Let's talk about Ni vs Ne then. Ni is conclusive, it purposefully tries to find the answer to something and understand a concept. Ne is expansive, it is less interested in "the answer" as it is in "all of the answers" so much as it builds upon them to find connections to other possibilities.
Ni/Se is like a detective with a pin board. Se is like the individual photos and newspaper clippings, the evidence of what "is" and what can be seen and Ni is the string that connects them all together, seeing what influenced what and why things are what they are all to get to the answer of "who did it?" so to speak, but the answer could be to any question really.
Ne/Si is more like memories and similies. Phrases like "that reminds me of--", "what if something different happened", "but it could also be something like--" or "imagine if there was--" are more common in a Ne thought trail. Ne is possibilities and Si influences that based on personal memories (as opposed to Se's more objective perceiving). It will start off at one singular point and expand like a spider web off in different directions. It's why Ne is more impulsive than Ni because for me, trying to predict things is like opening up a hallway to parallel timelines I explore what's happening behind each door no matter how unlikely it is. Sometimes I'll be content with that and then shrug with a "whatever will be will be" and wait for the future to come to me. Ni would not be content with this and be wanting to prepare for the most likely scenario whilst Ne is entertaining itself with something else.
I think my metaphors are getting convoluted. I hope you can follow this... Which one of those is more relatable?
As for depression, well, I know that, I've been there. I've seen a few changes, not all at once:
- I acted more introverted. (made me type myself as an INFP)
- I was more impulsive in a self-destructive way. I would imagine possible "adventures" and then switch off my brain in an attempt to just live in the moment. I was attempting to act like a Se dom but because I have no grasp on Se I came across as immature, uncharacteristically stupid and regretted a lot. I could only do this for short bursts at a time and most people found me more abrasive and stubborn than I normally am. (Kind of known as a Ne-Te grip)
- I came across as blunter, ruder, less interested in sensitivity of other's feelings and more in the facts. (this is Te, so I would imagine an ESFP could relate too)
- I would retreat and become strangely nostalgic about things. I found myself trying to relive past scenarios in my head and then try and work out all the other possible ways that I could have "fixed" them. It took me a long time to realise that trying to reimagine what you could have done different in the past could only get you so far. Sometimes I would spend weeks longing to live in that past and explore a different path and where that would have brought me to today. (I believe this was the closest I understand to a "Si-grip")
- I would get anxious about anything that wasn't a familiar comfort. Happy memories influenced what I lived off of and I was too scared to step back out into the unfamiliar. (obviously this wasn't who I was at all. This is anxiety, every type can get anxiety but to me it was also Fi-Si loop)