retrograde amnesia

n. Defect in retrieving old memories. The individual who has retrograde amnesia becomes unable to recall the events that occurred and the knowledge that existed before the onset of the amnesia. It is generally associated with anterograde amnesia. Retrograde amnesia can impair both semantic memory (memories mediated through a semantic system, such as verbal memory) and episodic memory (memory for events), but procedural memory 
(skills and habits) is usually relatively better preserved. Retrograde amnesia is associated with damage of different structures of the socalled brain memory system, such as the hippocampus, but specific forms of retrograde 
amnesia (for example, retrograde amnesia for words or faces) can be found in cases of cortical damage. Diverse pathological conditions are associated with retrograde amnesia, such as traumatic head injury and brain infections. Retrograde amnesia usually follows a temporal gradient: remote memories are more easily accessible than events occurring just prior to the pathological condition. – AA

▶ See also AMNESIA