Modeling an auditory stimulated brain under altered states of consciousness using the generalized Ising model
Sivayini Kandeepan,
Jorge Rudas,
Francisco Gomez,
Bobby Stojanoski,
Sreeram Valluri,
Adrian Mark Owen,
Lorina Naci,
Emily Sophia Nichols,
Andrea Soddu
Affiliations
Sivayini Kandeepan
Department of Physics and Astronomy, University of Western Ontario, 1151 Richmond St, London, Ontario, N6A 3K7, Canada.; Department of Physics, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda, Sri Lanka; Brain and Mind Institute, University of Western Ontario, 1151 Richmond St, London, Ontario, N6A 3K7, Canada; Corresponding author: Sivayini Kandeepan. Department of Physics and Astronomy, University of Western Ontario, 1151 Richmond St, London, Ontario, N6A 3K7, Canada.
Jorge Rudas
Institute of Biotechnology, Universidad Nacional de Colombia, Cra 45, Bogotá, Colombia.
Francisco Gomez
Department of Mathematics, Universidad Nacional de Colombia, Cra 45, Bogotá, Colombia
Bobby Stojanoski
Brain and Mind Institute, University of Western Ontario, 1151 Richmond St, London, Ontario, N6A 3K7, Canada
Sreeram Valluri
Department of Physics and Astronomy, University of Western Ontario, 1151 Richmond St, London, Ontario, N6A 3K7, Canada.
Adrian Mark Owen
Brain and Mind Institute, University of Western Ontario, 1151 Richmond St, London, Ontario, N6A 3K7, Canada; Department of Physiology and Pharmacology and Department of Psychology, University of Western Ontario, 1151 Richmond St, London, Ontario, N6A 3K7, Canada.
Lorina Naci
Trinity College Institute of Neuroscience, Trinity College Dublin, College Green, Dublin 2, Ireland
Emily Sophia Nichols
Brain and Mind Institute, University of Western Ontario, 1151 Richmond St, London, Ontario, N6A 3K7, Canada; Faculty of Education, University of Western Ontario, 1151 Richmond St, London, Ontario, N6A 3K7, Canada.
Andrea Soddu
Department of Physics and Astronomy, University of Western Ontario, 1151 Richmond St, London, Ontario, N6A 3K7, Canada.; Brain and Mind Institute, University of Western Ontario, 1151 Richmond St, London, Ontario, N6A 3K7, Canada
Propofol is a short-acting medication that results in decreased levels of consciousness and is used for general anesthesia. Although it is the most commonly used anesthetic in the world, much remains unknown about the mechanisms by which it induces a loss of consciousness. Characterizing anesthesia-induced alterations to brain network activity might provide a powerful framework for understanding the neural mechanisms of unconsciousness.The aim of this work was to model brain activity in healthy brains during various stages of consciousness, as induced by propofol, in the auditory paradigm. We used the generalized Ising model (GIM) to fit the empirical fMRI data of healthy subjects while they listened to an audio clip from a movie. The external stimulus (audio clip) is believed to be at least partially driving a synchronization process of the brain activity and provides a similar conscious experience in different subjects. In order to observe the common synchronization among the subjects, a novel technique called the inter subject correlation (ISC) was implemented.We showed that the GIM—modified to incorporate the naturalistic external field—was able to fit the empirical task fMRI data in the awake state, in mild sedation, in deep sedation, and in recovery, at a temperature T* which is well above the critical temperature. To our knowledge this is the first study that captures human brain activity in response to real-life external stimuli at different levels of conscious awareness using mathematical modeling. This study might be helpful in the future to assess the level of consciousness of patients with disorders of consciousness and help in regaining their consciousness.
