Figure 1.

Schematic representation of experimental procedure. Following recovery from surgery, administration of cocaine and saline were paired with distinct environmental cues. Six conditioning sessions (three cocaine; three saline) were conducted. Before each session, animals were placed into a clear Plexiglas test chamber (26 × 26 × 33 cm³) for 1–3 h. Conditioning sessions commenced with the introduction of black or white walls to the chambers and injection of animals with either saline (1.0 ml/kg, i.p.) or cocaine (1.0 ml/kg, 20 mg/kg, i.p.). Treatment order, drug–environment pairing and order of environment presentation were counterbalanced between groups. Rats were tested 24 h later, in the drug-free state, for changes in locomotor activity (LMA) and mPFC neurotransmission that occur on exposure to the cocaine- or saline-associated cues. For additional details, see Materials and Methods (‘Conditioning and Microdialysis Procedures').