Anterograde amnesia
Anterograde amnesia is the inability to form new long-term memories after an injury or illness, while memories from before it stay mostly intact. The person can hold a thought for a few seconds but loses it soon after. The hippocampus is the structure most often involved. It is the mirror image of retrograde amnesia, which erases memories from before the event.
In more detail
Memory has to move from short-term into long-term storage, a process called consolidation, and the hippocampus and nearby areas in the medial temporal lobe do much of that work. When they are damaged, the first steps still function: the person can follow a conversation and repeat a phone number. But the new content never settles into long-term storage, so it is gone minutes later.
Not every kind of memory is lost. In the famous case of Henry Molaison, known as H.M., surgery in 1953 removed parts of both temporal lobes to treat severe epilepsy. He could no longer form new memories of events and facts, yet he improved at a mirror-drawing task over several days without remembering that he had practiced. Skills and habits (procedural memory) are spared, while memory for events (episodic memory) and facts is hit hardest.
Forget the film version, where a blow to the head makes someone forget who they are. Real amnesia is rarer and narrower than movies show, and this page is for studying the concept, not for diagnosing anything. If you worry about your own memory or someone else's, talk to a doctor.
Anterograde vs retrograde amnesia
| Feature | Anterograde amnesia | Retrograde amnesia |
|---|---|---|
| What is lost | The ability to form new memories after the event | Memories formed before the event |
| Direction in time | Forward: the future cannot be stored | Backward: the past cannot be reached |
| Older memories | Mostly intact | Lost, often the most recent ones first |
| New learning afterwards | Severely impaired for events and facts | Usually possible |
| Common causes | Hippocampal damage, head injury, stroke, encephalitis, heavy alcohol use, some sedatives | Head injury, stroke, encephalitis, degenerative disease |
| Classic example | H.M. after his 1953 surgery | Losing the minutes to years before a head injury |
| Memory trick | Antero: new information does not go in | Retro: old information cannot be fetched |
Example
A psychology exam asks: a patient chats normally but cannot recall meeting the nurse an hour ago, although he remembers his wedding in 1990. Which type is it? Anterograde amnesia. New events do not become long-term memories, while old ones remain. If the same patient could not remember his wedding but could learn new faces, it would be retrograde.
How StudyPDF does this
Memory disorders are a standard exam topic in psychology and neuroscience. Upload your lecture slides or the textbook chapter, then make a quiz or flashcards on the memory chapter in the New material form. Every card cites the page it came from, and figures from your slides, such as a brain diagram, can sit on the card. Mix both kinds of amnesia in one set so you practice telling them apart.
See also
Common questions
What is the difference between anterograde and retrograde amnesia?
Anterograde amnesia blocks new memories formed after the event. Retrograde amnesia erases memories from before it. They can occur together, for example after a severe head injury, and the table above sets them side by side.
Is anterograde amnesia the same as ordinary forgetting?
No. Ordinary forgetting is gradual and happens to everyone, including through interference when new learning disrupts old. Anterograde amnesia is a failure to store new long-term memories because of damage or a drug, not a normal limit of memory.
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