Testosterone Administration Related Differences in Brain Activation during the Ultimatum Game

Area of Science:

• Neuroscience
• Social Psychology
• Endocrinology

Background:

• The Ultimatum Game reveals responders reject unfair offers, deviating from pure profit maximization.
• This behavior correlates with activation in brain regions like the amygdala, insula, and dorsolateral prefrontal cortex (dlPFC).
• Previous research on testosterone's role in the Ultimatum Game yielded inconsistent results.

Purpose of the Study:

• To investigate the influence of testosterone on decision-making and neural responses during the Ultimatum Game.
• To examine the specific roles of the amygdala and testosterone in social behavior.
• To clarify inconsistent findings regarding testosterone's effects in economic games.

Main Methods:

• A double-blinded, placebo-controlled study administering 60mg of Tostrex (testosterone) or placebo.
• fMRI scans were conducted on healthy male and female volunteers playing the Ultimatum Game 3 hours post-administration.
• Behavioral data (offer acceptance rates) and fMRI data (brain activation) were analyzed.

Main Results:

• Participants receiving testosterone tended to accept more unfair offers compared to the placebo group, irrespective of gender.
• fMRI analysis showed greater activation in the right dlPFC for unfair versus fair offers in the testosterone group.
• Higher testosterone levels correlated with increased activity in the caudate nucleus.

Conclusions:

• Testosterone administration appears to modulate decision-making in the Ultimatum Game, potentially by altering neural processing in regions like the dlPFC.
• Findings suggest testosterone plays a complex role in social decision-making and economic behavior.
• Further research is needed to fully elucidate the neurobiological mechanisms underlying testosterone's influence on social behavior.