Sex differences in prefrontal hemodynamic response to mental arithmetic as assessed by near-infrared spectroscopy.
BACKGROUND
Sex differences in cognitive tasks have been widely investigated. With brain-imaging techniques, the functions of the brain during the performance of tasks can be examined.


OBJECTIVE
Mental arithmetic and near-infrared spectroscopy (NIRS) were used to assess sex differences in prefrontal area activation in a functional brain study.


METHODS
Healthy college students were recruited to perform 2 mental arithmetic tasks. In the first (easy) task, students had to subtract a 1-digit number from a 3-digit number. In the second (difficult) task, they had to subtract a 2-digit number from a 3-digit number. Changes in the concentration of oxygenated hemoglobin (oxy-Hgb) in the prefrontal area during the tasks were measured with NIRS.


RESULTS
Thirty students (15 men, 15 women; mean [SD] age: 24.9 [2.2] and 24.3 [2.6] years, respectively) were recruited from Southeast University, Nanjing, China, to participate in the study. The concentration of oxy-Hgb increased during both mental arithmetic tasks (difficult task vs easy task, mean [SD] % arbitrary units: 4.36 [4.38] vs 2.26 [2.82]; F(1,28) = 222.80; P < 0.01). Significant interactions of task x sex (F(1,28) = 82.95), time x sex (F(1,28) = 34.48), task x time (F(1,28) = 222.57), and task x time x sex (F(1,28) = 83.09) were obtained (all, P < 0.01). However, for the 2 tasks, no significant differences between men and women were observed in the mean (SD) response time (men vs women, sec: 3.60 [0.74] vs 3.56 [0.49] for the easy task, 6.55 [0.77] vs 6.44 [0.75] for the difficult task; F(1,28) = 0.67; P = NS) or accuracy rate (men vs women, %: 95.33 [7.40] vs 92.77 [8.80] for the easy task, 62.67 [28.56] vs 54.67 [18.75] for the difficult task; F(1,28) = 0.54; P = NS). Male students showed neural efficiency (less prefrontal activation in subjects with better performance) during the difficult task.


CONCLUSIONS
In these subjects, sex differences in prefrontal response when performing mental arithmetic were associated with the intensity of the task. Compared with men, women had greater efficiency in task performance (ie, less activation or oxygen consumption for equal performance).
Yang
Hongyu
H
Key Laboratory of Child Development and Learning Science, Ministry of Education, Southeast University, Nanjing, China.
Wang
Ying
Y
Zhou
Zhenyu
Z
Gong
Hui
H
Luo
Qingming
Q
Wang
Yiwen
Y
Lu
Zuhong
Z
D000328:Adult; D001931:Brain Mapping; D002560:Cerebrovascular Circulation; D003071:Cognition / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D007839:Functional Laterality; D006439:Hemodynamics; D006801:Humans; D008297:Male; D055641:Mathematical Concepts; D010108:Oxyhemoglobins / Q000378:metabolism*; D017397:Prefrontal Cortex / Q000098:blood supply*; D011340:Problem Solving / Q000502:physiology*; D012737:Sex Factors; D019265:Spectroscopy, Near-Infrared; D055815:Young Adult
D010108:Oxyhemoglobins