Our results indicated that two neuro-behavioral states may be explored with this methodology: a Proactive brain state that actively plans the response to the sensory information and is characterized by delta-beta activity, and a Reactive brain state that processes incoming information and reacts to environmental ... Reactive brain is a term used to describe a person's brain that is constantly on the lookout for danger and reacts to stimuli quickly. This can make it difficult for someone to focus and be productive, as they are constantly worried about what might happen next. Reactive brain can also make it difficult to control emotions, as they can be easily triggered.