Normally, the sensory neurone is at its resting potential. The axon membrane is negative on the inside. When pressure is applied to the Pacinian corpuscle, the membrane of the neurone stretches and a stretch-mediated sodium ion channel changes shape and widens to allow the diffusion of sodium ions into the neurone.The potential of the neurone changes and it becomes depolarised resulting in a generator potential which then creates an action potential (electrical impulse) that passes along the neurone.