Whole-brain functional connectome-based multivariate classification of post-stroke aphasia
Introduction
Aphasia, mostly caused by left hemisphere lesions, results in disturbances in the comprehension and formulation of language [1]. Post-stroke aphasia (PSA) is related to higher mortality, higher costs, and occupational problems [2]. Although there are a number of structural and functional researches exploring the language architecture in PSA [3–5], its pathophysiology and potential clinical application remains unknown.
Resting-state functional magnetic resonance imaging (fMRI) techniques have become a focus in clinical studies [6]. The use of local brain activity and remote connectivity-based resting-state fMRI can help us understand the pathophysiology of PSA in detail. Remote functional connectivity has been used to investigate the underlying mechanism of language processing in aphasia [4], [7], [8], [9]. It was found that patients with PSA showed alterations of resting-state functional connectivity in the default-mode network [10] and the frontoparietal network [11]. Moreover, changes in local brain activity and associated remote functional connectivity patterns were examined to enhance the understanding of the pathophysiological mechanisms of aphasia [3].
Multivariate pattern analysis (MVPA) is a data-driven technique that is useful in distinguishing patients from controls [12]. The method plays a critical role in understanding neuroimaging data and is able to identify core features contributing to the classification or prediction of PSA [6], [13], [14]. Brain connectome-based multivariate classifications have been reliably identified for patients and controls using individual-level information [15]. Furthermore, whole-brain functional connectivity can be used as potential feature to distinguish patients from controls [16], [17], [18], which would be helpful in the understanding of the pathophysiology of PSA.
To this end, we utilized the MVPA method based on whole-brain functional connectivity to distinguish PSA patients from controls. We hypothesized that whole-brain functional connectivity could be used as feature to classify successfully. This study may contribute to the understanding of the pathophysiology and clinical application of PSA.
Section snippets
Subjects
Seventeen patients with PSA (all right-handed, six females and 11 males, aged, 53.53 ± 14.06 years) were recruited from Fuzhou Hospital, China. A subset of these patients had participated in one of our earlier studies [3–5]. Patients were recruited according to the following criteria: (i) first stroke occurred in the left hemisphere; (ii) age of > 18 and < 85 years; (iii) native Chinese speaker; (iv) aphasia persistent at day 1 post-stroke; and (v) right-handed. Participants were excluded if they
Demographics and clinical characteristics of participants
Patients with PSA and HCs did not significantly differ in age (two-sample t-test, P = 0.98), gender (χ2-test, P = 0.90), or years of education (Mann–Whitney U test, P = 0.58; see Table 1 in [3]). Stroke-related clinical characteristics of patients were tested using the ABC [31], [32]. The ABC provides the following information: aphasia quotient, which includes spontaneous speech, auditory comprehension, repetition, and naming scores; performance quotient, which includes reading/writing, praxis, and
Discussion
To discriminate patients with PSA from healthy controls, we combined linear SVM and LOOCV methods using whole-brain functional connectome. We found that consensus connections were distributed in FPN, SMN, AN, and VN, and the highest weight of classification was the right ROL.
Our findings showed that abnormal functional connections were associated within the FPN, AN, and SMN. Most regions in these networks are involved in language processing (e.g., MTG and STG) [37]. The dorsal pathway lies
Conclusion
In sum, we combined linear SVM and whole-brain functional connectome-based classification to distinguish PSA patients from controls with high accuracy. Altered functional connections were identified in the SMN, FPN, AN, and VN. We suggest that whole-brain functional connectivity could be used as a feature to explore the pathophysiology in PSA patients.
Declaration of interest
All authors disclosed no relevant conflict of interest.
Acknowledgments
This work was supported by the 863 project (2015AA020505), Natural Science Foundation of China (61533006, and 81471653), China Postdoctoral Science Foundation (2013M532229), Fundamental Research Funds for the Central Universities (ZYGX2013Z004), and Sichuan provincial health and family planning commission research project (16PJ051).
Mi Yang, Dental, Deputy director of the physician, Department of Stomatology, the Fourth people's Hospital of Chengdu. She is also the Ph.D. student of Biomedical Engineering at University of Electronic Science Technology of China, Her main research direction includes: Multi- model imaging method and application in Post-stroke Aphasia and Orthodontic tooth. She have published over 10 articles including scientific reports, Brain topography and Medicine etc.
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Cited by (0)
Mi Yang, Dental, Deputy director of the physician, Department of Stomatology, the Fourth people's Hospital of Chengdu. She is also the Ph.D. student of Biomedical Engineering at University of Electronic Science Technology of China, Her main research direction includes: Multi- model imaging method and application in Post-stroke Aphasia and Orthodontic tooth. She have published over 10 articles including scientific reports, Brain topography and Medicine etc.
Jiao Li received the B.S. degree from University of Electronic Science and Technology of China (UESTC), in 2015. She is currently working toward the M.S. degree in UESTC. Her main research interest is data analysis of functional magnetic resonance imaging.
Zhiqiang Li received the B.S. and the M.S. degrees from University Electronic of Science Technology of China (UESTC), in 2013 and 2016, respectively. Her main research direction includes: Brain Imaging method, fMRI data analysis and pattern recognition.
Dezhong Yao, Ph.D., Professor of Biomedical Engineering at University of Electronic Science Technology of China, fellow of Natural Science Foundation for Distinguished Young Scholars, and Distinguished Professor of changjiang river scholars. Prof. Chen devotes himself to the research of EEG and fMRI technique and cognitive applications; Brain-machine interface, Multi- model imaging method and application in Nervous disease and mental disease etc. He have published over 150 SCI articles including NeuroImage, Human Brian Mapping, IEEE Trans BME etc.
Wei Liao received the B.S., M.S. and Ph.D. degrees from the University of Electronic Science and Technology of China (UESTC), Chengdu, China, in 2004, 2008, and 2011 respectively. He is currently a Professor at the School of Life Science and Technology, UESTC. His research interests include functional magnetic resonance imaging and image processing.
Huafu Chen, Ph.D., Professor of Biomedical Engineering at University of Electronic Science Technology of China (UESTC), fellow of Natural Science Foundation for Distinguished Young Scholars, and Distinguished Professor of Changjiang River scholars. Prof. Chen devotes himself to the research of brain pattern recognition technique and cognitive applications; Dynamic Brain network; Multi-model imaging method and application in Nervous disease and mental disease etc. He have published over 120 SCI articles including Brain, NeuroImage, Human Brian Mapping, IEEE Trans MI/BME etc.