Trace fear upregulates membrane AMPA receptor GluA1 subunits within the ACC. (A) We exposed adult (8-12 wks) C57 mice to one of 4 conditions: trace fear conditioning, delay fear conditioning, shock only, or exposure to the chamber (all treatments lasted 43 min). (B) 48 h later, in a novel environment, mice exposed to trace fear conditioning exhibit robust freezing behavior in response to the CS. (C) We performed western blot analysis of ACC samples extracted immediately following conditioning. (D) Mice exposed to trace fear conditioning show a significant upregulation of membrane bound GluA1 in the ACC (chamber: n = 8; trace fear: n = 8; shock: n = 6; delay: n = 8; F = 6.70). (E) Total GluA1 levels within the ACC were not affected by trace fear conditioning (chamber: n = 6; shock:, n = 4, trace fear: n = 6; F = 0.06.. (F) Membrane bound GluA2/3 expression levels were not affected by trace fear conditioning (chamber: n = 5; shock:, n = 4, trace fear: n = 5; F = 0.113. (* P < 0.02 ).