Precise LHb Inactivation Protocol

A day before microinjection in experiments 2a and 2b, the injection cannula (Plastics One, Roanoke, VA, USA), which extended 1 mm beyond the guide was inserted into the guide cannula and left in place for 1 min. This was done to control for any initial mechanical damage done by the injector. On a test day, rats were injected with a combination of baclofen and muscimol (Bac/Mus, Sigma) in 0.9% saline, GABA b and a agonists respectively, or vehicle. Both injections used a volume of 0.2 μL (50 ng/0.2 μL baclofen and muscimol) and a 0.15 μL/min infusion rate. This is similar to other LHb inactivation studies that used baclofen and muscimol (Stopper and Floresco, 2014 (link); Mathis et al., 2015 (link)). The injection cannula was connected to a 10 μl syringe (Hamilton) via polyethylene tubing (PE 20) using an infusion pump (KD Scientific).