Scientists may be a step closer to pinpointing the birthplace of dreams, thanks to a 73-year-old woman. The woman suffered a stroke that affected the blood flow to the right inferior lingual gyrus, which is located deep in the rear of the brain. Researchers Claudio Bassetti and Matthias Bischof monitored the stroke victim's brainwaves for six weeks. They found that she experienced the temporary loss of several brain functions, most of them visual―a not unusual occurrence in such stroke cases. A few days after the stroke, the patient’s visual acuity and other faculties returned, but then something quite bizarre occurred:Her dreaming ceased completely. According to Bassetti, the results of the study “describe for the first time in detail the extent of lesion necessary to produce loss of dreaming in the absence of other neurological deficits.”
The finding was of further consequence to the researchers for another reason. The patient's rapid-eye-movement (REM) sleep―a neurologically active period in which the brain generates about five times as much electricity as when awake―continued normally during the study. This is significant because dreams normally occur during periods of REM sleep, which make up 20 to 25 percent of sleep. The area of the brain that controls REM sleep, the pons, is a primitive part of the brain stem that regulates such basic reflexes as breathing, and this had previously led to speculation that REM sleep must have developed before dreaming, which is thought to be a more sophisticated process. This latest study ― by suggesting that dreams are either generated in, or transmitted through, the right inferior lingual gyrus ― thus confirms speculation that dreams come from a more sophisticated region of the brain.