This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Impulsivity is a significant component of the behavioral and neurocognitive abnormalities seen in patients with schizophrenia. The Go/No-Go task has been used extensively to study response inhibition in a variety of populations. It requires the subject to make a response in the presence of the 'go' stimulus and to make no response in the presence of the 'no-go' stimulus. Commission errors (responding in the presence of the no-go stimulus) are interpreted as failures of response inhibition and are increased in patients with frontal lesions, aggressive male adolescents, and psychopaths. The current study aims to use fMRI to examine the neurophysiological basis of response inhibition in patients with schizophrenia (SZ)or schizoaffective disorder (SZA) using the go/no-go task. In our pilot data, presented at the ICSR in 2003, fifteen inpatients with SZ or SZA were tested on a go/no-go task in a functional magnetic resonance imaging study on a 3T scanner. Violent behavior was assessed with the Life History of Aggression questionnaire, and patients were divided into more violent and less violent groups. For no-go responses compared to resting conditions, the more violent patients showed greater activation in the right anterior cingulate (Brodmann s Area [BA] 32), the left middle frontal gyrus (BAs 9 and 46), the left superior temporal gyrus (BA22), the left inferior frontal gyrus (BAs 9 and 46), right middle frontal white matter, and the thalamus. The current results suggest that more violent patients show greater activation in a fronto-temporo-limbic circuit in situations requiring response inhibition. As a comparison task, we are administering a competing programs task that indexes cognitive flexibility vs. stability is generally involves more dorsal frontal regions than the go/no-go task.
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