Bowers W J, Zacharko R M, Anisman H
Behav Brain Res. 1987 Jan;23(1):85-93. doi: 10.1016/0166-4328(87)90245-2.
The effect of uncontrollable footshock was evaluated in animals responding for intracranial self-stimulation from the nucleus accumbens and the substantia nigra (pars compacta) in a descending current intensity paradigm. Responding for brain stimulation from the nucleus accumbens was found to be affected by the stressor at the upper end of the rate-intensity curve. In contrast, responding for brain stimulation from the substantia nigra was unaffected by the stressor at any of the current intensities employed. The variations of responding for self-stimulation from the nucleus accumbens were unrelated to alterations of locomotor activity or rearing. It is suggested that stressor-provoked reductions of responding for intracranial self-stimulation are not a result of the brain stimulation taking on aversive properties, but rather reflect a reduction in the reinforcing or motivational value associated with the stimulation.
在一个递减电流强度范式中，对从伏隔核和黑质（致密部）进行颅内自我刺激做出反应的动物，评估了不可控足部电击的影响。发现在速率-强度曲线的上端，应激源会影响对伏隔核脑刺激的反应。相比之下，在所采用的任何电流强度下，对黑质脑刺激的反应都不受应激源的影响。伏隔核自我刺激反应的变化与运动活动或竖毛行为的改变无关。研究表明，应激源引起的颅内自我刺激反应减少，不是因为脑刺激具有厌恶性质，而是反映了与刺激相关的强化或动机价值的降低。
