Final answer:
Dr. Wilder Penfield was the first to map language sites in the brain using electrical stimulation, a technique which allowed real-time observation of brain function.
Step-by-step explanation:
The mapping of language sites using electrical stimulation was first accomplished by Dr. Wilder Penfield. While prominent figures such as Paul Broca and Karl Wernicke made significant contributions to the understanding of brain regions involved in language, it was Penfield who directly mapped the brain's language functions using electrical stimulation. This technique involved probing the surface of the brain's cortex while the patient was under local anesthesia, allowing Penfield to observe and record responses to the electrical stimulation and thus mapping the functionalities of different cortical areas.