I’ve been thinking about the way the brain processes language, admittedly in a rather unscientific way, prompted by my own experience of interpreting and reading several articles on the Internet. While reading one of my favourite blogs, The Dilbert blog, written by Scott Adams, I learnt about a condition called Spasmodic Dysphonia, which led Adams to lose his voice 18 months ago. The problem is completely context-specific, for example he could carry on talking in conferences in front of large audiences but was unable to express himself at home. It is obviously extremely debilitating, but Scott never lost hope of one day recovering his speech, and last week, he found a cure: repeating a nursery rhyme again and again, which seemed to "remap his brain". His entry about how he found a solution to his problem is really inspirational. This also reminded me of a condition known as Foreign Accent Syndrome, which causes some people to start speaking in a foreign accent after a stroke.
For my part, whenever I am interpreting, I always marvel at how my brain seems to be able to do two completely, and seemingly competing, activities at the same time: think about a sentence in English while actually saying it in French. It really feels like having two brains, and it puzzles me no end. Here is an example of what can happen:
I was interpreting in a brewery a couple of weeks ago (yes, it was as fun as it sounds), and the person who was showing us around said: "The reason why this type of beer is produced in Kent is that, among other things, this region is excellent for growing barley." So I started conveying this to the French visitors, and while one half of my brain was busy with the converting/talking process (Ce type de bière est produit dans le Kent car etc.), this is what was going on in the other half:
BARLEYBARLEYBARLEYBARLEY OH NO WHAT’S BARLEY IN FRENCH AAAAAAAAARGH
Thankfully, both parts of my brain came together exactly when needed, right at the end of the sentence. I’ve tried to write down what happened to make it clearer: red and blue for either side of the brain, purple when it all came together exactly at the right time:
"Ce type BARLEYBARLEYBARLEYBARLEY de bière BARLEYBARLEYBARLEYBARLEY est produit I’VE FORGOTTEN WHAT BARLEY IS IN FRENCH dans le Kent pour plusieurs raisons BARLEYBARLEYBARLEYBARLEY et en particulier parce que cette région OH NO WHAT’S BARLEY IN FRENCH se prête très bien AAAAAAAAAAARGH à la culture de l’orge."

This is what was happening absolutely simultaneously. While I’m talking, seemingly very calm, conveying information to some very interested people, a part of my brain is seized by panic and is actually verbalising the process of searching for the right word.
How is this possible? What actually goes on in an interpreter’s brain? Does anyone know if "The Idiot’s guide to the brain and language" has been written? I’d love to learn more about how the brain processes language and if anyone has had any interesting experiences in this area.