Question: which technique measures the electrical activity of brain cells directly
[{'answer': 'Electroencephalography ( EEG )', 'provenance': [{'wikipedia_id': '21402632', 'title': 'Electroencephalography', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 31, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '21402632', 'title': 'Electroencephalography', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 902, 'bleu_score': 0.9168931008256701, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 18105436514192202684}, 'section': 'Section::::Abstract.'}]}]