Story time!
I once bumped my head and got complete retrograde amnesia. I lost basically all of my episodic memory — that is, the memory of all my past experiences. My semantic memory appeared to be intact, which meant I retained my general knowledge of the world, such as who was prime minister. However, I basically lost all sense of my identity for a while. I didn't even remember my name at first. Honestly, I don't know if I can say that I ever truly remembered my name after the fact; I was fortunate that my memory did return to me gradually over the course of many days, weeks and months, but because I was told my name many times over that period, I never got that sense of remembering my name (I'm going to use the psuedonym Ann for the sake of this story)
Anyway, it was terrifying at the time, but now that I'm past the dread and trauma of it all, I can reflect on it as a cool experience. A few days after the accident, when I still had very little memory of who I was, I went to a Christmas party with many of my friends. However, it felt like being in a room full of strangers. It was awkward at first when I arrived; people didn't know how to act towards me, and seemed uncertain of whether I was still the person they knew. That was a fear I shared. However, they seemed to ease up quite quickly, because it seemed that my personality was still authentic to the person they knew, even if I had to start from scratch in getting to know them. It's a bizarre experience to reflect on, because now I have two sets of memories of meeting some of my dearest friends for the first time.
The most distressing part of it all was when I had gotten to know some of the people in my life, and had put together many of the fragments about who I was. I wasn't sure that I was that person though. I felt like an intruder in someone else's life, and I was terrified that I wasn't the same person. All the wonderfully supportive people around me — how could I call them my friends when I wasn't the same Ann that had earned their friendship. Apparently I still acted like her, but if I was her, why was there such a stark division between the two versions of Ann in my head: there was the Ann who existed before the accident, and the Ann that I was afterwards — I didn't know whether I could consider them to be the same. If we were the same person, why was I talking about "her" rather than "me"?
Some months after the accident, a romantic relationship started between me and my best friend. We had been close friends for a few years prior, and he later confessed to me that a part of him was anxious that maybe we wouldn't have been together if not for the bump to my head. I was surprised to hear this, because my friend was a super charismatic guy and this kind of anxiety seemed out of character for him. I understood where he was coming from though. I told him that it would be nice if I could tell him that his worry was a silly one, and that of course the amnesia wasn't the only reason we were together. However, I didn't actually know whether I was the same person. By then, it felt like the vast majority of my memories had returned, and no-one reported any discernible personality change to me. However, I had no way to know what significant memories, if any, were still missing to me. I didn't think that his fears were true, but ultimately, I had no way of knowing, and I just had to live with that — and unfortunately, so did he.
One of the most disconcerting aspects of it all was how it felt to rediscover a memory. Have you ever had something remind you of a memory that was tucked away so deep in your mind that you didn't even know you still had it until something brought it to the surface? A foggy fragment from childhood perhaps? Well that's what regaining my memories felt like. In the early days, it was extremely vague bits that I remembered.
The first fragment was in the hospital waiting room, when I remembered that the friend who was with me was someone who reuses day old tea bags (they will take the mug they used the previous day and add a new teabag in with the old one, and pour in new hot water). Bear in mind that this was a person who I had initially thought had drugged and kidnapped me, because my first memory after the fall was feeling dizzy in a room, surrounded by complete strangers who claimed to be my friends. I was so overjoyed and surprised to have something come back to me that I loudly exclaimed this revelation in the half full hospital waiting room. The first thing I remembered of my best friend was snow, because of a road trip we'd taken together the previous year. The next fragment about him was barbeques (he enjoyed getting people together for one in the Summer), and the next bit was Lord of the Rings. At first, it felt like I was receiving loose, disparate fragments about a person, but over time, it began to feel more like I was filling in the final pieces in a mostly complete jigsaw. But then, that's not far from how it feels to be close friends about a person, and to discover new facts about them, despite having known them for years.
Nowadays, when I have that feeling of a long forgotten memory returning to me, I'm unsure of whether it's another fragment returning to me post amnesia, or if it's just the regular kind of remembering stuff. It's been around 6 years since the accident, so I have a heckton of new memories on top of that. A few years ago, I had that peculiar feeling of a memory returning, and I assumed that it was another amnesia thing returning, but then I realised that this particular rediscovered fragment happened after the accident, so this was just normal, run of the mill forgetting. That was jarring to realise that memory has always been fallible like this. Whilst yes, complete retrograde amnesia is a super rare experience, nothing had really changed.
Memories are always slippery things. I've read neuroscience research that suggests that when we remember a thing, we're sort of rewriting the memory. It's like if every time you checked out a book from the library, you weren't allowed to return that specific book, but instead had to write out the book and return a new copy of the same book. Even if you try hard to be accurate, there's inevitably going to be some errors in transcription (just look at transcription errors in manuscripts before the invention of the printing press). This means that the more you check out a particular book, the more likely it is to be changed. Trippy stuff, huh? That's what I mean when I say that nothing had really changed. The amnesia made me feel unstable because I didn't have my memories to rely on to build my sense of reality, but memories will always be fallible. We like to pretend they're not, but everything we perceive is filtered through our own subjective filters, and then each time we reflect on our recollections, we pass those memories through the filter again. Even before my amnesia, my memories were not an accurate reflection of reality — that's just a lie that makes us feel more at ease with the inherent instability of our own perceptions and experiences. That fact was brought to my attention in a rather abrupt way, but it's one of the reasons I'm oddly glad for this absurd experience. It was certainly philosophically interesting.
I could talk forever on this topic, because it was a hell of a ride, but I'll stop here, because this comment is long enough already. I'm open to answering any questions that y'all want to throw at me though, because God knows there aren't many people with an experience like this. You don't have to worry about being overly intrusive or about upsetting me, though be aware that I might not get round to answering your questions.