The Colliculi

Modified: 2020-06-10

The inferior and superior colliculi together comprise the colliculi. The inferior colliculus (here, inferior mean further from the front) is responsible for reflexive responses to auditory stimuli. If I were to surprise you with a loud noise, you would look up. That response of looking up is controlled by the inferior colliculus. Note that we can sometimes prevent such responses from occurring, while sitting in a deer stand, for example. We may prevent ourselves from looking when we hear the sounds of twigs cracking.

The superior colliculus, the next bump anterior (closer to the front of the brain) to the inferior colliculus, serves a similar function, but now the stimuli are visual. When you turn quickly to see something, some movement you detected out of the corner of your eye, for instance, it is your superior colliculus that makes you do that. An interesting example involving the superior colliculus is the design of B-52 bomber cockpits. B-52 pilots practice takeoffs with heavy curtains drawn over the windows of the bomber. They do this because the light from a nuclear explosion is so bright that should a nuclear bomb explode near them while they were taking off, they would not be able to prevent themselves from looking at it. The light is so bright that it would burn out their retinas, blinding them. So, the curtains prevent that from happening.

Another science fiction example comes from a Star Trek episode. Spock is temporarily blinded by McCoy. Vulcans had evolved on a planet where one of the suns flared on occasion. So, vulcans possessed a nictitating membrane that reflexively covered their eyes when a bright light flashed. Bet you did not think you would also learn Vulcan physiology too! (This part is NOT on any tests :-)

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