Types of memory
What are the different types of memory, and where in the brain are they stored?
It’s probably unsurprising to hear that your memory of how to swim differs from, say, your first kiss or the name of your teacher in Year 3. But, interestingly, these memories appear to be processed in different ways in your brain.
Our understanding of the different types of memory is changing, thanks to brain imaging. In the past, memories have been divided into ‘explicit’ or ‘declarative’ memories (in essence, memories we knew we had) and ‘implicit’ memories (unconscious memories). This distinction is proving less useful, though, as any type of memory can have a conscious or unconscious element.
Episodic memory (also sometimes referred to as autobiographical memory) is made up of personal memories; it is our ‘filmic’ recollection of past experiences. Much of this activity takes place in the medial temporal lobe, encoded by the hippocampus and stored in the cortex. Memories that are particularly emotional, including phobias and flashbacks, fall into this category. They are initially encoded in the amygdala.
Procedural memory, or ‘how to’ memory (eg how to swim or ride a bicycle), is stored in the cerebellum and putamen (part of the striatum). The hippocampus (which is very much involved in episodic memory) was previously not thought to be involved. However, research into patients with Alzheimer’s disease who have trouble with their procedural memory has pointed to changes in activity in the hippocampus.
Semantic memory is for facts. Exactly where these are registered in the brain is up for debate. One theory proposes that they are registered by the cortex and end up in the temporal lobe; another theory proposes that, like episodic memory, the hippocampus and temporal lobes are involved.Lead image:
Kārlis Dambrāns/Flickr CC BY