High confidence spatial long-term memories produce greater cortical activity in males than females.

Many functional resonance imaging (fMRI) studies have reported sex differences during long-term memory. The present fMRI investigation aimed to identify whether sex differences exist during high- versus low-confidence accurate spatial memories. During the study phase, abstract shapes were presented to the left or right of fixation. During the test phase, each shape was presented at fixation and participants made an old-"left" or old-"right" judgment followed by an "unsure" or "sure" response. The conjunction of female high- versus low-confidence spatial memory and male high- versus low-confidence spatial memory identified common activity in visual processing regions and parietal cortex, which suggests amplification of activity in some of the regions commonly associated with long-term memory yields high confidence. The contrast of female high- versus low-confidence spatial memory and male high- versus low-confidence spatial memory did not produce any significant activity. However, the reverse contrast produced greater male than female activity in the lateral prefrontal cortex, parietal cortex, sensorimotor cortex, and visual processing regions. An independent region-of-interest (ROI) analysis (ROIs were identified by contrasting hits versus misses) produced complementary results in the lateral prefrontal cortex. Greater lateral prefrontal cortex activity suggests a higher degree of subjective confidence in males than females, greater parietal cortex and visual processing activity suggests more vivid visualization in males than females, and greater activity in sensorimotor cortex indicates that males have a more reactive processing style than females. More broadly, the present and previous functional sex differences argue against the practice of collapsing across sex in cognitive neuroscience studies.