The dreams of Mary Shelley, author of “Frankenstein,” involved a pale student kneeling beside a corpse that was jerking back to life. Paul McCartney’s contained the melody of “Yesterday,” while director James Cameron’s inspired the “Terminator” films.
With their eerie mixture of the familiar and the bizarre, it is easy to look for meaning in these nightly wanderings. But why do our brains take these journeys, and why do they contain such outlandish twists and turns?
(BIGSTOCK) - Dreams inspire great works but also harbor the bizarre. Scientists are discovering how dreams and the brain work.
Unfortunately for armchair psychoanalysts, Sigmund Freud’s attempts to interpret dreams remain hotly disputed. Nevertheless, neuroscientists and psychologists have recently made big strides in understanding the way the brain builds our dreams and the factors that shape those curious stories. Along the way, they have found startling hints that our use of technology may be permanently changing the nature of this fundamental human experience.
Anyone who has ever awakened feeling amazed by a dream, only to forget its contents before reaching the shower will understand the difficulties of studying such an ephemeral state of mind. Some of the best attempts to catalogue dream features either asked participants to jot them down as soon as they woke up or had volunteers sleep in a lab where they were awakened and immediately questioned at intervals in the night.
Such experiments have shown that our dreams tend to be silent movies: Just half contain traces of sounds. It is even more unusual to enjoy a meal or feel damp grass beneath your feet while asleep: Taste, smell and touch appear only very rarely in dreams.
Similar studies have tried to pin down factors that might influence what we dream about, but with little effect.
More recently, scientists have been looking at the brain’s activity during sleep for clues to the making of dreams. Of particular interest is the idea that sleep helps to cement our memories for future recall. After first recording an event in the hippocampus — which can be thought of as the human memory’s printing press — the brain transfers its contents to the cortex, where it files the recollection for long-term storage.
This has led some psychologists to suspect that certain elements of a given memory may surface in our dreams as the different pieces of information are passed across the brain. Studying participants’ diaries of real-life events and comparing them with their dream records, Mark Blagrove and his team from Britain’s Swansea University have found that memories enter our dreams in two separate stages. They first float into our consciousness on the night after the event itself, which might reflect the initial recording of the memory; then they reappear five to seven days later, which may be a sign of consolidation.
Even so, it is quite rare for a single event to appear in a dream in its entirety; instead, memories emerge piecemeal. “What usually happens is that small fragments are recombined into the ongoing story of the dream,” says neuroscientist Patrick McNamara at Northcentral University in Prescott Valley, Ariz. And the order in which the different elements appear might reflect the way a memory is broken down and then repackaged during consolidation.