673
With stimulation beyond the theta - range three phenomena occurred : shift of the burst frequencies to higher or lower harmonics of stimulation frequencies ; complex interactions of basic background frequency with rhythm of stimulation ( " beating " ) ; return to background theta - burst frequency in spite of continuing stimulation ( " escape " ) .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
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