Mechanisms of the Basal Ganglia for Arm-Hand Coordination

摘要

The basal ganglia (BG) appears to play a dual role in the performance ofvoluntary movements: (1) the direct path is primarily involved in providing an estimate of the next sensory state to the cortex, and (2) the indirect path is mainly responsible for the inhibition of movement while the cortex is either involved in choosing the next motor command for execution, or while waiting for a 'go' signal to indicate the end of a delay period. Its strong ties with the supplementary motor area (SMA), a region involved with planning sequential movements, suggest the basal ganglia assists in movement planning and performance by providing the SMA with information regarding the expected state, such that SMA may begin planning the next sequence of the behavior. Disruption of normal motor function, such as that seen in Parkinson's disease, demonstrates a difficulty in performing sequential movements, with some patients exhibiting slower movement or a pause between sequences. This may be attributed to the indirect pathway, which prevents the next sensory state from reaching the cortex, thus inhibiting it from preparing to execute the next movement in a sequence. A computer model of neural networks involved in arm movement was-developed to demonstrate the suggested relationship between the two pathways.