Abstract
Generalization during aversive decision-making allows us to avoid a broad range of potential threats following experience with a limited set of exemplars. However, over-generalization, resulting in excessive and inappropriate avoidance, has been implicated in a variety of psychological disorders. Here, we use reinforcement learning modelling to dissect out different contributions to the generalization of instrumental avoidance in two groups of human volunteers (N = 26, N = 482). We found that generalization of avoidance could be parsed into perceptual and value-based processes, and further, that value-based generalization could be subdivided into that relating to aversive and neutral feedback - with corresponding circuits including primary sensory cortex, anterior insula, amygdala and ventromedial prefrontal cortex. Further, generalization from aversive, but not neutral, feedback was associated with self-reported anxiety and intrusive thoughts. These results reveal a set of distinct mechanisms that mediate generalization in avoidance learning, and show how specific individual differences within them can yield anxiety.
Highlights
During aversive decision-making, generalization allows application of direct experience with a limited subset of dangerous real-world stimuli to a much larger set of potentially related stimuli
We address three key questions: first, is there good evidence for generalization in avoidance learning in humans?; second, can we distinguish behavioural and neural components relating to Neuroscience perceptual, aversive value, and safety value?; and third, which if any component predicts relevant psychological symptoms? We used a custom-designed perceptual task in conjunction with reinforcement learning modelling to study two groups: a laboratory-based sample (N = 26) who performed a pain avoidance task with concurrent neuroimaging, and a larger cohort of individuals (N = 482), who performed a monetary loss avoidance task online alongside a battery of questionnaires designed to probe relevant psychological symptom dimensions (Gillan and Daw, 2016)
Significant clusters were observed in the mid cingulate cortex, left parietal operculum, right inferior parietal lobule and inferior frontal gyrus À but we found no evidence of encoding of value generalization-derived Prediction error (PE) signals in V1, the amygdala, or ventromedial prefrontal cortex (vmPFC)
Summary
During aversive decision-making, generalization allows application of direct experience with a limited subset of dangerous real-world stimuli to a much larger set of potentially related stimuli. Previous work on aversive generalization has focused on predicting punishments in passive (Pavlovian) designs Such studies have revealed evidence of heightened subjective, physiological and neural responses to stimuli that bear perceptual similarity to learned exemplars (Dymond et al, 2015). In the Pavlovian case, several well-established behavioural phenomena implicate valuerelated processes at play in generalization across species (Hanson, 1959; Schechtman et al, 2010) That both perceptual and value processes might operate in parallel may explain why recent neuroimaging studies have highlighted different brain areas (e.g. limbic cortex vs primary sensory regions) as being key to Pavlovian aversive generalization in humans (Onat and Buchel, 2015; Laufer et al, 2016). It is likely that generalization over these states can influence behaviour: for example in the Pavlovian case, evidence for this is seen in ‘peakshift’ effects, whereby the presence of a perceptually similar safety cue appears to inhibit response to nearby aversive cues (Hanson, 1959).
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