As I start putting together my formal paper about ethics as a social technology, I've been researching the relationship between language and cognition. A few researchers have called the "inner monologue" phenomenon essential to (or even constitutive of) cognition--we talk to ourselves (either out loud or in our heads) as a way of working out problems. This seems right to me: as most people who have done any kind of deep thinking know, it helps tremendously to have an interlocutor (real or imaginary) off which to bounce ideas. This point has led me to consider something related (albeit tangential), though, about which I'd love to get some input.
I'm certain that everyone has had the "inner monologue" experience of speaking to oneself silently--you might rehearse a speech in your mind before you give it, silently repeat the list of things you need to pick up at the grocery store, or try to work out a philosophical problem by talking to yourself in your head. While it's certain that this sort of process is linked to language--it's hard to see how a pre-linguistic animal could think linguistically--I wonder how close this relationship is. Jerry Fodor (among others) holds the position that mental representation happens in a meta-linguistic form that he terms "Mentalese"--while thinking in Mentalese might feel like thinking in (say) English, it differs in slight but important ways. If this theory is correct, it would seem that different brain processes would have to govern true language and Mentalese language (or inner monologues); we should expect, then, to see the two occasionally come apart.
Here's my question, then: when a person suffers a stroke (or some other kind of brain injury) that interrupts speech functions (as damage to certain parts of the left hemisphere often does), is the inner monologue similarly interrupted? If so, is this always the case, or is it possible to lose the ability to express our thoughts symbolically (either through speech or writing) but still be able to represent thoughts to ourselves in Mentalese? If the latter is correct, that would seem to bolster the Fodorian position that inner speech is fundamentally different from linguistic representation; if the two faculties are inseparable, though, that would seem to cast doubt on the principled distinction between inner monologue and public language.
I'm researching this question as we speak, but I'm interested in seeing if anyone out there has any first-hand experience with this--have you ever suffered a stroke, or known someone who has? If you lost language, did you also lose the ability to form thoughts with propositional content? Did one faculty return before the other, or are they mutually supportive? Any input is appreciated.