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First , we conducted a systematic PubMed search to identify eight fMRI investigations that met the following inclusion criteria : case - control , longitudinal design ; pre - and post - treatment contrasts with a healthy comparison group ; and antipsychotic - free or antipsychotic - naive patients with schizophrenia at the start of the investigation .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
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