Haptic fMRI: Accurately estimating neural responses in motor, pre-motor, and somatosensory cortex during complex motor tasks

Abstract

Haptics combined with functional magnetic resonance imaging (Haptic fMRI) can non-invasively study how the human brain coordinates movement during complex manipulation tasks, yet avoiding associated fMRI artifacts remains a challenge. Here, we demonstrate confound-free neural activation measurements using Haptic fMRI for an unconstrained three degree-of-freedom motor task that involves planning, reaching, and visually guided trajectory tracking. Our haptic interface tracked subjects' hand motions, velocities, and accelerations (sample-rate, 350Hz), and provided continuous realtime visual feedback. During fMRI acquisition, we achieved uniform response latencies (reaching, 0.7-1.1s; tracking, 0.4-0.65s); minimized hand jitter (<;8mm); and ensured reliable motion trajectories (tracking, <;7mm root-mean-square error). In addition, our protocol decorrelated head motion from both hand speed (r=-0.03) and acceleration (r=-0.025), which reliably produced low head motion levels (<;0.4mm/s between scan volumes) and a low fMRI temporal noise-to-signal ratio (<;1%) across thirty-five scan runs. Our results address the primary outstanding Haptic fMRI confounds: motion induced low spatial-frequency magnetic field changes, which correlate neural activation across cortex; unreliable motions and response latencies, which reduce statistical power; and task-correlated head motion, which causes spurious fMRI activation. Haptic fMRI can thus reliably elicit and localize heterogeneous neural activation for different tasks in motor (movement), pre-motor (planning), and somatosensory (limb displacement) cortex, demonstrating that it is feasible to use the technique to study how the brain achieves three dimensional motor control.

f2MOVE: fMRI-compatible haptic object manipulation system for closed-loop motor control studies

“…Moreover, building on our previous experience on low-cost wearable kinematic body-sensor networks [16], we aimed at developing an easily affordable neurotechnological tool. Its cost is limited to the customized camera price, in contrast to the expences involved in fMRI-compatible motion tracking approaches which rely on a robotic manipulandum for motion detection and/or perturbation [17], [18]. f2MOVE, thus offers an accessible technological and methodological platform to re-approach the objectives of motor neuroscience in examining the neural foundation of sensorimotor control and learning.…”

Haptics-mediated approaches for enhancing sustained attention: framework and challenges

“…Such approaches usually lead haptic interfaces to be suitable only for a limited set of motor tasks. Recently, Menon et al [158,159] developed an fMRI-compatible haptic device for real-time interaction across the scanner workspace. The remaining challenges are to develop a transparent six-degrees-of-freedom fMRI-compatible haptic interface that can support a multi-kilohertz control rate and to demonstrate the fidelity of the haptic display at high magnetic field strengths during high-resolution multiplexed scanning with sub-millimeter and millisecond timescales [159].…”