Nucleus accumbens dopamine and work requirements on interval schedules
Nucleus accumbens dopamine and work requirements on interval schedules
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DOI：
10.1016/s0166-4328(02)00292-9
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发表时间：
2002-12-02
影响因子：
2.7
通讯作者：
Salamone, JD
中科院分区：
文献类型：
--
作者：
Correa, M;Carlson, BB;Salamone, JD
大量证据表明，伏隔核多巴胺(DA)参与了仪器反应输出的调节，对DA传递的干扰扰乱了大鼠克服工作相关反应成本的能力。本实验旨在评估伏隔多巴胺耗竭对可变间隔时程的影响，以确定时程的间歇性本身是否是伏隔多巴胺耗竭敏感性的重要决定因素。为此，使用了两个可变间隔30 S杠杆按压时间表，每个都在间隔要求上增加了不同的响应要求。在其中一个时间表中，动物在间隔过去后的第一次反应中得到加强(串联可变间隔/固定比率1：VI/FR1)。在另一个时间表上，附加了一项额外的工作要求，要求大鼠在间隔后做出五次反应以接受增援(串联可变间隔/固定比率5：VI/FR5)。附加额外的工作要求导致基线培训期间的答复率更高。训练结束后，将抗坏血酸载体或6-羟基多巴胺(6-OHDA)注入大鼠伏隔核。DA耗竭对反应的影响具有高度的时序依赖性。在低反应要求(V1/FR1)条件下，DA耗竭对杠杆按压没有显著影响，但在反应要求较高(VI/FR5)的条件下，DA耗竭严重扰乱了对程序的反应。在手术后4周的测试中，高反应要求的按计划反应的中断显示恢复。在第二个实验中，评估了6-OHDA对开阔场地自发活动的影响。与用药组相比，DA耗竭组大鼠在术后8天的运动和养育方面存在障碍，但在术后29天的测试中则没有，这表明伏隔区DA耗竭后的运动功能恢复。这些实验结果支持伏核DA参与调节行为激活的假说。杠杆挤压实验表明，伏隔内多巴胺的耗竭干扰了使大鼠克服诸如工作相关反应成本等行为限制的过程，并表明强化本身的间歇性本身并不是决定伏隔DA耗竭敏感性的最关键因素。(C)2002 Elsevier Science B.V.保留所有权利。
Considerable evidence indicates that nucleus accumbens dopamine (DA) is involved in the regulation of instrumental response output, and that interference with DA transmission disrupts the ability of rats to overcome work-related response costs. The present experiments were conducted to assess the effects of accumbens DA depletions on the performance of variable interval schedules, to determine if the intermittence of a schedule, in itself, is an important determinant of sensitivity to accumbens DA depletions. For this purpose, two variable interval 30 s lever pressing schedules were used, each with different response requirements added to the interval requirement. For one of the schedules, the animals were reinforced for the first response after the interval elapsed (tandem variable interval/fixed ratio 1: VI/FR1). On the other schedule an additional work requirement was attached by requiring the rats to make five responses after the interval in order to receive reinforcement (tandem variable interval/fixed ratio 5: VI/FR5). Attachment of the additional work requirement led to greater response rates during baseline training. After training, rats were injected with either ascorbate vehicle or 6-hydroxydopamine (6-OHDA) into the nucleus accumbens. The effects of DA depletion on responding were highly schedule-dependent. DA depletions had no significant effect on lever pressing under the condition with low response requirement (V1/FR1), but these depletions substantially disrupted responding on the schedule with the higher response requirement (VI/FR5). The disruption of responding on the schedule with the high response requirement showed recovery over the 4 weeks of post-surgical testing. In a second experiment, the effect of 6-OHDA on spontaneous locomotion in an open field was assessed. The DA-depleted animals had impairments in locomotion and rearing compared with the vehicle treated rats when tested 8 days after surgery, but not when tested 29 days after surgery, which demonstrates recovery of locomotor function after the accumbens DA depletions. The results of these experiments support the hypothesis that nucleus accumbens DA is involved in regulating behavioral activation. The lever pressing experiment indicates that depletions of DA in the accumbens interfere with the processes that enable rats to overcome behavioral constraints such as work-related response costs, and suggest that the intermittence of reinforcement per se is not the most critical factor in determining sensitivity to accumbens DA depletions. (C) 2002 Elsevier Science B.V. All rights reserved.