The identification of a genetic locus at chromosome 1:135 Mb for locomotion in a novel stressful environment for young animals, which contains Ntrk3, is consistent with our previous findings of gene expression differences in a neurotrophic factor (i.e., FGF2) between the bHR and bLR animals and how augmentation with FGF2 early in life rescues the anxiety-like phenotype in the bLRs that have low FGF2 expression (Turner et al., 2011). This evidence concerns the gene NTRK3 and Anxiety.