eli5 What happens in your brain when you can’t remember something that you are certain you know?



I was trying to remember a word that I’ve used numerous times. The word took me about 2 days to remember. It was chronic, as in my chronic back pain. I knew it started with a c and I knew what it meant but had a very hard time remembering what it was. I also knew some words that were similar but not quite correct. What was happening in my brain to cause this?

In: Biology

Memory recall can be inhibited by similar but incorrect things. In this case, similar but wrong words. But you could also get memory inhibition from similar but wrong locations when trying to remember where you went “that one time.”

Memory inhibition is the technical phrase. And it’s an important part of memory: our memories would be useless if we didn’t have a way to tell them to shut up except when we need them. But we’re not perfect, so sometimes we inhibit the wrong one. Oops.

I think the basic background to explain why this happens is to keep in mind the brain is very interconnected, and when you store/retrieve memory, it’s not the same as looking at a photo of something you saw. my background is psychology, not necessarily hardcore bio, just so you know. So my knowledge of the biology is mostly functional for specific aspects of perception and memory.

Memories are reconstructive: it’s more that you save some key features that remind you of the context, and then when those features are activated (by the environment, or you actively trying to recall), you reconstruct what you think happened. During this process, you fill in missing details and may not even be aware of it (studies show confidence in your memory of something isn’t correlated with accuracy, so feeling confident isn’t a good indicator of how good the memory is).

Well… what happens if the features of memory A are *really* similar to memory B? You may accidentally retrieve memory B. In the brain, this is likely related to neural inhibition. Activating pathway B to retrieve the wrong memory is reducing the signal from pathway A. So the info is there, it’s just not strong enough to get retrieved into conscious experience. Other reasons for inhibition include just not activating enough features to “find” what you’re trying to remember. E.g., it’s easier to remember something if you’re in the same context of when that thing happened. That includes physical environment and psychological environment: it’s easier to remember things that make you angry when you *are* angry.