If I enter a room with certain odor, I can sense the odor. However, if I stay there for some time I cannot sense it anymore. A new entrant to the room can still smell it or I have to leave the room for some time and upon returning I can sense it again. Does our nose detect only if there is change in odor?
1 Answer
Senses in general adapt to continuous stimulation due to various processes. One such process is simply the exhaustion of the reserves of a receptor, or secondary neuron, due to a depletion of neurotransmitters. Entering a room activates a fresh pool of chemical receptors, thereby generating a clear sense of smell. However, this dims due to adaptation. Exiting and re-entering the room after a while revives the neuronal response. More central adaptive responses may also play a role. A comparable effect is seen in the tactile sense. For example, the awareness of wearing a ring or watch fades quickly. Changing its position revives the percept. So yes, sensory systems like olfaction and touch are more responsive to differential stimuli.