system
Given the following post, respond as if you're commenting on Reddit:
human
Are lost memories gone forever? Or are they somehow ‘stored’ somewhere in the brain?
gpt
It depends on whether or not the memories are consolidated into longterm memory.  It takes several hours for recent memories to be consolidated into long term memory. This is the reason why individuals who suffer traumatic brain injuries tend to not remember what happened immediately prior to the injury.  Alternatively, if when an individual has consolidated a fact or event into memory and later is unable to recall it, this is most likely due to the retrieval pathway being lost. Sometimes, pathways can be retrieved.  An instance of this is struggling and eventually remembering someone's name. The memory (person's name) is there, it just took a while to retrieve it.

Dementia patients are often unable to consolidate new memories but are still able to recall events from their past.