May 03

Memory speed

As a followup to the question to what is the memory capacity of the brain, I got the question: how long does it take to retrieve a memory or create a new one?

I don’t think there are precise known answers to either of those, but if I had to guess, I’d put the minimum retrieval time in the 600-800ms range based on Ken’s work with the late positivity associated with successful recognition.  Obviously, sometimes it takes a lot longer to retrieve, especially if you have to “search memory” or retrieve context.

For storing a memory, it’s complicated by consolidation, but I’m guessing the guys looking at neural synchonry in the medial temporal lobe are going to pick up the earliest signal of a new memory being created.  A review of gamma-band synchrony by Jensen et al. (2007) cites a report by Osipova et al. (2006) with MEG that shows the beginning of increased synchrony predictive of memory at what appears to be around 600ms or so.

So is the answer to both questions, “Somewhere between 6 tenths of a second and a lifetime” – ?  Too pithy?

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