腦底部的多巴胺神經(jīng)元是正常運(yùn)動(dòng)行為的關(guān)鍵，它們的損失會(huì)導(dǎo)致帕金森氏癥等疾病,。然而,，多巴胺神經(jīng)元的活性與身體運(yùn)動(dòng)無關(guān)，而是與獎(jiǎng)勵(lì)事件有關(guān),。最近的理論表明,，多巴胺神經(jīng)元作為一個(gè)同質(zhì)的功能集團(tuán)通過與獎(jiǎng)勵(lì)相關(guān)的信號來引導(dǎo)運(yùn)動(dòng)學(xué)習(xí),。
現(xiàn)在，用對“正”刺激和“負(fù)”刺激做出巴甫洛夫條件反射的猴子所做的一項(xiàng)研究表明,，多巴胺神經(jīng)元比這一模型所暗示的異質(zhì)性要更強(qiáng)一些,。位于腦中稍有不同的區(qū)域中的不同類別的多巴胺神經(jīng)元，對愉快的和不愉快的刺激有特定反應(yīng),，對與這些事件相關(guān)的誘發(fā)刺激也有特定反應(yīng),。這表明，多巴胺神經(jīng)元在學(xué)習(xí)控制中的參與情況要更為復(fù)雜,，它們所編碼的信號也要比簡單的獎(jiǎng)勵(lì)更為微妙,。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 459, 837-841 (11 June 2009) | doi:10.1038/nature08028
Two types of dopamine neuron distinctly convey positive and negative motivational signals
Masayuki Matsumoto1 & Okihide Hikosaka1
Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892-4435, USA
Midbrain dopamine neurons are activated by reward or sensory stimuli predicting reward1, 2, 3, 4. These excitatory responses increase as the reward value increases5. This response property has led to a hypothesis that dopamine neurons encode value-related signals and are inhibited by aversive events. Here we show that this is true only for a subset of dopamine neurons. We recorded the activity of dopamine neurons in monkeys (Macaca mulatta) during a Pavlovian procedure with appetitive and aversive outcomes (liquid rewards and airpuffs directed at the face, respectively). We found that some dopamine neurons were excited by reward-predicting stimuli and inhibited by airpuff-predicting stimuli, as the value hypothesis predicts. However, a greater number of dopamine neurons were excited by both of these stimuli, inconsistent with the hypothesis. Some dopamine neurons were also excited by both rewards and airpuffs themselves, especially when they were unpredictable. Neurons excited by the airpuff-predicting stimuli were located more dorsolaterally in the substantia nigra pars compacta, whereas neurons inhibited by the stimuli were located more ventromedially, some in the ventral tegmental area. A similar anatomical difference was observed for their responses to actual airpuffs. These findings suggest that different groups of dopamine neurons convey motivational signals in distinct manners.
