3680
The central serotonergic system matures during the adolescent period , and its immaturity during early adolescence may contribute to adolescent risk taking , as deficits in central serotonergic function have been associated with impulsivity , aggression , and risk taking .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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