 Combining fMRI and visual neuroscience techniques, this protocol will study the functional neuroanatomic underpinnings of smooth pursuit eye movement SPEM deficits in schizophrenia. We aim to establish a pathophysiological model of the illness based on the SPEM paradigm. Such a disease model may provide safe in vivo examination of the effects of pharmacological interventions, comorbidity, and functionality relating to schizophrenia. For example, patients with schizophrenia have high comorbidity of nicotine use. High incidence of substance abuse in schizophrenia suggests that the two conditions may share some common pathophysiology. Excessive nicotine use in schizophrenia is increasingly viewed as a form of self-medication by patients to correct underlying pathophysiological changes caused by the illness. We have found that nicotine can transiently improve smooth pursuit eye movement deficits in patients. We are currently examining the nicotinic effect on the learning components of smooth pursuit eye movement in schizophrenic patients using fMRI. This is an example on how carefully validated behavioralimaging paradigm can be used as a pathophysiological model in aiding the study of complex brain illness including schizophrenia and substance abuse. Clearly, this research direction also requires a parallel research effort that aims at in-depth understanding of the foundational neural mechanism of the smooth pursuit eye movement itself. 