Experimentally naïve mice matched the proportions of their temporal investments (visit durations) in two feeding hoppers to the proportions of he food income (pellets per unit session time) derived from them in three experiments. The coupling between the behavioral investment and food income varied across experiments, from no coupling to strict coupling. Using cumulative records, we tracked matching on a feeding by feeding basis. Matching was observed from the outset and did not improve with training. When the numbers of pellets received were proportional to time invested, investment was unstable, swinging abruptly from sustained almost complete investment in one hopper to sustained almost complete investment in the other. Animals sometimes switched hoppers in the absence of any change in returns pellets obtained / time invested). We suggest that matching reflects an innate (unconditioned) program that matches the ratio of expected visit durations to the ratio between the current estimates of expected incomes. As matching behavior reflects the involvement of both temporal memory and place memory, it can be used as a general screen for memory abnormalities in genetically modified mice. Because matching emerges from the outset, it is typically possible to assess performance in three or fewer sessions. |
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| Use of an IRT-Based Procedure to Establish Fixed-Ratio Performance in Genetically Altered Mice. |
| JONATHAN W. PINKSTON (University of Kansas) |
| Abstract: Several authors have suggested that operant lever pressing is unsuitable for use in differentiating among genetically altered mouse strains. Such research, however, generally has not had the benefit of training procedures informed by established behavioral principles, which may account for some difficulties noted in previous research. In our lab, for example, we have developed a training procedure that rapidly establishes fixed-ratio performance in mice. Our procedure provides an individually tailored training regimen to shape responding based on interresponse times. Because fixed-ratio performance is typically characterized by a ‘run’ of a rapid succession of responses, the program increases the prevailing ratio only when the last several emitted responses have relatively short interresponse times, specifically less than 1 second. Thus, the program uses short interresponse times to identify reasonably well-differentiated fixed-ratio performance and then increases the ratio, repeating this process until the terminal schedule value is reached. Our data have shown this method of training to be very effective in establishing lever pressing at moderate fixed-ratio values. The existing data from several strains will be presented and shown to be comparable to that of other species in terms of pattern and overall response rate. Such similarities show that the lever press may be effectively studied with mice, an outcome that underscores the importance of having a knowledge base grounded in basic learning principles for the design of future studies in the field of mouse behavioral genetics. |
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| Interval-Timing in the Genetically Modified Mouse. |
| FUAT BALCI (Rutgers University), Efstathios Papachristos (Rutgers University), Charles Gallistel (Rutgers University) |
| Abstract: A genetic approach to the molecular, cellular systems and neurobiology of the circadian clock has proved fruitful. This encourages a similar approach to the neurobiology of the interval timing mechanism, in which one uses behavioral screens to find individual mutant mice with gross quantitative abnormalities in their interval timing. Here, we report a behavioral screen for the quantitative study of interval timing and interval memory that is simple and efficient and works well in the C57 BL/6 mouse, the background-strain for most experimental genetic manipulations. Mice learn to switch from a short-latency feeding station to a long-latency station when the short latency has passed without a feeding. The psychometric function is the cumulative distribution of switch latencies. Its median measures timing accuracy and its interquartile interval measures timing precision. We use this screen to test the hypothesis that Gastrin-Releasing Peptide-Receptor knockout mice show enhanced (i.e., prolonged) freezing because they are more uncertain than wild types about when to expect the shock. The knockouts show normal accuracy and precision in timing. We argue that interval timing and memory should generally be tested in putative learning and memory mutants and that this paradigm allows this to be done simply and efficiently. |
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| Effects of Methamphetamine on Operant Responding of C57BL/6J Mice. |
| TROY J. ZARCONE (University of Rochester Medical Center), Anna Shapiro (University of Rochester Medical Center), Mollie Tubbs (University of Rochester Medical Center), Dena Carbonari (University of Rochester Medical Center) |
| Abstract: The purpose of these studies was to examine the direct and aftereffects of methamphetamine on operant performances in C57BL/6J male mice, a common background strain used for knockout mice and drug abuse studies. Mice were trained to perform a hole-poke response under a fixed presentation of varying reinforcement schedules. Methamphetamine was administered either just prior to the session to determine the direct effects or administered the day before in a separate environment to determine the after-effects. The C56BL/6J mice readily develop operant responding under computer automated training procedures and develop reliable response patterns in the presence of a fixed presentation of stimulus/reinforcement schedules. Both the direct and aftereffects of methamphetamine depend on the environmental context of the operant. These results show that the C57BL/6J mouse can be readily trained and produce reliable dose effect functions. The present data can be used for comparison to other genetically modified mice derived from the C57BL/6J background strain. |
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