Department of Psychology, University of Amsterdam, Amsterdam, The Netherlands.
Hum Brain Mapp. 2012 Jan;33(1):246-52. doi: 10.1002/hbm.21195. Epub 2011 May 5.
The nucleus accumbens and medial frontal cortex (MFC) are part of a loop involved in modulating behavior according to anticipated rewards. However, the precise temporal landscape of their electrophysiological interactions in humans remains unknown because it is not possible to record neural activity from the nucleus accumbens using noninvasive techniques. We recorded electrophysiological activity simultaneously from the nucleus accumbens and cortex (via surface EEG) in humans who had electrodes implanted as part of deep-brain-stimulation treatment for obsessive-compulsive disorder. Patients performed a simple reward motivation task previously shown to activate the ventral striatum. Spectral Granger causality analyses were applied to dissociate "top-down" (cortex → nucleus accumbens)- from "bottom-up" (nucleus accumbens → cortex)-directed synchronization (functional connectivity). "Top-down"-directed synchrony from cortex to nucleus accumbens was maximal over medial frontal sites and was significantly stronger when rewards were anticipated. These findings provide direct electrophysiological evidence for a role of the MFC in modulating nucleus accumbens reward-related processing and may be relevant to understanding the mechanisms of deep-brain stimulation and its beneficial effects on psychiatric conditions.
伏隔核和内侧前额叶皮层（MFC）是参与根据预期奖励调节行为的回路的一部分。然而，由于不可能使用非侵入性技术从伏隔核记录神经活动，因此人类中它们的电生理相互作用的精确时间景观仍然未知。我们在接受深部脑刺激治疗强迫症的患者中同时记录了伏隔核和皮层的电生理活动（通过表面 EEG）。患者执行了一个简单的奖励动机任务，该任务先前被证明可以激活腹侧纹状体。应用频谱 Granger 因果分析来区分来自皮层的“自上而下”（皮层→伏隔核）和来自伏隔核的“自下而上”（伏隔核→皮层）的直接同步（功能连接）。当预期到奖励时，来自皮层到伏隔核的“自上而下”方向的同步性在额中部位达到最大值，并且明显更强。这些发现为 MFC 在调节伏隔核与奖励相关的处理中的作用提供了直接的电生理证据，可能与理解深部脑刺激的机制及其对精神疾病的有益影响有关。
