It is not possible to divide states of being into the neat
categories of consciousness and unconsciousness. Too many curious
and interesting states lie between, challenging a simple definition.
These altered states of consciousness defy objective description
because they are intensely personal. Nevertheless, these
experiences, which range from the mild distraction of a daydream to
wild, drug-induced hallucinations, can have certain common
characteristics related to the change of perceptions of the self and
the outside world. The term "altered states" covers a number of
phenomena. Some arise naturally and
automatically (dreaming, for example, is thought to be common to all mammals). Others are attained through learned techniques such as meditation. Some are induced by drugs. Other still - the vision and trance states - are highly controversial, and many people doubt their existence. To understand altered states one must assess subjective accounts of what it is like to "be in" these states, along with objective research that tries to identify their physiological basis and effects. Figure 33 shows the brain scan for some of the altered states listed below.
Dreaming - Vivid visual dreams light up the visual cortex; nightmares trigger activity in the amygdala and the hippocampus flares up from time to time to replay recent events. The areas, which seem to be most commonly active are the pathways carrying alerting signals from the brainstem and the auditory cortex; supplementary motor area and visual association areas - all of which produce the "virtual reality" effect of dreaming. Activity is decreased in the dorsolateral prefrontal cortex, the area of waking thought and reality testing (Figure 33). Studies have shown that dreaming sleep occurs in a wide range of animal species. Figure 34 shows a dreaming cat. When its pons is surgically removed to permit movement during REM
sleep, the very nice cat becomes a vicious tiger when it is dreaming and throws itself at imaginary prey.
Daydream - Many surveys suggest that ordinary men and women, who are neither disturbed nor neurotic, spend a large part of each day in some sort of fantasy, reverie or daydream. This kind of quick fantasy rarely has a structured narrative. It is the moment when we stop paying attention to what we are seeing and hearing and switch into an inner theatre of the imagination where we can play at wish fulfillment (Figure 35). But there are other fantasies qualitatively different from these "wouldn't it be nice if ..." stories. These are sustained fantasies, which often seem to have been crafted, worked and reworked to meet some more profound psychological need. When one daydreams, normal inhibitions are bypassed. The