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Title:

Repeatability Assessment of a functional MRI task stimulating the Vergence Neural System in Binocularly Normal Controls

Discipline: Biomedical Engineering, Signal Processing, Functional Brain Imaging

Presenter:

Cristian Morales

Abstract:

Introduction: Vergence is the inward and outward rotation of the eyes to track targets located from a far to near spatial location or vice versa. Pilot studies support that the frontal eye fields (FEF), supplementary eye field (SEF), parietal eye fields (PEF) and cerebellar vermis (CV) are involved within the vergence neural system. The present study aims to assess the reliability of the activation maps obtained using functional Magnetic Resonance Imaging (fMRI). Materials and Methods: A total of 27 binocularly normal control participants were recruited to perform a vergence eye movement task while fMRI datasets on two different visits. Functional MRI volumes were preprocessed using a standard procedure with SPM12. A first-level analysis was performed using a general linear model to obtain the Beta weights. Eight Region of Interests (ROI) were selected: Left and Right (L/R) FEF, L/R PEF, L/R primary visual cortex (V1), SEF, and CV. Broca area served as a negative ROI control. Peak Beta weights within ROI from each participant and each visit were extracted and used to calculate the peak Intra Class Correlation (ICC). Results: The peak ICC in the selected ROIs were the following: RFEF=0.53, LFEF=0.41, CV=0.59, LV1=0.83, RV1=0.81, LPEF=0.69, RPEF=0.61, SEF=0.45, and Broca=0. Conclusions: The test/retest repeatability of the beta weights of the fMRI activation on the vergence neural system were greater than 0.40 for all ROIs. The control ROI (Broca area) had an ICC=0. The vergence stimulus of symmetrical steps investigated here has been shown to be a stable and repeatable experimental design.

Author(s):

Cristian Morales, Elio M. Santos, Mitchell Scheiman, Suril Gohel, Xiaobo Li, Bharat Biswal, Chang Yaramothu, John Vito d’Antonio-Bertagnolli, and Tara L. Alvarez

Funding Acknowledgements:

Research was supported in part by the National Eye Institute of the National Health Institute, NEI R01EY023261