The Amygdala

The amygdala is an unconscious processor that receives incoming sensory information and then processes this information for an emotional response. These emotional responses may be a defence to a perceived threat (one of the critical functions of this “early warning system”). The amygdala learns how to respond to various stimuli based on it’s reference to implicit memory and makes decisions on how to initiate an emotional reaction to such stimuli. The emotional memory learned and utilised by the amygdala is implicit or unconscious and is in contrast with explicit (declarative) memory that is processed by the hippocampus.

The amygdala sits in both left and right hemispheres as part of the ‘limbic system’ most commonly recognised as the emotional processing centre. Left and right amygdala have separate memory systems but work together to evaluate incoming information and process an emotional response. The right amygdala is associated with negative emotions such as fear and sadness, whereas the left amygdala has been associated with both positive and negative emotional responses.


Clinical Relevance:

The amygdala plays a major role in fear and anxiety. Incoming information goes to the thalamus and then directly to the amygdala while another slower path goes to the neocortex. If the amygdala perceives the record of experiences in the hippocampus matches incoming information, and the amygdala judges that the stimuli is a fight, flight or freeze situation, then the amygdala triggers the HPA (hypothalmic-pituitary-adrenal) axis and “hijacks” the prefrontal cortex (PFC)—partly due to blood flow being redirected from the PFC to the limbic system. This amygdala activity processes information milliseconds earlier than the neocortex, so in the case where implicit memory matches incoming stimuli, the amygdala acts before any possible direction from the neocortex can be received. If, however, the amygdala does not perceive a match to the incoming stimulus then it acts according to the directions received from the neocortex. When the amygdala perceives a threat, it initiates a response to keep us safe from threat, and this may not be the most adaptive response.

The hypersensitivity and overactivity of the amygdala is at the core of anxiety based disorders such as generalised anxiety disorder, phobias, PTSD, and other limbic driven states that inhibit positive, rational (cortical) responses to stressors. Down regulating amygdala reactivity and resulting HPA cascade is of primary importance when treating clients suffering from fear driven conditions. Cognitive therapeutic techniques are of little value to someone who cannot be “cognitive”, and so a bottom-up approach needs to be employed to bring the PFC “back online”, so to speak. Creating an environment of safety and calm becomes the first step in helping the client regulate their amygdala reactivity. Allison and Rossouw (2013) describe the importance of a safe and controlled environment to effect change:

A therapeutic environment facilitates an enriched safe environment where psychotherapy has the potential to facilitate neural change and proliferation. Safety is essential for people in distress because it down-regulates the hypothalamus-pituitary adrenal system. When the fear response, which is triggered from the pons, amygdala, basal ganglia, hypothalamus, pituitary and adrenal glands, is activated, the distress activates the release of the corticotrophin releasing factor, adrenocorticotrophic hormone, adrenalin and cortisol. If these patterns are activated frequently, the patterns of firing will become well established resulting in a default neural activation when a trigger is received. Through psychotherapy it is possible to facilitate down-regulation of the stress response system and encourage the development of new patterns of neural activation. Hence it is vital to enable change through the provision of a safe environment in which the individual can experience controlled incongruence, or stress, to prevent activation of the default distress response. A controlled environment is essential; however, if change is facilitated too quickly, the stress signal may be activated and the habitual pathological patterns facilitated. (Allison & Rossouw, 2013)


Further Information:

The Amygdala on Scholarpedia

The two “Think Big” videos below feature Joseph LeDoux (an expert memory researcher) and his thoughts about this amazing little bit of our brain…


Allison, K. L., & Rossouw, P. J., (2013). The therapeutic alliance:Exploring the concept of “safety” from a neuropsychotherapeutic perspective. International Journal of Neuropsychotherapy, 1(1), 21-29.
doi: 10.12744/ijnpt.2013.0021-0029

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