Impulsivity characterization in the Roman high- and low-avoidance rat strains: behavioral and neurochemical differences

Neuropsychopharmacology. 2010 Apr;35(5):1198-208. doi: 10.1038/npp.2009.224. Epub 2010 Jan 20.


The selective breeding of Roman high- (RHA) and low-avoidance (RLA) rats for rapid vs extremely poor acquisition of active avoidance behavior in a shuttle-box has generated two phenotypes with different emotional and motivational profiles. The phenotypic traits of the Roman rat lines/strains (outbred or inbred, respectively) include differences in sensation/novelty seeking, anxiety/fearfulness, stress responsivity, and susceptibility to addictive substances. We designed this study to characterize differences between the inbred RHA-I and RLA-I strains in the impulsivity trait by evaluating different aspects of the multifaceted nature of impulsive behaviors using two different models of impulsivity, the delay-discounting task and five-choice serial reaction time (5-CSRT) task. Previously, rats were evaluated on a schedule-induced polydipsia (SIP) task that has been suggested as a model of obsessive-compulsive disorder. RHA-I rats showed an increased acquisition of the SIP task, higher choice impulsivity in the delay-discounting task, and poor inhibitory control as shown by increased premature responses in the 5-CSRT task. Therefore, RHA-I rats manifested an increased impulsivity phenotype compared with RLA-I rats. Moreover, these differences in impulsivity were associated with basal neurochemical differences in striatum and nucleus accumbens monoamines found between the two strains. These findings characterize the Roman rat strains as a valid model for studying the different aspects of impulsive behavior and for analyzing the mechanisms involved in individual predisposition to impulsivity and its related psychopathologies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Avoidance Learning
  • Biogenic Monoamines / metabolism
  • Conditioning, Operant
  • Corpus Striatum / metabolism*
  • Drinking Behavior
  • Female
  • Impulsive Behavior / metabolism*
  • Models, Animal
  • Neuropsychological Tests
  • Nucleus Accumbens / metabolism*
  • Phenotype
  • Rats
  • Reaction Time
  • Reward
  • Species Specificity
  • Time Factors


  • Biogenic Monoamines