Morehead State University
Continuous Progressive Ratio Schedules as an Assessment of the Effects of Amphetamine on Motivation
Institution
Morehead State University
Faculty Advisor/ Mentor
Wesley White; Clinton Blair
Abstract
Animals appear to pass through a sequence of physiological/ psychological states following amphetamine administration (stimulant, depressant, and recovery states). The purpose of this research was to see if the presence of these states could be inferred from changes in performance on a progressive ratio schedule. On a progressive ratio schedule, the number of responses required to obtain reward is increased after each reward, and changes in progressive ratio breakpoint (the highest ratio the subject completes) have been used to assess the effects of treatments on motivation. Subjects were eight female Sprague-Dawley rats. Animals were trained in one of four operant conditioning stations to respond on a progressive ratio schedule for food reward. Once trained, animals were transferred to one of eight monitoring stations where they could be continuously housed and where they could initiate responding on a progressive ratio schedule at different times during the light-dark cycle. When the pattern of breakpoints across the light-dark cycle stabilized, animals were administered a dose of amphetamine, and breakpoints at different times in the light-dark cycle were again assessed. Compared to baseline, amphetamine caused a change in the pattern of breakpoints seen at different times in the light-dark cycle. The change in the pattern of breakpoints suggested that the animals were in different physiological/ psychological states at different times post amphetamine administration. Continuous progressive ratio schedules could be used to assess a wide variety of treatments on motivation.
Continuous Progressive Ratio Schedules as an Assessment of the Effects of Amphetamine on Motivation
Animals appear to pass through a sequence of physiological/ psychological states following amphetamine administration (stimulant, depressant, and recovery states). The purpose of this research was to see if the presence of these states could be inferred from changes in performance on a progressive ratio schedule. On a progressive ratio schedule, the number of responses required to obtain reward is increased after each reward, and changes in progressive ratio breakpoint (the highest ratio the subject completes) have been used to assess the effects of treatments on motivation. Subjects were eight female Sprague-Dawley rats. Animals were trained in one of four operant conditioning stations to respond on a progressive ratio schedule for food reward. Once trained, animals were transferred to one of eight monitoring stations where they could be continuously housed and where they could initiate responding on a progressive ratio schedule at different times during the light-dark cycle. When the pattern of breakpoints across the light-dark cycle stabilized, animals were administered a dose of amphetamine, and breakpoints at different times in the light-dark cycle were again assessed. Compared to baseline, amphetamine caused a change in the pattern of breakpoints seen at different times in the light-dark cycle. The change in the pattern of breakpoints suggested that the animals were in different physiological/ psychological states at different times post amphetamine administration. Continuous progressive ratio schedules could be used to assess a wide variety of treatments on motivation.