Journal of Advances in Medicine and Medical Research

The prefrontal lobe, which is more evolved in humans compared to other mammals, has extensive connections with many other areas of the brain including the thalamus, hypothalamus, hippocampus, and amygdala. The prefrontal lobe functions include ambition, cognition, emotions, information evaluation, mental integration, voluntary activity, and organized response. Violent behavior is related to aggression, with less serotonin, gamma-aminobutyric acid interaction, more dopamine, and more testosterone. Violent behavior is reinforced by negative experiences including viewing of violence in childhood and successful problem solving by violence. Every person has a natural and intrinsic need to establish the meaning of life, relative to ambition. Purpose in life (PIL)/ikigai means an attitude to establish the meaning of life. The term PIL/ikigai has been commonly used in daily life for many years in Japan. PIL/ikigai contributes to a greater ability to cope with stress, i.e., greater pleasure and comfort as well as less anxiety and confusion during stressful situations. This process leads to increasing serotonin and decreasing testosterone. PIL/ikigai is reinforced by positive experiences, including being moved by persons and events, success in challenging events, spending time in beautiful natural surroundings, and warm-hearted human relations. Moderate aerobic exercise, e.g., walking and running, causes pleasure. This process results in improvement of the autonomic nervous system, i.e., optimal balance between the sympathetic nervous system and parasympathetic nervous system, and optimally balanced secretions of dopamine, β-endorphin, and serotonin. PIL/ikigai, performing aerobic exercise and violent behavior are prefrontal lobe functions. Prefrontal lobe function develops even during adulthood as the result of experiences. Thus, PIL/ikigai and moderate aerobic exercise may prevent and improve violent behavior.