1. Role of the orbitofrontal cortex and the dorsal striatum in incentive motivation for cocaine
- Author
-
Marie-Pier Filion, Anne-Noël Samaha, Ellie-Anna Minogianis, and Alice Servonnet
- Subjects
Male ,medicine.medical_specialty ,Baclofen ,medicine.medical_treatment ,media_common.quotation_subject ,Drug-Seeking Behavior ,Prefrontal Cortex ,Self Administration ,Striatum ,03 medical and health sciences ,Behavioral Neuroscience ,chemistry.chemical_compound ,Cocaine-Related Disorders ,0302 clinical medicine ,Cocaine ,Reward ,Internal medicine ,Medicine ,Premovement neuronal activity ,Animals ,Rats, Wistar ,Saline ,Sensitization ,030304 developmental biology ,media_common ,0303 health sciences ,Motivation ,business.industry ,Muscimol ,musculoskeletal, neural, and ocular physiology ,Addiction ,Corpus Striatum ,3. Good health ,Rats ,body regions ,Behavior, Addictive ,medicine.anatomical_structure ,Endocrinology ,nervous system ,chemistry ,Orbitofrontal cortex ,business ,Reinforcement, Psychology ,psychological phenomena and processes ,030217 neurology & neurosurgery - Abstract
Drug addiction involves increased incentive motivation for drug. Intermittent access to cocaine (IntA; 5–6 minutes ON, 25–26 minutes OFF, for 5–6 hours/session) enhances motivation to take the drug. The orbitofrontal cortex (OFC) and the dorsal striatum (DS) are part of a corticolimbic circuit that encodes incentive value and regulates reward-directed behaviour. We predicted that inactivation of the OFC, DS or both suppresses incentive motivation for cocaine after IntA experience. Male Wistar rats had IntA to cocaine (0.25 mg/kg/infusion) for 10 sessions. The rats developed a ‘loading’ pattern of intake, taking most of their cocaine in the first minute of each drug-available period. They also developed psychomotor sensitization to self-administered cocaine. We then measured incentive motivation for cocaine using a progressive ratio schedule of reinforcement (PR). Before some PR sessions, rats received microinfusions of a baclofen/muscimol cocktail (0.3 and 0.03 nmol/hemisphere, respectively, or saline) to temporarily inactivate the OFC or DS, or to disconnect the two regions. None of these treatments changed spontaneous locomotion in cocaine-naive rats. However, both baclofen/muscimol and saline infusions influenced cocaine self-administration behaviour. Infusing baclofen/muscimol or saline into the OFC or into the OFC and contralateral DS decreased responding for cocaine under PR, with baclofen/muscimol and saline having similar effects, except that only OFC-DS disconnection with baclofen/muscimol slowed the pace of cocaine intake. Baclofen/muscimol or saline into the DS also reduced responding for cocaine under PR, but baclofen/muscimol was more effective. We conclude that neuronal activity in the OFC and DS might regulate incentive motivation for cocaine.
- Published
- 2018