title: Premature responding is associated with approach to a food cue in male and female heterogeneous stock rats.
abstract: Disorders of behavioral regulation, including attention deficit hyperactivity disorder (ADHD) and drug addiction, are in part due to poor inhibitory control, attentional deficits, and hyper-responsivity to reward-associated cues.
  
  
  
  To determine whether these traits are related, we tested genetically variable male and female heterogeneous stock rats in the choice reaction time (CRT) task and Pavlovian conditioned approach (PavCA). Sex differences in the response to methylphenidate during the CRT were also assessed.
  
  
  
  In the CRT task, rats were required to withhold responding until one of two lights indicated whether responses into a left or right port would be reinforced with water. Reaction time on correct trials and premature responses were the operational definitions of attention and response inhibition, respectively. Rats were also pretreated with oral methylphenidate (0, 2, 4 mg/kg) during the CRT task to determine whether this drug would improve performance. Subsequently, during PavCA, presentation of an illuminated lever predicted the delivery of a food pellet into a food-cup. Lever-directed approach (sign-tracking) and food-cup approach (goal-tracking) were the primary measures, and rats were categorized as "sign-trackers" and "goal-trackers" using an index based on these measures.
  
  
  
  Sign-trackers made more premature responses than goal-trackers but showed no differences in reaction time. There were sex differences in both tasks, with females having higher sign-tracking, completing more CRT trials, and making more premature responses after methylphenidate administration.
  
  
  
  These results indicate that response inhibition is related to reward-cue responsivity, suggesting that these traits are influenced by common genetic factors.
authors.affiliation: Department of Psychology, State University of New York at Buffalo, Buffalo, NY, USA. cpking@buffalo.edu.
authors.forename: Christopher P
authors.initials: CP
authors.lastname: King
authors.affiliation: Department of Psychiatry, University of California San Diego, La Jolla, CA, USA.
authors.forename: Abraham A
authors.initials: AA
authors.lastname: Palmer
authors.affiliation: Department of Pediatrics, Human and Molecular Genetics, Center Medical College of Wisconsin, Milwaukee, WI, USA.
authors.forename: Leah C Solberg
authors.initials: LC
authors.lastname: Woods
authors.affiliation: Department of Psychology, State University of New York at Buffalo, Buffalo, NY, USA.
authors.forename: Larry W
authors.initials: LW
authors.lastname: Hawk
authors.affiliation: Research Institute on Addictions, Buffalo, NY, USA.
authors.forename: Jerry B
authors.initials: JB
authors.lastname: Richards
authors.affiliation: Department of Psychology, State University of New York at Buffalo, Buffalo, NY, USA.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Meyer
mesh_terms: D000818:Animals; D002755:Choice Behavior / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology*; D003463:Cues; D005247:Feeding Behavior / Q000523:psychology*; D005260:Female; D005502:Food; D007266:Inhibition, Psychological; D008297:Male; D023421:Models, Animal; D009042:Motivation; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time; D012201:Reward
keywords: Action impulsivity; Associative learning; Autoshaping; Classical conditioning; Conditioned response; Feeding behavior; Incentive salience; Motivation; Reward stimuli; Stimulant drugs