Dreamed movement elicits activation in the sensorimotor cortex.

During lucid REM sleep, performing a dreamed hand movement activates the sensorimotor cortex in the same way as an actual movement. By combining fMRI and NIRS with polysomnography, the study used eye signals as temporal markers to link neural activity to specific dream content. This provides first evidence that the contents of REM-associated dreams can be visualized by neuroimaging, overcoming the previous impossibility of experimentally controlling spontaneous dream activity.

Study at a glance

Abstract

Since the discovery of the close association between rapid eye movement (REM) sleep and dreaming, much effort has been devoted to link physiological signatures of REM sleep to the contents of associated dreams [1-4]. Due to the impossibility of experimentally controlling spontaneous dream activity, however, a direct demonstration of dream contents by neuroimaging methods is lacking. By combining brain imaging with polysomnography and exploiting the state of "lucid dreaming," we show here that a predefined motor task performed during dreaming elicits neuronal activation in the sensorimotor cortex. In lucid dreams, the subject is aware of the dreaming state and capable of performing predefined actions while all standard polysomnographic criteria of REM sleep are fulfilled [5, 6]. Using eye signals as temporal markers, neural activity measured by functional magnetic resonance imaging (fMRI) and near-infrared spectroscopy (NIRS) was related to dreamed hand movements during lucid REM sleep. Though preliminary, we provide first evidence that specific contents of REM-associated dreaming can be visualized by neuroimaging.