Abstract
Mental rotation of 3D objects demonstrates one of the largest sex differences. We investigated sex and sex hormones-related differences in behaviour and event related potentials (ERP) using a modified Shepard and Metzler task composed of sequentially presented 3D figures in 29 men and 32 women. We demonstrated a significant increase in response time and decrease in both accuracy and positivity of the parietal ERP with increasing angular disparity between the figures. Higher angular disparity evoked an increase of global field power (GFP) from 270 to 460 ms and different activation topographies from 470 to 583 ms with lower parietal, but higher left frontal positivity. Flatter slopes in higher angular disparity condition suggest distinct strategies being implemented depending on the difficulty of the rotation. Men performed the task more accurately than women. Performance accuracy in women tended to be negatively related to estradiol while the response time tended to increase with increasing progesterone. There were no associations with testosterone. Women demonstrated higher GFP and an increased positivity over the parietal scalp area, while men showed higher activation in the left frontal cortex. Together these findings indicate dynamic angular disparity- and sex-related differences in brain activity during mental rotation of 3D figures.
Highlights
Mental rotation of 3D objects demonstrates one of the largest sex differences
Studies showed a female-like neural activation pattern in mental rotation task among subjects with a complete androgen insensitivity syndrome[17] and male-to-female transsexuals after a cross-sex hormone treatment[26]. These results indicate that sex differences in regional brain function during mental rotation are influenced by sex steroids
As a number of behavioural and Functional magnetic resonance imaging (fMRI) studies suggested that the levels of estradiol, progesterone and testosterone have significant influence on the performance and associated brain activity during mental rotation[5,21,23], we aimed to assess the relationship between sex steroids and the event related potentials (ERP) during the mental rotation of www.nature.com/scientificreports
Summary
Mental rotation of 3D objects demonstrates one of the largest sex differences. We investigated sex and sex hormones-related differences in behaviour and event related potentials (ERP) using a modified Shepard and Metzler task composed of sequentially presented 3D figures in 29 men and 32 women. Women demonstrated higher GFP and an increased positivity over the parietal scalp area, while men showed higher activation in the left frontal cortex Together these findings indicate dynamic angular disparity- and sex-related differences in brain activity during mental rotation of 3D figures. To systematically probe the strategies that may have been used to solve the task, www.nature.com/scientificreports experimenters have employed a series of methods, such as the variation in the complexity of the stimuli[28], the self-report questionnaires about the strategies that participants used[5,29], different instructions[8], the evaluation the slope of response time[8,30,31], or the evaluation of brain activity during mental rotation[5,16,18] These analyses suggested that males were biased towards a global evaluation and whole-object rotation strategy, while females more often employed rotation-independent piecemeal strategies, such as counting blocs or noting the relative orientations of the object parts[8,15,16]. Whereas the high temporal resolution of the electroencephalography (EEG) allows for a decomposition of the cognitive process into a sequence of processing stages using information from the event related potentials (ERPs)[38]
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