Parallel Alterations of Functional Connectivity during Execution and Imagination after Motor Imagery Learning

BACKGROUND: Neural substrates underlying motor learning have been widely investigated with neuroimaging technologies. Investigations have illustrated the critical regions of motor learning and further revealed parallel alterations of functional activation during imagination and execution after learning. However, little is known about the functional connectivity associated with motor learning, especially motor imagery learning, although benefits from functional connectivity analysis attract more attention to the related explorations. We explored whether motor imagery (MI) and motor execution (ME) shared parallel alterations of functional connectivity after MI learning. METHODOLOGY/PRINCIPAL FINDINGS: Graph theory analysis, which is widely used in functional connectivity exploration, was performed on the functional magnetic resonance imaging (fMRI) data of MI and ME tasks before and after 14 days of consecutive MI learning. The control group had no learning. Two measures, connectivity degree and interregional connectivity, were calculated and further assessed at a statistical level. Two interesting results were obtained: (1) The connectivity degree of the right posterior parietal lobe decreased in both MI and ME tasks after MI learning in the experimental group; (2) The parallel alterations of interregional connectivity related to the right posterior parietal lobe occurred in the supplementary motor area for both tasks. CONCLUSIONS/SIGNIFICANCE: These computational results may provide the following insights: (1) The establishment of motor schema through MI learning may induce the significant decrease of connectivity degree in the posterior parietal lobe; (2) The decreased interregional connectivity between the supplementary motor area and the right posterior parietal lobe in post-test implicates the dissociation between motor learning and task performing. These findings and explanations further revealed the neural substrates underpinning MI learning and supported that the potential value of MI learning in motor function rehabilitation and motor skill learning deserves more attention and further investigation

The correlation between the tapping rate and or for the experimental group.

<p>Note. Abbreviations: rPPL–right posterior parietal lobe; SMA–supplementary motor area; rStria–right Striatum; lStria–left Striatum.</p

The connectivity degree of pre-tests and post-tests for all ROIs in the motor imagery task of the experimental group.

<p>(A) The surface visualization of all 12 ROIs with node sizes indicating their relative value of . Red indicates that of the ROIs were significantly altered after motor imagery learning, while blue indicates that of the ROIs were not significantly altered after motor imagery learning. (B) of pre-tests and post-tests for all ROIs (* represents the significant alterations, corrected p<0.05).</p

The connectivity degree of pre-tests and post-tests for all ROIs in the motor execution task of the experimental group.

<p>(A) The surface visualization of all 13 ROIs with node sizes indicating their relative value of . Red indicates that of the ROIs were significantly altered after motor imagery learning, while blue indicates that of the ROIs were not significantly altered after motor imagery learning. (B) of pre-tests and post-tests for all ROIs (* represents the significant alterations, corrected p<0.05).</p

Mean button press rate (A) and mean number of errors (B) for pre-tests and post-tests of the experimental group and the control group.

<p>Mean button press rate (A) and mean number of errors (B) for pre-tests and post-tests of the experimental group and the control group.</p

The connectivity degree of pre-tests and post-tests for all ROIs in the motor imagery task of the control group.

<p>(A) The surface visualization of all 12 ROIs with node sizes indicating their relative value of . Blue indicates that of the ROIs were not significantly altered after motor imagery learning. (B) of pre-tests and post-tests for all ROIs.</p

The interregional connectivity between the rPPL and other ROIs of pre-tests and post-tests in the motor imagery task of the experimental group.

<p>(A) The surface visualization of all 12 ROIs with line width indicating the relative value of . Red indicates the were significantly altered after motor imagery learning, while blue indicates the were not significantly altered after motor imagery learning. (B) The of pre-tests and post-tests between the rPPL and other ROIs (* represents the significant alterations, corrected p<0.05).</p

The interregional connectivity between the rPPL and other ROIs of pre-tests and post-tests in the motor execution task of the experimental group.

<p>(A) The surface visualization of all 13 ROIs with line width indicating the relative value of . Red indicates the were significantly altered after motor imagery learning, while blue indicates the were not significantly altered after motor imagery learning. (B) The of pre-tests and post-tests between the rPPL and other ROIs (* represents the significant alterations, corrected p<0.05).</p

The connectivity degree of pre-tests and post-tests for all ROIs in the motor execution task of the control group.

<p>(A) The surface visualization of all 13 ROIs with node sizes indicating their relative value of . Blue indicates that of the ROIs were not significantly altered after motor imagery learning. (B) of pre-tests and post-tests for all ROIs.</p