The Memories of States
How the Brain Stores and
Retrieves Traumatic Experience
Bruce D. Perry
All organ systems in the human body have, to some degree, the property of memory: the capacity, unique to life forms, to bring elements of an experience from one moment in time to another. Memory is the foundation of every biological process -- from reproduction to gene expression to cell division, from receptor-mediated communication to the development of more complex physiological systems (including neurodevelopment) -- and it forms the basis of the immune, neuromuscular and neuroendocrine systems. Through complex physiological processes, elements of experience can even be carried across generations. Elements of the collective experience of the species are reflected in the genome, while the experience of the individual is reflected in the expression of that genome.
No biological system has a more sophisticated capacity to make and store internal representations of the external world -- and the internal world -- than the human central nervous system, the human brain. All nerve cells store information, and this storage is time-bound, contingent upon previous patterns of activity ( Singer 1995; Thoenen 1995). Neurons are specifically designed to respond and modify themselves in response to external cues (e.g.,