Do you believe that sorta thing?
I will tentatively say yes, but only for one reason: That there is another layer of 'us' below our personality and ego. Let's call it the 'autopilot'. When one is awake and active, there is a 'personality' that sort of 'oversees' our consciousness. We will call this 'you'. It is the 'you' that makes you 'you'. Your name, your opinions, preferences, emotions, all part of the whole package.
When you think of 'thinking', you think of how your brain controls your body, and how your mind looks out through your eyes and processes information. And when you are awake and going about your day you are 'thinking'. I mean consciously 'thinking', like with the inner voice and everything.
But have you ever had those times, like lets say when you are driving, and you realize you have 'spaced' it and cannot remember the last minute or so? Even though you may have even sat through red lights and drove perfectly normally? Or sleepwalking. Your motor skills function well enough to walk and move around, but the 'you' part of your brain is not there. Some people even do complex tasks while sleepwalking like getting dressed etc. Anyone ever heard of those people who take too much xanax and drive around and cannot remember it later?
I watch true crime shows alot, and this one guy and his wife were murdered in bed, bashed their skulls in with a crowbar, and the guys brain was destroyed, yet a while after the killer left, he was still alive, and he got out of bed, pouring blood from his cracked skull, and went and got dressed, made breakfast, and got the newspaper from his porch, all in 'autopilot'. Then he dropped dead with the newspaper in his hand in the front hall.
These are forms of trance states, which are illustrative of how what we think of as 'us' is just an overlay over another sentience, one who is somewhat robotic yet still functional. So my best guess is, if there is some 'autopilot' underneath our 'egos', maybe that is a clue or indicator of the 'stem of the tree'