Affective bias as a rational response to the statistics of rewards and punishments

  1. Erdem Pulcu
  2. Michael Browning  Is a corresponding author
  1. University of Oxford, United Kingdom

Abstract

Affective bias, the tendency to differentially prioritise the processing of negative relative to positive events, is commonly observed in clinical and non-clinical populations. However, why such biases develop is not known. Using a computational framework, we investigated whether affective biases may reflect individuals' estimates of the information content of negative relative to positive events. During a reinforcement learning task, the information content of positive and negative outcomes was manipulated independently by varying the volatility of their occurrence. Human participants altered the learning rates used for the outcomes selectively, preferentially learning from the most informative. This behaviour was associated with activity of the central norepinephrine system, estimated using pupilometry, for loss outcomes. Humans maintain independent estimates of the information content of distinct positive and negative outcomes which may bias their processing of affective events. Normalising affective biases using computationally inspired interventions may represent a novel approach to treatment development.

Article and author information

Author details

  1. Erdem Pulcu

    Department of Psychiatry, University of Oxford, Oxford, United Kingdom
    Competing interests
    No competing interests declared.
  2. Michael Browning

    Department of Psychiatry, University of Oxford, Oxford, United Kingdom
    For correspondence
    michael.browning@psych.ox.ac.uk
    Competing interests
    Michael Browning, has received travel expenses from Lundbeck for attending conferences..
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-9108-3144

Funding

Medical Research Council (MR/N008103/1)

  • Michael Browning

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Human subjects: All participants provided written informed consent. The study was reviewed and approved by the Medical Sciences Interdepartmental Research Ethics Committee of Oxford University (ref number MSD-IDREC-C1-2014-216).

Copyright

© 2017, Pulcu & Browning

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

Metrics

  • 4,950
    views
  • 653
    downloads
  • 56
    citations

Views, downloads and citations are aggregated across all versions of this paper published by eLife.

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Open citations (links to open the citations from this article in various online reference manager services)

Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)

  1. Erdem Pulcu
  2. Michael Browning
(2017)
Affective bias as a rational response to the statistics of rewards and punishments
eLife 6:e27879.
https://doi.org/10.7554/eLife.27879

Share this article

https://doi.org/10.7554/eLife.27879

Further reading

    1. Neuroscience
    Jian Dong, Mian Chen ... Matthijs Verhage
    Research Article

    Dense core vesicles (DCVs) transport and release various neuropeptides and neurotrophins that control diverse brain functions, but the DCV secretory pathway remains poorly understood. Here, we tested a prediction emerging from invertebrate studies about the crucial role of the intracellular trafficking GTPase Rab10, by assessing DCV exocytosis at single-cell resolution upon acute Rab10 depletion in mature mouse hippocampal neurons, to circumvent potential confounding effects of Rab10’s established role in neurite outgrowth. We observed a significant inhibition of DCV exocytosis in Rab10-depleted neurons, whereas synaptic vesicle exocytosis was unaffected. However, rather than a direct involvement in DCV trafficking, this effect was attributed to two ER-dependent processes, ER-regulated intracellular Ca2+ dynamics, and protein synthesis. Gene Ontology analysis of differentially expressed proteins upon Rab10 depletion identified substantial alterations in synaptic and ER/ribosomal proteins, including the Ca2+ pump SERCA2. In addition, ER morphology and dynamics were altered, ER Ca2+ levels were depleted, and Ca2+ homeostasis was impaired in Rab10-depleted neurons. However, Ca2+ entry using a Ca2+ ionophore still triggered less DCV exocytosis. Instead, leucine supplementation, which enhances protein synthesis, largely rescued DCV exocytosis deficiency. We conclude that Rab10 is required for neuropeptide release by maintaining Ca2+ dynamics and regulating protein synthesis. Furthermore, DCV exocytosis appeared more dependent on (acute) protein synthesis than synaptic vesicle exocytosis.