Sinema has voted for federal stimulus spending. I think there is need for economic stimulus. Stimulation is a physical response to a stimulus. Habituation can be described as decreased response to a repeated stimulus. The increase in fMRI signal in response to a stimulus is additive. Phototropism is the growth of an organism in response to a light stimulus. This mechanism allows PIN3 to be repositioned in response to an environmental stimulus. Researchers determine a threshold for the stimulus that will be used as the subliminal stimulus. Allodynia is pain experienced in response to a normally painless stimulus. Voltage gated sodium channels open in response to a stimulus and close again. Alternatively visual hallucination is the perception of an external visual stimulus where none exists. It is the process whereby an animal ceases responding to a stimulus. Reward sensitization normally occurs following chronically high levels of exposure to the stimulus. This led to the establishment of the poverty of the stimulus argument. Dopaminergic activity decreases with repeated stimulus presentation.