p494fig13.18 Realizing the above constraints favor one particular circuit.  Circuits (a) and (b) are impossible.  Circuit (d) allows previously occurring sensory cues to be stored in STM.  Circuit (e) in addition enables a CS can be stored in STM without initiating conditioning in the absence of a US.<BR>||  Learning to control nonspecific arousal and read-out of the CR: two stages of CS.  (d) & (e) polyvalent cells.