8. How does the brain represent the passing of time?
As anyone who has sat through an excruciatingly boring lecture or blazed through a good book can attest, our perception of time can be extremely subjective. From one day to the next,a group of cells in the hypothalamus known as the suprachiasmatic nuclei receive signals from the retina that help synchronize the body’s circadian clock.
Time processing at much shorter timescales, however, lacks the regularity of the circadian rhythm. Because auditory signals are processed by the brain much faster than visual ones, the brain has to actively synchronize the two signals—a fact that gives television producers a hundred millisecond wriggle room for mismatch between audio and video channels. A lowered ability to calibrate different sensory inputs could also explain why elderly people become more susceptible to falls.
