‘I remember when …’ we may say, but after reading this book, one wonders if our memories really are reliable.

The Norwegian sisters who authored this book are a novelist (Hilde) and a clinical neuropsychologist (Ylva). History, science and personal anecdotes pepper this far from academic delving into that mysterious aspect of our lives we call memory.

The ‘seahorse’ of the title comes from the dissection of a brain in 1564 in Bologna, Italy, by one Dr Julius Caesar Arantius. Only shortly before that time, such scientific study of corpses had been strictly forbidden, so he took extreme care as he sliced millimetre by millimetre into a brain donated by a mortuary. He was intrigued to find something in the temporal lobe, curled up like a silkworm, which when prised loose, was the beginning of memory research.

For that ‘worm’ looked more like a seahorse, so he named it hippocampus meaning ‘horse sea monster’ in Latin.

It was hundred of years before it became clear that the hippocampus holds on to memories while they are maturing, before they are stored elsewhere in the brain.

Many years of research were carried out last century with a man who’d had each of his hippocampi removed to help his epileptic seizures, and thus lost the ability to store memories; and with yet another man (with intact hippocampi) who forgot nothing.

The book features scientists, but also the taxi drivers of London who store intricate memories of streets and lanes; a man with PTSD after surviving a terror attack on a Norwegian island in 2011; divers set memory tasks to perform on land as well as underwater; chess players; false memories implanted in volunteers; and even a Brisbane university researcher who understands that memory plays a role in imagining the future.

Losing memory, through injury or brain disease, could be the subject of a whole other book, the authors say, eventually concluding that we are our memories, with each individual carrying a whole galaxy of life’s moments.

Don’t forget to read this book. It is truly memorable.

Reviewed by Jennifer Somerville