▁place ▁of ▁speech ▁generation ▁( in ▁w ake ful ness , ▁but ▁this ▁would ▁also ▁apply ▁to ▁speech ▁during ▁dream ing ) ▁where by ▁it ▁would ▁no ▁longer ▁necessarily ▁be ▁class ified ▁as ▁a ▁strictly ▁secondary ▁process . ▁ ▁Such ▁revis ions ▁would , ▁He yn ick ▁points ▁out , ▁potentially ▁make ▁the ▁phenomen on ▁of ▁ver bal ▁language ▁in ▁dream s ▁less ▁anom alous ▁in ▁the ▁ps y cho anal yt ic ▁scheme , ▁and ▁without ▁the ▁need ▁to ▁resort , ▁as ▁Fre ud ▁did , ▁to ▁the ▁re play ▁hypothesis ▁as ▁an ▁" ad ▁h oc " ▁exped ient . ▁ ▁Modern ▁models ▁of ▁dream ▁generation ▁ ▁Activ ation - syn thesis ▁hypothesis ▁The ▁activation - syn thesis ▁hypothesis ▁of ▁dream ▁generation ▁first ▁proposed ▁by ▁Harvard ▁University ▁psych iat rist s ▁John ▁All an ▁Hob son ▁and ▁Robert ▁Mc Car ley ▁in ▁the ▁late ▁ 1 9 7 0 s ▁drew ▁upon ▁the ▁discovery ▁earlier ▁in ▁the ▁de cade ▁of ▁the ▁p onto - gen ic ulo - oc cip ital ▁( PG O ) ▁imp uls es ▁which ▁during ▁the ▁night ly ▁RE M ▁periods ▁( the ▁phys i ological ▁stage ▁of ▁sleep ▁which ▁is ▁most ▁associated ▁with ▁the ▁phenomen ological ▁experience ▁of ▁v ivid ▁dream ing ) ▁are ▁fired ▁off ▁from ▁the ▁brain ▁stem ▁and ▁travel ▁to ▁the ▁visual ▁areas ▁of ▁the ▁cor tex . ▁ ▁In ▁the ▁visual ▁area ▁of ▁the ▁cor tex , ▁according ▁to ▁the ▁model , ▁the ▁imp uls es ▁call ▁up ▁largely ▁at ▁random