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

Distinct neural systems subserving sequence representations

Direct comparison of visual and motor contrasts would reveal distinct neural systems
associated with the visual and motor settings, respectively (Table 3). In the early
visual > motor comparison, left anterior putamen in the dorsal aspect, left ventral
striatum and left hippocampus were activated. Apart from the subcortical activity,
activation of the medial prefrontal cortex, anterior cingulate, right superior parietal
cortex, and right occipital cortex near the middle occipital gyrus were also observed.
Similarly, extensive cortical and subcortical activation was also observed in the late
stage. Subcortical activation loci were found in the left dorsal putamen (anterior
region) and left hippocampus. The activation in the left dorsal putamen was stronger
in the late stage and extended into posterior putamen also. Cortical activation was in
the precuneus, middle frontal gyrus, the occipital lobe, and the temporal lobe (BA 39).
An interesting observation is the transition of activity observed from the left anterior
putamen to left anterior and posterior putamen by the late stage in the visual setting
(Table 3).

While the visual setting activated several subcortical and cortical sites, activity in the
motor setting was restricted mainly to cortical loci. In the early motor > visual
contrast, activation was observed in the precuneus, right occipital cortex near the
lingual, fusiform and middle occipital gyri and in the right inferior frontal gyrus
(IFG). While activation in the right IFG remained till the late stage, additional areas in
the left prefrontal cortex (BA 9,  10 and 45), anterior cingulate, and caudal

supplementary motor area (SMA) were activated in the late stage. There were

activations in the right cerebellum (anterior lobe) and left caudate body in the late
stage of the motor setting.

Table 3. Locations of significant BOLD signal comparing the two rotated conditions

Brain area

Cluster size

Coordinates (mm)

(voxels)

T value

16

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