Reasoning and brains are semantically related in mental condition topic. In some cases you can use "Reasoning" instead a noun "Brains", when it comes to topics like reason.
Reasoning noun – The thought processes that have been established as leading to valid solutions to problems. Brains and reasoning are semantically related in mental condition topic. You can use "Brains" instead a noun "Reasoning", if it concerns topics such as reason. Nearby Words: reason, reasonable, reasoned, reasonably
The unchanged survivors use this fact to construct barricades that most humans could easily dismantle by moving a few pieces around but the "changed" brains are incapable of reasoning out the puzzle.
While Cortana is unique in that she was based off a cloned brainnote the reasoning for this and others typically being created from dead brains is because the process destroys the brain the AI is being modeled after, her developing rampancy becomes one of the major plot threads in Halo 4.
His basic reasoning may be tied to the ambient temperature (trolls, having silicon-based brains, run hot away from their mountain homes) that puts him squarely in Crouching Moron, Hidden Badass in low temps but he has developed more than a little guile over the course of several books.