system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 How does the brain remember something it forgotten when we think hard enough?
gpt
Longer-term memories aren't stored as specific or whole parts, they are stores in bits linked by associations and neural networks. You can access memories by associating something that is currently happening with a specific memory. For example, you can walk past a restaurant and remember a great meal you had there. You can also bring up memories unrelated to anything around you by recalling them. In order to recall memory, you have to work through the different links and fill in the blanks. If you are trying to remember someone you met at work, you might recall their face, put a name to the face, bring up their job title, etc. until you have a complete picture.

Thinking and remembering are functionally similar processes. It's basically all about finding connections, and that might not be an instantaneous process.