During body-scan ('sweeping') meditation, what does brain-imaging (e.g. fMRI) look like? I do not know how extensively body scans have been studied with brain-imaging techniques, e.g. fMRI.

Body scan is a meditation technique developed by Jon Kabat-Zinn. It was derived from a meditation practice ('sweeping') of the Burmese U Ba Khin tradition. 


  "It involves systematically sweeping through the body with the mind,
  bringing an affectionate, openhearted, interested attention to its
  various regions, customarily starting from the toes of the left foot
  and then moving through the entirety of the foot [...] From there, the
  focus moves into, successively, and slowly, the entirety of the pelvic
  region, including the buttocks and the genitals [...] and finally, to
  the face and head."
  
  "We are systematically and intentionally moving our attention through
  the body, attending to the various sensations in the different
  regions. That we can attend to these body sensations at all is quite
  remarkable. That we can do it at will, either impulsively or in a more
  disciplined systematic way, is even more so."
  
  "We might describe what we are doing during a body scan as tuning in
  or opening to those sensations, allowing ourselves to become aware of
  what is already unfolding."


I found it quite easy to practice and had interesting and unusual experiences (mostly pleasant).

My question is: Would any brain and brain-imaging expert - given this description - dare to guess roughly how a body scan may look like in a "brain scanner", e.g. recorded with fMRI?

I am not such an expert, nevertheless I dare to guess.

Presumably, a body scan will - mainly but not solely - take place in the areas of the cortical homunculus in the primary motor and sensory cortices.  

I would guess that it is here that most of body scan related neural activity will occur. But in which manner: how will activity evolve and literally move around, how will it look like in the "brain scanner"?

Five possibilities come to my mind:


Experts and laymen will see nothing but a generally increased, enigmatically billowing activity of the cortical homunculus.
An expert would see some significant patterns, but only vague and hard to communicate.
Even the layman could see something:


an overall increased activity of the cortical homunculus with somehow changing peaks of activity (highlights, representing the body region the attentional focus is currently on)
a mostly "dark" cortical homunculus with a wandering spotlight of activity 
a mostly dark cortical homunculus with a fading-in/fading-out spotlight every now and then



Which of these possibilities do you - if you happen to be a brain and/or brain-imaging expert - consider the most probable one? Other possibilities are welcome!

And of course hints to studies where this question has been experimentally attacked.

(I found one study but didn't delve deeper into it: there are too few images in it.)
Disclaimer: I'm not a brain expert or brain-imaging expert or neuroscientist.

In this YouTube video at around 15 minutes, you can find Dr. Zindel Segal presenting fMRI scans on depression patients practising mindfulness-based meditation (most probably Mindfulness Based Cognitive Therapy or MBCT). But I'm not sure if it includes body scanning. MBCT was based on Kabat-Zinn's Mindfulness Based Stress Reduction (MBSR).

There are more fMRI scans shown in this YouTube video by neuroscientists presenting at the 10th Global Conference on Buddhism in Toronto this year. Again, I'm not sure if it includes body scanning.

Probably, you can contact the four neuroscientists in these videos plus Kabat-Zinn, to seek the precise answer to your question. Who knows? Maybe you might give them a new idea for a study, if it has not been done already.

Also see this answer.