neuroscience - Why is there no solid evidence (histological, fMRI) that the vestibular hair cells of the inner ear contribute to 53% of the respiratory drive?

There are these papers which strongly imply that the inner ear hair cells, and not the medulla, is primarily the driving factor in the CO2 drive reflex

https://www.ncbi.nlm.nih.gov/pubmed/21130842

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3988803/

But every fMRI study done on chemoreceptors has shown only areas of the brain and carotid bodies light up in response to CO2. I could not find any fMRI study papers showing that the inner ears light up in response to CO2 or any histological evidence that the hair cells of the inner ear are chemosensitive and play a larger role in chemosensation than the brain like these studies are trying to imply. It is said the central chemoreceptors in the brain contribute to 85% of the CO2 drive reflex and the peripheral chemoreceptors contribute 15%, which seems to leave little room for the inner ear hair cells to play such a vital and significant part.