Testosterone, cortisol, and fNIRS-based cortical activation associated with competitive task persistence and...

Motivation for social or resource-related rewards is regulated by areas of the brain that control executive functioning and regulate attention, including the prefrontal cortex (PFC) and temporoparietal junction (TPJ). Testosterone and cortisol are two steroid hormones that influence behaviors related to motivation in social competition and are thought to do so via their independent and interactive effects on these same brain networks. Yet there remains relatively limited evidence for functional hormone-brain correspondence during status contests in humans. In ~120-130 participants, we measured frontal-temporal cortical patterns of neural activity via functional near-infrared spectroscopy (fNIRS), salivary testosterone and cortisol, and task performance in a competitive key-pressing contest for rewards in which the cognitive difficulty of the task was varied. Participants completed the task under one of three conditions for incentivizing performance: a cash prize, positive social judgement, or negative social judgement. The competitive task was associated with increased neural activity bilaterally across the PFC and decreased TPJ activity, especially as task difficulty increased. Individuals who performed better showed greater frontal cortical activation overall and were more likely to have increasing testosterone across the task, but only if cortisol levels simultaneously declined. While hormone change across the task had limited direct ties to brain activity, basal testosterone predicted right vlPFC activation, while the interaction of basal testosterone and cortisol predicted activity in the right TPJ depending on task difficulty. Incentive condition had no clear effects on patterns of brain activity or hormone-brain relationships. These findings support an emerging model of testosterone and cortisol's influence on implicit brain processes underlying attention and goal salience when pursuing social goals. More broadly, this research raises new directions for understanding the neuroendocrine mechanisms behind social and reward-seeking behavior.