Neural Plasticity in Action Recognition: A VBM and fMRI Study




Levy, Shira

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In our day-to-day interactions, we use our own motor representations to understand the actions of those around us. How we relate to others is an important part of life. Understanding motor representations can help us to better learn and grow, conduct relationships, assess intent, and increase the quality of our daily lives. Further, understanding how we acquire motor representations can help us better understand this mechanism as we use it. The acquisition of these motor representations can be described by functional changes in the brain as well as structural changes in the brain. The relationship between these expressions of plasticity is not well understood. In this study, I sought to establish if a mediation equation would explain the results of an action recognition study. Participants were taught a novel one ball juggling cascade task either by physically performing it (nonvisual motor group) or by means of observation (nonmotor visual group). The group who physically performed the task learned completely without visual input ensured by blindfolds. The observation group was taught a visual task with physical practice. Magnetic resonance imaging (MRI) scans were taken before, during, and after training. The functional magnetic resonance imaging (fMRI) results represented functional changes between time points. These results showed the changes in action recognition as a result of training. A voxel-based morphometry (VBM) analysis, performed on the structural MRI images, represented the structural changes. These results were overlaid to determine regions which spatially overlap for both functional and structural changes, with the head of the hippocampus as the only brain region which demonstrated both. A region of interest (ROI) analysis was conducted on the individual images for the head of the hippocampus to obtain mean intensities. These means were entered into Baron and Kenny’s (1986) mediation equations to determine if structural changes act as a mediator on the relationship between time and functional changes. While the equations for the relationship between time on functional changes and time on structural changes were significant, the relationship between structural changes on functional changes was not significant. Therefore the requirements of Baron and Kenny (1986) were not upheld, leading to the conclusion that structural changes do not act as a mediator in the relationship between time and functional changes.



Motor learning, Mediation, Voxel-based morphometry, Functional magnetic resonance imaging, Plasticity, Skill acquisition