What is provided is an apparatus and method of modifying a nervous system signal by selectively electrically stimulating a mammalian nerve comprising: applying a dermal patch having an integral electrode in proximity to an axon in a vagus nerve or one or more of its branches or tributaries； determining a stimulation corresponding to the axon in the vagus nerve or the branch or tributary, by logic of the dermal patch； applying the stimulation by the electrodes and a stimulator integral to the dermal patch to produce an electric field； and selectively activating the axon in the vagus nerve or the branch or tributary by the electric field.
