Memory is the process in which information is encoded, stored, and retrieved. Information that reaches the five senses in the forms of chemical and physical stimuli is electrically encoded. In the storage phase, information is maintained over periods of time. The third process occurs when the retrieval of information that has been stored is located and returned to consciousness.
Sensory memory lasts less than a second. Short-term memory lasts for several seconds to a minute, and its capacity is also very limited. Long-term memory can store much larger quantities of information for potentially unlimited duration (sometimes a whole life span). Its capacity is immeasurably large.
Short-term memory is dependent on regions of the frontal lobe (especially dorsolateral prefrontal cortex) and the parietal lobe. Long-term memory, on the other hand, is maintained by more stable and permanent changes in neural connections widely spread throughout the brain. The hippocampus is essential for learning new information, and to the consolidation of information from short-term to long-term memory, although it does not seem to store information itself. Without the hippocampus, new memories are unable to be stored into long-term memory.
Numerous researchers have indicated that chronic stress may lead to changes in cytoarchitecture of the hippocampus itself, and to creating deficits in explicit recall memory (McEwen, 1992; Uno, Tarara, Else, Suleman, & Sapolsky, 1989; Watanabe, Gould, & McEwen, 1992; Wooley, Gould, & McEwen, 1990).
According to Teicher (2002, pp. 68-75), the brain itself suffers pernicious effects from abuse that actually “mediate development in vulnerable brain regions” as follows:
- Limbic irritability. This is manifested by markedly increased prevalence of symptoms suggestive of temporal lobe epilepsy (TLE) and by an increased incidence of clinically signiﬁcant EEG (brain wave) abnormalities. [This embraces the possibility of sensory, motor, perceptual, and/or emotional changes].
- Deﬁcient development and differentiation of the left hemisphere. This is manifested throughout the cerebral cortex and the hippocampus, which is involved in memory retrieval. [This may include heightened right hemispheric development (to the detriment of the left hemisphere); deficiency in development of the left hippocampus—and hence language development, verbal memory, and possibly dissociative symptoms].
- Deﬁcient left-right hemisphere integration. This is indicated by marked shifts in hemispheric activity during memory recall and by underdevelopment of the middle portions of the corpus callosum, the primary pathway connecting the two hemispheres [that directly mediates hemispheric integration].
- Abnormal activity in the cerebellar vermis (the middle strip between the two hemispheres of the brain). This appears to play an important role in emotional and attentional balance, and regulates electrical activity within the limbic system. [This may manifest in decreased serotonin production in the hippocampus, and decreased receptors for glucocorticoids leading to increased sensitivity to fear; and a heightened adrenaline response. This may also suppress immune and inflammatory responses].
© 2016 – Stefan J. Malecek, Ph.D., MAC