Episodic memory refers to the recollection of autobiographical information within the brain and, along with semantic memory, makes up the declarative memory division in the brain. Autobiographical information, as the name suggests, is any event or experience directly having to do with the self. Declarative memory is a subdivision making up one half of all memory classifications, with its counterpart being procedural memory. Procedural memory, also known as implicit memory, is learned information of the conscious and subconscious that is involved in the knowledge necessary to complete tasks.
An example to illustrate the difference between procedural and declarative memory is playing the guitar. In order to play a guitar, the person playing may utilize implicit knowledge of how to actually play, just like riding a bike. In the implicit realm, one can accomplish a task without referencing the experience of learning it. If a person thinks back to a specific event, however, perhaps being at a guitar lesson, he or she drawing upon episodic, hence declarative, memory.
Neurological matters are rarely specific to one region or structure in the brain, and memory is no exception. The medial temporal lobe, containing the hippocampus as well as the prefrontal cortex, are the primary structures working together to achieve an episodic retention of information. Age, pharmacological agents, and other variables may contribute to changes in this functioning. Generally speaking, however, these are the main cognitive resources for episodic memory and other declarative functions.
Cognitive neuroscience is a complex field. Few have even a vague understanding, and virtually none possess full comprehension of the complex and abstract processes involved in producing memory. For these reasons, the understanding of the brain, memory, and neurological functioning is often speculative and debatable.
In many diseases, such as Alzheimer's and autism, there has been evidence of damage to the hippocampus. This may explain why those suffering from Alzheimer's often forget significant past life events, for example, a wedding or the birth of a child. This may also play a role in autism as sufferers are cognitively compromised in a number of ways.
As the deterioration of the hippocampus and other brain structures grows severe enough, the loss of episodic memory increases in significance. If the gradual decline of one with Alzheimer's disease is studied, for example, the patient may experience brief episodic losses, such as forgetting what they ate for dinner or what they did last week. When the disease progresses, more significant episodic memory losses are sadly experienced.
