In addition, we specify circumstances under which a second party may have a large, medium, or minimal influence on the content of traumatic memory. The model, which is based on findings from modern cognitive neuroscience, also provides a neurobiologically sound alternative to the psychodynamic concept of repression. At a physiological level, dissociation may occur because of increases in concentrations of glucocorticoids released during stress.
Glucocorticoids differentially affect the physiology of the amygdala and hippocampus.
Thus, increasing stress enhances coding of emotional memory but disrupts coding of spatiotemporal context. Under traumatic stress, emotional memories are laid down without a significant contribution from the hippocampal system. This pool is, essentially, a population of traumatic memory fragments. Upon retrieval, traumatic memories cannot be experienced as a memorial event with a beginning, end, and internal spatiotemporal structure. Notice that, by the model, all true traumatic memories are recovered in the sense of being reconstructed from memory fragments.