Many neuroscientists believe that hostility is related to fear and anxiety. It is a response to threatening stimuli. The parts of the brain involved in mediating hostile behavior in humans are within a circuit classically known as the limbic system. Specifically, hostility is controlled by the prefrontal cortex, amygdala, hypothalamus, thalamus and paraquaductal gray matter.
Prefrontal Cortex
The prefrontal cortex is in an area of the brain called the cerebrum. The cerebrum is large and contains regions that are important for many functions. The prefrontal cortex is important for reasoning and decision-making. According to the International Handbook of Anger, parts of the prefrontal cortex appear to be important in weighing the benefit of an aggressive response vs. the risks incurred by such a response.
Amygdala
The amygdala is an area of the brain linked to fear and anxiety, according to Psycheducation.org. It is a small section of tissue in the cerebrum's temporal lobe. According to neuroscientist Joseph LeDoux's book, "Synaptic Self," the amygdala works with the prefrontal cortex to balance information associated with fear in the brain. The amygdala processes the emotional aspect of fear, while the prefrontal cortex processes the cognitive information and decides on a response.
Thalamus
The thalamus is an area of the brain beneath the cerebrum. It acts as a gateway for sensory information entering the brain, routing it to the appropriate areas of the cerebrum, including the amygdala. According to a study at the New York University Center for Neural Science, the thalamus imparts information about the intensity of auditory stimuli to the amygdala.
Hypothalamus
The hypothalamus is beneath the thalamus, near the upper portion of the brain stem. It is a small structure responsible for regulating the actions of the autonomic nervous system. This is the system responsible for the "fight or flight" response to threat, according to the textbook "Neuroscience: Exploring the Brain."
Periaquaductal Gray Matter
The midbrain contains an area known as the PAG, or periaquaductal gray matter. This small area is connected by neurons to the hypothalamus. According to the the textbook "Neuroscience: Exploring the Brain," damage to PAG tissue inhibits the ability to respond aggressively.
References
- "The International Handbook of Anger"; Michael Potegal, Gerhard Stemmler and Charles Spielberger; 2010
- Psycheducation.org: The Amygdala
- "Synaptic Self"; Joseph LoDoux; 2003
- "Response Properties of Single Units in Areas of Rat Auditory Thalamus That Project to the Amygdala"; Experimental Brain Research; Fabio Bordi and Joseph LeDoux; March 1994
- "Neuroscience: Exploring the Brain" Third Edition; Mark Bear, Barry Connors and Michael Paradiso; 2007
