NEOCORTEX AND SENSORY-MOTOR INTEGRATION I. Introduction The neocortex plays a vital role in the cerebral cortex, making up around 90% ofthis brain region. This lecture focuses on the organization of the neocortex, sensory informationprocessing, and sensory-motor integration. II. Neocortex Organization A. Horizontal Division The neocortex is divided both vertically into six neuron layers and horizontally intocortex regions. Korbinian Brodmann initially classified the cerebral cortex into 52 regions. Naming conventions like BA (Brodmann areas) are used, e.g., primary motorcortex (M1) is BA 4, and primary visual cortex (V1) is BA 17. Additional or modified divisions are made based on new anatomical or functionalfindings. B. Development and Features The neocortex is highly developed in humans, with pronounced gyri(convolutions) and sulci (furrows). It participates in higher-order brain functions. Sensory information reaches the corresponding sensory fields directly. Associative fields link information between sensory and motor fields. III. Sensory-Motor Integration A. Motor Fields Motor areas include the primary motor cortex (M1), premotor area (PMA), andsupplementary motor area (SMA). These areas have a somatotopic structure, mapping the body's parts, forming thedescending tract (approx. 40% PMA/SMA, 30% M1, 30% S1). Techniques like transcranial magnetic stimulation (TMS) help assign properties tocortex areas.
B. Neural Movements Planning PMA encodes target location and hand execution simultaneously during pointingmovements. Special neurons encode target location and the movement itself. SMA is vital for imagination of movements and bimanual coordination. SMA enables the ability to abort planned movements due to external signals. Senso-motoric circuits often handle action planning and execution, not just theprefrontal cortex. In conclusion, the neocortex, with its highly organized structure and sensory-motorintegration, is essential for various higher-order brain functions and motor control.Understanding its role enhances our comprehension of brain functionality.