Monitoring eye movements during fMRI tasks with echo planar images.

Verifying task compliance during functional magnetic resonance imaging (fMRI) experiments is an essential component of experimental design. To date, studies of oculomotor tasks such as smooth pursuit eye movements have either measured task performance outside the magnet and assumed similar performance during functional neuroimaging, or have used MR-compatible eye movement recording devices, which can be costly and technically difficult to use. We describe a simple method to visualize and quantify eye movements during an imaging experiment using the gradient echo images. We demonstrate that local eye movements will influence whole-head motion correction procedures, resulting in inaccurate movement parameters and potentially lowering the sensitivity to detect activations.