Neurobiology of Language: Insights from Direct Cortical Recording

Knight, R. T. .

Intracranial recording provides a unique method to examine the neural dynamics supporting language with unprecedented spatio-temporal resolution. High frequency band neural activity (high gamma; HG, 70-250 Hz) combined with oscillatory connectivity metrics can be used to assess local and network mechanisms during linguistic processing. The HG response indexes local cortical excitability has been used to study phoneme and word representation at sub-centimeter resolution, speech suppression, categorical phoneme representation and the temporal evolution of language in peri-sylvian cortices. Intracranial recording have provided surprising findings challenging prior notions of language organization and control. In contrast to classic theories, direct cortical recording has shown that Broca?s area is not involved in speech articulation but serves as a premotor region. Recent work has also shown that hippocampal theta rhythms are critical for extracting semantic information during sentence processing and that prefrontal regions outside of classic peri-sylvian regions support lexical selection. Intracranial recordings can also be used to decode real and imagined speech providing a basis for development of implanted neuroprosthetics devices to treat disabling disorders of speech.