L-VGCC antagonists in the BLA impair long-term memory of fear extinction. A, Schematic of behavioral protocol. B, Mean ± SE postshock freezing after three conditioning trials. C, Mean ± SE percentage freezing to 10 CS tones 24 h after training in rats given intra-BLA infusions of ACSF (n = 10), 1 μg of verapamil (n = 8), or 5 μg of verapamil (n = 6) 15 min before testing. D, Mean ± SE percentage freezing to 10 CS tones 24 h after extinction training, drug-free. E, Mean ± SE postshock freezing. F, Mean ± SE percentage freezing to 10 CS tones 24 h after training in rats given intra-BLA infusions of 50% saline, 50% DMSO vehicle (n = 9) or 8 μg of nifedipine (n = 14) 15 min before testing. G, Mean ± SE percentage freezing to 10 CS tones 24 h after extinction training, drug-free. H, Rats receiving nifedipine were divided into low and high freezing subgroups (Nifed/low frz, n = 6; Nifed/high frz, n = 8) based on their percentage freezing to the first tone on extinction training day. Average freezing is compared between these and the vehicle group for freezing to the first and last tones on training day and the first tone on extinction testing day.