Dept. of Neuroscience, Medical University of South Carolina, Charleston, SC, USA.
Dept. of Neuroscience, Medical University of South Carolina, Charleston, SC, USA.
Brain Res. 2010 Sep 10;1351:57-63. doi: 10.1016/j.brainres.2010.07.002. Epub 2010 Jul 31.
Among the brain structures involved in processing affective stimuli, the roles of the prefrontal cortex (PFC) and the mesocorticolimbic dopaminergic (DA) innervation are well established. In contrast to our understanding of the reward stimuli, less is known about how strong somatic stimulation is processed within the PFC. Here, we examined the effects of a strong pinch delivered to the rat posterior paw on spontaneous and current-evoked activity of PFC neurons using intracellular recordings in anesthetized rats. Following the paw pinch, pyramidal cells exhibited a significant decrease in spontaneous activity along with a significant increase in the current-evoked firing. The increase in current-evoked firing elicited by the paw pinch was inversely correlated with the baseline firing rate. Systemic administration of a selective dopamine D2 receptor antagonist partially blocked the effects elicited by the paw pinch on cortical excitability, whereas systemic administration of a D1 antagonist seems to facilitate paw-mediated increases in evoked firing. These results suggest that strong somatic stimuli decrease spontaneous firing while increasing depolarization-evoked firing in a DA receptor dependent manner. These mechanisms may help in the control of the signal to noise ratio or the salience of information processing in the PFC following strong somatic stimulation.
在参与处理情感刺激的大脑结构中，前额叶皮层（PFC）和中脑边缘多巴胺能（DA）神经支配的作用已得到充分证实。与我们对奖励刺激的理解相比，人们对 PFC 内如何处理强烈的躯体刺激知之甚少。在这里，我们使用麻醉大鼠中的细胞内记录来检查对大鼠后爪施加强烈捏合时对 PFC 神经元的自发和电流诱发活动的影响。捏合后，锥体神经元的自发活动明显减少，而电流诱发的放电明显增加。捏合引起的电流诱发放电的增加与基线放电率呈反比。系统给予选择性多巴胺 D2 受体拮抗剂可部分阻断捏合对皮质兴奋性的影响，而系统给予 D1 拮抗剂似乎可促进由爪子介导的诱发放电增加。这些结果表明，强烈的躯体刺激以 DA 受体依赖的方式降低自发放电，同时增加去极化诱发的放电。这些机制可能有助于在强烈的躯体刺激后控制 PFC 中的信号与噪声比或信息处理的显着性。
