The Limits of Dream

Since the time of Freud, the body has been ascendant in cognitive science, the
mind hidden and apparently described by neuron-to-neuron chemical connections
in the central nervous system. The last half of the 20th century presented
challenges to scientific understanding and logic that would force a profound
change in the older sciences. Mathematics, astronomy, physics, chemistry, genetics,
and cellular biology, scientific fields once characterized by simple formulas
reflecting concrete fact, transformed into complex interrelated spheres of activity
now defined by algorithms of possibility. In contrast, cognitive neuroscience
developed in this era, a distinctly new and apparently unique area of science,
exemplifying simplicity. Brain activities became amenable to easy understanding
when modeled on sequential firing of neurons as modulated by neurochemical
transmitters at the synaptic junctions between cells. This simple model has been
extraordinarily productive, serving as the basis for medical approaches as diverse
as pharmacologically based psychiatry and neurosurgery.
Unfortunately, like most myths that simplicity disappears with closer examination.
Simple “truths” of cognitive science flounder. For instance, everyone knows
(check the textbooks) that the rapid eye movement (REM) sleep we see occurring
every 90 minutes each night is dreaming – right?
Except that almost all research indicates the contrary. REM sleep does not equate
with dreaming. REM sleep occurs without dreaming and dreaming occurs without
REM sleep. The two cognitive states are doubly dissociable. There is little evidence
that an actual physiologic correlate for dreaming exists. Although the REM sleep we
see on our electrical recordings of the brain during sleep is a state in which dreaming
may occur, dreaming also occurs throughout the other stages of sleep.
Many neuroscientists have built their careers on simple neurotransmitter constructs
of CNS functioning. There is...