Figure 4. Effects of catecholaminergic nuclei activation on aversive memories, and their relationship with the retroactive memory benefit for conceptually-related items.

(Left Panel) A subsequent memory general linear modeling (GLM) analysis was performed for items that were incidentally encoded during the conditioning phase of the experiment. Each trial from conditioning was sorted by CS type (CS+ or CS−) and whether it was remembered 24 hours later (hit or miss). BOLD signal was extracted from an anatomical atlas-defined VTA/SN and locus coeruleus (LC) mask for each of the conditioning-phase trials. (Middle Panel) VTA/SN activation was significantly greater when participants successfully encoded CS+ items (dark red bar), and was also more engaged during encoding of CS+ compared to CS− items during conditioning. LC activation was significantly greater during successful item encoding, which was primarily driven by memory enhancement effects for CS+ items. Colored boxplots represent 25th–75th percentiles of the data, the center line the median, and the error bars the s.e.m. Overlaid dots represent individual participants. (Right Panel) Activation-related aversive memory enhancement scores for the VTA/SN (top) and LC (bottom) were computed by subtracting encoding-related parameter estimates for CS− trials (i.e., hit minus miss) from encoding-related parameter estimates for CS+ trials. The VTA/SN aversive memory enhancement measure was positively correlated with the magnitude of the retroactive memory benefit (RME) across participants, but LC scores were not. *p < .05. ~p < .01.