TACR1 and attention deficit-hyperactivity disorder: We deployed a mouse line with homozygous knockout of the tachykinin 1 receptor gene (Tacr1-/-) because of its validity to model several aspects of ADHD, including (a) the three phenotypes stated above, (b) their responsiveness to several drugs approved for ADHD treatment, (c) reduced dopamine signalling in PFC and striatum, and (d) the genetic risk - given polymorphisms of TACR1 in a subgroup of ADHD-patients30–35.