What determines how a stimulus is interpreted?

The sensations of sweet and bitter detected by taste buds, stretching of a muscle which stimulates stretch receptors, sounds we hear, images we see, and all other sensory information are all conveyed by similar means—the movement of Na+ or K+ ions across the cell membrane, causing a change in membrane polarization, which, if above threshold, leads to a generation of action potentials in sensory neurons. These action potentials are distinguished as different sensations because the various sensory neurons are connected to different regions in the brain.

It does not matter where the impulses originate or what stimulus initiates the impulses. It only matters what part of the brain is stimulated. Specific sensations are the brain’s interpretation of incoming stimuli. What an animal senses, then, is shaped and constrained by the nature of its sensory receptors and the wiring of its nerve cells. If somehow you could cross the optic nerve with the acoustic nerve, you would then see thunder and hear lightning!

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