I can only say how it is from my personal perspective, so don't take this as an expert opinion.
For me, a big difference between dissociation and shutdown is that in a shutdown I lose skills.
So, dissociation= feeling detached from my surroundings and as though things are unreal, but I can still process everything properly and move my body when I want to, and speak.
In shutdown, there is the same detachment, but my motor skills and visual processing deteriorate, and I can't speak.
I hope that helps.
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Music Theory 101: Cadences.
Authentic cadence: V-I
Plagal cadence: IV-I
Deceptive cadence: V- ANYTHING BUT I ! !! !
Beethoven cadence: V-I-V-I-V-V-V-I-I-I-I-I-I-I-I-I-I-I
-I-I-I-I-I-I-I-I! I! I! I I I