Bonakdarpour B, Beeson P M, DeMarco A T, Rapcsak S Z
Cognitive Neurology and Alzheimer Disease Center, Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
Department of Speech, Language and Hearing Sciences, University of Arizona, Tucson, AZ, USA.
Neuroimage Clin. 2015 Mar 24;8:87-94. doi: 10.1016/j.nicl.2015.03.014. eCollection 2015.
Although fMRI is increasingly used to assess language-related brain activation in patients with aphasia, few studies have examined the hemodynamic response function (HRF) in perilesional, and contralesional areas of the brain. In addition, the relationship between HRF abnormalities and other variables such as lesion size and severity of aphasia has not been explored. The objective of this study was to investigate changes in HRF signal during language-related neural activation in patients with stroke-induced aphasia (SA). We also examined the status of the HRF in patients with aphasia due to nonvascular etiology, namely, primary progressive aphasia (PPA). Five right handed SA patients, three PPA patients, and five healthy individuals participated in the study. Structural damage was quantified with T1-weighted MR images. Functional MR imaging was performed with long trial event-related design and an overt naming task to measure BOLD signal time to peak (TTP) and percent signal change (ΔS). In SA patients, the average HRF TTP was significantly delayed in the left hemisphere regions involved in naming compared to healthy participants and PPA patients. However, ΔS was not different in SA patients compared to the other two groups. Delay in HRF TTP in the left hemisphere naming network of SA patients was correlated with lesion size and showed a negative correlation with global language function. There were no significant differences in the HRF TTP and ΔS in the right hemisphere homologues of the naming network or in the left and the right occipital control regions across the three groups. In PPA patients, HRF had a normal pattern. Our results indicate that abnormal task-related HRF is primarily found in the left hemisphere language network of SA patients and raise the possibility that abnormal physiology superimposed on structural damage may contribute to the clinical deficit. Follow-up investigations in a larger sample of age-matched healthy individuals, SA, and PPA patients will be needed to further confirm and extend our findings.
尽管功能磁共振成像（fMRI）越来越多地用于评估失语症患者与语言相关的脑激活情况，但很少有研究考察过脑损伤周围及对侧区域的血液动力学反应函数（HRF）。此外，HRF异常与其他变量（如损伤大小和失语严重程度）之间的关系尚未得到探究。本研究的目的是调查中风后失语症（SA）患者在与语言相关的神经激活过程中HRF信号的变化。我们还检查了非血管性病因导致的失语症患者，即原发性进行性失语症（PPA）患者的HRF状况。五名右利手SA患者、三名PPA患者和五名健康个体参与了本研究。用T1加权磁共振图像对结构损伤进行量化。采用长时程事件相关设计和明显的命名任务进行功能磁共振成像，以测量血氧水平依赖（BOLD）信号达到峰值的时间（TTP）和信号变化百分比（ΔS）。与健康参与者和PPA患者相比，SA患者中参与命名的左半球区域的平均HRF TTP显著延迟。然而，SA患者的ΔS与其他两组并无差异。SA患者左半球命名网络中HRF TTP的延迟与损伤大小相关，且与整体语言功能呈负相关。三组在命名网络右半球对应区域或左右枕叶对照区域的HRF TTP和ΔS均无显著差异。在PPA患者中，HRF模式正常。我们的结果表明，与任务相关的HRF异常主要出现在SA患者的左半球语言网络中，并提出结构损伤叠加异常生理状态可能导致临床缺陷的可能性。需要在更大样本的年龄匹配健康个体、SA患者和PPA患者中进行后续研究，以进一步证实和扩展我们的发现。
