title: Noradrenergic modulation of risk/reward decision making.
abstract: BACKGROUND
  Catecholamine transmission modulates numerous cognitive and reward-related processes that can subserve more complex functions such as cost/benefit decision making. Dopamine has been shown to play an integral role in decisions involving reward uncertainty, yet there is a paucity of research investigating the contributions of noradrenaline (NA) transmission to these functions.
  
  
  OBJECTIVE
  The present study was designed to elucidate the contribution of NA to risk/reward decision making in rats, assessed with a probabilistic discounting task.
  
  
  METHODS
  We examined the effects of reducing noradrenergic transmission with the α2 agonist clonidine (10-100 μg/kg), and increasing activity at α2A receptor sites with the agonist guanfacine (0.1-1 mg/kg), the α2 antagonist yohimbine (1-3 mg/kg), and the noradrenaline transporter (NET) inhibitor atomoxetine (0.3-3 mg/kg) on probabilistic discounting. Rats chose between a small/certain reward and a larger/risky reward, wherein the probability of obtaining the larger reward either decreased (100-12.5 %) or increased (12.5-100 %) over a session.
  
  
  RESULTS
  In well-trained rats, clonidine reduced risky choice by decreasing reward sensitivity, whereas guanfacine did not affect choice behavior. Yohimbine impaired adjustments in decision biases as reward probability changed within a session by altering negative feedback sensitivity. In a subset of rats that displayed prominent discounting of probabilistic rewards, the lowest dose of atomoxetine increased preference for the large/risky reward when this option had greater long-term utility.
  
  
  CONCLUSIONS
  These data highlight an important and previously uncharacterized role for noradrenergic transmission in mediating different aspects of risk/reward decision making and mediating reward and negative feedback sensitivity.
authors.affiliation: Department of Psychology and Brain Research Centre, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
authors.forename: David R
authors.initials: DR
authors.lastname: Montes
authors.forename: Colin M
authors.initials: CM
authors.lastname: Stopper
authors.forename: Stan B
authors.initials: SB
authors.lastname: Floresco
mesh_terms: D058647:Adrenergic alpha-2 Receptor Agonists / Q000494:pharmacology; D058669:Adrenergic alpha-2 Receptor Antagonists / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D002755:Choice Behavior / Q000187:drug effects; D003000:Clonidine / Q000494:pharmacology; D003216:Conditioning, Operant / Q000187:drug effects*; D003657:Decision Making / Q000187:drug effects*; D016316:Guanfacine / Q000494:pharmacology; D008297:Male; D011336:Probability; D051381:Rats; D020318:Rats, Long-Evans; D012201:Reward; D012306:Risk; D012309:Risk-Taking; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D058669:Adrenergic alpha-2 Receptor Antagonists; D015016:Yohimbine; D016316:Guanfacine; D003000:Clonidine