Department of Anatomy and Neurobiology, Boston University School of Medicine, 72 East Concord Street, L 1004, Boston, MA, 02118, USA; Berenson-Allen Center for Noninvasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, KS 158, Boston, MA, 02215, USA.
Eur J Neurosci. 2014 Jun;39(11):1973-81. doi: 10.1111/ejn.12584. Epub 2014 Apr 9.
The human dorsolateral prefrontal cortex (dlPFC) is crucial for monitoring and manipulating information in working memory, but whether such contributions are domain-specific remains unsettled. Neuroimaging studies have shown bilateral dlPFC activity associated with working memory independent of the stimulus domain, but the causality of this relationship cannot be inferred. Repetitive transcranial magnetic stimulation (rTMS) has the potential to test whether the left and right dlPFC contribute equally to verbal and spatial domains; however, this is the first study to investigate the interaction of task domain and hemisphere using offline rTMS to temporarily modulate dlPFC activity. In separate sessions, 20 healthy right-handed adults received 1 Hz rTMS to the left dlPFC and right dlPFC, plus the vertex as a control site. The working memory performance was assessed pre-rTMS and post-rTMS using both verbal-'letter' and spatial-'location' versions of the 3-back task. The response times were faster post-rTMS, independent of the task domain or stimulation condition, indicating the influence of practice or other nonspecific effects. For accuracy, rTMS of the right dlPFC, but not the left dlPFC or vertex, led to a transient dissociation, reducing spatial, but increasing verbal accuracy. A post-hoc correlation analysis found no relationship between these changes, indicating that the substrates underlying the verbal and spatial domains are functionally independent. Collapsing across time, there was a trend towards a double dissociation, suggesting a potential laterality in the functional organisation of verbal and spatial working memory. At a minimum, these findings provide human evidence for domain-specific contributions of the dlPFC to working memory and reinforce the potential of rTMS to ameliorate cognition.
人类背外侧前额叶皮层（dlPFC）对于监控和操纵工作记忆中的信息至关重要，但这种贡献是否具有特定领域的特异性仍未解决。神经影像学研究表明，双侧 dlPFC 的活动与工作记忆有关，而与刺激域无关，但无法推断这种关系的因果关系。重复经颅磁刺激（rTMS）有可能测试左、右 dlPFC 是否对等贡献于言语和空间域；然而，这是第一项使用离线 rTMS 来暂时调节 dlPFC 活动以研究任务域和半球相互作用的研究。在单独的会话中，20 名健康的右利手成年人接受了 1Hz rTMS 刺激左侧 dlPFC 和右侧 dlPFC，以及顶点作为对照部位。在 rTMS 前后使用言语-'字母'和空间-'位置'版本的 3 -back 任务评估工作记忆表现。反应时间在 rTMS 后更快，与任务域或刺激条件无关，表明受练习或其他非特异性影响。对于准确性，只有右侧 dlPFC 的 rTMS，而不是左侧 dlPFC 或顶点，导致了短暂的分离，降低了空间准确性，提高了言语准确性。事后相关性分析发现这些变化之间没有关系，表明言语和空间域的基础是功能独立的。跨时间进行合并，存在双重分离的趋势，表明言语和空间工作记忆的功能组织可能存在潜在的偏侧性。至少，这些发现为 dlPFC 对工作记忆的特定领域贡献提供了人类证据，并加强了 rTMS 改善认知的潜力。
