Frontal Cortex and Human Behavior: Evidence from Intracranial Recording
Robert T. Knight, University of California, Berkeley
Robert T. Knight, MD
Abstract & Learning Objectives: Neuropsychological evidence has documented the critical role of prefrontal cortex (PFC) in the control of cognitive and social processing with extensive lateral or orbital PFC damage resulting in a profound disintegration of goal-directed behavior. This lecture will first describe novel neural activity linked to cognition recently unveiled by intracranial recordings in humans. Second, these brain signals will be used to link PFC function to cognitive control across a range of tasks. Direct cortical recording (electrocorticography; ECoG) provides unique insights in the role of PFC in cognition and social interaction. Since the discovery of the EEG in the 1920’s, neurophysiological dogma stated that the human cortex did not generate reliable rhythms above 50-60 Hz. However, findings over the last decade report neural activity up to 250 Hz in the human cortex. Every cognitive process examined with intracranial recording including language, attention, memory and decision-making generates task-specific high frequency activity in the range of 70-250 Hz (high frequency band; HFB). Importantly, the HFB band has superb spatial localization and task specificity. HFB recording has provided novel insights into the role of Broca’s area in language processing, the hierarchical organization of PFC, and the critical role of PFC in contextual processing, decision making and working memory. Importantly, the HFB is phase locked to the trough of slower cortical oscillations with different PFC dependent tasks eliciting unique spatial patterns of HFB-theta coupling. These results provide evidence that transient coupling between low- and high-frequency brain activity provides a mechanism for effective communication in distributed neural networks engaged during PFC dependent cognitive processing. The results obtained from the study of PFC patients and from intracranial recording support the proposal that the devastating human prefrontal syndrome can be viewed as a failure of PFC control of distributed neural networks subserving human behavior.
After attending this session, learners will be able to demonstrate that they:
Understand the role of high frequency brain activity in cognition
Understand the role of low frequency brain oscillations in establishing networks supporting cognition
Understand the key role of prefrontal cortex in orchestrating neural networks in the service of cognition
Speaker Biography: Dr. Knight received a BS in Physics from the Illinois Institute of Technology, an MD from Northwestern University Medical School, did Neurology training at UC San Diego and Post-Doctoral training at the Salk Institute. He was at UC Davis from 1980-1998 and moved to UC Berkeley in 1998 where he served as Director of the Helen Wills Neuroscience Institute until 2011. Dr. Knight has twice received the Jacob Javits Award from the National Institute of Neurological Disorders and Stroke for distinguished contributions to neurological research, the IBM Cognitive Computing Award, the German Humboldt Prize in Neurobiology and the Distinguished Career Contribution Award from the Cognitive Neuroscience Society. He studies neurological patients with frontal lobe damage and records electrical signals directly from the brain in neurosurgical patients to understand the role of prefrontal cortex in behavior. His laboratory is also engaged in developing a speech prosthesis for use in patients with disabling neurological disorders.