The close proximity of catecholamine-containing cells to the 'mesencephalic locomotor region' (MLR).
D000818:Animals; D001923:Brain Chemistry; D001931:Brain Mapping; D002395:Catecholamines / Q000032:analysis*; D002415:Cats; D004558:Electric Stimulation; D008124:Locomotion; D008636:Mesencephalon / Q000166:cytology* / Q000378:metabolism; D009474:Neurons / Q000032:analysis*; D013569:Synapses / Q000378:metabolism
D002395:Catecholamines