It has been previously reported that increased numbers of dopaminergic interneurons in the OB might actually be associated with impaired olfactory function in different neurodegenerative diseases (Huisman et al., 2004; Mundiñano et al., 2011); therefore, our findings of an enhancement in TH+ OB neuron counts (in both dopamine-depleted and healthy hemispheres) might even have detrimental effects. Here, TH is linked to neurodegenerative disease.