Event Details:
Brain mechanisms of normal and impaired consciousness
Hal Blumenfeld, PhD
Professor of Neurology and Neuroscience and Neurosurgery
Yale University
Host: Jin-Hyung Lee
Abstract
Combining data from normal perceptual tasks and impaired states such as epilepsy may provide important new insights into mechanisms of consciousness.
Consciousness depends on widespread brain networks, so it has long been mysterious why focal seizures impair consciousness. In focal temporal lobe seizures, intracranial EEG and blood flow imaging show depressed frontoparietal function resembling slow wave sleep. Experimental models demonstrate activation of subcortical inhibitory neurons which switch off subcortical arousal, leading to depressed cortical function and impaired consciousness. Deep brain stimulation of thalamus and brainstem arousal circuits can restore consciousness and purposeful behavior during and after seizures.
During normal conscious perception of visual stimuli at 50% detection threshold intracranial EEG demonstrates a wave of broadband gamma activity through successive regions of association cortex. Meanwhile, specific visual, association cortex and default mode networks undergo polyphasic on/off switching that may control information flow. fMRI measurements with the same task show transient activation of cortical-subcortical arousal and attention networks with conscious perception.
Normal conscious perception and pathological states like epilepsy share common anatomical and physiological mechanisms for activity changes in large-scale networks.
Curriculum Vitae
Related papers
[1] Wendy X. Herman, Rachel E. Smith, Sharif I. Kronemer, Rebecca E. Watsky, William C. Chen, Leah M. Gober, George J. Touloumes, Meenakshi Khosla, Anusha Raja, Corey L. Horien, Elliot C. Morse, Katherine L. Botta, Lawrence J. Hirsch, Rafeed Alkawadri, Jason L. Gerrard, Dennis D. Spencer and Hal Blumenfeld. A Switch and Wave of Neuronal Activity in the Cerebral Cortex During the First Second of Conscious Perception. Cerebral Cortex, 2017; 1–14. DOI: 10.1093/cercor/bhx327
[2] Adam J. Kundishora, Abhijeet Gummadavelli, Chanthia Ma, Mengran Liu, Cian McCafferty, Nicholas D. Schiff, Jon T. Willie, Robert E. Gross, Jason Gerrard and Hal Blumenfeld. Restoring Conscious Arousal During Focal Limbic Seizures with Deep Brain Stimulation. Cerebral Cortex, March 2017;27:1964–1975. Cerebral Cortex, March 2017;27:1964–1975. DOI: 10.1093/cercor/bhw035