What Does EEG Tell Us About Consciousness? Paul L. Nunez (Biomedical Engineering, Tulane University, Encinitas, CA ) PL13
Electroencephalography (EEG) is the recording of electrical potentials, usually from the human scalp but sometimes directly from the brain surface. Over the past 80 years, EEG has provided many robust signatures of consciousness, revealing dynamic patterns of information in the neocortex that indicate sleep stages, anesthesia depth, various kinds of mental activity, selective attention, and more. The robust scalp data mainly involve oscillations at low frequencies (< 20 Hz), whereas cortical recordings typically focus on higher frequency gamma range (>30 Hz). These oscillations together with various measures of functional connections between brain regions constitute much of the dynamic patterns correlated with conscious, semi-conscious, and unconscious states. Since my early career move from engineering and theoretical physics to neuroscience in 1971, my professional life has often focused on EEG technical issues-how to accurately record, analyze, and interpret EEG. In contrast, today's narrative is directed to a general audience by replacing technical discussions with analogs and metaphors. My approach to the EEG/consciousness connection rests on the following conceptual framework that enjoys full consistency with mainstream brain science: 1. Brains and minds are correlated; that is, many consciousness signatures have been discovered. 2. Brains are genuine complex systems; more complex than most other living things. 3. Brains, like other complex systems, consist of nested hierarchies of subsystems that operate at different levels of organization (spatial scales). 4. Consistent with this picture, signatures of consciousness are observed over a wide range of scales. 5. Multiple conscious, unconscious, and semi-conscious entities coexist within each human brain. 6. Interactions between these subsystems contribute substantially to making the human brain 'human.' This framework is explored in several of my books, including The New Science of Consciousness: Exploring the Complexity of Brain, Mind, and Self, Prometheus Books, 2016. I argue here that EEG and other data support an idea labeled the multiscale conjecture, which posits that consciousness manifests at multiple levels of brain organization, and no single scale need be special. Thus, the various dynamic patterns of information, observed as consciousness signatures, as measured with different experimental methods (EEG, ECoG, fMRI, PET, etc.) may all contribute to the mind. In this view, consciousness is rooted in the dynamic patterns of multiple interacting scales. Although fully consistent with mainstream science, the multiscale conjecture allows room for both materialistic and non-materialistic interpretations. I argue that materialism and dualism are not as distinct as many think. Some aspects of dualism appear fully consistent with modern science. For example, all interpretations of quantum mechanics rely on the existence of some sort of hidden reality or 'shadow world' that we can never observe directly, but nevertheless influences the familiar world of our senses.