Modulation of rotational behavior in healthy volunteers by cortisol administration

Asymmetrical turning behavior is an established indicator of asymmetrical dopaminergic activity and thought to be a manifestation of hemispatial neglect. We set out to find converging support for the hypothesis that cortisol modulates frontal dopaminergic asymmetrical activity, and hence dopaminergically mediated approach behaviors, by studying the effect of cortisol administration on turning behavior in healthy subjects. Both when our subjects attempted to rotate through a target angle (twice 360°) in a clockwise or anticlockwise direction with reduced sensory input, cortisol induced a relative clockwise turning bias. Furthermore, this effect interacted with scores on novelty seeking, a putative indicator of individual differences in dopaminergic function: subjects scoring higher on novelty seeking demonstrated a smaller or no increase after cortisol administration in their clockwise turning bias. The results provide converging support for the hypothesis that cortisol modulates frontal dopaminergic asymmetrical activity. As we discuss, they further point to the possible involvement of the insula in cortisol effects.