basal ganglion neuron quantity Trait.ontology VT:0003242 The proportion or number of neurons in the group of nuclei associated with the ability to carry out willed movements, including the caudate, putamen, nucleus accumbens, globus pallidus, substantia nigra, and subthalamic nucleus. Note that Charles W. considers this distinct from degeneration basal ganglion neuron number basal ganglion morphology trait