An MR-compatible gyroscope-based arm movement tracking system

Cortical and subcortical areas involved in the regulation of reach movement speed in the human brain: An fMRI study

“…We investigated the neural control of naturalistic arm movement speed in the human brain by combining fMRI-BOLD imaging with concurrent measurements of actual wrist speed using a custom build movement tracking system (Shirinbayan & Rieger, 2017). In our approach, we took care of separating speed-specific from speedunspecific BOLD-activation by orthogonalizing the continuous speed predictor with respect to the binary movement per se predictor in the GLM.…”

“…We used an MR-compatible gyroscope-based arm movement tracking system to capture the movement kinematics while the subjects performed the task inside the scanner (G1-5 in Figure 1). For individual arm joints, the movement tracker converts the measured angular velocity (provided by MEMS gyroscopes) to angular displacement and combines the resulting rotations with the movement simulation of a realistic arm skeleton model in the OpenSim software (Delp et al, 2007;Seth, Sherman, Eastman, & Delp, 2010) to provide different kinematic variables such as displacement, velocity, and trajectory of points of interest that can be placed at any position on the arm (Shirinbayan & Rieger, 2017). For the fMRI-analyses, we use the average speed of individual movements (as opposed to maximum speed) measured at the wrist, because the slow BOLD-response cannot follow the rapid changes in the movement speed profile and wrist speed is the independent variable that was varied in many studies on neuronal speed coding (e.g., Churchland, Afshar, et al, 2006a;Churchland, Santhanam, et al 2006b;Golub et al, 2014;Moran & Schwartz, 1999;Schwartz, 1992).…”

“…Our gyroscope-based arm tracking system (Shirinbayan & Rieger, 2017) allowed us to measure naturalistic multi-joint arm movements and to compare the wrist kinematics to the shoulder and elbow kinematics of the reach movements. Particularly, the speed profiles (averaged over all subjects) were highly correlated (wrist-elbow: 0.92, wrist-shoulder: 0.87, elbow-shoulder: 0.96).…”

“…We measured the actual endpoint speed of reach movements with a custom build MR-compatible arm movement tracking system (Shirinbayan & Rieger, 2017) during fMRI-scanning and used these measurements of actual (wrist) movement speed to reveal speed-related brain activity. Unlike single-cell recordings, which are restricted to a small brain region/neuronal population, fMRI allows us to noninvasively probe reach movement speed effects in both cortical and subcortical regions of the human brain.…”

“…In our study we defined movement speed as the amplitude of the movement velocity vector. We measured the actual endpoint speed of reach movements with a custom build MR-compatible arm movement tracking system (Shirinbayan & Rieger, 2017) during fMRI-scanning and used these measurements of actual (wrist) movement speed to reveal speed-related brain activity. We compare the patterns of brain activation correlating with varying endpoint speed to patterns of brain areas exhibiting a categorical response, independent of speed variation, to the presence or absence of movement (denoted "movement per se" from here on) and report effect sizes to characterize the selectivity of brain areas for speed and movement per se.…”