Hints of how the brain “sees” dreams emerge

Nerve cells that help us see the world stay on the clock during sleep, too. The spooky eye movements associated with REM sleep — and the ensuing nerve cell behavior — may help people “see” their dream world, scientists report August 11 in Nature Communications.

The results come from a study conducted on people who had electrodes implanted deep into their brains as a treatment for epilepsy. Those electrodes eavesdropped on individual nerve cells, or neurons, in the medial temporal lobe, a brain area known to help make sense of visual information. When people moved their eyes while awake, single neurons in the MTL showed distinct behavior, becoming sluggish just before rapid eye movements and springing into action just afterward. The neurons behaved similarly during REM sleep, a stage of sleep that often comes with vivid dreams.

Because participants weren’t asked about the quality of their dreams, researchers can’t yet say how the neurons’ behavior might relate to dream imagery.