Statistical modeling of behavioral dynamics during propofol-induced loss of consciousness

Abstract

Background Accurate quantitative analysis of the changes in responses to external stimuli is crucial for characterizing the timing of loss and recovery of consciousness induced by anesthetic drugs. We studied induction and emergence from unconsciousness achieved by administering a computer-controlled infusion of propofol to ten human volunteers. We evaluated loss and recovery of consciousness by having subjects execute every four seconds two interleaved computer delivered behavioral tasks: responding to verbal stimuli (neutral words or the subject's name), or less salient stimuli of auditory clicks. New Method We analyzed the data using state-space methods. For each stimulus type the observation model is a two-stage binomial model and the state model is two dimensional random walk in which one cognitive state governs the probability of responding and the second governs the probability of correctly responding given a response. We fit the model to the experimental data using Bayesian Monte Carlo methods. Results During induction subjects lost responsiveness to less salient clicks before losing responsiveness to the more salient verbal stimuli. During emergence subjects regained responsiveness to the more salient verbal stimuli before regaining responsiveness to the less salient clicks. Comparison with Existing Method(s) The current state-space model is an extension of previous model used to analyze learning and behavioral performance. In this study, the probability of responding on each trial is obtained separately from the probability of behavioral performance. Conclusions Our analysis provides a principled quantitative approach for defining loss and recovery of consciousness in experimental studies of general anesthesia.

The mind-body problem; three equations and one solution represented by immaterial-material data

“…When this dynamic process is terminated (for example, a cerebral hypoxia, for only 4-8 minutes), the abstract dimension of the mind ceases permanently. In such a case the brain may still be able to produce an arousal state, but one without awareness (consciousness and mental identity are permanently lost, or severe impaired), a condition described in the literature as persistent vegetative state (47).…”

“…The consequence of data transfer (between SNS and ANS) is not a summing effect of the two neuroinformational entities, because these two structures (having distinct/ complementary roles) present actually synergistic actions (and have no sense if one is isolated/ studied separately from the other) (1). While some cerebral structures support internal mental reality (colors for example), other structures are involved in experiential sense of self (continuity of 'I' experience), according to imagistic studies (21,47,48). Accordingly, the SNS and ANS together create through emergentism a complex neuro-informational entity which is able to support a dynamic processing and representation of mental substance (as immaterial-material nature) of the mind (1,40).…”

Neural Signatures of α2 Adrenergic Agonist-Induced Unconsciousness and Awakening by Antagonist

“…1B, C). Task engagement indicates a probability of any 78 response initiation, including correct responses and failed attempts, and task performance 79 represents a probability of correct responses only Wong et al, 2014) (Fig. 1B).…”

“…The animal's trial-by-trial button-holding responses were used to define two metrics to 311 allow quantification of behavioral endpoints: task engagement and task performance probability 312 . Task engagement indicates a probability of any response initiation, including 313 correct responses and failed attempts, and task performance represents a probability of correct 314 responses only Wong et al, 2014) (Fig. 1B, C).…”

In Reply

“…The probability of response to these sounds was used to identify in each subject time points for loss and recovery of consciousness, which were used to identify electroencephalogram signatures of propofol-induced unconsciousness and sedation. 2,4,5 …”