Phm 107

For self-administration studies, rats were placed in operant chambers (ENV-008CT, Med Associates, St. Albans, VT)
inside sound-attenuating chambers (ENV-018CT, Med Associates). The operant boxes were outfitted with two nose poke devices
each containing a yellow light (ENV-114BM), which were located on either side of a pellet receptacle (ENV-200R7M. Med
Associates) attached to a dispenser (ENV-203-45, Med Associates) filled with 45 mg sucrose pellets. A white house light was on
the wall opposite the nose poke devices. Drug solutions were delivered via a variable infusion rate syringe pump (PHM-107, Med
Associates) connected by Tygon tubing to a single channel plastic swivel (375/22PS, Instech Laboratories, Plymouth Meeting,
PA) on a counter-balanced arm (PHM-110-SAI, Med Associates). The Tygon tubing inside the operant chamber was protected with a
stainless-steel spring. Data were collected using MED-PC Software (SOF-735, Med Associates).

Experimental sessions were conducted in two standard operant conditioning chambers controlled by Med-PC IV software (Med Associates; St. Albans, VT) as described in detail previously (Bertz and Woods, 2013 (link)). Each chamber was contained inside a light- and sound-attenuating cubicle and was located in a separate room of the laboratory. The right wall of each chamber contained a white incandescent houselight (ENV-215M, Med Associates) and the speaker for a tone generator (ENV-224AM and ENV-230, Med Associates). Two nose-poke manipulanda containing LED stimulus lights (ENV-114BM, Med Associates) could also be inserted into the right wall. When the nose-pokes were removed from the chamber, they were replaced by blank aluminum panels.
Motorized syringe drivers (PHM-107, Med Associates) were located outside of the light- and sound-attenuating cubicles to deliver IV drug injections. Syringes were attached to Tygon tubing (S-54-HL, Norton Performance Plastics) leading to a counterweighted fluid swivel (375/22PS, Instech Laboratories) and spring tether.