Previous studies have shown that female rats exhibit different patterns of drug seeking during multiple phases of cocaine addiction when compared with males. However, the underlying mechanisms for these sex differences remain largely unknown. Here, we used a cocaine self-administration/reinstatement model to examine neuronal activation, as determined by Fos expression, following cue-induced reinstatement of cocaine seeking in male and female rats. Fos expression revealed both similarities between sexes in some brain regions, as well as selective sexually dimorphic patterns. As compared to no cue control subjects, conditioned cues induced higher Fos expression in the Cg1 region of the anterior cingulate cortex, but lower expression in the nucleus accumbens in both males and females. Females exhibited higher Fos expression than males in multiple brain regions, including the agranular insular cortex, dorsal medial caudate-putamen, nucleus accumbens shell, ventral tegmental area, dorsal subiculum, and ventral CA1 and CA3 regions of the hippocampus. Notably, only Fos expression in the prelimbic cortex, nucleus accumbens shell, basolateral amygdala, and ventral subiculum correlated positively with lever responding in response to conditioned cues across males and females. These findings indicate that while sexually dimorphic Fos activation does occur, the relationship between cue-induced cocaine seeking and neuronal activation may be similar for males and females in key brain regions of the relapse circuit.

A recent line of research has suggested that memory systems evolved to encode fitness-relevant information more effectively than other types of information-a phenomenon known as the "survival processing effect" (Nairne, Thompson, & Pandeirada Journal of Experimental Psychology: Learning, Memory, and Cognition 33:263-273, 2007). However, the basis for the effect has been debated. In addition, it is unknown whether or not individuals will adjust their judgments of learning (JOLs) to reflect the survival processing effect. In three experiments, participants rated 16 words for their relevance to a survival scenario and another 16 words for their relevance to a bank robbery scenario. In Experiment 1A (with no JOLs), the survival processing effect emerged; in Experiment 1B (with JOLs), no survival processing effect emerged, but JOLs were higher in the survival condition. In both cases, these findings were confounded by higher relevance ratings in the survival condition. In Experiment 2, relevance was manipulated within each list, and the survival processing effect was eliminated. Instead, both recall and JOL magnitude were related to level of congruity between the words and type of processing. Together, these results provide further evidence for the role of congruity in the survival processing effect and JOLs.