The limbic system, also called the paleomammalian brain, is a complex collection of brain structures that lie on both sides of the thalamus, directly under the cerebrum. It is thought by some neuroscientists that it was added to the forebrain in the course of evolution.
The main limbic structures include the hippocampus (memory centre), the amygdala (anger, anxiety and stress centre) and the limbic cortex that interconnects with the prefrontal cortex, which is responsible for reasoning and judgment.
The limbic system supports functions such as emotion, behaviour and motivation and is devoted to supporting our survival structures that protect and regulate human emotions. Research suggests that it appears to be primarily responsible for emotional life, and it has a great deal to do with the formation of memories.
This information suggests that emotional wellbeing and happiness is linked to the wellbeing of the limbic system. Therefore it is possible that a deterioration of the limbic system could lead to more negative, out of control emotions such as rage and depression, leading to violence and a general neurological decline.