title: Habitual alcohol seeking: time course and the contribution of subregions of the dorsal striatum.
abstract: BACKGROUND
  Addictions are defined by a loss of flexible control over behavior. The development of response habits might reflect early changes in behavioral control. The following experiments examined the flexibility of alcohol-seeking after different durations of self-administration training and tested the role of the dorsal striatum in the control of flexible and habitual alcohol self-administration.
  
  
  METHODS
  Rats were trained to lever-press to earn unsweetened ethanol (EtOH) (10%). The sensitivity of the lever-press response to devaluation was assessed by prefeeding the rats either EtOH or sucrose before an extinction test after different amounts of training (1, 2, 4, and 8 weeks). We subsequently tested the role of the dorsomedial striatum (DMS) and dorsolateral striatum (DLS) in controlling alcohol seeking with reversible inactivation techniques (baclofen/muscimol: 1.0/.1 mmol/L, .3 μL/side).
  
  
  RESULTS
  We find that operant responding for EtOH early in training is goal-directed and reduced by devaluation, but after 8 weeks of daily operant training, control has shifted to a habit-based system no longer sensitive to devaluation. Furthermore, after relatively limited training, when responding is sensitive to devaluation, inactivation of the DMS greatly attenuates the alcohol-seeking response, whereas inactivation of the DLS is without effect. In contrast, responding that is insensitive to devaluation after 8 weeks of training becomes sensitive to devaluation after inactivation of the DLS but is unaffected by inactivation of the DMS.
  
  
  CONCLUSIONS
  These experiments demonstrate that extended alcohol self-administration produces habit-like responding and that response control shifts from the DMS to the DLS across the course of training.
authors.affiliation: Ernest Gallo Clinic and Research Center, University of California at San Francisco, San Francisco, California, USA. laura.corbit@sydney.edu.au
authors.forename: Laura H
authors.initials: LH
authors.lastname: Corbit
authors.forename: Hong
authors.initials: H
authors.lastname: Nie
authors.forename: Patricia H
authors.initials: PH
authors.lastname: Janak
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D016739:Behavior, Addictive / Q000503:physiopathology*; D003216:Conditioning, Operant / Q000187:drug effects* / Q000502:physiology; D003342:Corpus Striatum / Q000187:drug effects* / Q000502:physiology; D000431:Ethanol / Q000494:pharmacology*; D005108:Extinction, Psychological / Q000187:drug effects* / Q000502:physiology; D006184:Habits; D007858:Learning / Q000502:physiology*; D008297:Male; D023421:Models, Animal; D051381:Rats; D020318:Rats, Long-Evans; D012646:Self Administration
chemical_list: D000431:Ethanol