[Connectivity between cortex and basal ganglia revealed by the diffusion-weighted imaging]

Abstract

Regional brain function is determined by extrinsic connectivity and intrinsic property (Paasingham et al, 2002). The function of basal ganglia has long been associated with motor movements in human, while its connectivity pattern, studied in macaque monkeys has shown widespread connections with cerebral cortex. Recent technical advances in diffusion-weighted magnetic resonance imaging (DWI) allowed us to look at global neuronal fiber connections in human brain. This technique is based on restricted diffusion motion of water molecule in brain tissue, particularly in white matter, and recent progresses in high resolution acquisition and modeling for local diffusion property are expected to locate connections in more accurate, sensitive and quantitative manner. Validation of this technique is now also evaluated by experiments comparing with the results of neuronal tracers in macaque brain, and some of them show consistent findings in terms of location of connections. The human connectivity between cortex and striatum showed closest pattern as found in macaque monkey, however a large quantity of connection of striatum was originated from dorsal frontal cortex, known as a unique location that executes goal-directed behavior. Future studies using high-resolution DWI may allow us to clarify detailed patterns of connectivity between cortex and basal ganglia, and their pathological changes in diseased brain.