Declarative memory is our memory for facts. There is a common belief that declarative memory is further broken down into two components: Episodic (memory for past and personally experienced events), and Semantic (knowledge for the meaning of words and how to apply them).
In general, the hippocampus and cortex are involved in declarative memory. Neocortex is also associated with declarative memory. In particular, this includes the right frontal and temporal lobes for the episodic component, and the temporal lobes for the semantic component.
The psychologist who first proposed this idea was Endel Tulving. In the case of episodic memory, Tulving notes that the subject not only has the memory, but can remember something about the setting in which the memory was learned. Conversely, for semantic memory, the subject cannot recall the context of the initial learning.
Tulving argued that episodic memory was the system that was tested in most memory experiments, which required subjects to recall lists of words. He reasoned that if a subject failed to recall a word in a particular list, it was due to the fact that he/she failed to recall a particular episode (i.e., list) and not the meaning of the word. Semantic memory can be defined as the knowledge for the meaning of words and how to apply them.
For example, if we are asked to memorize a list of fruits and then, during a recall, if we fail to remember say mango and apple, it is not because we have forgotten these common names. It is because we fail to remember them as part of the list. This caused Tulving to make the distinction between memory for ‘meanings’ (semantic) versus memory for ‘episodes’ or experiences (episodic).
Studies of amnesiacs have been the most common form of evidence used to distinguish declarative memory from the other prominent type of LTM known as procedural memory. Amnesiacs are known to lack the ability to add to their de-clarative memory stores (episodic or semantic).
A well-known case in medical research involves the patient known as HM, who had the anterior and medial portions of his temporal lobes removed to prevent epileptic seizures. HM and similar patients have normal memory of events before their trauma but they can’t form new long-term memories. This suggests that the frontal and medial temporal lobe structures are required for adding information to declarative memory. Several researchers have accepted this case as support for the distinction of memory pathways.