No significant changes in synaptic density and gray matter volume following motor learning—a pilot study

In animal neurophysiology, motor learning induces long-term potentiation- and depression-like plasticity. In humans, gray matter volume (GMV) changes, measured non-invasively by MRI, in response to motor learning are interpreted as a surrogate measure of plasticity. Here we measure synaptic density with positron emission tomography (PET) to investigate the learning-induced synaptic plasticity more directly, and MRI-based GMV to investigate structural plasticity.

In this pilot study, twenty-two volunteers participated in a simple or complex (group factor) four-week motor training on a bimanual tracking task. Learning progress was modelled individually. [18F]SynVesT-1 PET and T1-weighted MRI were acquired at baseline (PRE) and immediately after the motor training (POST), and at MID for MRI only (time factor). Average standard uptake value ratios (SUVR), GMV and average cortical thickness in six a priori chosen VOIs of the visuomotor network were statistically compared over time, group and time-by-group, and associated with learning.

Participants’ performance improved significantly, and more for the complex than the simple training group. The VOI-based PET and GM analyses did not yield any significant results. In this pilot study, we did not identify significant changes in [18F]SynVesT-1 synaptic density as a surrogate marker for plasticity after motor learning in the a priori chosen VOIs.

This work was supported by KU Leuven (C16/15/070, PDMT2/24/077), the Research Foundation Flanders (G089818N, G039821N, 11F6921N, V434023N), the Excellence of Science grant (EOS 30446199, MEMODYN) and the Hercules fund AUHL/11/01 (R-3987) and I005018N. The funders played no role in study design, data collection, analysis and interpretation of data, or the writing of this manuscript. These authors contributed equally: Stephan P.

Movement Control & Neuroplasticity Research Group, Department of Movement Sciences, Group Biomedical Sciences, KU Leuven, Heverlee, Belgium Melina Hehl, Stephan P. Swinnen & Koen Cuypers KU Leuven, Leuven Brain Institute (LBI), Leuven, Belgium Melina Hehl, Patrick Dupont, Koen Van Laere, Stephan P. Swinnen & Koen Cuypers Neuroplasticity and Movement Control Research Group, Rehabilitation Research Institute (REVAL), Hasselt University, Diepenbeek, Belgium Translational MRI, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut, USA Laboratory for Cognitive Neurology, Department of Neurosciences, KU Leuven, Leuven, Belgium Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium Division of Nuclear Medicine, University Hospitals UZ Leuven, Leuven, Belgium The authors declare no competing interests.

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