Monoaminergic modulation of decision-making under risk of punishment in a rat model

The ability to decide advantageously among options that vary in both their risks and rewards is critical for survival and well-being. Previous work shows that some forms of risky decision-making are robustly modulated by monoamine signaling, but it is less clear how monoamine signaling modulates decision-making under risk of explicit punishment. The goal of these experiments was to determine how this form of decision-making is modulated by dopamine, serotonin, and norepinephrine signaling, using a task in which rats choose between a small, 'safe' food reward and a large food reward associated with variable risks of punishment. Preference for the large, risky reward (risk-taking) was reduced by administration of a D2/3 dopamine receptor agonist (bromocriptine) and a selective D2 agonist (sumanirole). The selective D3 agonist PD128907 appeared to attenuate reward discrimination abilities but did not affect risk-taking per se. In contrast, drugs targeting serotonergic and noradrenergic signaling had few if any effects on choice behavior. These data suggest that in contrast to other forms of risky decision-making, decision-making under risk of punishment is selectively modulated by dopamine signaling, predominantly through D2 receptors.