The majority of the brain relies on emotions, particularly the amygdala, insular cortex, periaqueductal gray, and hippocampus—all of which are components of the limbic system.

The limbic system regulates emotion and behavioral responses. The parts of the limbic system adapt to our emotional state. For example, the size of the hippocampus is affected by moods. When someone is depressed, they have a smaller hippocampus. When someone is happier, they have a larger hippocampus. When someone feels emotion, the brain correlates it to chemical messengers like dopamine, and each messenger is assigned to an emotion which is how the brain recognizes the different feelings.  

These emotions play a role in our brain’s work and even how much we can concentrate. Stress affects memory and attention span, just like other emotions affect memory and attention differently. These variables affect how we learn, remember or perceive things as time passes on.  

There are two different ways to remember. First, there is cognitive thinking. Cognitive thinking focuses on retaining outside information. This type of thinking helps us learn more and remember new things. We use cognitive thinking in many different aspects of our lives—notably, in school, where we are concerned with learning new topics and facts.

The other way we remember things is through autobiographical thinking. This is more self-induced and mainly about oneself. It involves how you think and react to situations. This is more long-term, consisting of episodes that have been recollected your entire life. 

These different forms of remembering correlate with our emotions. For example, someone could have a specific memory that could be autobiographical or cognitive that is associated with emotion and could then be connected with stress. When things are remembered, they connect to specific emotions, so our brain correlates them together. 

The brain is a fully connected system affected by emotions and different types of thinking. Each aspect is affected by another, and the way we choose to behave changes the productivity and activity of the brain.