Miliaressis E, Rompre P P, Laviolette P, Philippe L, Coulombe D
Physiol Behav. 1986;37(1):85-91. doi: 10.1016/0031-9384(86)90388-4.
Eleven rats were trained to press a lever in an operant chamber in order to earn rewarding trains of cathodal rectangular pulses of fixed intensity and variable frequency. The rate-frequency functions were examined under administration of two neuroleptics (pimozide and chlorpromazine) and three manipulations that interfered with bar pressing (muscular relaxation with methocarbamol, increased lever weight, and limitation of maximum response rates by an F1 reinforcement schedule). Chlorpromazine, and pimozide at low dosages produced a near parallel shift of the rate-frequency functions on the logarithmic axis of pulses, suggesting that these drugs decreased the reinforcing efficacy of the stimulation. The three conditions that interfered with bar-pressing decreased the asymptotic rates and produced small or moderate lateral shifts. Changes in the reinforcing efficacy of the stimulation following the above manipulations were inferred from the shift in the number of pulses required at zero and half-maximal performance (theta 0 and M50 indices, respectively). In the cases of the manipulations that interfered with bar-pressing, M50 indicated a larger artifactual change in the efficacy of the stimulation, compared to theta 0. This phenomenon was mainly due to the fact that the asymptote of the altered functions was shifted towards higher pulse numbers.
训练了11只大鼠在操作性条件反射箱中按压杠杆，以获得固定强度和可变频率的阴极矩形脉冲奖励序列。在给予两种抗精神病药物（匹莫齐特和氯丙嗪）以及三种干扰杠杆按压的操作（用美索巴莫进行肌肉松弛、增加杠杆重量以及通过F1强化程序限制最大反应率）的情况下，检查了频率函数。氯丙嗪和低剂量的匹莫齐特在脉冲对数轴上使频率函数产生近乎平行的移动，表明这些药物降低了刺激的强化效力。三种干扰杠杆按压的条件降低了渐近速率，并产生了小或中等程度的横向移动。通过零性能和半最大性能时所需脉冲数的变化（分别为θ0和M50指数）推断上述操作后刺激强化效力的变化。在干扰杠杆按压的操作中，与θ0相比，M50表明刺激效力的人为变化更大。这种现象主要是由于改变后的函数渐近线向更高的脉冲数移动。
