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.

The decline of verbal and visuospatial working memory across the adult life span

“…Contrary to the results of the study by Li et al, women outperformed men in both tasks in this study, even in the more difficult version (2-back). In contrast, when testing with letters (Schmidt et al 2009), words and faces (Haut and Barch 2006), neither behavioral nor functional activation (with fMRI) differences were observed between the sexes. In the visuospatial domain, one study (Lejbak et al 2011) observed that men outperformed women in the n-back task.…”

“…Moreover, men were faster than women in all the tasks, denoting that even when discrimination levels are equivalent between sexes, men achieve this performance in shorter time. The majority of the studies (e.g., Schmidt et al 2009;Goldstein et al 2005;Speck et al 2000) failed to find sex differences in working memory reaction times. However, in tasks from the visuospatial domain, there is some evidence that men are faster than women (Loring-Meier and Halpern 1999).…”

Gender Differences in Verbal and Visuospatial Working Memory Performance and Networks

“…Using near-infrared spectroscopy in 50 participants, predominant left-hemispheric activations were also found in females, while performance was equal compared to males in this study [21]. However, two further studies using fMRI in larger samples did not find any consistent sex differences, either on the behavioral or on the brain level [22] (n = 50), [27] (n = 49 + 61). The only study to date that used a so-called Sternberg task to investigate gender effects on the neural representations of WM (n = 33) also did not find differences in task performance.…”

“…While some authors did not find gender effects on WM task performance [19,20,21,22], others reported differences between the sexes [23,24]. The same is true for the corresponding brain activations which also were found to differ in some [19,20,21,23,25] but not all studies [22,26,27]. Besides the use of different WM paradigms (N-back, Sternberg item recognition tasks) and domains (spatial, verbal), again the fact of sometimes very small and inhomogeneous samples is likely to have contributed to these inconsistencies.…”

The contributions of handedness and working memory to episodic memory

“…In terms of gender differences, a female advantage in episodic memory retrieval is predominantly reported (e.g., Geffen, Moar, O'Hanlon, Clark, & Geffen, 1990;Herlitz, Nilsson, & Bäckman, 1997;Herlitz & Rehnman, 2008;Hultsch, Masson, & Small, 1991). However, there are mixed findings about the presence of gender differences in WM (Loring-Meier & Halpern, 1999;Lynn & Irwing, 2008;Schmidt et al, 2009).…”