Sensorimotor gating in animal models is the involuntary, preattentive inhibition of a response to a sensory stimulus. Completion of goal-directed behavior is optimized by the inhibition of competing cognitive or motor processes. Sensorimotor gating can be operationalized using the startle response, which is a reflex contraction of the skeletal musculature in response to an intense, abrupt stimulus. Prepulse inhibition occurs in several sensory modalities and in several species including rats and humans. A common strategy for studying the limbic-motor control of locomotor activity and appetitive behaviors in rats involves the use of receptor-specific drugs, administered both systemically and in localized intracerebral infusions, to construct an anatomical and pharmacologic map of the neural substrates of the dependent measure. The chapter reviews evidence which indicates that limbic cortico-striato-pallido-pontine circuitry controls sensorimotor gating of the startle reflex, and that startle gating is deficient in patients with schizophrenia, and in patients with other disorders of deficient limbic-motor gating. Sensorimotor gating deficits in psychiatric patients.