Galbicka G, Fowler K P, Ritch Z J
Department of Medical Neurosciences, Walter Reed Army Institute of Research, Washington, D.C. 20307-5100.
J Exp Anal Behav. 1991 Sep;56(2):205-15. doi: 10.1901/jeab.1991.56-205.
Two fixed-consecutive-number-like procedures were used to examine effects of acute d-amphetamine administration on control over response number. In both procedures, rats were required to press the left lever at least once and then press the right lever to complete a trial. The consecutive left-lever presses on each trial comprised a "run." Under the targeted percentile schedule, reinforcement was provided if the current run length was closer to the target length (16) than half of the most recent 24 runs. This differentially reinforced run length while holding reinforcement probability constant at .5. A second group acquired the differentiation under the targeted percentile schedule, but were then shifted to a procedure that yoked reinforcement probability by subject and run length to that obtained under the targeted percentile schedule. The two procedures generated practically identical control run lengths, response rates, reinforcement probabilities, and reinforcement rates. Administration of d-amphetamine disrupted percentile responding to a greater degree than yoked control responding. This disruption decreased reinforcement frequency less in the former than the latter procedure. The similar baseline responding under these two procedures suggests that this difference in sensitivity was due to behavioral adjustments to drug prompted by reduction of reinforcement density in the yoked control but not the percentile schedule. These adjustments attenuate the drug's effects under the former, but not the latter, procedure.
采用两种类似固定连续数目的程序来检验急性给予右旋苯丙胺对反应次数控制的影响。在这两种程序中，大鼠需要至少按压一次左侧杠杆，然后按压右侧杠杆以完成一次试验。每次试验中连续按压左侧杠杆的次数构成一次“连续按压”。在目标百分位数程序下，如果当前连续按压长度比最近24次连续按压的一半更接近目标长度（16），则给予强化。这在保持强化概率恒定为0.5的同时，对连续按压长度进行差别强化。第二组在目标百分位数程序下习得这种区分，但随后转换到一种程序，该程序根据动物个体和连续按压长度将强化概率与在目标百分位数程序下获得的强化概率相匹配。这两种程序产生的实际控制连续按压长度、反应率、强化概率和强化率几乎相同。给予右旋苯丙胺对百分位数反应的干扰程度大于匹配控制反应。在前一种程序中，这种干扰导致的强化频率降低幅度小于后一种程序。这两种程序下相似的基线反应表明，这种敏感性差异是由于在匹配控制程序中强化密度降低促使对药物的行为调整，而在百分位数程序中则没有。这些调整在前一种程序中减弱了药物的作用，而在后一种程序中则没有。
