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Resting-State Theta Oscillations and Reward Sensitivity in Risk Taking
Females demonstrate greater risk aversion than males on a variety of tasks, but
the underlying neurobiological basis is still unclear. We studied how theta (4–7 Hz)
oscillations at rest related to three different measures of risk taking. Thirty-five
participants (15 females) completed the Bomb Risk Elicitation Task (BRET), which
allowed us to measure risk taking during an economic game. The Domain-Specific Risk-
Taking Scale (DOSPERT) was used to measure self-assessed risk attitudes as well as
reward and punishment sensitivities. In addition, the Barratt Impulsiveness Scale (BIS11)
was included to quantify impulsiveness. To obtain measures of frontal theta asymmetry
and frontal theta power, we used magnetoencephalography (MEG) acquired prior to
task completion, while participants were at rest. Frontal theta asymmetry correlated
with average risk taking during the game but only in the female sample. By contrast,
frontal theta power correlated with risk taking as well as with measures of reward and
punishment sensitivity in the joint sample. Importantly, we showed that reward sensitivity
mediated a correlation between risk taking and the power of theta oscillations localized
to the anterior cingulate cortex. In addition, we observed significant sex differences
in source- and sensor-space theta power, risk taking during the game, and reward
sensitivity. Our findings suggest that sensitivity to rewards, associated with resting-state
theta oscillations in the anterior cingulate cortex, is a trait that potentially contributes to
sex differences in risk taking.