We're slowly realizing that the universe we perceive is quite different from the real thing. Light frequencies are turned into nerve impulses which our brain interprets as light and color. Pulses of greater and lesser density of air—sound waves—are turned into nerve impulses that our brain interprets as sound; yet other nerve impulses are felt as pain.
Some of us have been subjected to this knowledge often enough that we
tend to think that all of stimuli processing occurs within the brain. However, this is
not entirely true. The eye, for example, does a considerable amount of manipulation
before the nerve impulses are sent to the brain. Thus the frog's eye is
hypersensitive to such moving objects as flies, resulting in a barrage of nerve
impulses to the brain, while the immobile is pretty much ignored. And ourselves? Look
to where our mountains meet the sky; a nice, crisp demarcation between the two—thanks
to our eye construction that emphasizes borders. The brain really doesn't have to
have a formal vote on things like this—after all, the eyes clearly have it.
Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.
The Franklin Mountains from the east. Where mountain meets sky is emphasized by mechanisms of the eye. Photograph by A.H. Harris.