The reduced locomotor activity of the −/fl,Cre+ mice is quite remarkable since it has been concluded from other mouse models with reduced BDNF levels that not only heterozygous BDNF-deficient mice can show mild signs of hyperactivity, but that mice with a higher rate of BDNF reduction in the nervous system display hyperactivity and develop anxiety-like behavior [12,28]. The gene discussed is BDNF; the disease is Anxiety.