Disruption in Pavlovian-Instrumental Transfer as a Function of Depression and Anxiety

The Pavlovian-Instrumental Transfer (PIT) paradigm examines probabilistic and reinforcement learning. Disruptions in mechanisms that mediate PIT (i.e., cues not triggering adaptive behaviors) are thought to be contributors to psychopathology, making the study of probabilistic and reinforcement learning clinically relevant. The current study evaluated an appetitive PIT effect and its relationship with symptom dimensions spanning depression and anxiety, with a particular focus on anhedonia. Forty young adults ranging in scores across dimensions of depression and anxiety symptoms completed the PIT paradigm and self-report symptom measures. The PIT paradigm consisted of three phases. The instrumental phase consisted of a contingent association in which participants squeezed a handgrip for monetary reward. The Pavlovian phase established a purely predictive association between three visual stimuli (CS?+?, CS-, baseline) and presence or absence of monetary reward. In the transfer phase, participants’ responses allowed for examination of whether motivational characteristics of Pavlovian predictors influenced the vigor of their handgrip squeezes (instrumental action), which were formerly independent of Pavlovian associations. Analyses revealed a baseline-reward PIT effect, whereby a reward-associated Pavlovian cue enhanced instrumental responding in the transfer phase. However, there were no significant differences between CS?+?and CS- or CS- and baseline cues, suggesting a disrupted interaction of Pavlovian and instrumental learning. Further, the appetitive PIT effect captured in this paradigm was not associated with anhedonia, fears, or general distress. Future work should investigate the influence of mood states using more specific appetitive PIT paradigms to further understanding of the implications of disrupted reflexive and instrumental responding.

     

Manipulating affective state influences conditioned appetitive responses

Affective states influence how individuals process information and behave. Some theories predict emotional congruency effects (e.g. preferential processing of negative information in negative affective states). Emotional congruency should theoretically obstruct the learning of reward associations (appetitive learning) and their ability to guide behaviour under negative mood. Two studies tested the effects of the induction of a negative affective state on appetitive Pavlovian learning, in which neutral stimuli were associated with chocolate (Experiment 1) or alcohol (Experiment 2) rewards. In both experiments, participants showed enhanced approach tendencies towards predictors of reward after a negative relative to a positive performance feedback manipulation. This increase was related to a reduction in positive affect in Experiment 1 only. No effects of the manipulation on conditioned reward expectancies, craving, or consumption were observed. Overall, our findings support the idea of counter-regulation, rather than emotional congruency effects. Negative affective states might therefore serve as a vulnerability factor for addiction, through increasing conditioned approach tendencies.     

Fearing shades of grey: individual differences in fear responding towards generalisation stimuli

Individual differences in fear generalisation have been proposed to play a role in the aetiology and/or maintenance of anxiety disorders, but few data are available to directly support that claim. The research that is available has focused mostly on generalisation of peripheral and central physiological fear responses. Far less is known about the generalisation of avoidance, the behavioural component of fear. In two experiments, we evaluated how neuroticism, a known vulnerability factor for anxiety, modulates an array of fear responses, including avoidance tendencies, towards generalisation stimuli (GS). Participants underwent differential fear conditioning, in which one conditioned stimulus (CS+) was repeatedly paired with an aversive outcome (shock; unconditioned stimulus, US), whereas another was not (CS?). Fear generalisation was observed across measures in Experiment 1 (US expectancy and evaluative ratings) and Experiment 2 (US expectancy, evaluative ratings, skin conductance, startle responses, safety behaviours), with overall highest responding to the CS+, lowest to the CS? and intermediate responding to the GSs. Neuroticism had very little impact on fear generalisation (but did affect GS recognition rates in Experiment 1), in line with the idea that fear generalisation is largely an adaptive process.