We hypothesised that reward-driven effects rely on a flexible communication of information between brain areas that encode reward value and those that track the sensory features of stimuli. To test this proposal, we used a combination of behavioural testing, neuroimaging (electroencephalography; EEG, functional magnetic resonance imaging; fMRI) and advanced data analysis methods. This approach allowed us to characterise the behavioural signatures of reward-driven effects under different contexts and to unravel their neuronal correlates in healthy human participants.
Two major findings of the project are depicted in the attached figure. In summary, we found that depending on the type of decisions that are made and on other contextual factors, such as the contingency of rewards on choices, different patterns of connections between brain areas underlie the reward-driven effects (see Figure 1). For instance, when a simple perceptual decision is underway (such as deciding on the tilt direction of the striped pattern in panel A) and rewards from visual or auditory modality are presented as task-irrelevant distractors, a network comprising higher valuations areas, attention- and sensory-related areas (OFC, IPS and V1/A1, respectively) orchestrate the reward-driven effects. In this case, coding of reward value in valuation areas is modality-independent (i.e. similar for visual and auditory rewards) but differentiates between the two later. However, in situations where a value-based decision between options is required (see panel B), especially when assigned values dynamically change, the differentiation of the source of rewards (visual versus auditory) occurs already at the level of higher valuation areas. This latter scheme allows a flexible adjustment of choice based on the changes in the surroundings.
