Effects of transcranial direct current stimulation on cortical and subcortical persistent activity

根据计划和目标指导我们作出反应的能力是人类行为的一个基本方面。工作记忆(WM)--暂时记忆信息的能力--比如当一个人记住他想要拨打的电话号码时，这是认知中研究最多的方面之一。大脑的两个区域，前额叶和后顶叶皮质，与工作记忆表现关系最密切。允许暂时改变大脑活动的非侵入性实验技术能够极大地增加我们对WM的理解，因为它们允许在特定大脑区域的活动和WM能力之间建立直接关系。经颅直流电刺激是一种安全、非侵入性的脑刺激方法，正在迅速普及。在这项技术中，微弱的电流被施加到头部表面，这被认为会导致大脑兴奋性的微妙、持久的变化。前额叶和顶叶皮质的tDCs已被证明影响人类的WM表现，但由于缺乏tDCs的动物模型，我们对导致这些认知变化的大脑活动变化的理解受到限制。非人灵长类动物可以很容易地接受训练，执行WM任务，并且具有与人类相似的皮质区域。本研究的目的是通过结合tDCs和WM任务中猕猴前额叶和后顶叶皮质的脑活动记录，来加深我们对tDCs对脑活动的影响的理解。

The ability to guide our responses on the basis of plans and goals is a fundamental facet of human behaviour. Working memory (WM) - the ability to temporarily retain information- such as when one holds in mind a phone number one wishes to dial, is one of the most studied aspects of cognition. Two brain areas, the prefrontal and posterior parietal cortex, have been most closely linked to WM performance. Non-invasive experimental techniques that allow temporary modifications of brain activity have the capability to add greatly to our understanding of WM, since they allow establishment of a direct relationship between activity in a particular brain area and WM ability. Transcranial direct current stimulation (tDCS) is a safe, non-invasive method of brain stimulation that is rapidly gaining in popularity. In this technique, weak electrical currents are applied to surface of the head, which are believed to lead to subtle, long-lasting changes in excitability of the brain. tDCS of both prefrontal and parietal cortex has been shown to influence WM performance in humans but our understanding of the changes in brain activity responsible these cognitive changes is limited by our lack of animal models of tDCS. Non-human primates can be readily trained to perform WM tasks, and have similar cortical areas to humans. The objective of this research is to advance our understanding of the effects of tDCS on brain activity by combining tDCS and recordings of brain activity in the prefrontal and posterior parietal cortex of rhesus macaques performing a WM task.