Test-retest reliability of fMRI experiments during robot-assisted active and passive stepping

Journal of NeuroEngineering and Rehabilitation, 2015 · DOI: 10.1186/s12984-015-0097-2 · Published: November 6, 2015

Simple Explanation

This study examines how consistently functional MRI (fMRI) measures brain activity during repeated active and passive stepping movements using a robot-assisted device called MARCOS. The researchers investigated the reliability of brain activation patterns in healthy individuals during active stepping (where participants move their legs) and passive stepping (where the robot moves their legs). The results showed that while motor performance was more consistent during passive movements, brain activation patterns were more stable during active movements.

Study Duration

Six weeks apart

Participants

16 healthy participants

Evidence Level

Not specified

Key Findings

1
Reliability of motor performance was higher during passive than active movements, as seen in lower RMSE for passive movements.
2
ICC ranged from 0.48 to 0.72 during passive movements and from 0.77 to 0.85 during active movements.
3
Regional overlap of activations was also higher during active than during passive movements.

Research Summary

The present study explored the test-retest reliability of motor performance and brain activation of a novel robot-aided experimental fMRI paradigm at the individual and group-level. The consistency of task-induced blood oxygenated level dependent (BOLD)-signal was compared between repeated measurements of active and passive gait-like stepping in the MR-compatible stepper MARCOS. The results of the present study in healthy participants indicate that activations during passive movements are less robust over repeated measurement sessions than those during active movements despite lower variability of motor performance during passive movements.

Practical Implications

Clinical Trials

The MARCOS robot-aided fMRI paradigm can be used to investigate supraspinal adaptations in paretic patients undergoing gait-rehabilitation.

Rehabilitation Programs

Findings suggest the importance of considering both motor performance variability and neural activation patterns when designing rehabilitation programs.

Neurophysiological Principles

This study is feasible for studies investigating basic neuro-physiological principles and to draw conclusions that can be generalised to the populations from which the study participants were selected.

Study Limitations

1
High dropout rate exemplifies that the test-retest reliability of the presented paradigm is a priori and is limited by the task-induced head motion in many participants.
2
High variability of ICCsingle between individual participants during both movement conditions renders the presented approach less suitable for making inferences at the single-subject level.
3
As the mean age of stroke patients is usually higher than that of the healthy participants in the present study, test-retest reliability of the presented paradigm could hence be lower when applied to a stroke cohort.

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