Molly Birnbaum - When all you can smell is your brain

In the summer of 2005 Molly Birnbaum was out jogging near her home in Brookline Massachusetts when she was hit by a car.

The impact fractured her skull and severed her olfactory nerves, leaving her without a sense of smell.

The prognosis was bad - Birnbaum was told she would never smell again. Depressed and deprived of her sense of smell, and therefore taste, she was forced to give up her place at culinary college and with it, her ambitions of becoming a chef.

Instead of resigning herself to living without scent, Birnbaum ended up on a quest to find out more about this mysterious sense, and eventually got her sense of smell back.

She tells this story in her book Season to Taste.

I started to get a few scents back one at a time, slowly but very attached to memory and emotion. As that went on I began to be very curious as to what was going on in my nose, in my brain, how come I didn't know anything about the sense of smell even though it so affected my life.

So I began to talk to scientists and doctors about the science of smell. I spoke with chefs and perfumers and I spent time in a flavour lab in New Jersey, I went to a perfume school in France, and spent time with neurologist Oliver Sacks and really tried to explore what it means to smell.

A little while after the accident I was helping my mother to cook dinner. I was chopping a bunch of fresh rosemary, and all of a sudden this smell hit me out of nowhere. It had been so long since I had smelt anything I was shocked. It was just this glorious scent of herbs and earthy rosemary and it reminded me of my childhood. It gave me a lot of hope.

At one point i became convinced i could smell my own brain. This was very disturbing. One common thing when people lose their sense of smell is to experience phantom smells - smells that don't actually exist from a concrete source in reality. I have met people who have had horrible ones - rotting smells, or garlic smells when they are trying to eat a fresh peach - but for me it was much more subtle.

Towards the beginning of my experience I could smell this one smell all the time. The only way I could make sense of it was that this smell was coming from within me, that it was probably my brain. It was one of the stories I told myself to make sense of this experience.

I think what I really lost was the emotional component to certain memories, the memories we have when we smell something familiar and are immediately transported back to a moment in our past - kind of like a punch in the gut emotion. When I couldn't smell I could still remember these events, I just didn't have that punch in the gut. And I worried about how, if I could never smell again, that would affect the memories that I should be making in the future.

6 Emotions You Never Knew You Had

CAN you name the six basic emotions? Take a straw poll of your friends and we guarantee that you will find no consensus. Yet psychologists are unequivocal: joy, sadness, anger, fear, surprise and disgust. These are the Big Six, quite literally, the in-your-face emotions - the ones that everyone the world over exhibits with the same dramatic and characteristic facial expressions. They have been the subjects of intense research for over half a century, not least because of the role they have played in our survival as a species.

Times have changed, though. Our ancestors may have had daily need of fear to flee predators, anger to conquer foes and disgust to avoid diseases, but we live in a more subtle world in which other emotions have come to the fore. There are many contenders. Avarice, embarrassment, boredom, depression, jealousy and love, for example, might epitomise the modern age. Yet some more obscure emotions may be increasingly relevant today. Here we explore five of them, any one of which could make a case to be promoted to a place alongside the Big Six.