REM sleep is triggered by _____________________.
|  | 
   |  | high frequency waves in the cortex; | 
   |  | monophasic, low frequency, high amplitude waves in the pons; | 
   |  | dreams; | 
   |  | monophasic, low frequency, high amplitude waves in the cortex; | 
   |  | monophasic, low frequency, high amplitude waves in the lateral geniculate nucleus; |