Prepulse inhibition (PPI), which reflects the important mechanisms inhibiting interference and protecting information processing, is widely recognized as a model for studying both sensorimotor gating and schizophrenia. PPI can be top-down modulated by higher-order cognitive processes, such as attention and emotion. This dissertation focuses on the hierarchically organized top-down modulation of PPI by fear conditioning and perceptual spatial separation (selective spatial attention). Systematic and cross-level researches on rat behavioral model, neural pathways, and neurophysiological mechanisms were conducted, and the neuro-developmental model of schizophrenia was also applied which demonstrates that isolation rearing in rats can disrupt the attentional modulation of PPI. The findings from this research will not only promote the understanding of the brain mechanisms in information processing under complex environment, the animal model based on deficient attention-on-gating modulation function will also advance the psychological and neurobiological research on schizophrenia.