Figure 3.

Fear in extinction. (A) A scatterplot compares mean nose poke suppression to the A2 cue during the final half of discrimination (x-axis) to mean nose poke suppression to the A1 cue on the first extinction trial for Control (black) and EA rats (red). There was zero correlation between the two measures across all rats (R² = 0.07, p = 0.25). (B) A scatterplot compares mean nose poke suppression to the A2 cue over the final half of discrimination (x-axis) to mean nose poke suppression to A1 during the first extinction session for Control (black) and EA rats (red). There was a significant, positive correlation between the two measures across all rats (R² = 0.48, p < 0.01). (C) A scatterplot compares mean nose poke suppression to A2 over the final half of discrimination (x-axis) to mean nose poke suppression to A1 over all extinction sessions for Control (black) and EA rats (red). There was a significant, positive correlation between the two measures across all rats (R² = 0.63, p < 0.01). Note that one Control rat achieved a negative suppression ratio, indicating he increased, rather than suppressed, nose poking during the cue in extinction. (D) Mean nose poke suppression to A1 (y-axis) over the six sessions of extinction is plotted for Control (black fill) and EA rats (red fill) that showed Lo (black outline) or Hi (gray outline) fear to the uncertain A2 cue in the final half of discrimination (individual data taken from Figure 2C). “Lo” rats were the half of each group (Control, n = 5; EA, n = 5) showing the lowest levels of fear to the probabilistic cue in discrimination. “Hi” rats were the half of each group (Control, n = 5; EA, n = 5) showing the highest levels of fear. Rats were separated into “Lo” and “Hi” for illustrative purposes only. ANCOVA was performed with the level of fear to the probabilistic cue as a covariate.