Sentence:  In view of the important role which emotional disturbances play in the genesis of neurotic and psychotic disorders and the parallelism observed between autonomic states and psychological behavior in several instances , it is further suggested that a hypothalamic imbalance may play an important <WSD>role</WSD> in initiating mental changes . 
Meaning of the word marked with <WSD> tags:  the actions and activities assigned to or required or expected of a person or group