Monitoring gait motor imagery across experimental conditions before and during fMRI

Introduction: Gait imagery (GI) is widely used in neurorehabilitation and functional neuroimaging to investigate locomotor control without overt movement. Previous studies have shown that GI can induce measurable changes in subsequent motor performance and movement quality (Kolářová et al., 2022). Mental chronometry and imagery vividness have been proposed as practical measures of GI quality and may help characterize individual differences in imagery performance (Thai et al., 2025). However, it remains unclear how GI performance changes across different experimental conditions, particularly when performed in the magnetic resonance imaging (MRI) environment. Therefore, the aim of this study was to evaluate the temporal evolution of performance of imagined walking and imagery vividness across conditions ranging from sitting immediately after gait practice to repeated GI during fMRI.Methods: Twenty-one healthy volunteers (12 men, 9 women; age 35.1 ± 9.4 years) participated in the study. Participants completed actual overground walking (W), seated GI training (TR), GI while lying supine in the 3 Tesla MRI scanner without image acquisition (MR), and repeated GI during two functional magnetic resonance imaging (fMRI) runs (T1, T2). Actual and imagined walking times for a 10-m walking task were recorded. During MRI-related conditions (MR, T1, T2), participants indicated completion of each imagined walking 10-m cycle using a response button. Following each imagery condition, visual and kinesthetic vividness were rated using a 7-point Likert scale (1 = very low vividness, 7 = highly vivid imagery). Foot accelerometer data were simultaneously recorded during MRI-related conditions to monitor possible overt lower-limb movements during GI.Results: Mean completion time during actual walking (W) was 8.10 ± 1.89 s (1.24 m/s). Mean GI times were 7.58 ± 2.72 s (1.32 m/s) during seated GI training (TR), 8.27 ± 2.66 s (1.21 m/s) during supine imagery in the MRI scanner without image acquisition (MR), 8.59 ± 2.97 s (1.16 m/s) during the first fMRI run (T1), and 8.74 ± 3.18 s (1.14 m/s) during the second fMRI run (T2). Visual vividness ratings were 4.95 ± 1.10 in TR, 4.62 ± 1.28 in MR, 4.70 ± 1.45 in T1, and 4.84 ± 1.21 in T2. Kinesthetic vividness ratings were consistently lower, reaching 4.35 ± 1.18 in TR, 3.81 ± 0.93 in MR, 4.00 ± 1.30 in T1, and 4.05 ± 1.22 in T2. Both visual and kinesthetic vividness decreased after the transition from seated imagery to the MRI environment and partially recovered during repeated fMRI runs.Conclusions: The MRI environment altered subjective imagery experience, as reflected by reduced visual and kinesthetic vividness, but simultaneously decelerated the performance between imagined and actual walking. Mental chronometry and imagery vividness therefore appear to provide complementary measures of GI quality. Together with movement monitoring, these measures may represent practical control tools for validating GI performance and supporting the interpretation of subsequent fMRI analyses.Acknowledgements: MJ, BK and PeH were supported by MH CZ – DRO (FNOL, 00098892). AH was supported by Slovenian Research and Innovation Agency (J2-60046, P2-0041). PH was supported by the Grant Agency of Masaryk University project MUNI/SC/1939/2024.