A recent study published in the prestigious Nature Journal has shed new light on the functional organization of the motor cortex (M1) of the human brain. By employing precision functional mapping (PFM) and functional magnetic resonance imaging (fMRI), researchers identified a dual system within M1 that melds action and body control into a common circuit characterized by a somato-cognitive action network (SCAN) that alternates with effector regions. This interdigitation of action control-linked and motor effector regions clearly interrupts the classic homunculus, with regions showing distinct connectivity, structure, and function that correspond to task-evoked activities during tongue, hand, and foot movements. The study findings were verified by analyzing data from nearly 50,000 individuals obtained from three large fMRI studies, and placed in inter-species (macaques versus humans), clinical (postpartum stroke), and developmental (neonatal, infantile, childhood, and adulthood periods) contexts. The dual network integrates the mind and the body, aligned with the sensory systems, and may enable the execution of action plans. The study suggests that this system for whole-body action planning punctures M1 and is critical for fine motor control, linked to SCAN, which is critical for integrating goals, bodily movements, and physiology, and also enables anticipatory breathing, cardiovascular, and postural changes. Overall, this study provides valuable new insights into the functional organization of the motor cortex and has important implications for our understanding of brain function and motor control.
