Relationship between activation of prefrontal cortex and testosterone in N-back task
Authors: Aoki Makiko, Satoshi Suzuki, Ryouma Anzai
Abstract: Purpose: Individual and gender differences are an important topic in the study of human cognition. In general, it has been shown that women are superior at verbal ability and associative memory, while men are better at tasks related to numbers, logic, and spatial recognition. Among them, it has been reported that cerebral blood flow in the prefrontal cortex increases during the N-back task, a working memory task. The relationship between sex hormones and cerebral blood flow remains unelucidated, although sex hormones and depressive mood are both factors that affect the function of the prefrontal cortex (cognitive function). Therefore, the present study aimed to clarify the relationship between the testosterone and cognitive function.Methods: The subjects included 6men and 16 women aged 20–35 years. Near infrared spectroscopy (NIRS), a brain function imaging device, was attached to the forehead of the subjects, and Oxyhemoglobin (Oxy-Hb) was measured during the N-back task. Oxy-Hb was measured during the N-back task using a NIRS system in the CHs 1-4 (right side), CHs 7-10 (center), and CHs 13-16 (left side) , and saliva was collected to measure the testosterone concentration. Subsequently, the correlation coefficient between the initial activation and testosterone concentration was calculated. This study was approved by the Institutional Review Board of the Kanagawa institute of technology (No. 20191011-01).Result: The items that were significantly correlated with testosterone were the initial activation CH13-16 in the 0-back task (r=48, p=.02). And the correct response rate (r=.42, p=.03), reaction time (p=.46, p=.03) and initial activation of CH13-16 (r=.68, p=.007) in the 1-back task. Conclusion: In adults, testosterone was associated with initial activation of the NIRS Oxy-Hb signal in the 0-back and 1-back tasks. Furthermore, in the 1-back task, testosterone was associated with correct response rate, the reaction time, and initial activation of the NIRS Oxy-Hb signal of CH13-16. This result suggests that testosterone may be related to left prefrontal cortex activation and responsiveness to presentation of the N-back task.
Keywords: N-back task NIRS testosterone
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