Final answer:
The statement that the substantia nigra appears black due to the melanin pigment in nigral cells is true. Substantia nigra's dark hue is because of neuromelanin in its dopaminergic neurons associated with movement and behavior, and its degeneration is linked to Parkinson's disease.
Step-by-step explanation:
The statement that the substantia nigra appears black to dark brown because nigral cells contain melanin pigment is True. The substantia nigra, which is a part of the midbrain, contains neurons that produce the neurotransmitter dopamine. The dark pigmentation of the substantia nigra is due to the presence of a high concentration of neuromelanin, a form of melanin, in the dopaminergic neurons of this area. The presence of melanin within these neurons is associated with the regulation of various brain functions, including voluntary movement and aspects of behavior. Notably, the degeneration of the substantia nigra is a hallmark of Parkinson's disease, which leads to movement disorders among other symptoms.