Fig. 2

A hierarchical flowchart showing long-term memory classification. Long-term memory has been classified into explicit and implicit to differentiate their retrieval processes. While explicit memory is retrieved with efforts, implicit memory retrieval is automatic and unconscious. The explicit memory sub-classification into episodic and semantic is to explain that events personally experienced are not exactly the same as the general knowledge of existence of objects around us. The implicit memory sub-classification into sensory and motor is to separate sensory processing in somatosensory areas from motor programming in the motor association areas before both sensory and motor memories are integrated in the complementary multi-integration system where the two connect to give meaning to our behaviors. An explicit memory can progress to implicit memory depending on how frequently and emotionally it is recalled and reconsolidated. It is based on the general principle of persistent changes in the strength of connections (synaptic plasticity) between neurons; active connections tend to get stronger, whereas those that are not used get weaker and can eventually disappear entirely