Fig. 3
a Schema of experimental protocol. Rats were divided into three groups. NoRet and Ret− receiving 8 US-CS pairings (4 per session across 2 days), whereas the Ret + group received 7 US-CS pairings across training (4 in first session and 3 in the second). b All groups acquired fear conditioning to a similar level across pairings during training. The NoRet and Ret group received 8 pairings, whilst Ret+ received 7, to equate for CS-US pairing exposure across days. c The Ret− and Ret+ groups had similar freezing levels during memory reactivation (Ret). d All groups extinguished fear over the session. NoRet and Ret+ groups were presented with 19 CSs whilst Ret− were presented with 18 CSs to equate for CS exposure across days. e Following extinction all groups had reduced fearful behavior to the CS to an equivalent level. During the reacquisition (ReAcq) session the CS was presented again coterminous with a footshock to all groups. f The NoRet animals reacquired freezing to the greatest extent, significantly more than the Ret− group and the Ret+ group
