Using the idea of equipotentiality we can explain how someone who's received damage to a specific part of their brain can relearn how to perform actions that were lost due to brain damage. Since the area of the brain that was originally performing this function is damaged and unusable, the brain compensates and can code that information in other parts of the brain. Through Lashley's ideas of equipotentiality and the law of mass action, he is saying that the brain is functioning as a whole unit and that over all damage to the brain effects it's over all functioning. This starts to go against localization theories which would say that the brain is only functioning in specific regions and the brain's ability to perform at any given task is only effected by the overall damage to that area of the brain and damage to an unrelated area shouldn't affect the task. However, equipotentiality and the law of mass action don't mean that there is no localization. There are certain functions that have been pinned to specific parts of the brain, language and the senses for example, but for things like learning or behavior there is no specific area identified yet, and these are the brain activities that have the flexibility to be coded in different areas of the brain after damage has been sustained.