Neurophilosophy of Consciousness
Neurophilosophy of Consciousness – Neural Mechanisms of Visual Consciousness, Dreaming, and Hypnosis
Principal Investigator: ANTTI REVONSUO
Researchers: Niina Salminen-Vaparanta, Valdas Noreika
Center for Cognitive Neuroscience, University of Turku
Neurophilosophy is a new field that investigates whether empirical neuroscience can solve traditional philosophical problems concerning the relationship between mind and brain. Consciousness is one of the main topics in neurophilosophical research. In neuroscience, this relationship is now being studied by searching for the neural correlates of consciousness in the brain. "Consciousness" in this context refers to subjective experience as such. The core of the philosophical problem is this: We still do not understand how any purely physical system (such as the brain) could produce any subjective experiences at all. There is an "explanatory gap" between our subjective psychological experiences (such as sensations, perceptions, emotions as we feel them) and the objective neurophysiological activities in the brain that seem to be coupled with them. It is difficult to see how or why any type of neural activity should give rise to any subjective experiences.
The main purpose of the present project is to run several theoretically crucial experiments to study the neural correlates of consciousness. We will use a whole spectrum of brain sensing and imaging methods (EEG, PET, fMRI, TMS) and we will apply them to the most promising model systems in consciousness research: (PI1) visual consciousness, dreaming, hypnosis, and (PI2) unconsciousness induced by anesthesia. The basic idea in these experiments is to directly contrast two conditions: When consciousness (subjective experience) is present in the mind is contrasted with when it is absent. The purpose is then to determine which neural activities covary with the presence vs absence of consciousness. This project also aims to evaluate whether or not such empirical findings will lead toward a neuroscientific explanation of consciousness, and to a final solution to the traditional philosophical "mind-brain" -problem.
Contact: revonsuo(at)utu.fi, tel: +358 2 333 6340
Neurophilosophy of Consciousness – Neural Mechanisms of Loss of Consciousness Induced by Anesthetic Agents
Principal Investigator: HARRY SCHEININ1
Researchers: Kimmo Kaskinoro2, Ruut Kirla3, Anu Maksimow2, Jaakko Långsjö2, Kaike Kaisti3, Sargo Aalto2
1Turku PET Centre, University of Turku, Turku, Finland, 2University of Turku, 3Turku University Hospital
This project is part of a consortium project "Neurophilosophy of Consciousness" attempting to reveal neural correlates of consciousness by targeting on four different states of consciousness: (1) Visual consciousness in perception, (2) Stimulus-independent contents of consciousness during sleep and dreaming, (3) Alteration of consciousness during hypnosis, and (4) Loss of consciousness induced by different anesthetic agents.
Unconsciousness induced by general anesthesia constitutes an excellent platform to study the neural basis of consciousness. A series of Positron Emission Tomography (PET) imaging and electroencephalography (EEG) studies on healthy human subjects will be carried out to reveal the neural correlates of loss of consciousness induced by anesthetic agents acting through different mechanisms of action (GABA-enhancement, a2-agonism, NMDA-antagonism). EEG will be continuously collected and PET scanning performed at baseline and during anesthesia and/or increasing concentrations of the drugs. PET will be used to quantify cerebral metabolic rate for glucose (using 18F-labeled fluorodeoxyglucose) and cerebral blood flow (using 15O-labeled H2O). Because of the short half-life of 15O (2 min), the assessment of cerebral blood flow possesses clear advantages over measuring cerebral metabolic rate for glucose by allowing repetitive measurements and more complex study designs. The depth of anesthesia will be measured using clinical scoring, quantitative EEG, bispectral index (BIS), EEG spectral entropy and novel EEG analysis methods measuring cortical connectivity. EEG data will be correlated to simultaneously gathered clinical and PET data.
The results may lead to the discovery of new and better objective indicators of the depth of anesthesia, and new insights into the understanding of neural mechanisms behind drug-induced loss of consciousness and ultimately the mechanisms of action of (general) anesthetics.
Contact: harry.scheinin(at)utu.fi, tel. +358 2 313 1870