How does the brain wake us up from daydreams?

Boston Children's Hospital researchers have discovered how the brain works while it "drowses" in daydreams and deviates from reality.

It turns out that the brain stimulates activity in a part of it called the dentate gyrus, to maintain full focus on the environment around us while daydreaming.

The research team found that the same neural activity also helps form memories. 

Our brains replay past events during sleep or daydreaming, in a form of synchronized activity known as 'spike ripple', allowing us to consolidate our memories.

The team, in collaboration with researchers from Ivan Soltesz's laboratory at Stanford University, began exploring another unknown neural activity pattern: simultaneous spikes of activity in the "dentate gyrus", which is part of the hippocampus.

They found that stimulation of activity occurs when the "wandering" brain is stimulated, which may help us quickly process new information and orient ourselves to what is happening in our environment.

The dentate gyrus enhances associative memory, where a sensory stimulus (for example, a series of loud sounds) is stored as memory, so that we associate the noise with a smoke alarm going off and the potential need to evacuate.

The dentate gyrus may affect attention and arousal in people with attention-deficit/hyperactivity disorder or post-traumatic stress disorder.

“We found a brain mechanism to break up periods of mind-wandering and reorganize the cognitive map to match reality,” says Jordan Farrell, a researcher at the Rosamund Stone Zander Center for Translational Neuroscience at Boston Children's Hospital.

The researchers hope to expand the scope of the study to include children with epilepsy, in cooperation with doctors at Boston Children's Hospital.

The results were published in the journal Nature.