title: Assessing contributions of nucleus accumbens shell subregions to reward-seeking behavior.
abstract: BACKGROUND
  The nucleus accumbens (NAc) plays a key role in brain reward processes including drug seeking and reinstatement. Several anatomical, behavioral, and neurochemical studies discriminate between the limbic-associated shell and the motor-associated core regions. Less studied is the fact that the shell can be further subdivided into a dorsomedial shell (NAcDMS) and an intermediate zone (NAcINT) based on differential expression of transient c-Fos and long-acting immediate-early gene ΔFosB upon cocaine sensitization. These disparate expression patterns suggest that NAc shell subregions may play distinct roles in reward-seeking behavior. In this study, we examined potential differences in the contributions of the NAcDMS and the NAcINT to reinstatement of reward-seeking behavior after extinction.
  
  
  METHODS
  Rats were trained to intravenously self-administer cocaine, extinguished, and subjected to a reinstatement test session consisting of an intracranial microinfusion of either amphetamine or vehicle targeted to the NAcDMS or the NAcINT.
  
  
  RESULTS
  Small amphetamine microinfusions targeted to the NAcDMS resulted in statistically significant reinstatement of lever pressing, whereas no significant difference was observed for microinfusions targeted to the NAcINT. No significant difference was found for vehicle microinfusions in either case.
  
  
  CONCLUSIONS
  These results suggest heterogeneity in the behavioral relevance of NAc shell subregions, a possibility that can be tested in specific neuronal populations in the future with recently developed techniques including optogenetics.
authors.affiliation: Undergraduate Program, Northeastern University, Boston, MA, United States.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Reed
authors.affiliation: Undergraduate Program, Northeastern University, Boston, MA, United States.
authors.forename: David G C
authors.initials: DG
authors.lastname: Hildebrand
authors.affiliation: Undergraduate Program, Northeastern University, Boston, MA, United States.
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Santangelo
authors.affiliation: Undergraduate Program, Northeastern University, Boston, MA, United States.
authors.forename: Anthony
authors.initials: A
authors.lastname: Moffa
authors.affiliation: Undergraduate Program, Northeastern University, Boston, MA, United States.
authors.forename: Ashley S
authors.initials: AS
authors.lastname: Pira
authors.affiliation: Undergraduate Program, Northeastern University, Boston, MA, United States.
authors.forename: Lisa
authors.initials: L
authors.lastname: Rycyna
authors.affiliation: Undergraduate Program, Northeastern University, Boston, MA, United States.
authors.forename: Mia
authors.initials: M
authors.lastname: Radic
authors.affiliation: Undergraduate Program, Northeastern University, Boston, MA, United States.
authors.forename: Katherine
authors.initials: K
authors.lastname: Price
authors.affiliation: Undergraduate Program, Northeastern University, Boston, MA, United States.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Archbold
authors.affiliation: Undergraduate Program, Northeastern University, Boston, MA, United States.
authors.forename: Kristi
authors.initials: K
authors.lastname: McConnell
authors.affiliation: Undergraduate Program, Northeastern University, Boston, MA, United States.
authors.forename: Lauren
authors.initials: L
authors.lastname: Girard
authors.affiliation: Undergraduate Program, Northeastern University, Boston, MA, United States.
authors.forename: Kristen
authors.initials: K
authors.lastname: Morin
authors.affiliation: Undergraduate Program, Northeastern University, Boston, MA, United States.
authors.forename: Anna
authors.initials: A
authors.lastname: Tang
authors.affiliation: Department of Psychology, Northeastern University, Boston, MA, United States.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Febo
authors.affiliation: Department of Psychology, Northeastern University, Boston, MA, United States. Electronic address: jstellar@albany.edu.
authors.forename: James R
authors.initials: JR
authors.lastname: Stellar
mesh_terms: D000661:Amphetamine / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D003042:Cocaine / Q000008:administration & dosage; D003216:Conditioning, Operant / Q000187:drug effects* / Q000502:physiology*; D005108:Extinction, Psychological / Q000187:drug effects / Q000502:physiology; D008297:Male; D008845:Microinjections; D009714:Nucleus Accumbens / Q000033:anatomy & histology / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012201:Reward; D012646:Self Administration
chemical_list: D000661:Amphetamine; D003042:Cocaine
keywords: Cocaine; Nucleus accumbens; Nucleus accumbens shell; Reinstatement; Self-administration; Subregions