Question

When an olfactory receptor is stimulated, what type of change must happen before it signals the brain that a change has occurred?

Answer 1

When an olfactory receptor is stimulated, a generator potential must be produced by the receptor before it signals the brain that a change has occurred.

In order to reach the threshold of the cell, a graded potential must be generated by the neuron of  the olfactory receptor. At threshold, an action potential will be generated, referred to as the generator potential. The brain then receives this generator potential in order to decode it.