Struggling to distinguish the smell of bubblegum from petrol could be early sign of dementia 

Random sensory quotes

We have photons—that is sight. We have pressure—that is touch. We have molecules—that is smell or taste. And finally we have vibrations in the air—that is the essence of sound. Each of those different types of physical stimulus must somehow be converted into the electrical signals that the brain is then capable of interpreting. That’s the transduction process.

— Neuroscientist James Hudspeth