Methamphetamine (MA) is a potent psychostimulant capable of exerting both rewarding and aversive effects, the balance of which likely drives variation in voluntary MA intake. Understanding the genetic factors underlying sensitivity to these effects of MA is critical for developing effective treatments. The activity of dorsal raphe serotonin neurons is linked to reward processing. Here, we performed whole-cell patch-clamp electrophysiology in dorsal raphe serotonin neurons from mice with high or low MA intake corresponding with high or low MA reward sensitivity. The MA drinking (MADR) mice consist of the MA reward sensitive MA high drinking (MAHDR) and the MA reward insensitive MA low drinking (MALDR) lines. MA is a trace amine-associated receptor 1 (TAAR1) agonist, and MAHDR mice are homozygous for a mutation in the Taar1 gene, Taar1