Problem is Cody we just do not know. There are lots of reported cases, a english speaking person speaking Welsh post stroke, an American speaking Spanish transiently post a head injury. Some theories suggest it is a form of aphasia due to neurological damage where you cannot speak the language you know. However it does not account for how she speaks a language she never previously learnt. Some people theorise that it incorporates a well known condition called foreign accent syndrome, a well known case is a Norwegian person from world war 2 developing a German accent after a shrapnel injury. However some theorise that as the formation of speech is a precise co-ordination of multiple body parts that any change to this will change accent, tone, pace and inflection which could ‘mimic’ another accent purely by happenstance.
Some say the second language simply sounds fluent to a non speaker of that language but is simply the accent and heavily error ridden when translated. However this does not account for the English speaker who developed Welsh (which his Welsh speaking wife translated accurately). And my previous patient who spoke fluent French as it was formally assessed and proved as such.
There is a condition called Hyperthymesia where you can remember consciously every detail of your entire life, however some areas of psychological dispute this. The ‘we only use 10% of our 100 billion neurones at any time’ has pretty much been disproved now. But if the brain can ‘file and store’ subconsciously every experience, and all it needs is the correct ‘key’ to access it and return it to the conscious - think of a smell reminding you of something long forgotten such as a autumn morning fresh air catapulting you back to your walk to first school decades previously. Or freshly baked bread reminding you of a specific breakfast with your family 50 years ago - then the husband with a Welsh speaking wife may of subconsciously learnt Welsh and the rewiring from the stroke (aphasia) worked as the ‘key’ to access all the Welsh words and language he never knew he could speak. Yet this does not explain my patient who’s family asserted that she never had any French lessons at school, never watched a French dubbed film and never left the UK during her life. As much as we like to state facts and generate theories it is cases such as hers that show how little we really know and how much we have yet to learn.
Always a Wasp