It’s probably a problem of non-specificity: if you say “the brain” some folks will consider just the prefrontal cortex, where thought happens. Olfactory nerves,

It’s probably a problem of non-specificity: if you say “the brain” some folks will consider just the prefrontal cortex, where thought happens. Olfactory nerves, where the smell happens, is a different enough concept that it might not align with the reader’s preconceptions of “the brain.”