Belke Terry W, Pierce W David, Welsh Tenea M
Mount Allison University, Sackville, New Brunswick, Canada.
University of Alberta, Edmonton, Alberta, Canada.
Behav Processes. 2018 Dec;157:91-101. doi: 10.1016/j.beproc.2018.09.003. Epub 2018 Sep 13.
The current study compared the development of response patterns for operant wheel-running and lever-pressing on fixed-interval schedules. Eleven female Long-Evans rats were exposed to fixed-interval (FI) 15-s, 30-s, and 60-s schedules with wheel revolutions as the operant behavior and sucrose solution as reinforcement. Subsequently, a lever was mounted in each wheel and rats responded on an FI-30 s schedule of sucrose reinforcement. Operant lever-pressing on average developed a scalloping pattern of low responding early in the reinforcement interval followed by an increase in pressing to the moment of reinforcement. In contrast, average operant wheel-revolutions peaked early in the reinforcement interval followed by a plateau, a pattern that did not change over sessions. Variation in the FI-schedule value (interval size) with operant wheel-running did not alter the pattern of running throughout the reinforcement interval, but merely parsed this pattern at different points. Cumulative records for the last session showed long postreinforcement pauses (PRP) for lever pressing. Wheel running, however, rose quickly after reinforcement and continued throughout the reinforcement interval. Overall and local wheel-running rates decreased and PRP duration increased as the interval size of the FI schedule increased. We propose that the automatic reinforcement generated by wheel running, but not lever pressing, provides an account of the poor temporal regulation of operant wheel-running in our study.
本研究比较了在固定间隔时间表上，操作性轮转和杠杆按压反应模式的发展情况。11只雌性Long-Evans大鼠被置于固定间隔（FI）15秒、30秒和60秒的时间表中，以轮转作为操作性行为，蔗糖溶液作为强化物。随后，在每个轮子上安装一个杠杆，大鼠按照FI-30秒的蔗糖强化时间表做出反应。操作性杠杆按压平均在强化间隔早期呈现出低反应的扇贝形模式，随后在强化时刻按压次数增加。相比之下，操作性轮转的平均值在强化间隔早期达到峰值，随后趋于平稳，这种模式在各实验阶段没有变化。FI时间表值（间隔时长）的变化对操作性轮转的影响是，在整个强化间隔内不改变轮转模式，只是在不同时间点对该模式进行划分。最后一个实验阶段的累积记录显示，杠杆按压出现了较长的强化后停顿（PRP）。然而，轮转在强化后迅速上升，并在整个强化间隔内持续。随着FI时间表间隔时长的增加，整体和局部的轮转速率下降，PRP持续时间增加。我们认为，轮转产生的自动强化作用，而非杠杆按压，解释了本研究中操作性轮转时间调节不佳的现象。
