Dream

Dreaming is the subjective experience of remembered and imaginary images, sounds/voices, words, thoughts or sensations during sleep, usually involuntarily. The scientific discipline of dream research is oneirology. Dreaming has been associated with rapid eye movement (REM) sleep, a lighter form of sleep that occurs during the latter portion of the sleep cycle, characterized by rapid horizontal eye movements, stimulation of the pons, increased respiratory and heart rate, and temporary paralysis of the body. However, this association has been questioned since it may be that dream recall after REM sleep is common and because dreams are more easily recalled after waking from light REM sleep.

Neurology of dreams

There are many competing theories as to the neurological cause of the dreaming experience. The state of Rapid Eye Movement (REM) sleep is commonly associated with dreams, though it is not known whether dreams actually occur more frequently during this light sleep stage or are simply recalled more easily. REM sleep is known to be produced by a brain region known as the pons.

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The activation synthesis theory developed by Allan Hobson and Robert McCarley state that the brain tries to interpret random impulses from the pons as sensory input. Memory, attention and the other features lacking in a dream state depend on the lack of norepinephrine and serotonin, producing a psychotic state, as well as a lack of orientation to time, place and person.

Related Topics:
Activation synthesis theory - Allan Hobson - Robert McCarley - Norepinephrine - Serotonin

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Research by Mark Solms seems to suggest that dreams are generated in the forebrain, and that REM sleep and dreaming are two different brain systems.

Related Topics:
Mark Solms - Forebrain

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Tarnow suggests that dreams are ever present excitations of the long term memory system (even during waking life - McCarley also observes that when asked to recall the last thought, people often report thoughts that are somewhat hallucinatory). The strangeness of dreams is then due to long term memories being stored in dream format (reminiscent of the Penfield & Rasmussen?s findings that electrical excitations of cortex give rise to experiences similar to dreams). During waking life an executive function interprets long term memory consistent with reality checking.

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The debate between these and other theories is ongoing.

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