Distinct striatal regions for planning and executing novel and automated movement sequences.

ABSTRACT

The basal ganglia-thalamo-cortical circuits are viewed as segregated parallel feed back loops crucially involved in motor control, cognition, and emotional processing. Their role in planning novel, as compared to overlearned movement patterns is as yet not well defined. We tested for the involvement of the associative striatum (caudate/anterior putamen) in the generation of novel movement patterns, which is a critical cognitive requirement for non-routine motor behavior. Using event related functional MRI in 14 right-handed male subjects, we analyzed brain activity in the planning phase of four digit finger sequences. Subjects either executed a single overlearned four digit sequence (RECALL), or self-determined four digit sequences of varying order (GENERATE). In both conditions, RECALL and GENERATE, planning was associated with activation in mesial/lateral premotor cortices, motor cingulate cortex, superior parietal cortex, basal ganglia, insula, thalamus, and midbrain nuclei. When contrasting the planning phase of GENERATE with the planning phase of RECALL, there was significantly higher activation within this distributed network. At the level of the basal ganglia, the planning phase of GENERATE was associated with differentially higher activation located specifically within the associative striatum bilaterally. On the other hand, the execution phase during both conditions was associated with a shift of activity towards the posterior part of the putamen. Our data show the specific involvement of the associative striatum during the planning of non-routine movement patterns and illustrate the propagation of activity from rostral to dorsal basal ganglia sites during different stages of motor processing.