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Neurobehavioral effects of repeated binge toluene exposure as measured by a waiting-for-reward operant task
Available online at www.sciencedirect.com
Neurotoxicology and Teratology 29 (2007) 588 – 590 www.elsevier.com/locate/neutera
Abstracts BTS 1 Neurobehavioral effects of repeated binge toluene exposure as measured by a waiting-for-reward operant task
BTS 2 Use of interval schedules to examine motivation and sustained attention
S.E. Bowen a,b, P. McDonald a a Department of Psychology, Wayne State University, USA b Department of Obstetrics and Gynecology, Wayne State University, USA
N.C. Cross a, J.J Chelonis a, M.N. Finch a, M.C. Edwards b, R.L. Baldwin b a State University of New York at Brockport, USA b University of Arkansas for the Medical Sciences and Arkansas Children’s Hospital, USA
The practice of inhaling solvents for recreational purposes continues to be a world-wide public health concern. Toluene, a volatile solvent in many abused products, is known to adversely affect the central nervous system. However, the neurobehavioral effects of toluene following high-concentration binge exposure patterns typical of abuse remain understudied. To study the effects of repeated toluene exposure on cognitive function, we assessed the effects of binge toluene exposure on behavioral impulse control in Swiss Webster mice using a “wait-for-reward” operant task. Mice were trained on a fixed-ratio (FR) schedule using sweetened milk as a reward. Upon achieving FR 15, a wait component was added, which delivered free rewards at increasing time intervals (2, 4, 6, s, etc, …). Mice continued to receive free rewards until they pressed a separate signaled lever that reinstated the FR component (FR Reset). Once proficient in the prescribed operant parameters, mice were exposed to either 1000 or 6000 ppm toluene, or 0 ppm (controls) for 30 min/day for 40 days. In order to compensate for the acute effects of toluene exposure, operant behavior was monitored 23 h later. Repeated toluene exposure decreased response rates, the number of FR resets, and increased mean wait time, resulting in a higher response to reinforcer ratio than exhibited by controls. Mice receiving the highest exposure (6000 ppm) showed a dramatic decrease in the ability to obtain the number of rewards achieved prior to toluene exposure which was reversed when toluene exposure ceased. Mice receiving the lowest exposure (1000 ppm) showed little change in the ability to achieve pre-exposure rewards. These results indicate that repeated binge exposures to high concentrations of toluene can significantly hamper performance as measured by a waitingfor-reward task, suggesting a significant impact on cognitive function. (Supported by grants DA15095 and DA15951.) doi:10.1016/j.ntt.2007.08.020
doi:10.1016/j.ntt.2007.08.004
Ratio schedules of reinforcement have been used extensively as behavioral measures of motivation in pharmacological and psychological research. In contrast, little research has utilized initial performance on interval schedules to examine motivation. The present study compared motivation using Variable Interval (VI-20s) and Fixed Interval (FI-20s) schedules of reinforcement for eight children with ADHD and fifteen controls. For this study, half of participants with ADHD and half of controls performed the 30-min VI-20s schedule first, while the other half performed the 30-min FI-20s schedule first. For the purposes of this study, data from each task were divided into three blocks of 10 min each. Children with ADHD made fewer responses on the first two blocks of the VI schedule compared to controls, regardless of whether the VI task was performed first or second. However, children with ADHD made similar responses to control children when the FI schedule was performed first, but made significantly fewer responses on block one and two compared to control children when the FI schedule was performed second. The present findings indicate that performance on FI and VI schedules of reinforcement may be a useful measure of motivation and may be influenced by the participant’s ability to sustain attention to the task. doi:10.1016/j.ntt.2007.08.021
BTS 3 Effects of reinforcer type on performance of psychological tasks S.L. Freas a , J.J. Chelonis a, L.B. Forzano a, M.G. Paule b a State University of New York College of Brockport, USA b National Center for Toxicological Research, USA
Neurotoxicology and Teratology 29 (2007) 588 – 590 www.elsevier.com/locate/neutera
Abstracts BTS 1 Neurobehavioral effects of repeated binge toluene exposure as measured by a waiting-for-reward operant task
BTS 2 Use of interval schedules to examine motivation and sustained attention
S.E. Bowen a,b, P. McDonald a a Department of Psychology, Wayne State University, USA b Department of Obstetrics and Gynecology, Wayne State University, USA
N.C. Cross a, J.J Chelonis a, M.N. Finch a, M.C. Edwards b, R.L. Baldwin b a State University of New York at Brockport, USA b University of Arkansas for the Medical Sciences and Arkansas Children’s Hospital, USA
The practice of inhaling solvents for recreational purposes continues to be a world-wide public health concern. Toluene, a volatile solvent in many abused products, is known to adversely affect the central nervous system. However, the neurobehavioral effects of toluene following high-concentration binge exposure patterns typical of abuse remain understudied. To study the effects of repeated toluene exposure on cognitive function, we assessed the effects of binge toluene exposure on behavioral impulse control in Swiss Webster mice using a “wait-for-reward” operant task. Mice were trained on a fixed-ratio (FR) schedule using sweetened milk as a reward. Upon achieving FR 15, a wait component was added, which delivered free rewards at increasing time intervals (2, 4, 6, s, etc, …). Mice continued to receive free rewards until they pressed a separate signaled lever that reinstated the FR component (FR Reset). Once proficient in the prescribed operant parameters, mice were exposed to either 1000 or 6000 ppm toluene, or 0 ppm (controls) for 30 min/day for 40 days. In order to compensate for the acute effects of toluene exposure, operant behavior was monitored 23 h later. Repeated toluene exposure decreased response rates, the number of FR resets, and increased mean wait time, resulting in a higher response to reinforcer ratio than exhibited by controls. Mice receiving the highest exposure (6000 ppm) showed a dramatic decrease in the ability to obtain the number of rewards achieved prior to toluene exposure which was reversed when toluene exposure ceased. Mice receiving the lowest exposure (1000 ppm) showed little change in the ability to achieve pre-exposure rewards. These results indicate that repeated binge exposures to high concentrations of toluene can significantly hamper performance as measured by a waitingfor-reward task, suggesting a significant impact on cognitive function. (Supported by grants DA15095 and DA15951.) doi:10.1016/j.ntt.2007.08.020
doi:10.1016/j.ntt.2007.08.004
Ratio schedules of reinforcement have been used extensively as behavioral measures of motivation in pharmacological and psychological research. In contrast, little research has utilized initial performance on interval schedules to examine motivation. The present study compared motivation using Variable Interval (VI-20s) and Fixed Interval (FI-20s) schedules of reinforcement for eight children with ADHD and fifteen controls. For this study, half of participants with ADHD and half of controls performed the 30-min VI-20s schedule first, while the other half performed the 30-min FI-20s schedule first. For the purposes of this study, data from each task were divided into three blocks of 10 min each. Children with ADHD made fewer responses on the first two blocks of the VI schedule compared to controls, regardless of whether the VI task was performed first or second. However, children with ADHD made similar responses to control children when the FI schedule was performed first, but made significantly fewer responses on block one and two compared to control children when the FI schedule was performed second. The present findings indicate that performance on FI and VI schedules of reinforcement may be a useful measure of motivation and may be influenced by the participant’s ability to sustain attention to the task. doi:10.1016/j.ntt.2007.08.021
BTS 3 Effects of reinforcer type on performance of psychological tasks S.L. Freas a , J.J. Chelonis a, L.B. Forzano a, M.G. Paule b a State University of New York College of Brockport, USA b National Center for Toxicological Research, USA