bioRxiv Preprint Server
July 27, 2021
Michelle J. Redinbaugh, Mohsen Afrasiabi, Jessica M. Phillips et al.
preprint
Deep brain stimulation (DBS) of the central lateral thalamus in macaques can produce episodes resembling absence epilepsy, termed absence-like activity (ALA), characterized by decreased behavior, vacant staring, and low-frequency oscillations. The likelihood of ALA depended on stimulation frequency. During ALA, neural complexity (entropy) and integration (Φ*), an index of consciousness, decreased, and communication within cortico-striato-thalamic circuits changed substantially. Power spectral density and coherence at low frequencies increased, especially in thalamo-parietal and cortico-striatal pathways. Decreased consciousness and neural integration corresponded to shifts in network configurations that dissociated parietal and subcortical structures. The same DBS method, at different frequencies, can also increase consciousness in anesthetized macaques, offering a flexible tool for studying consciousness and informing clinical research on absence epilepsy and other disorders of consciousness.
bioRxiv Preprint Server
April 7, 2020
Mohsen Afrasiabi, Michelle J. Redinbaugh, Jessica M. Phillips et al.
preprint
Simultaneous recordings from frontal, parietal, striatal, and thalamic regions in macaques during wakefulness, sleep, and anesthesia, along with deep-brain thalamic stimulation, show that parietal cortex, striatum, and thalamus contribute more to the level of consciousness than frontal cortex. This supports Integrated Information Theory over Global Neuronal Workspace Theory and Higher-order Theories, but Integrated Information Theory does not account for subcortical structures like the striatum. The authors propose that thalamo-striatal circuits have a cause-effect structure that generates integrated information.
bioRxiv Preprint Server
October 1, 2019
Michelle J. Redinbaugh, Jessica M. Phillips, Niranjan A. Kambi et al.
preprint
Consciousness requires the capacity to experience the environment and internal states. Recordings from macaques show that during unconsciousness, spiking activity is selectively reduced in deep cortical layers and thalamus, along with diminished interactions at alpha and gamma frequencies. Gamma-frequency stimulation of the central lateral thalamus in anesthetized macaques counteracted these changes and restored consciousness. The findings suggest that the neural correlates of consciousness involve coordinated activity across corticocortical feedforward and feedback pathways, intracolumnar loops, and thalamocortical circuits.