Question: what is the role of the substantia nigra
[{'answer': 'reward and movement', 'provenance': [{'wikipedia_id': '46425', 'title': 'Substantia nigra', 'start_paragraph_id': 1, 'start_character': 111, 'end_paragraph_id': 1, 'end_character': 130, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '46425', 'title': 'Substantia nigra', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 561, 'bleu_score': 0.931506586060527, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5462091042344831829}, 'section': 'Section::::Abstract.'}]}]