Dynamic modulation of decision biases by brainstem arousal systems

Elife. 2017 Apr 11;6:e23232. doi: 10.7554/eLife.23232.

Abstract

Decision-makers often arrive at different choices when faced with repeated presentations of the same evidence. Variability of behavior is commonly attributed to noise in the brain's decision-making machinery. We hypothesized that phasic responses of brainstem arousal systems are a significant source of this variability. We tracked pupil responses (a proxy of phasic arousal) during sensory-motor decisions in humans, across different sensory modalities and task protocols. Large pupil responses generally predicted a reduction in decision bias. Using fMRI, we showed that the pupil-linked bias reduction was (i) accompanied by a modulation of choice-encoding pattern signals in parietal and prefrontal cortex and (ii) predicted by phasic, pupil-linked responses of a number of neuromodulatory brainstem centers involved in the control of cortical arousal state, including the noradrenergic locus coeruleus. We conclude that phasic arousal suppresses decision bias on a trial-by-trial basis, thus accounting for a significant component of the variability of choice behavior.

Keywords: Accumulator model; Decision-making; Locus Coeruleus; Neuromodulation; Trial-to-trial variability; fMRI; human; neuroscience.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Arousal*
  • Brain Stem / diagnostic imaging
  • Brain Stem / physiology*
  • Decision Making*
  • Female
  • Healthy Volunteers
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Models, Neurological
  • Young Adult

Grant support

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