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I'm a little bit confused about the role that the hippocampus plays in memory. I've heard that it stores episodic memories and then consolidates the important ones into long-term memory.

My question is: if it stores episodic memory which is a presumably pretty malleable form of short-term memory why can it not store working memory as well? Also isn't that what 'memory champions' learn to do?

Further: If this is the case then what are the functional differences (e.g. pros / cons) between this and working memory supplied by the prefrontal cortex? ...Is the prefrontal cortex memory even more malleable?

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    $\begingroup$ If you "store" working memory, it isn't working memory anymore. Yes, that's how "memory champions" exceed the normal capacity of working memory: they store things as episodic memories to retrieve later. $\endgroup$
    – Bryan Krause
    Sep 22 at 19:39
  • $\begingroup$ @BryanKrause Well, that's just semantics... What I'm really interested in is if it is indeed possible to 'use episodic memory as working memory' then why doesn't the brain do this by default? What draw backs are there? And what is the default way working memory is stored? $\endgroup$
    – profPlum
    Sep 22 at 19:46
  • $\begingroup$ Yes, I think your question is also just semantics. Working memory is not stored, that's what separates it from other forms of memory. If you were to store the thing that working memory contains, that would be something else that isn't working memory. $\endgroup$
    – Bryan Krause
    Sep 22 at 19:49
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    $\begingroup$ Look technically all memory is stored by definition, working or otherwise. If it were never stored it would be impossible to remember even an instant after it were created. An 'unstored memory' isn't even a memory, it's just external information that you don't know. $\endgroup$
    – profPlum
    Sep 22 at 19:52
  • $\begingroup$ My question is not semantics, working memory is a faculty of the mind for quickly encoding volatile memories for short-term use. I'm asking if there are any functional draw backs of this 'episodic working memory' compared to 'default working memory'. $\endgroup$
    – profPlum
    Sep 22 at 19:52
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The hippocampus is thought to respond to information that is being maintained in working memory in other areas. Areas that are commonly thought to maintain working memory include prefrontal cortex (reviews: Chai et al 2018 https://doi.org/10.3389/fpsyg.2018.00401) and entorhinal cortex (Fransen 2005; Egorov et al. 2002). For example, some information about recent trajectory comes to the hippocampus from prefrontal cortex via thalamus (Ito et al. 2015 https://www.nature.com/articles/nature14396).

Critically, episodic memory is not a form of working memory. Episodic memory refers to the content of memory, not the duration. Episodic memory storage occurs in different brain areas at different times. The hippocampus is specialized for rapid acquisition of long-term memories. Look up "systems consolidation of memory".

Also to address your discussion with Bryan, the general idea is that working memory is "stored" through mechanisms other than changing synaptic weights. For example, working memory can be "stored" through persistent activity (Sanders, et al. 2013, https://www.jneurosci.org/content/33/2/424.long) or short-term facilitation of synaptic weights (Mongillo, et al., 2008, https://science.sciencemag.org/content/319/5869/1543.abstract). Review here: https://doi.org/10.1016/j.conb.2013.10.008

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  • $\begingroup$ So does the hippocampus actually store any memory inside itself (even temporarily)? Also can you address the draw backs of repurposing episodic memory buffers to 'extend working memory', like memory champions do for example, (e.g. is it slower to write too?) $\endgroup$
    – profPlum
    Sep 29 at 21:59
  • $\begingroup$ yes, the hippocampus stores memory inside itself. Look up "systems consolidation of memory". $\endgroup$
    – honi
    Oct 11 at 15:12
  • $\begingroup$ i don't believe research has been done on the drawbacks of memory champion techniques as the sample size is way too small to make any concrete statements. $\endgroup$
    – honi
    Oct 11 at 15:13

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