Purpose: To develop and validate the functionality of a novel wide-view visual presentation system with a horizontal and vertical eccentricity angle of 60° for retinotopic mapping by functional MRI (fMRI).
Materials and methods: The wide-view presentation system consisted of a 52-mm diameter optical fiber, an entrance apparatus and a presentation apparatus. The terminal edge of the optical fiber at the entrance is flat, while the terminal edge on the presentation apparatus is a sphere of 60 mm in diameter. The subjects wore contact lenses with +20, +22, or +25 magnification to focus on the stimulus, and the visual field eccentricity angle could reach 60°. The signal to noise ratio valuation experiment was performed to evaluate the clarity and quality of the MRI picture image. Checkerboard and random dot stimuli were used to prove that this system could be applied to retinotopic mapping by fMRI.
Results: The results of the experiment demonstrated that the system is safe in the MRI environment with minimal distortion and can be used for visual retinotopic mapping studies. Wide-field mapping areas (V6, MST) were found in the human visual cortex. Compared with previous studies, the V1 and MT+ surface area approaches but does not fully cover the anatomical area. Nonetheless, the area achieved using the new system is larger than those achievable in previous fMRI studies.
Conclusion: We developed a versatile, low-cost system for presenting wide-view visual stimuli in the MRI environment. The fMRI retinotopic mapping results proved the viability of this system.
Copyright © 2011 Wiley-Liss, Inc.