First described in the 16th Century by Italian anatomist Costanzo Varoli, the pons consists of two parts: the tegmentum, which contains the reticular formation, and the pontine nuclei. It connects the medulla with the cerebellum, while its thick ascending and descending fibers, "gangly giants,"(1) reach from brain stem to neocortex. Its name is derived from the Latin for "bridge."
The prehistory of bridge-building may begin with humans swinging across chasms on vines. In the 16th Century, Spanish invaders of South America reported seeing Peruvian suspension bridges built from fibers "woven into cables of the thickness of a man's body." How old the technology was by that time is not known. Besides being triumphs of human ingenuity, bridges are places of imaginative space. Were ancient bridges the result of pontine fibers dreamed by ancient shaman/engineers?
The pons secretes a class of neurotransmitters called the amines, the best described of which are norepinephaline and serotonin, which serve to allow the higher brain to pontificate over the organism. During REM (dream) sleep, these substances are drastically reduced, replaced by the cholinergic neurotransmitters--secreted by another part of the pons--, especially acetycholine, a chemical commonly found the junctions of muscles and nerves. While we dream, acetycholine inhibits kinesthesis, except for the eyes. (REM is an acronym for Rapid Eye Movement.) The function of such eye-movement seems announce the passive viewing of images.
Michel Jouvet, who pioneered research into the neurobiology of dreams, calls REM sleep "paradoxical," because, although the cerebral cortex is flooded with images, it cannot link them to the body, which is atonic. Jouvet calls dreaming a third state, "a new form of an age-old concept--that of the Upanishads of Hindu mythology--according to which the human brain alternates between waking, sleeping without dreams, and sleeping with dreams."(2)
Via the amygdala, pontine cells can generate anxiety, initiating the common nightmare of being pursued but not being able to run, by sending strong signals to the cerebral cortex, where sensate impressions and memories would normally meet, but are now hampered by the dearth of amines. With this in mind, a leading investigator in the field wrote that "dreams are the product of our cortex's efforts to do the best it can under very difficult circumstances."(3)
while working on this trace of the journey, I wasn't able to remember my dreams, even if I tried at the moment of waking up. Something usual for me. I knew that I had dreamed, but of what I couldn't recall. Then impressions formed while awake began to substitute for dreams. Thus I arrived at a place dreamed as if I were still dreaming. Chuang-tzu's butterfly, or Psyche's honey?
(1) J. Hooper and D. Teresi, The three-Pound Universe.
New York, 1986. p.293.
(2) M. Jouvet, The Paradox of Sleep. Cambridge, MA., 1999. p.37.
(3) J.A. Hobson, "Order From Chaos." In, R. Conlan, Editor. States of Mind. New York, 1999. p.191.