fMRI Investigation of Cortical and Subcortical Networks in the Learning of Abstract and Effector-Specific Representations of Motor Sequences

To investigate the underlying causes for slower response times in the visual setting,
we performed correlation analysis of chunking patterns between the normal and
rotated settings. It has been shown that subjects spontaneously reorganize the
sequence into a number of chunks while learning the mxn task (Sakai et al. 2003,
Pammi et al. 2004). We identified the chunking patterns using the response times for
individual sets of the sequence. We assumed that the chunking patterns would have
stabilized by the late stage. Figure 3 displays the average response times for the six
sets in the late stage of normal and rotated settings for a representative subject. Since
a trial was terminated upon error, only successful trials were used to calculate the
chunking patterns. As shown in Figure 3, there was a significant correlation between
the chunking patterns of the normal and motor settings, while the chunking patterns
were different for the normal and visual settings. The correlation results for all the
subjects are tabulated in the supplementary material. These results clearly indicate
that subjects used similar representation of motor sequences for the normal and motor
settings, but developed a different representation of the motor sequence in the visual
setting. Taken together, high accuracy level and slower response times in the visual
setting in the late stage suggest that subjects might have successfully acquired a
second motor sequence in the visual setting.

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