Neural Correlates of Memory Function and Emotional Processing During Late Pregnancy: Evidence from Event Related Potentials

Studies on cognitive and emotional function during pregnancy draw a complex picture and do not entirely support the frequently self-reported cognitive decline among pregnant women. Research concerning neural changes accompanying pregnancy-related cognitive changes is scarce. We investigated behavioral and neural correlates of cognitive-affective processing in pregnant women (third trimester) compared with non-pregnant controls. Electrophysiological brain activity was recorded using a 64-channel EEG-ERP system while participants completed an emotional word recognition task. This task included an initial presentation of a continuous sequence of emotional and neutral words and a subsequent recognition memory test in which participants had to indicate for each word whether it was 'new' or 'old'. Contrary to the prevalent subjective perception, results indicated that recognition ability was not compromised during late pregnancy, since no group differences were found in error rates. However, pregnant women had slower reaction times than controls. Electrophysiological results indicated that pregnant women exhibited more pronounced amplitudes of the N1, P2 and N400 ERP components. Augmentation of these ERPs may reflect the recruitment of additional brain resources for perceptual processing. Pregnancy status interacted with emotional content of stimuli so that pregnant women had more pronounced N1 and N400 to negative words, but not to positive and neutral words. Pregnant women also had more pronounced N1 to 'new' words but not to 'old' words. These results suggest that during late pregnancy, women show increased sensitivity and responsiveness to new/unfamiliar stimuli in their environment, and particularly to negative stimuli that may indicate potential threat or danger. This may lead to more cautious behavioral style, which may be advantageous in optimizing fetal growth and development.