Final answer:
Quick recovery with minor long-lasting damage after supplementary motor cortex removal is due to the brain's neural plasticity, with the primary motor cortex and other regions adapting to compensate for the loss. Severe frontal lobe damage can have greater impacts due to its role in higher cognitive processes.
Step-by-step explanation:
The supplementary motor cortex is involved in the planning and coordination of movements, particularly those that are complex or not well-learned. When it's removed, other areas of the brain can compensate, taking over the functions of the supplementary motor cortex. This adaptability is known as neural plasticity, a characteristic of the brain that allows it to reorganize itself by forming new neural connections. Recovery after the removal of the supplementary motor cortex is typically quick because the primary motor cortex and other brain regions swiftly adapt to manage motor functions, resulting in only minor long-lasting damage. In contrast, severe damage to the frontal lobe can lead to significant changes in personality and behavior, as this region is crucial for executive functions such as decision-making, problem-solving, and regulating behavior. The frontal lobe contains the primary motor cortex, but also areas responsible for higher cognitive processes, which are not as easily compensated for by other brain regions when damaged.