Cognitive Neurology and Aphasia Unit, Centro de Investigaciones Médico-Sanitarias (CIMES), University of Malaga, Malaga, Spain.
Research Laboratory on the Neuroscience of Language, Faculty of Psychology and Speech Therapy, University of Malaga, Malaga, Spain.
Brain Struct Funct. 2023 Jun;228(5):1347-1364. doi: 10.1007/s00429-023-02655-6. Epub 2023 May 31.
Mixed transcortical aphasia (MTCA) is characterized by non-fluent speech and comprehension deficits coexisting with preserved repetition. MTCA may evolve to less severe variants of aphasias or even to full language recovery. Mechanistically, MCTA has traditionally been attributed to a disconnection between the spared left perisylvian language network (PSLN) responsible for preserved verbal repetition, and damaged left extrasylvian networks, which are responsible for language production and comprehension impairments. However, despite significant advances in in vivo neuroimaging, the structural and functional status of the PSLN network in MTCA and its evolution has not been investigated. Thus, the aim of the present study is to examine the status of the PSLN, both in terms of its functional activity and structural integrity, in four cases who developed acute post-stroke MTCA and progressed to different types of aphasia. For it, we conducted a neuroimaging-behavioral study performed in the chronic stage of four patients. The behavioral profile of MTCA persisted in one patient, whereas the other three patients progressed to less severe types of aphasias. Neuroimaging findings suggest that preserved verbal repetition in MTCA does not always depend on the optimal status of the PSLN and its dorsal connections. Instead, the right hemisphere or the left ventral pathway may also play a role in supporting verbal repetition. The variability in the clinical evolution of MTCA may be explained by the varying degree of PSLN alteration and individual premorbid neuroanatomical language substrates. This study offers a fresh perspective of MTCA through the lens of modern neuroscience and unveils novel insights into the neural underpinnings of repetition.
混合性经皮质性失语症（MTCA）的特点是言语不流畅和理解障碍并存，同时保留重复能力。MTCA 可能会演变为更轻微的失语症变体，甚至完全恢复语言能力。从机制上讲，MTCA 传统上归因于负责保留言语重复的左侧边缘语言网络（PSLN）与负责语言产生和理解障碍的受损左侧额外语言网络之间的连接中断。然而，尽管在活体神经影像学方面取得了重大进展，但 MTCA 中 PSLN 网络的结构和功能状态及其演变尚未得到研究。因此，本研究旨在检查 PSLN 的状态，包括其功能活动和结构完整性，研究对象是 4 名发生急性卒中后 MTCA 并发展为不同类型失语症的患者。为此，我们对 4 名患者的慢性期进行了一项神经影像学-行为学研究。其中 1 名患者的 MTCA 行为特征持续存在，而另外 3 名患者则发展为更轻微的失语症。神经影像学发现表明，MTCA 中保留的言语重复并不总是依赖于 PSLN 及其背侧连接的最佳状态。相反，右半球或左侧腹侧通路也可能在支持言语重复方面发挥作用。MTCA 临床演变的可变性可以通过 PSLN 改变的程度和个体的预病变神经解剖语言基础来解释。本研究通过现代神经科学的视角提供了对 MTCA 的新认识，并揭示了重复的神经基础的新见解。
