Postle Bradley R, Ferrarelli Fabio, Hamidi Massihullah, Feredoes Eva, Massimini Marcello, Peterson Michael, Alexander Andrew, Tononi Giulio
University of Wisconsin, USA.
J Cogn Neurosci. 2006 Oct;18(10):1712-22. doi: 10.1162/jocn.2006.18.10.1712.
Understanding the contributions of the prefrontal cortex (PFC) to working memory is central to understanding the neural bases of high-level cognition. One question that remains controversial is whether the same areas of the dorsolateral PFC (dlPFC) that participate in the manipulation of information in working memory also contribute to its short-term retention (STR). We evaluated this question by first identifying, with functional magnetic resonance imaging (fMRI), brain areas involved in manipulation. Next, these areas were targeted with repetitive transcranial magnetic stimulation (rTMS) while subjects performed tasks requiring only the STR or the STR plus manipulation of information in working memory. fMRI indicated that manipulation-related activity was independent of retention-related activity in both the PFC and superior parietal lobule (SPL). rTMS, however, yielded a different pattern of results. Although rTMS of the dlPFC selectively disrupted manipulation, rTMS of the SPL disrupted manipulation and STR to the same extent. rTMS of the postcentral gyrus (a control region) had no effect on performance. The implications of these results are twofold. In the PFC, they are consistent with the view that this region contributes more importantly to the control of information in working memory than to its STR. In the SPL, they illustrate the importance of supplementing the fundamentally correlational data from neuroimaging with a disruptive method, which affords stronger inference about structure-function relations.
理解前额叶皮质（PFC）对工作记忆的贡献是理解高级认知神经基础的核心。一个仍存在争议的问题是，背外侧前额叶皮质（dlPFC）中参与工作记忆信息操作的相同区域是否也对其短期保持（STR）有贡献。我们通过以下方式评估了这个问题：首先，利用功能磁共振成像（fMRI）确定参与操作的脑区。接下来，在受试者执行仅需要STR或需要STR加上工作记忆信息操作的任务时，对这些区域进行重复经颅磁刺激（rTMS）。fMRI表明，在PFC和顶上小叶（SPL）中，与操作相关的活动与与保持相关的活动是独立的。然而，rTMS产生了不同的结果模式。虽然dlPFC的rTMS选择性地干扰了操作，但SPL的rTMS对操作和STR的干扰程度相同。中央后回（一个对照区域）的rTMS对表现没有影响。这些结果的影响是双重的。在PFC中，它们与这样一种观点一致，即该区域对工作记忆中信息的控制比其STR更重要。在SPL中，它们说明了用一种干扰性方法补充来自神经成像的基本相关性数据的重要性，这种方法能对结构 - 功能关系进行更强有力的推断。
