Imagine: you wake up one morning and you can see everything. Different shades of color pop into existence. You suddenly see all the different reds in your favorite carpet. The green stalk of your lilies becomes sharply distinct from the green underbelly of its leaves. Your mocha-colored coffee table becomes…well, a more defined mocha color. Your sense of smell comes alive too. You can now tell everyone apart by the way their smell feels; your best friend’s delicate rogue rose perfume becomes her calling card, signaling her arrival and lingering long after she’s gone. You no longer even need a map to navigate. Since the bakery a mile away smells like it’s below your apartment, all you have to do is follow your nose.
Now, imagine that one day your senses go back to normal. The world’s colors become a dry palate and its smells no more interesting than a day-old candy wrapper. Imagine the loss you would feel. The nostalgia. This is what sometimes happens to people with an overactive rhinencephalon (our ancient ‘small brain’ that controls emotional tone and sensations.) It becomes extraordinarily active for a day or week at a time, then, it goes back to normal. We're not quite sure what causes it or why this part of the brain isn't hyperactive all the time. (Wouldn't it be beneficial?) But, we do know this phenomena real to those who have experienced it.