DREAMS

CONTEXT

The phase of sleep associated with vivid dreaming is called REM (rapid eye movement) sleep. Brainwave recordings show very little difference between REM and the awake state. Rapid eye movements are a puzzle to researchers because they are difficult to measure. A recent report addresses the question of whether eye movements are related to whatever is going on in dreams.

INTERPRETING DREAMS

• The early twentieth century was dominated by the theories of Sigmund Freud, focussed on the symbolic meaning of images recollected from dreams
• The discovery of REM sleep in 1952 led to a shift away from psychoanalysis.
• The brain was found to be as active in REM sleep as in the fully awake state. Yet the body was inactive, sleep.
• REM sleep was found in all mammals and birds.
• The recording of brain waves (EEG) provides fresh insights. These recordings showed very little difference between REM sleep and the awake state.
• The neuroscientist Mathew Wilson recorded brain activity in a rat while it was exploring a maze and not much later, obtained identical brainwaves when the same rat was in REM sleep.

ANALYSING THE DREAMS

• Analyzing 50,000 dreams led the compiler, Alvin Hall, to conclude that most dreams did not resemble surrealist paintings, and were fairly predictable. Children may smile while dreaming, as children were more likely to dream of animals, but adult dreams were not very pleasant and were filled with moments of anxiety.
• In a theory proposed by Francis Crick and Graeme Mitchison, dreaming served as a housekeeping function, a nightly sorting of that particular day’s happening. While sorting, a few important events were stored away as memories, the rest treated as clutter.
• Some studies indicated that either the direction or the frequency of eye movement matched the recollected mental process in the dream.
• An electrooculography (EOG) was used to record eye movements in sleeping human volunteers, it recorded whether eye movements were chiefly vertical (up-down)or horizontal( left-right )If the volunteer reported that he was looking upward in his dream, his recorded rapid eye movements were up-down
• Other studies attributed REM to random activity in the brain.

PRACTICING STRATEGIES

• A mouse in an open field frequently moves its eyes upward, scanning the sky for danger from birds. A human pedestrian will perform left-right scans, looking out for oncoming traffic. In both these instances, the eyes move in the same direction as the head.
• The brain keeps track of which way your head is pointed using nerve cells called Head Direction (HD) cells.
• In mice, using electrodes inserted in an HD cell, it has been shown that these cells are active when the head is moving.
• Senza and Scanziani recorded both REM as well as HD cell activity in sleeping mice. They showed that in its REM sleep, their mouse performed up-down eye movements similar to daytime scans of the sky.
• The HD cells too indicated the corresponding movement, although the head itself did not move, the mouse being asleep. It appears that the dream was about escaping from a predatory bird.

CONCLUSION

These studies can be helpful for persons who have experienced sudden, intense trauma suffering from post-traumatic stress disorder, recurring nightmares, and anxiety. A better understanding would lead to better rehabilitation strategies.