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| EAB III |
| Tuesday, May 31, 2005 |
| 1:00 PM–1:50 PM |
| Boulevard C (2nd floor) |
| Area: EAB |
| Chair: Michael W. Schlund (Kennedy Krieger Institute) |
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| Barholding During Acute Pain in the Laboratory Rat |
| Domain: Basic Research |
| STACEY LAGRAIZE (University of Maryland), James Kopp (University of Texas at Arlington), Perry N. Fuchs (University of Texas at Arlington), Denise Lott Arellano (University of Texas at Arlington) |
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| Abstract: In a series of daily one hour sessions, ten female albino (Holtzmann) rats were brought under the control of a CHAIN [FR1] [FR1] [EXT60”(COD10”)] schedule of reinforcement Following training, an inflammatory (painful) condition was induced (1% formalin injection) in each rat’s hindpaw prior to its exposure the chain schedule. A formalin-free posttest was administerd a day later. During the formalin test there was a marked increase in the latency to the first response in each chain and a comparable decrease in the number of chains completed per minute. These results are in accord wiith theories relating pain and overall activity. On the other hand, duration (bar holding) of the initial response in each chain was two to three times longer on average during the formalin (pain) test than during pretest and posttest sessions The latter finding is rather counerintuitive suggesting, as it does, an additve relationship between pain and effort expended during skill performances. Further work should uncover more on the exact nature of such an interaction. |
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| Neuroimaging Gender Differences During Reinforcement and Discriminative Stimulus Presentation |
| Domain: Basic Research |
| MICHAEL W. SCHLUND (Kennedy Krieger Institute), Michael F. Cataldo (Kennedy Krieger Institute) |
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| Abstract: Evidence from human and nonhuman drug studies suggests that gender differences in dopamine system ‘sensitivity’ affects behavioral sensitivity to reinforcement. Results show that women compared to men are more vulnerable to psychostimulant drugs, require more time to become addicted, experience more cravings to drug cues, and show greater increases in blood flow in frontal-striatal ‘reward’ pathways drug cues. Similarly, female rats compared to male rats acquire cocaine self-administration behavior more rapidly and learning is less negatively affected by dopamine antagonists. In this presentation, we will present results of two BOLD fMRI investigations that measured brain activation in groups of human males and females during reinforcement (money gain) and during presentation of discriminative stimuli. In general, results revealed gender differences in frontal-striatal-thalamic regions, suggesting that gender may be a significant source of between-subject variability in fMRI data. Another intriguing question for future research is whether gender differences reflect fixed (hardwired) dopamine system differences or reflects the action of other variables such as learning history, task instructions or the motivational significance of money. |
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