A-magnetic optic-mechanical device to quantify finger kinematics for fMRI studies of bimanual coordination.

Several fMRI studies have been performed to detect the neural correlates of stable bimanual coordination patterns in humans. Only few of those studies were accompanied by the on-line recording of the relative phase of fingers or hands, but none with high space and time resolutions. Conversely, the high-resolution recording of fingers' kinematics during fMRI would permit the quantification of the instantaneous fingers' positions, from which the instant at which transitions between different bimanual coordination patterns occur might be detected. This information could then be used to analyze fMRI data and detect the neural correlates of pattern transitions. We describe an a-magnetic optic-mechanical device (AMOMeD) able to monitor the fingers' positions during fMRI studies on bimanual coordination with 2 mm space resolution and 1 ms time resolution. From the instantaneous fingers' positions (recorded with an optical fiber system and a dedicated acquisition system), the oscillation amplitude, frequency, velocity and relative phase of fingers' are calculated. The signal from the fMRI trigger can be acquired simultaneously to synchronize the behavioral outcomes with the fMRI analysis. The results of our study show that this device does not affect fMRI signals, and that fMRI data can be processed using the simultaneous behavioral information to detect the brain areas activated during the transitions between different bimanual coordination patterns.