Sentence:  In view of the important role which emotional disturbances <WSD>play</WSD> 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 role in initiating mental changes . 
Meaning of the word marked with <WSD> tags:  act or have an effect in a specified way or with a specific effect or outcome