Human brain in the coronal orientation. Amygdalae are shown in dark red. The structural and functional brain changes in posttraumatic stress disorder pdf complex can be further subdivided into the lateral, the basal, and the accessory basal nuclei.

There are functional differences between the right and left amygdala. In one study, electrical stimulations of the right amygdala induced negative emotions, especially fear and sadness. Each side holds a specific function in how we perceive and process emotion. The right and left portions of the amygdala have independent memory systems, but work together to store, encode, and interpret emotion.

The right hemisphere is associated with negative emotion. It plays a role in the expression of fear and in the processing of fear-inducing stimuli. When an individual is presented with a conditioned, aversive stimulus, it is processed within the right amygdala, producing an unpleasant or fearful response. This emotional response conditions the individual to avoid fear-inducing stimuli. It also plays a significant role in the retention of episodic memory. This type of memory does not require conscious recall. The right amygdala plays a role in the association of time and places with emotional properties.