Department of Psychiatry and Psychotherapy, Center for Translational Research in Systems Neuroscience and Clinical Psychiatry, Georg August University, Goettingen, Germany.
Neuropsychobiology. 2012;65(3):133-40. doi: 10.1159/000332335. Epub 2012 Feb 24.
Recent functional neuroimaging studies have provided evidence that human verbal working memory is represented by two complementary neural systems, a left lateralized premotor-parietal network implementing articulatory rehearsal and a presumably phylogenetically older bilateral anterior-prefrontal/inferior-parietal network subserving non-articulatory maintenance of phonological information. In order to corroborate these findings from functional neuroimaging, we performed a targeted behavioural study in patients with very selective and circumscribed brain lesions to key regions suggested to support these different subcomponents of human verbal working memory.
Within a sample of over 500 neurological patients assessed with high-resolution structural magnetic resonance imaging, we identified 2 patients with corresponding brain lesions, one with an isolated lesion to Broca's area and the other with a selective lesion bilaterally to the anterior middle frontal gyrus. These 2 patients as well as groups of age-matched healthy controls performed two circuit-specific verbal working memory tasks. In this way, we systematically assessed the hypothesized selective behavioural effects of these brain lesions on the different subcomponents of verbal working memory in terms of a double dissociation.
Confirming prior findings, the lesion to Broca's area led to reduced performance under articulatory rehearsal, whereas the non-articulatory maintenance of phonological information was unimpaired. Conversely, the bifrontopolar brain lesion was associated with impaired non-articulatory phonological working memory, whereas performance under articulatory rehearsal was unaffected.
The present experimental neuropsychological study in patients with specific and circumscribed brain lesions confirms the hypothesized double dissociation of two complementary brain systems underlying verbal working memory in humans. In particular, the results demonstrate the functional relevance of the anterior prefrontal cortex for non-articulatory maintenance of phonological information and, in this way, provide further support for the evolutionary-based functional-neuroanatomical model of human working memory.
最近的功能神经影像学研究提供了证据，表明人类言语工作记忆由两个互补的神经系统来表示，一个是左侧的运动前顶叶网络，用于执行发音复述；另一个是假定在进化上更古老的双侧额前/顶下网络，用于维持语音信息的非发音维持。为了证实这些来自功能神经影像学的发现，我们对关键区域的患者进行了一项有针对性的行为研究，这些区域被认为支持人类言语工作记忆的这些不同子成分。
在一个由超过 500 名接受高分辨率结构磁共振成像评估的神经科患者组成的样本中，我们确定了 2 名具有相应脑损伤的患者，其中 1 名患者的脑损伤局限于布罗卡区，另 1 名患者的双侧额中前回有选择性损伤。这 2 名患者以及年龄匹配的健康对照组都进行了两个特定于电路的言语工作记忆任务。通过这种方式，我们系统地评估了这些脑损伤对言语工作记忆不同子成分的选择性行为影响，以进行双重分离。
证实了先前的发现，布罗卡区的损伤导致发音复述时的表现下降，而语音信息的非发音维持不受影响。相反，双侧额极的脑损伤与非发音语音工作记忆受损有关，而发音复述的表现不受影响。
本项在具有特定和局限脑损伤的患者中的实验性神经心理学研究证实了两个互补的言语工作记忆大脑系统的假设双重分离。特别是，结果表明额前皮质在语音信息的非发音维持方面具有功能相关性，从而为人类工作记忆的基于进化的功能神经解剖学模型提供了进一步的支持。
