This theory of dreaming was first proposed in 1977 by Hobson and McCarley. At the onset of REM sleep, random signals (known as PGO spikes) arise from the Pons (a structure located on the brain stem) and travel up the mid brain to the cortex. This stimulates the cortex and the brain tries to make sense of these signals or “noise”. There is no external stimuli so the brain creates dream imagery from this noise (internal stimuli). Therefore the theory originally suggested that dreams were in fact meaningless. (Hobson later revised his theory to acknowledge the possibility that dreams may have meaning).