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

Motor-normal experiments

All the activations associated with motor-normal experiments during both the early
and late stages are summarized in Table 2 and Figure 5. In motor > follow contrast
(Table 2a), there is a general trend of decrease in activation from early to late stage in
various subcortical regions such as in the anterior lobe (culmen) of right cerebellum,
bilateral thalamus (pulvinar), right caudate body, bilateral dorsal putamen (anterior
and posterior aspects), and bilateral globus pallidus. However, the trend in the cortical
regions is a mixed one. Sustained activity was found in the left inferior parietal lobule,
left primary motor cortex, and left somatosensory cortex. While there is no residual
activity in the right middle temporal gyrus and right middle occipital gyrus by the late
stage, activity in the left middle occipital gyrus decreased by the late stage. Activation
was found bilaterally in the superior parietal cortex, inferior parietal lobule and
precuneus in both early and late stages. An increase in activation was observed in both
the dorsal and ventral regions of left premotor. While the activation in superior
parietal cortex seems to decrease from early to the late stage, that in the dorsal
premotor area in the left hemisphere becomes stronger by the late stage of motor
setting. Thus a transition of activation seems to be taking place from the parietal-
premotor areas in the early stage to premotor areas by the late stage of motor setting.
Interesting thing to note is the absence of activity in the anterior dorsal striatum by the
late stage and lack of any activity in the ventral striatum and the hippocampus in the
motor setting. In motor > normal contrast, persistent activity was found in the left
superior and inferior parietal cortical areas and in the early stage an additional locus
of activation was found in the right middle temporal gyrus (Table 2 b).

Table 2a. Locations of significant BOLD signal in the early and late stages of motor > follow contrast

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