Enhanced Nogo-P3 amplitudes of mothers compared with non-mother women during an emotional Go/Nogo task

Abstract

Background: It is known that emotion regulatory responses of humans are changed by the experiences they have, but in particular, they are changed by becoming a mother. A recent study has found how a woman's emotion regulatory response to a child's crying changes after becoming a mother. However, mothers' emotion regulatory responses other than those to children and the association between emotion regulatory response and parental stress are still unknown.

Methods: Eighteen healthy Japanese females (nine mothers and nine non-mothers) participated in the experiment. They performed an emotional Go/Nogo task, with facial expressions of others (angry, happy, and neutral faces) used as emotional stimuli. The percentage of correct responses, response time, and event-related potentials (ERPs) during the task was measured.

Results: This comparison revealed that the mother group had a larger P3 (Nogo-P3) amplitude than the non-mother group when Nogo trials were held. This indicates that in mothers, there was greater activation of the behavioral inhibition-related brain areas than in non-mother women when they inhibited inappropriate behavior following recognition of facial expressions of others. In addition, in the mother group, there was a negative correlation between parental stress levels and Nogo-P3 amplitudes evoked by angry faces. This suggests that there is a relation between the level of parental stress of mothers and their emotion regulatory responses to angry faces.

Conclusions: Our results demonstrate that mothers' emotion regulatory processes may differ from those of non-mothers in response, not only to a child's crying but also to expressions of emotions by others, and also suggest that the inhibitory recognition activity of mothers can be affected by parental stress.

Keywords: Behavioral inhibition; Emotion regulation; Event-related potentials (ERPs); Mothers; Nogo-P3; Parental stress.

Fig. 1

Example of the stimuli used in the emotional Go/Nogo task. These pictures are the example of the facial stimuli used in this study. The task included images of angry, happy, and neutral faces

Fig. 2

Electrode positions and three areas of interest. The blue, red, and orange solid-line circles indicate three areas of interest at the fronto-central region (FCz, FC3, and FC4, respectively). FCz, FC3, and FC4 mean the areas of interest around FCz, FC3, and FC4 according to the 10-20 system

Fig. 3

Average ERP waveforms and N2 and P3 components in each area of interest. The black line and the blue line indicate waveforms of the mother group and non-mother group respectively. The solid line, dashed line, and a dashed-dotted line indicate waveforms elicited by angry, happy, and neutral faces respectively. The peak amplitude between 200 and 300 ms and the average amplitude in the epoch between 400 and 600 ms were defined as N2 component and P3 component respectively

Fig. 4

Nogo-N2 amplitudes in FC3. The gray column and the blue column indicate data of the mother group and the non-mother group respectively. The Nogo-N2 amplitudes evoked by happy faces were smaller than the Nogo-N2 amplitudes by neutral faces. *p < 0.05

Fig. 5

Nogo-P3 amplitudes in FCz. The gray column and the blue column indicate data of the mother group and the non-mother group respectively. The Nogo-P3 of the mother group were larger than those of the non-mother group. Only in the FC3, the Nogo-P3 evoked by angry faces were larger than those by other two emotions. *p < 0.05, **p < 0.01, ***p < 0.001

Fig. 6

Correlation between PSI and Nogo-P3 amplitude in FC3 evoked by angry faces. □ indicates the data of each participant in the mother group. The vertical axis and the horizontal axis represent the Nogo-P3 amplitude evoked by angry faces in FC3 and the total PSI score respectively. There was a negative correlation between the mother group’s total PSI score and the Nogo-P3 amplitude in FC3 evoked by angry faces