Where are the images and ideas from dreams located in the brain, and is there any way to capture them?
—Derek Meier, Chicago
Mark A. W. Andrews, director and professor of physiology at Lake Erie College of Osteopathic Medicine at Seton Hill University in Greensburg, Pa., replies:
The answer to the latter part of your question is simply, “No.” Although we have technology that can measure general brain activity, we have no method for assessing or capturing our individual thoughts and dreams.
To evaluate our future potential to do so, it is important to understand which areas of the brain are associated with dreaming. Most dreams occur during the stage of sleep when slumberers start making rapid eye movements, called REM sleep. The imagery a sleeping brain concocts appears to originate in the reticular formation (RF), a diffuse, intricate collection of more than 100 networks of neurons arranged throughout the brain. The RF helps to regulate essential processes, including waking and sleeping cycles and cardiac function. The RF’s neural networks link up with the cerebral cortex, which regulates how we think and remember. But the widespread connections between the RF and the rest of the brain make dreams difficult to study.
In addition to the RF, dreaming involves the limbic system, often referred to as the emotional brain. Areas of the visual cortex responsible for recognizing complex visual scenes as well as the anterior cingulate gyrus, which governs attention and motivation, are also active during REM sleep. Interestingly, regions of the frontal cortex involved in thought and judgment while we are awake remain relatively calm throughout REM sleep, possibly accounting for the bizarre and illogical content of some dreams.
Currently scientists are able to probe human brain activity in several ways. We can record brain waves using EEG. With PET scans and functional MRI, we can observe fluctuations in brain activity by measuring changes in blood flow and levels of nutrients.
These established techniques are not powerful enough to document dreams, but a newer method may enable a breakthrough. Recently neuroscientists have implanted single electrodes in the cortex to record the activity of single neurons believed to be associated with a single thought or image. One day such implanted electrodes might let us log and play back our thoughts and dreams.