McDougall S A, Zolman J F, Mattingly B A
Behav Neurosci. 1987 Apr;101(2):254-63. doi: 10.1037//0735-7044.101.2.254.
In four experiments, the effects of augmenting or blocking dopamine receptor activity on response suppression learning of Colburn X Colburn chicks were determined. In each experiment, 4-day-old chicks were trained to key peck for heat reward and then tested for response suppression learning by using either a response-contingent punishment or an extinction-punishment task. Before response suppression testing, different groups of chicks were injected ip with apomorphine (1.0, 2.0, or 4.0 mg/kg) either alone or after pretreatment with haloperidol (0.5 or 1.0 mg/kg). Regardless of the response suppression task used, chicks injected with apomorphine had difficulty inhibiting their responding; whereas, chicks injected with haloperidol, either alone or before apomorphine treatment, responded on fewer trials than saline-treated chicks. During extinction testing, 4-day-old chicks given only apomorphine showed the typical suppressive effect of punishment on responding rather than the paradoxical punishment-induced increase in responding found in normal 1-day-old chicks. These results indicate that activation of dopamine receptors retards response suppression learning of the 4-day-old chick, but functional changes in central dopaminergic mechanisms are not primarily responsible for the normal age-dependent improvement in response suppression learning of the young chick.
在四项实验中，确定了增强或阻断多巴胺受体活性对科尔伯恩×科尔伯恩雏鸡反应抑制学习的影响。在每项实验中，对4日龄雏鸡进行训练，使其通过啄键获取热奖励，然后使用反应性惩罚或消退-惩罚任务对其反应抑制学习进行测试。在反应抑制测试前，不同组的雏鸡腹腔注射阿扑吗啡（1.0、2.0或4.0毫克/千克），单独注射或在预先用氟哌啶醇（0.5或1.0毫克/千克）预处理后注射。无论使用哪种反应抑制任务，注射阿扑吗啡的雏鸡在抑制反应方面都有困难；而单独注射氟哌啶醇或在阿扑吗啡治疗前注射氟哌啶醇的雏鸡，其反应次数比生理盐水处理的雏鸡少。在消退测试期间，仅给予阿扑吗啡的4日龄雏鸡表现出惩罚对反应的典型抑制作用，而不是正常1日龄雏鸡中发现的惩罚诱导的反应反常增加。这些结果表明，多巴胺受体的激活会延迟4日龄雏鸡的反应抑制学习，但中枢多巴胺能机制的功能变化并非幼雏反应抑制学习中正常的年龄依赖性改善的主要原因。
