Department of Psychology, Cognitive and Brain Science Program, University of Nevada, Reno, NV 89557, United States.
Neurosci Lett. 2012 Jul 19;521(2):148-51. doi: 10.1016/j.neulet.2012.05.074. Epub 2012 Jun 7.
Cognitive performance, including performance on working memory (WM) tasks declines with age. Changes in brain activations are one presumed contributor to WM decline in the healthy aging population. In particular, neuroimaging studies show that when older adults perform WM tasks there tends to be greater bilateral frontal activity than in younger adults. We hypothesized that stimulating the prefrontal cortex in healthy older adults would improve WM performance. To test this hypothesis we employed transcranial direct current stimulation (tDCS), a neurostimulation technique in which small amounts of electrical current are applied to the scalp with the intent of modulating the activity in underlying neurons. Across three testing sessions we applied sham stimulation or anodal tDCS to the left (F3) or right (F4) prefrontal cortex to healthy older adults as they performed trials of verbal and visual 2-back WM tasks. Surprisingly, tDCS was uniformly beneficial across site and WM task, but only in older adults with more education. In the less educated group, tDCS provided no benefit to verbal or visual WM performance. We interpret these findings as evidence for differential frontal recruitment as a function of strategy when older adults perform WM tasks.
认知表现，包括工作记忆 (WM) 任务的表现，随着年龄的增长而下降。大脑活动的变化被认为是健康老龄化人群 WM 下降的一个原因。特别是，神经影像学研究表明，当老年人执行 WM 任务时，他们的双侧额叶活动往往比年轻人更大。我们假设刺激健康老年人的前额叶皮层会改善 WM 表现。为了验证这一假设，我们采用了经颅直流电刺激 (tDCS)，这是一种神经刺激技术，通过在头皮上施加少量电流来调节下神经元的活动。在三次测试中，我们在健康老年人执行言语和视觉 2 回 WM 任务时，对左侧 (F3) 或右侧 (F4) 前额叶皮层施加假刺激或阳极 tDCS。令人惊讶的是，tDCS 在所有部位和 WM 任务中都是均匀有益的，但只在受教育程度较高的老年人中。在受教育程度较低的群体中，tDCS 对言语或视觉 WM 表现没有帮助。我们将这些发现解释为证据，表明当老年人执行 WM 任务时，前额叶的招募是策略的函数。
