Stimulation

[Sarah]

The irritating action of various agents (stimuli) on muscles,nerves, or a sensory end organ, by which activity is evoked;especially, the nervous impulse produced by various agents on nerves,or a sensory end organ, by which the part connected with the nerve isthrown into a state of activity; irritation.

[Jason Yan]

Encouragement of something to make it develop or become more active.

[Sarah]

an action or thing that causes someone or something to become more active or enthusiastic, or to develop or operate: