Collocations for stimulus - noun

great, major, powerful, strong
negative, positive
conditioned, unconditioned
environmental, external
plant growth responses to environmental stimuli

initial
auditory, sensory, verbal, visual
emotional, intellectual, sexual
economic, fiscal, monetary

act as, give, provide
react to, respond to

come from sth
The initial stimulus came from a letter in the newspaper.

bill, package, plan (all AmE)
Congress passed the President's economic stimulus package.

stimulus for
The very act of lying down in bed should provide a strong stimulus for sleep.

stimulus to
A reduction in corporate tax should act as a stimulus to economic activity.
a response to a stimulus

a response to a stimulus
The pupils dilate in response to chemical stimuli.