Episodic memory is what makes people the person they are. Disruptions and complete failure of this memory function have profound effects on how people cope with their personal daily lives.
What is episodic memory?
Episodic memory has an identity-forming effect, as it is only through its functioning that the individual becomes the personality that he or she is. It is localized in the hippocampus, among other areas, shown in yellow. Episodic memory belongs to the so-called declarative long-term memory. It is localized in the hippocampus, temporal and frontal lobes. All individual experiences and situations are stored in it. With the help of episodic memory, a person is thus able to travel into the individual past and plan his future. All events that the person makes in the course of his life are stored there in their exact situational context and can – if there is no impairment of the episodic memory – be retrieved in this form. In old age, the ability to remember personal experiences decreases continuously. To function optimally, episodic memory requires information from semantic memory. General knowledge, factual knowledge and general experiences are stored there. It is characteristic for the functioning of the episodic memory that most of the neuronal connections are created only for a short time, unless the person can associate them with personal experiences and experiences of his past. The memory of past events is usually triggered by key stimuli from the personal environment (music, smells, certain people, etc.) or from within the individual (emotions). The contents stored in episodic memory are sorted according to their valence by the feelings of the person concerned. The better the general memory performance, the more information can also be retrieved from the episodic memory.
Function and task
Episodic memory has an identity-forming effect, since the individual only becomes the personality he or she is through its functioning. Therefore, it is also called autobiographical memory. With the help of the personal experiences and adventures stored in the self, the individual can evaluate and classify current experiences. The memory stored in the episodic memory therefore also has a behavior-modifying effect: If the event is evaluated negatively, the person concerned draws different consequences from it than if he or she evaluates it positively. Memories of bad experiences, for example, cause avoidance of situations that are similar to what was originally experienced. The person “learns” from past experiences. Personal experiences from earlier times also enable the individual to imagine certain experiences in the future and to make plans for the future. Situations in the past that have positive connotations are always viewed positively later: A piece of music that was linked to a happy experience will still evoke similar feelings of happiness 20 years from now. It can therefore have an additional motivating and mood-lifting effect. In addition, episodic memory helps to remember things that have been forgotten or lost. By going back to the relevant situation in which the person lost the object, he or she usually finds it again (for example, the lost purse that is retrieved when going back to the store). Objective content of interest to the individual, which can be linked to their own experiences, is also stored in autobiographical memory: A reader will still be able to remember book contents that are interesting to him many years from now if he visualizes the situation in which he read the book at the time. Episodic memory can also have a social bonding function. Personal memories can be shared with others and thus strengthen human relationships, which in turn is deposited as a positive experience in autobiographical memory. The opposite experience is, of course, also possible.
Diseases and ailments
Episodic memory, like other memory functions, can be affected by accidents, illness, psychological strain, stress, and the aging process. People with poor memory can make inadequate use of the content stored in autobiographical memory.The current experience is not connected at all, incorrectly or only insufficiently with the corresponding experiences of the past. Concentration disorders also have a detrimental effect on episodic memory. The same applies to brain-organic disorders affecting the hippocampus, for example. A characteristic feature of this type of memory disorder is that the semantic memory functions perfectly, but the episodic memory no longer functions. New experiences can no longer be associated with previously made ones and permanently stored. In partial retrograde amnesia, the contents that are close to the time of the brain damage are preferably forgotten. If global amnesia is present, personal information dating back a long time is also affected. Current events and important experiences can then no longer be stored in episodic memory. Transient global amnesia (TGA) is usually limited to a duration of one to 24 hours. It is triggered by extreme mental or physical stress. The affected person has no orientation in space and time. In psychogenic amnesia, only one specific event in the individual’s past is no longer accessible. It is usually caused by a psychological trauma that represses the highly stressful experience. Impairments of autobiographical memory can be caused by craniocerebral trauma, stress, epileptic seizures, encephalitis, meningitis, brain tumors, migraine, stroke, dementia, Alzheimer’s disease, poisoning, circulatory disorders in the brain, psychological trauma, psychotropic drugs and alcohol abuse. They are treated by first eliminating the underlying disease. This can be done with the help of medication, psychotherapy, relaxation exercises (autogenic training, yoga, progressive muscle relaxation) and special memory training. Changing the body to an alkaline diet can also have a positive effect on episodic memory performance.
