NOS1 and Cognitive impairment: In favor of this hypothesis, mice deficient in Nos1, which encodes the neuronal NO synthase (nNOS) that converts arginine to NO, display cognitive impairments, aggressivity and hyperactivity as well as additional behavioral abnormalities (Nelson et al. 1995; Weitzdoerfer et al. 2004; Tanda et al. 2009).