SuttaCentral
"This discovery indicates that the vestibular system shapes perception even in different senses. This raises questions that border on the philosophical: How are we aware of the environment around us? What are the components of consciousness?
We can take our bodies for granted, regarding them as machines for carrying us around, but our bodies themselves actually shape the way we perceive and understand the world.
Try thinking about that next time you’re lying down."
I was thinking that proprioception must be one of the sense objects we perceive via the mind door, one to which more attention might profitably be paid when it’s working well. When it is working well we are generally unaware of it, tho we soon become aware it the system stops working.
My partner’s sense was compromised when he had radiotherapy to get rid of something that was growing around the vestibular; he fairly quickly established knowledge of what he can’can’t do and resumed onroad cycling and working up ladders.
I had significant vertigo attacks some years ago and found it was very difficult to be mindful of the dizziness and disorientation, while mindfulness of the nausea was easy, This makes me think that I must have meditating in a way that was based on some sort of sense orientation that I was so attached to, that I couldn’t meditate without it.
So I’m interested to learn more about the research this article reports, and also to examine the effects of meditating in different positions really thoroughly.
Stability
“An important role for proprioception is to allow an animal to stabilize itself against perturbations. For instance, for a person to walk or stand upright, they must continuously monitor their posture and adjust muscle activity as needed to provide balance. Similarly, when walking on unfamiliar terrain or even tripping, the person must adjust the output of their muscles quickly based on estimated limb position and velocity. Proprioceptor reflex circuits are thought to play an important role to allow fast and unconscious execution of these behaviors, To make control of these behaviors efficient, proprioceptors are also thought to regulate reciprocal inhibition in muscles, leading to agonist-antagonist muscle pairs.”—-Wikipedia
When the proprioceptors are functioning fully and maintaining balance in an activity such as walking, there is a sense of pleasure. That is also the attraction in more strenuous balance activities such as rock hopping up a creek bed strewn with boulders. This pleasure derives from the harmony which is a signal that balance has been achieved, the same sensation as when tuning an instrument string to the set pitch of a tuning fork. Since body precedes mind this skill is learnt as infants through hard knocks, but learning to balance the mind and recognize harmony is an activity which is the occupation of adult life.
This is referred to in the third tetrad where development of the basic skill of bringing the mind to a balance point between sleep and external distraction is called for. Recognizing when mental balance has or has not been achieved can be known not only through internal feeling, but also through signals from others. This skill is emphasized in the beginner’s stage of mindfulness:
“In this way he remains focused internally on the mind in & of itself, or externally on the mind in & of itself, or both internally & externally on the mind in & of itself.”—MN 10
That is an interesting question since (all?) our MRI scans are conducted on people who are lying down. Imagine having to redo years of MRI research on people standing up! 
They are working on alternatives so patients can be more comfortable…
https://www.wgtn.ac.nz/robinson/research/electromagnetics/mri
When we lay down our brain knows its at rest because the flow of our heart in oxygen and blood changes so we think differently as for dreaming stages …as for our body to sit it form in thinking as its stage is nor rest or standing in defeat …as the body standing it arises is not to suppress as its movement is to gain in search of fight n flight responsibilities thats our mindsets …human progess in all stages in mindfull matters and states its natural adaptation of heart flow is 
Oxygenated cells in reproduction to the brain n body functions …just a medics knowledge place patient on left strains blood flow to the heart 
to position to the right the heart pumps fully to heart n major organs in cpr when you lay flat all your body fluids seep to all organs fully to the eyes heart lungs kidneys n liver stationary even flows It all matters
