Well, there was this paper, which was rather interesting:
where they got Leigh Brasington to go through such states and get fMRI and EEG scans etc. of the process. Though, of course, not everyone will agree that this was jhana. It would be fascinating if someone could repeat the process and compare with other (obviously lay) jhana practitioners, e.g. Shaila Catherine coming from the Pa Auk Visuddhimagga approach. I guess the results would be somewhat different but perhaps there would be many similarities too.