Early and late correlates of consciousness. Investigating structures and neural connections involved in conscious perceptual experience with magnetic resonance and transcranial magnetic stimulation.
Research project objectives/Research hypothesis
The aim of this research project is to investigate the neural correlates of consciousness (NCC) in a complex and detailed manner. The investigation will refer to the discussion between two contradictory views, one that centers the neural basis of conscious perception in the frontal cortex and the other that favours engagement of the posterior parts of the brain. Our main hypothesis is that neither of those views can be sufficiently justified, as they strongly depend on the very conceptualisation of what is measured (i.e. if one associates conscious experience with sensory experience or with its post-perceptual interpretation), operationalisation of the consciousness measure (i.e. whether one uses objective measures of performance or subjective reports) and the kind of task that is used (e.g. perceptual identification or visual illusion). We claim that such an approach misses the bigger picture and that consciousness may require early activation of the sensory system as well as the late activation of the prefrontal cortex depending on the task condition and applied operationalisation of consciousness. In order to comprehensively investigate individual differences in the brain’s organisation, we plan to use a variety of tasks and combine them with magnetic resonance imaging (MRI) and transcranial magnetic stimulation (TMS). Such an integrative approach will enable us to find commonalities between various patterns of activation and structural basis of conscious experience.
Research project methodology
The project is to be executed within three research lines: behavioral, MRI and TMS studies. We plan to examine at least 300 subjects in order to overcome all the statistical challenges and collect a reliable set of data. The behavioral part will consists of a broad spectrum of tasks that will examine near-threshold perception, bistable perception and illusion in visual, auditory and visuo-auditory modalities and introspective judgments about the subjective experience. The second line of research consists of MRI studies. We will examine the structural differences, e.g. grey and white matter volume, cortical microstructure, as well as resting state functional connectivity that correlate with performance and reported conscious experience in the behavioral tasks. The third line of research consists of TMS studies. We plan to conduct at least two experiments in order to confirm the causal relationship between activity in certain brain areas and of conscious experience. For this reason the exact choice of tasks and of coordinates of stimulation will be based on results of MRI pilot studies.
Expected impact of the research project on the development of science
On the theoretical ground, despite years of research scientists have not managed to reach agreement on the subject of NCC. Considering presence of data supporting both the ‘frontal’ and ‘posterior’ localisation of the source of conscious experience, it seems indispensable to test both views in a complex manner. Our research proposal will allow us to test consciousness at different levels of perceptual processing. When it is combined with MRI analysis, it will allow us to discover the structural organisation’s correlates with conscious access. Up to now, most of the studies have focused on functional imaging of conscious experience, only a few have investigated their structural basis and none has done it in a complex manner. Additional TMS studies will allow us to determinate in noninvasive manner the role of those structures in generation of conscious experience. This project will have an impact on the entire field of consciousness research. We offer a new approach, developed in international cooperation with use of methodologically and theoretically advanced methods which will also help to clarify consciousness-related terminology, as we strongly believe that part of disagreement between the views presented in consciousness scientific literature stems from differences in the understanding of investigated problem.