I've had these tabs opened for a while...instead of summarizing, I'll just let you read...
"Speaking in Tongues" is a blog with contributors from "both sides of the aisle"
These articles all reference the same study (brain imaging of people speaking in tongues)
The Neurocritic (an "anti") - with graphics of the brain scans.
And Penn Medicine (the university where the test took place)
I found these very interesting...the tests seem to bear out what the speakers describe as happening to them. But (on the other hand), we can find our brains to be very suggestible.