Affiliations: Department of Neuropsychiatry, University of
Birmingham and BSMHFT, Birmingham, UK | Department of Neuropsychiatry, Institute of Neurology,
UCL, London, UK | University of Birmingham Medical School, Birmingham,
UK | Division of Neurosciences, University of Birmingham
and UHB, Birmingham, UK
Note: [] Corresponding author: Andrea Eugenio Cavanna, MD, Department of
Neuropsychiatry, University of Birmingham and BSMHFT, Barberry Building, 25
Vincent Drive, Birmingham B15 2FG, United Kingdom. E-mail:
A.Cavanna@ion.ucl.ac.uk
Abstract: Consciousness is a state so essentially entwined with human
experience, yet so difficult to conceptually define and measure. In this
article, we explore how a bidimensional model of consciousness involving both
level of arousal and subjective awareness of the contents of consciousness can
be used to differentiate a range of healthy and altered conscious states. These
include the different sleep stages of healthy individuals and the altered
states of consciousness associated with neurological conditions such as
epilepsy, vegetative state and coma. In particular, we discuss how arousal and
awareness are positively correlated in normal physiological states with the
exception of REM sleep, while a disturbance in this relationship is
characteristic of vegetative state, minimally conscious state, complex partial
seizures and sleepwalking.
