Brain circuitry to control arm movement
The MPC controls our arm movements and, thus, our interaction with the environment. Research in non-human primates has revealed that MPC contains different architectonic areas. However, it remains one of the least characterised brain regions, and the exact contributions of different areas to sensorimotor behaviour remain unclear. The EU-funded MIPFORACTION (Understanding the organisation of the medial parietal cortex: Sensorimotor integration for goal-directed behaviour) project addressed the need for better characterisation of the cortical areas involved in coordinating skilled arm movements. Their goal was to investigate the encoding in the MPC for reaching movements, and how information from the different senses influence these movements. The project combined modern physiological and anatomical methods utilising tracer injections (guided by MRI) and mapping of sensory (visual, somatosensory) responses. To study functionality of the region, researchers recorded the electrical brain activity of monkeys trained to reach to visual and proprioceptive targets. The results of the project study proved that MPC areas form connections with several brain areas in the frontal, temporal, limbic, and local parietal cortices. Study outcomes also supported the associative (neither strictly sensory nor motor) nature of MPC, demonstrating the absence of connections with primary sensory cortices and lack of purely sensory responses. Moreover, the posterior parietal region was found to contain histologically defined areas with some overlap in connectivity patterns and function, adding to the theories of distributed information processing. MIPFORACTION results improved understanding of the brain areas that form the medial part of the parietal association cortex and their contributions to sensorimotor behaviour. This knowledge enables further investigation of the cellular architecture of neurological syndromes, including optic ataxia. Understanding the contributions of medial parietal areas to movement will aid in the accurate placement of prosthetic devices to control artificial limbs. This kind of research aims to help patients suffering from brain lesions or degenerative diseases by restoring some degree of motor abilities.
