Neural and behavioral mapping of the visual field in true and simulated visual field deficits

Abstract

Abstract Purpose: Our goal was to assess the utility of functional magnetic resonance imaging (fMRI) in simultaneous mapping of perceptual and neural visual field deficits, and in the assessment of neural plasticity processes underlying spontaneous and medication‐induced visual field recovery. Methods: Neural function of two patients with predominantly unilateral visual field deficits and three volunteers with simulated scotomas was assessed using fMRI retinotopic mapping procedures. In the patients behavioral testing has also been done by asking for reports in a forced choice manner on the color of a 1.66° diameter circle patch pseudo‐randomly overlaid on the standard fMRI retinopic mapping stimuli. Results: Retinotopic mapping provided a reliable voxel‐based quantification of the extent of both real and simulated visual field deficits. The pattern of BOLD responses in retinotopic visual cortical areas – in particular in the primary visual cortex – showed close correlation with the performance in the perimetry tests, and the behavioral responses obtained during scanning. Moreover, we found a marked difference between true and simulated visual field deficits. Conclusions: The presented fMRI retinotopic mapping techniques are suitable for the simultaneous assessment of the functional and behavioral aspects of visual field loss, thus providing an opportunity to investigate neural plasticity in affected patient populations.