Individualized prediction of functional connectivity from structural connectivity

Poster No:

1184 

Submission Type:

Abstract Submission 

Authors:

Yiming Chen1, Weikang Gong2

Institutions:

1Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China, 2School of Data Science, Fudan University, Shanghai, China

First Author:

Yiming Chen  
Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University
Shanghai, China

Co-Author:

Weikang Gong  
School of Data Science, Fudan University
Shanghai, China

Introduction:

Understanding the relationship between structure and function of the human brain is an essential problem in neuroscience. However, building a reliable model that links individual brain structure and function is challenging, such as the relationship between structural connectivity (SC) and functional connectivity (FC).
Recent advances in deep learning have brought breakthroughs for the field of computational neuroimaging. The advantage of using deep learning models is that complex relations between brain structure and function can be uncovered, without preconditioning on any specific prior hypothesis.
Sarwar and his colleagues (Sarwar et al., 2021) are among the first to propose using deep learning models to predict functional connectivity from structural connectivity. Their work demonstrates that the deep learning model could capture structure-function coupling and surpass biophysical model. However, the proposed model does not guarantee that the predicted functional connectivity is a covariance matrix and they do not explore the limits of deep learning models in learning individual effects.
Although these deep learning models show promising potential in capturing structure-function coupling, the extent to which these models recapitulate individual-specific effects remains unclear. Our work adopts the transformer model (Vaswani et al. 2017) to predict the individual FC using the corresponding SC. By regressing the group mean in SC and FC, we explore the extent to which the model can learn the individual-specific structure-function pattern.

Methods:

We use the Human Connectome Project (HCP) (Van Essen et al., 2013) dataset which contains 1096 healthy subjects. Each individual was scanned by a customized 3T scanner to obtain dMRI data. We obtained minimally pre-processed diffusion-weighted MRI data and construct SC matrices for each individual. The HCP participants were also scanned for their resting state fMRI, which were collected through a 15-minute scan for each encoding direction (left-to-right and right-to-left). We construct a FC matrix for each individual using PCC, computing for 4 scans respectively and then averaging them. Both SC and FC are constructed using the Schaefer 200 atlas (Schaefer et al., 2018) and the Tian Subcortex atlas (Tian et al., 2020).
The transformer model (Vaswani et al. 2017) has a profound impact on deep learning. The core concept of Transformer is the self-attention (SA) mechanisms, which allows the model to weight the importance of each token in a sequence while taking into account the relationships between tokens across different positions. Although initially designed for natural language processing (NLP), Transformer's strong sequence modeling capabilities have shown considerable potential in analyzing complex multimodal medical imaging data. Therefore, we adopt the transformer model to deal with brain imaging data and learn the mapping between SC and FC.
Aimed at focusing on the individual-specific effects in structure-function coupling, we regress the group mean in SC and FC. Besides, in order to maximize the pearson correlation between the predicted FC and SC, we follow Lu Zhang et al.(2022) and add the Pearson's correlation coefficient (PCC) loss in addition to the normally used mean squared error prediction loss.
Supporting Image: Fig1.png
   ·(a) Schema of study design. (b) Architecture of transformer encoder
 

Results:

We use the Pearson Correlation Coefficient (PCC) between the predicted FC and true FC under the condition of regressing group mean as the metric. Our proposed model reaches r=0.18. The PCC between different subjects' predicted FC is about 0.09, which demonstrates that the individual-specific structure-function coupling surpasses group average structure-function coupling under the condition of regressing group mean. The average regional PCC between predicted FC and true FC reaches 0.21.
Supporting Image: Fig2.png
   ·(a) Curve of average between-subject PCC of predicted FC. (b) Curve of average PCC between predicted FC and true FC on the test set. (c) Average regional PCC between predicted FC and true FC.
 

Conclusions:

Under the condition of regressing group mean of SC and FC, our proposed transformer-based model can recapitulate significant individual-specific structure-function coupling of the human brain.

Modeling and Analysis Methods:

Connectivity (eg. functional, effective, structural) 1
fMRI Connectivity and Network Modeling 2

Novel Imaging Acquisition Methods:

Multi-Modal Imaging

Keywords:

FUNCTIONAL MRI
Machine Learning
STRUCTURAL MRI
Other - Connectivity

1|2Indicates the priority used for review

Abstract Information

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Please indicate below if your study was a "resting state" or "task-activation” study.

Resting state

Healthy subjects only or patients (note that patient studies may also involve healthy subjects):

Healthy subjects

Was this research conducted in the United States?

No

Were any human subjects research approved by the relevant Institutional Review Board or ethics panel? NOTE: Any human subjects studies without IRB approval will be automatically rejected.

Yes

Were any animal research approved by the relevant IACUC or other animal research panel? NOTE: Any animal studies without IACUC approval will be automatically rejected.

Not applicable

Please indicate which methods were used in your research:

Functional MRI
Structural MRI
Computational modeling

For human MRI, what field strength scanner do you use?

3.0T

Which processing packages did you use for your study?

FSL
Free Surfer

Provide references using APA citation style.

Sarwar, T., Tian, Y., Yeo, B. T., Ramamohanarao, K., & Zalesky, A. (2021). Structure-function coupling in the human connectome: A machine learning approach. NeuroImage, 226, 117609.
Vaswani, A. (2017). Attention is all you need. Advances in Neural Information Processing Systems.
Zhang, L., Wang, L., Zhu, D., & Alzheimer's Disease Neuroimaging Initiative. (2022). Predicting brain structural network using functional connectivity. Medical image analysis, 79, 102463.
Van Essen, D. C., Smith, S. M., Barch, D. M., Behrens, T. E., Yacoub, E., Ugurbil, K., & Wu-Minn HCP Consortium. (2013). The WU-Minn human connectome project: an overview. Neuroimage, 80, 62-79.
Schaefer, A., Kong, R., Gordon, E. M., Laumann, T. O., Zuo, X. N., Holmes, A. J., ... & Yeo, B. T. (2018). Local-global parcellation of the human cerebral cortex from intrinsic functional connectivity MRI. Cerebral cortex, 28(9), 3095-3114.
Tian, Y., Margulies, D. S., Breakspear, M., & Zalesky, A. (2020). Topographic organization of the human subcortex unveiled with functional connectivity gradients. Nature neuroscience, 23(11), 1421-1432.

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