Cerebral Cortex Advance Access originally published online on July 19, 2006
Cerebral Cortex 2007 17(5):1227-1234; doi:10.1093/cercor/bhl033
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Functional Connectivity of Cortical Networks Involved in Bimanual Motor Sequence Learning
1 Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA, 2 Section for Neurobiology, Physiology and Behavior, University of California, Davis, CA, USA
Address correspondence to Felice T. Sun, University of California, Berkeley, 118 Barker Hall, Berkeley, CA 94720, USA. Email: felice_sun{at}alum.mit.edu.
Motor skill learning requires the involvement and integration of several cortical and subcortical regions. In this study, we focus on how the functional connectivity of cortical networks changes with the acquisition of a novel motor skill. Using functional magnetic resonance imaging, we measured the localized blood oxygenation level–dependent (BOLD) signal in cortical regions while subjects performed a bimanual serial reaction time task under 2 conditions: 1) explicitly learning a novel sequence (NOVEL) and 2) playing a previously learned sequence (LEARNED). To investigate stages of learning, each condition was further divided into nonoverlapping early and late conditions. Functional connectivity was measured using a task-specific low-frequency coherence analysis of the data. We show that within the cortical motor network, the sensorimotor cortex, premotor cortex, and supplementary motor area have significantly greater inter- and intrahemispheric coupling during the early NOVEL condition compared with the late NOVEL condition. Additionally, we observed greater connectivity between frontal regions and cortical motor regions in the early versus late NOVEL contrast. No changes in functional connectivity were observed in the LEARNED condition. These results demonstrate that the functional connectivity of the cortical motor network is modulated with practice and suggest that early skill learning is mediated by enhanced interregional coupling.
Key Words: bimanual • coherence • dorsolateral prefrontal cortex • fMRI • supplementary motor area