The psychologist David Lisak explains the difference between the human response to danger under normal circumstances and a response to danger in a life-threatening situation. Under normal circumstances, information indicating danger is perceived by the senses and then processed by a complex network of neural connections. In this context, the stimuli perceived by the senses are also processed in the cortex, the part of the brain responsible for conscious memory and decision making. These complex procedures include a gating function that inhibits a sense of overwhelm by the intensity of the stimulation. However, due to this complexity, the processing of stimuli under normal circumstances is time-consuming.
Lions hunting
In an extreme and life-threatening situation that requires an immediate response, the sensory perceptions that signal danger are sent directly to the amygdala, a part of the brain that is responsible for feelings and for the regulation of autonomic body functions such as circulation, breathing and heart rate. The amygdala responds to the threat by releasing hormones (particularly adrenaline) that increase heart rate, muscle tone and breathing and cause a rise in blood pressure and blood sugar levels thereby enabling an escape or a fight for survival. This rapid processing of stimuli is carried out without a connection to the cortex and the experience, which is therefore outside of consciousness, is stored in the amygdala. It is in this way that the memory of the event is purely physical and not conscious. The gating function that is supposed to prevent the nervous system from being overwhelmed is also bypassed in this process (Lisak, 2002), and the extreme stimulation can cause cyclical reactions that continue to self-stimulate and re-enforce themselves. Kandel describes how such extreme stimulations can lead to the formation of pathological proteins (prion-like proteins) that are self-renewing and therefore do not depend on further or sustained stimulation to continue to exist. The synaptic connection that is created in this way is therefore continually renewed, even when the danger has passed, the stimulation has stopped and a response is no longer called for.
The two characteristics of traumatic memory are therefore:
- the implicit nature of the memory
- the persistence of trauma memory
Bibliography
Lisak, D. (2002). The Neurobiology of Trauma. Retrieved August 29, 2009, from http://www.nowldef.org/html/njep/dvd/pdf/neurobiology. pdf
Images
https://a-z-animals.com/blog/witness-the-wild-fight-for-survival-between-a-lionness-and-a-zebra/