title: Chronic ambulatory electrocorticography from human speech cortex.
abstract: Direct intracranial recording of human brain activity is an important approach for deciphering neural mechanisms of cognition. Such recordings, usually made in patients with epilepsy undergoing inpatient monitoring for seizure localization, are limited in duration and depend on patients' tolerance for the challenges associated with recovering from brain surgery. Thus, typical intracranial recordings, similar to most non-invasive approaches in humans, provide snapshots of brain activity in acute, highly constrained settings, limiting opportunities to understand long timescale and natural, real-world phenomena. A new device for treating some forms of drug-resistant epilepsy, the NeuroPace RNS® System, includes a cranially-implanted neurostimulator and intracranial electrodes that continuously monitor brain activity and respond to incipient seizures with electrical counterstimulation. The RNS System can record epileptic brain activity over years, but whether it can record meaningful, behavior-related physiological responses has not been demonstrated. Here, in a human subject with electrodes implanted over high-level speech-auditory cortex (Wernicke's area; posterior superior temporal gyrus), we report that cortical evoked responses to spoken sentences are robust, selective to phonetic features, and stable over nearly 1.5 years. In a second subject with RNS System electrodes implanted over frontal cortex (Broca's area, posterior inferior frontal gyrus), we found that word production during a naming task reliably evokes cortical responses preceding speech onset. The spatiotemporal resolution, high signal-to-noise, and wireless nature of this system's intracranial recordings make it a powerful new approach to investigate the neural correlates of human cognition over long timescales in natural ambulatory settings.
authors.affiliation: University of California, San Francisco, Department of Neurology, San Francisco, CA 94143, United States. Electronic address: vikram.rao@ucsf.edu.
authors.forename: Vikram R
authors.initials: VR
authors.lastname: Rao
authors.affiliation: University of California, San Francisco, Department of Neurosurgery, San Francisco, CA 94143, United States; Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94143, United States.
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Leonard
authors.affiliation: University of California, San Francisco, Department of Neurology, San Francisco, CA 94143, United States.
authors.forename: Jonathan K
authors.initials: JK
authors.lastname: Kleen
authors.affiliation: University of California, San Francisco, Department of Neurosurgery, San Francisco, CA 94143, United States; Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94143, United States.
authors.forename: Ben A
authors.initials: BA
authors.lastname: Lucas
authors.affiliation: NeuroPace, Inc., Mountain View, CA 94043, United States.
authors.forename: Emily A
authors.initials: EA
authors.lastname: Mirro
authors.affiliation: University of California, San Francisco, Department of Neurosurgery, San Francisco, CA 94143, United States; Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94143, United States.
authors.forename: Edward F
authors.initials: EF
authors.lastname: Chang
mesh_terms: D000293:Adolescent; D000328:Adult; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000379:methods*; D005071:Evoked Potentials; D005260:Female; D065818:Gamma Rhythm; D006801:Humans; D058542:Implantable Neurostimulators; D013067:Speech Perception / Q000502:physiology*; D013686:Telemetry; D013702:Temporal Lobe / Q000502:physiology*; D059015:Wireless Technology
keywords: Broca's area; Chronic electrocorticography; ECoG; Human; RNS System; Wernicke's area