A fiber optic-based system for behavioral eyeblink measurement in a MRI environment.

We previously described a reliable system to control the timing of multiple stimuli and to detect behavioral eyeblink responses in fMRI studies of learning in animals. Here, we report a significant advancement of the original system, which incorporates a fiber-optic probe in order to avoid the interference associated with the application of pulsed field gradients during MR imaging, particularly echo planar imaging. Eyeblink responses recorded with our fiber-optic probe and modified detection circuit demonstrate the ability of our new system to acquire behavioral data free of gradient-induced artifacts, thereby eliminating the need for low-pass filtering. This fiber optic-based system should be applicable to both animal and human imaging experiments.