Figure 6.

PN-FLX treatment results in fear extinction learning and recall deficits. A, PN-FLX mice exhibit comparable levels of freezing at baseline (pre), in response to the first and last tones of the training session, and in the post-training period (post), when compared with PN-VEH controls. B, During the extinction learning session, no baseline differences in pretone freezing in a novel extinction training environment is observable (pre). B, After the onset of the tones (without shocks), PN-VEH mice exhibit a progressive decrease in freezing to tone over the extinction session, while PN-FLX mice display significantly blunted decreases in freezing over the session (horizontal line indicates significant treatment × time interaction). PN-FLX mice also exhibit significantly higher post-training freezing levels, relative to controls (B, post). C, To investigate freezing behavior over multiple days, freezing levels of PN-FLX and PN-VEH mice were normalized to their respective starting freezing levels at D1. As observed in the non-normalized data of B, PN-FLX-treated mice displayed a deficit in extinction learning, when compared with PN-VEH controls on D1 (C, horizontal line indicates significant treatment × time interaction, stars without horizontal line indicate treatment effect on D1 end). Between D1 and D2, neither PN-VEH nor PN-FLX mice displayed extinction recall (D1 start vs D2 start, not statistically significantly different for either PN-VEH or PN-FLX). On D2, PN-VEH and PN-FLX mice displayed extinction learning (main effect of effect of time, no time × treatment interaction). Between D2 and D3, only PN-VEH displayed extinction recall, and PN-FLX mice froze significantly more than PN-VEH mice on D3. N values are indicated in the figure. *p < 0.05; **p < 0.01; ***p < 0.001.