Let us continue our discussion on memory processes. In Part One of this article, we talked about how memory processes are affected by trauma and how that can determine what information the brain is able to retain or store. We talked about the autonomic nervous system (the part of the central nervous system responsible for automatic functions we don't usually think about, such as breathing or the heart beating) and how traumatic memories can affect those functions. We also talked about how traumatic memories are stored differently than other types of memory, as well as the difference between implicit and explicit memory.
Now we will look at memory processes from a physiological perspective. We'll begin by looking at the physical brain, beginning with some very basic terms that will aid us in understanding which parts of the anatomy are involved in the functions of memory, learning, and emotion.
The human brain is an extremely complex organ. For the sake of this discussion, we will mention only those areas of the brain that play the greatest part in the processes and formation of memory. For a picture view and short glossary of some of these terms, please see the website at http://www.ahaf.org/alzdis/about/Anatomy...
Our main focus here will involve the area of the brain called the Limbic System, which is located deep within the center of the brain. This "system" consists of several structures, including the hippocampus (important in memory formation), the amygdala (center of major emotional activity), the thalamus (a "switching station" through which signals travel to various parts of the brain), and several other structures. Also part of the limbic system are those areas that are directly affected or closely connected to it, such as the olfactory system (smells can definitely trigger strong emotions) and the hypothalamus (center for the regulation of several body systems including hunger, thirst, respiration, body temperature, and the regulation of complex emotions such as anger and fatigue).
The limbic system controls mood and attitude. Its functions include setting the emotional tone of the mind, filtering and deciding the importance of events, storing highly charged emotional memories, moderating motivation, controlling appetite and sleep cycles, and processing the sense of smell. It is the part of the brain that determines our mood, is involved in clinical depression, perception of events, motivation, and how we view things from an emotional perspective (see website for BrainPlace.com listed below). According to one of the leading experts in the field of trauma and its treatment, Dr. Bessell van der Kolk (1994), the limbic system plays a major part in traumatic memory processes.
