Linking dopaminergic reward signals to the development of attentional bias: A positron emission tomographic study

Abstract

The attention system is shaped by reward history, such that learned reward cues involuntarily draw attention. Recent research has begun to uncover the neural mechanisms by which learned reward cues compete for attention, implicating dopamine (DA) signaling within the dorsal striatum. How these elevated priority signals develop in the brain during the course of learning is less well understood, as is the relationship between value-based attention and the experience of reward during learning. We hypothesized that the magnitude of the striatal DA response to reward during learning contributes to the development of a learned attentional bias towards the cue that predicted it, and examined this hypothesis using positron emission tomography with [¹¹C]raclopride. We measured changes in dopamine release for rewarded versus unrewarded visual search for color-defined targets as indicated by the density and distribution of the available D₂/D₃ receptors. We then tested for correlations of individual differences in this measure of reward-related DA release to individual differences in the degree to which previously reward-associated but currently task-irrelevant stimuli impair performance in an attention task (i.e., value-driven attentional bias), revealing a significant relationship in the right anterior caudate. The degree to which reward-related DA release was right hemisphere lateralized was also predictive of later attentional bias. Our findings provide support for the hypothesis that value-driven attentional bias can be predicted from reward-related DA release during learning.

Keywords: Dopamine; Dopamine release positron emission tomography; Incentive salience; Reward learning; Selective attention.

Figure 1

Experimental task. Time course and trial events for the training phase (A) and test phase (B).

Figure 2

Imaging results. Visual depiction on averaged MRIs of VOIs and observed correlation between value-based distraction post-training and reward-related dopamine release during training in the right anterior caudate across participants. vS = ventral striatum, CN = caudate nucleus, PU = putamen. The left panel presents a coronal slice through the basal ganglia. The middle panel presents a parasagittal slice through the caudate nucleus. The right panel presents a parasagittal slice through the putamen.

Figure 3

Observed correlation between value-based distraction post-training and reward-related dopamine release during training across all VOIs.

Figure 4

Observed correlation between value-based distraction post-training and the degree to which reward-related striatal DA release was more right hemisphere lateralized (computed as the difference in reward-related DA release in the right minus the left hemisphere).