Complexity of brain dynamics as a correlate of consciousness in anaesthetized monkeys

Summary

The complexity of brain activity can serve as a correlate of consciousness. In monkeys, electrocorticogram recordings were analyzed using information quantifiers to compare stages of general anesthesia. For propofol and medetomidine, the anesthetized state showed a reduction in brain activity complexity. Conversely, ketamine produced an increase in complexity measurements, linked to increased activity in certain brain regions. Complexity of brain activity is a good indicator for evaluating different levels of consciousness awareness, in both anesthetized and non-anesthetized states.

Study at a glance

Abstract

The use of anaesthesia is a fundamental tool in the investigation of consciousness. Anesthesia procedures allow to investigate different states of consciousness from sedation to deep anesthesia within controlled scenarios. In this study we use information quantifiers to measure the complexity of electrocorticogram recordings in monkeys. We apply these metrics to compare different stages of general anesthesia for evaluating consciousness in several anesthesia protocols. We find that the complexity of brain activity can be used as a correlate of consciousness. For two of the anaesthetics used, propofol and medetomidine, we find that the anaesthetised state is accompanied by a reduction in the complexity of brain activity. On the other hand we observe that use of ketamine produces an increase in complexity measurements. We relate this observation with increase activity within certain brain regions associated with the ketamine used doses. Our measurements indicate that complexity of brain activity is a good indicator for a general evaluation of different levels of consciousness awareness, both in anesthetized and non anesthetizes states.