What is happening in our brains when we decide on a course of action? Using functional imaging, Professor Ray Dolan's group at the Wellcome Trust Centre for Neuroimaging at University College London (UCL) is unpicking the neural circuitry underlying different contributions to decision-making.

One important influence comes from 'reward': the benefits we expect from an action. In theory, decisions are affected by experience – whether, previously, a reward was more or less than we expected. In animals, dopamine pathways have been implicated in reward learning, and Professor Dolan and colleagues have now shown the same is true in people. Agents that alter dopamine signalling also affect subjects' ability to choose the most rewarding option.

A striking feature of human decision-making is its susceptibility to the context in which choices are presented: the so-called framing effect. This is a challenge to assumptions of 'rational' human behaviour, such as those used in economics. Functional imaging has revealed a central role for the amygdala in framing effects, emphasising the importance of emotional processing.

Finally, we often face a dilemma between acting on what we already know and trying something new that might be better for us. In a collaboration with the UCL Gatsby Computational Neuroscience Unit, which integrated computational models of decision-making with neuroimaging data, the group discovered that different brain areas are active in these two situations. This suggests that harvesting a safe option involves distinct neural processing systems from those associated with trying a less certain alternative.

This work emphasises how complex human decision-making is. There is not one 'analytical centre' that determines choice but a host of interconnected systems influencing the way we think – and the way we act.

Image: Professor Ray Dolan; Mark Lythgoe and Chloe Hutton

External links

• Pessiglione M et al. Dopamine-dependent prediction errors underpin reward-seeking behaviour in humans. Nature 2006;442(7106):1042–5.
• De Martino B et al. Frames, biases, and rational decision-making in the human brain. Science 2006;313(5787):684–7.
• Daw ND et al. Cortical substrates for exploratory decisions in humans. Nature