No gender differences in brain activation during the N-back task: an fMRI study in healthy individuals

Abstract

Gender differences have been well established in verbal and spatial abilities but few studies have examined if these differences also extend into the domain of working memory in terms of behavioural differences and brain activation. The conclusions that can be drawn from these studies are not clear cut but suggest that even though gender differences might not be apparent from behavioural measures, the underlying neural substrate associated with working memory might be different in men and women. Previous research suggests activation in a network of frontal and parietal regions during working memory tasks. This study aimed to investigate gender differences in patterns of brain activation during a verbal version of the N-back working memory task, which incorporates the effects of increased demands on working memory. A total of 50 healthy subjects, aged 18 to 58 years, that were equally split by gender were recruited matched for age, levels of education and ethnicity. All subjects underwent functional magnetic resonance imaging. We found that men and women performed equally well in terms of accuracy and response times, while using similar brain regions to the same degree. Our observations indicate that verbal working memory is not affected by gender at the behavioural or neural level, and support the findings of a recent meta-analysis by Hyde ([ 2005]: Sex Roles 53:717-725) that gender differences are generally smaller than intra-gender differences in many cognitive domains.

Figure 1

Differences in accuracy according to condition and gender. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

Figure 2

Mean response times according to condition and gender. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

Figure 3

Overlap in brain activation between males (blue) and females (red) during the N‐back.

Figure 4

Main effect of task in males during the N‐back (height threshold P < 0.001 uncorrected; cluster‐level P < 0.05 corrected).

Figure 5

Main effect of task in females during the N‐back (height threshold P < 0.001 uncorrected; cluster‐level P < 0.05 corrected).