In Search of Memory

This is a memoir about memory. Eric Kandel tells the story of how a Jewish boy born in Vienna, who watched the Nazis invade his home in 1938, ended up as a professor in New York and a Nobel Prize winner. Personal history and science walk hand in hand from start to finish, and that is what makes the book feel much more human than a dry treatise.

He leaves Austria as a child, crosses the ocean with his family, and gets his education in the United States. He studies history and literature at Harvard, falls in love with psychoanalysis, and only then decides to go to medical school. It was this curiosity about Freud that led him to the question that guided his life: where, exactly, does memory live in the brain?

His journey shows that great discoveries rarely follow a straight line. Kandel switches fields, bets on a humble creature, and spends decades working on a problem that many colleagues thought was impossible to tackle with the tools of the time.

When Kandel started out, psychoanalysis explained the mind in one way, and brain biology explained it in another. The two fields barely spoke to each other. He decided a bridge was needed: understanding processes like learning and remembering through what happens inside and between nerve cells.

It was a risky bet. Neuroscientists back then preferred to study movement and the senses, which are simpler to measure. Talking about memory and emotion in a laboratory was seen as bold, even reckless. Kandel insisted that thought has a physical basis and that if we want to treat mental illnesses, we need to understand that physical machinery.

Think of a mechanic who only knows how to fix a car by reading the owner's manual. Sooner or later, he will have to open the hood. The book argues that psychiatry has to open the hood without abandoning the driver, meaning it must combine listening to people with understanding neural circuits.

A famous case in memory research is that of H.M., a man who had parts of his temporal lobe removed in surgery to control epilepsy seizures. After the operation, he lost the ability to form new everyday memories. He could hold a normal conversation, but he would forget it minutes later.

Curiously, he could still learn new skills, like drawing while looking in a mirror, without remembering that he had ever practiced. This led scientists to separate two systems. Explicit memory stores facts and episodes, like your neighbor's name or what you ate yesterday. Implicit memory stores habits and motor skills, like riding a bike.

A region called the hippocampus proved essential for the first type. This finding gave Kandel's lab a target: even if explicit memory was too complex to tackle right away, implicit memory could be studied in very simple animals. That is where the sea slug came in.