Engel B T, Talan M I
Laboratory of Behavioral Sciences, National Institute on Aging National Institutes of Health, Baltimore, MD 21224.
Physiol Behav. 1991 Feb;49(2):373-82. doi: 10.1016/0031-9384(91)90058-v.
Each of three monkeys was operantly conditioned to slow its heart, to exercise (lift weights) and to attenuate the tachycardia of exercise by combining these two skills. Each was further tested during beta-adrenergic blockade (atenolol), combined alpha-adrenergic blockade (prazosin) and beta-adrenergic blockade, or cholinergic blockade (methylatropine). During all experiments heart rate, stroke volume, intraarterial blood pressure, O2 consumption, and CO2 production were recorded on a beat-to-beat basis. Each animal was able to attenuate the tachycardia of exercise under each of the drug conditions, indicating that "central command" is not the expression of fixed, cardiovascular and pulmonary reflexes elicited by somato-motor commands, but rather is an adaptive behavior, determined by environmental contingencies and mediated by cardiovascular and pulmonary as well as somato-motor commands. The ability of the animals to perform with greater cardiac efficiency during the combined exercise and heart rate slowing task relative to the exercise-only task was not affected by sympathetic blockade; however, parasympathetic blockade did reduce cardiac efficiency.
三只猴子通过将减缓心率、锻炼（举重）这两项技能相结合，从而学会在运动时减缓心动过速，实现操作性条件反射。每只猴子在接受β-肾上腺素能阻滞剂（阿替洛尔）、联合α-肾上腺素能阻滞剂（哌唑嗪）和β-肾上腺素能阻滞剂或胆碱能阻滞剂（甲基阿托品）治疗期间，都进行了进一步测试。在所有实验过程中，逐搏记录心率、每搏输出量、动脉内血压、耗氧量和二氧化碳生成量。每只动物在每种药物条件下都能够减缓运动时的心动过速，这表明“中枢指令”并非是由躯体运动指令引发的固定心血管和肺反射的表现，而是一种适应性行为，由环境偶然性决定，并由心血管、肺以及躯体运动指令介导。与仅进行运动的任务相比，动物在联合运动和心率减缓任务中表现出更高心脏效率的能力不受交感神经阻滞的影响；然而，副交感神经阻滞确实降低了心脏效率。
