Periodic Reporting for period 4 - RewardedPerception (Functional circuits mediating the effects of reward value on perception within and across sensory modalities)
Berichtszeitraum: 2021-08-01 bis 2023-04-30
Recently, it has been demonstrated that reward signals are not only represented in our brains in terms of their hedonic value or expected utility, but also have a strong effect on the very basic mechanisms of sensory processing. Stimuli associated with high reward have been consistently shown to have a richer and stronger sensory representation than those paired with low rewards. This sensory hyper-sensitization can explain certain pathological states such as enhanced responsiveness of addicted patients towards hedonic cues. On the other hand, when used under controlled conditions, the sensory hyper-sensitization can be used in clinical settings to rehabilitate perceptual impairments such as poor vision or audition.
The overarching objective of the RewardedPerception Project was to unravel the basic neural mechanisms through which reward value influences sensory processing. As such, this project provides a critical first step towards using reward-based effects in applied fields such neurodiagnostics or neurorehabilitation and educational settings.
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.