(I think it’s the frontal and temporal lobes.) the guy who inspired Rain Man has an issue with his corpus callosum. It’s almost as though the brain is capable of massive amounts but it hobbled by connectivity .
The area around the Wernicke's lobe, or however it's called, is definitely associated with it. I make a lot of whacky observations on KF, and although they are all 100% true and reflective of reality, it's directly related to my health. In short, I genuinely don't have the same brain structure as most because of that whole "my chest hurts" deal.
In most cases, language and culture develops in a similar way, so people approach problems in certain ways. If you damage that language component, the language develops differently and you can form a completely different conclusion, when told the same thing.
Wernicke's Aphasia, in its worst forms, is the one where people speak with a normal cadence, but in complete gibberish. It is a spectrum, though, and some people are only lightly affected. This is how the Unabomber was caught - he would make weird spelling mistakes, adding letters into words, and used phrases in the wrong pattern. He wrote "You can't eat your cake, and have it too" - implying that he remembers things in an odd, chronological way. It was a subtlety throughout his writing, which was recognised by his brother. Kaczynski essentially damaged the normal linguistic method of learning, and instead, substituted his own which reflected how he actually saw things. From that, your entire worldview changes.
And to also add some of my own experience into understanding Uncle Ted - if you have a linguistic disorder, propaganda and marketing aren't suited to you. Your understanding of things is warped by the unique way that your brain "forms" it - in normal circumstances, the information is processed in a different order, to come to the same conclusion.
So you can instantly detect deceit. Honesty is easy, since the order is different but the conclusion is the same. When people assume you understand things in a normal way, your brain takes a completely different route and the sentence sounds "uncanny" for a completely different reason than what the liar was expecting.