Hajnal Andras, Norgren Ralph
Department of Neural and Behavioral Sciences H181, The Pennsylvania State University, College of Medicine, Hershey, PA 17033, USA.
Physiol Behav. 2005 Mar 16;84(3):363-9. doi: 10.1016/j.physbeh.2004.12.014. Epub 2005 Jan 27.
Although it has been associated with the release of dopamine in the forebrain, reward remains a conundrum in neuroscience. Sucrose is inherently rewarding and its sensory message reaches the brain via the gustatory system. In rodents, the central gustatory system bifurcates in the pontine parabrachial nuclei, one arm forming a standard thalamocortical axis, the other distributing widely in the limbic forebrain. We report here that lesions of the gustatory thalamus fail to affect dopamine overflow during sucrose licking (149+/-5% vs. 149+/-4% for controls). Similar damage to the parabrachial nuclei, which severs the limbic taste projection, substantially reduces dopamine release from the nucleus accumbens (121+/-4% vs. 168+/-9% for sham operated controls; p<0.02). This represents the first demonstration that the affective character of a sensory stimulus might separate from the thalamocortical system as early as the second central synapse.
尽管奖励与前脑多巴胺的释放有关，但它在神经科学领域仍然是一个谜。蔗糖本身就具有奖赏性，其感官信息通过味觉系统传递到大脑。在啮齿动物中，中枢味觉系统在脑桥臂旁核处分叉，一条分支形成标准的丘脑皮质轴，另一条则广泛分布于边缘前脑。我们在此报告，味觉丘脑损伤并不会影响蔗糖舔舐过程中的多巴胺溢出（对照组为149±5%，损伤组为149±4%）。对臂旁核的类似损伤切断了边缘味觉投射，显著降低了伏隔核中的多巴胺释放（假手术对照组为168±9%，损伤组为121±4%；p<0.02）。这首次证明了感觉刺激的情感特征可能早在第二个中枢突触处就与丘脑皮质系统分离。
