For a long time, it has been assumed that dopaminergic (DA) neurons in both the ventral tegmental area (VTA) and the substantia nigra pars compacta (SNc) uniformly respond to rewarding and aversive stimuli by either increasing or decreasing their activity, respectively. This response was believed to signal information about the perceived stimuli's values. The identification of VTA&SNc DA neurons that are excited by both rewarding and aversive stimuli has led to the categorisation of VTA&SNc DA neurons into two subpopulations: one signalling the value and the other signalling the salience of the stimuli. It has been shown that the general state of the brain can modulate the electrical activity of VTA&SNc DA neurons, but it remains unknown whether this factor may also influence responses to aversive stimuli, such as a footshock (FS). To address this question, we have recorded the responses of VTA&SNc DA neurons to FSs across cortical activation and slow wave activity brain states in urethane-anaesthetised rats. Adding to the knowledge of aversion signalling by midbrain DA neurons, we report that significant proportion of VTA&SNc DA neurons can change their responses to an aversive stimulus in a brain state-dependent manner. The majority of these neurons decreased their activity in response to FS during cortical activation but switched to increasing it during slow wave activity. It can be hypothesised that this subpopulation of DA neurons may be involved in the ‘dual signalling’ of both the value and the salience of the stimuli, depending on the general state of the brain.

中文翻译：

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乌拉坦麻醉下中脑多巴胺能神经元对足部电击的脑状态依赖性反应

长期以来，人们一直认为腹侧被盖区 (VTA) 和黑质致密部 (SNc) 的多巴胺能 (DA) 神经元分别通过增加或减少其活动来统一响应奖励和厌恶刺激。人们认为这种反应传达了有关感知刺激值的信息。被奖赏性和厌恶性刺激兴奋的 ​​VTA 和 SNc DA 神经元的识别导致将 VTA 和 SNc DA 神经元分为两个亚群：一个发出刺激值的信号，另一个发出刺激的显着性信号。研究表明，大脑的一般状态可以调节 VTA 和 SNc DA 神经元的电活动，但尚不清楚该因​​素是否也可能影响对厌恶刺激（例如足部电击 (FS)）的反应。为了解决这个问题，我们记录了乌拉坦麻醉大鼠中 VTA 和 SNc DA 神经元对皮质激活和慢波活动大脑状态的 FS 的反应。增加中脑 DA 神经元厌恶信号传导的知识，我们报告说，很大一部分 VTA 和 SNc DA 神经元可以以大脑状态依赖的方式改变其对厌恶刺激的反应。这些神经元中的大多数在皮层激活期间响应 FS 降低了其活动，但在慢波活动期间转为增加其活动。可以假设，根据大脑的总体状态，DA 神经元的这个亚群可能参与刺激值和显着性的“双重信号传导”。