On 5 November 2015 Renate Rutiku will defence her doctoral thesis „Refining the methodology for investigating the neural correlates of consciousness“ in the Council of the Faculty of the Social Sciences and Education.
Supervisor: professor Talis Bachmann (University of Tartu)
Opponent: professor Marcello Massimini (University of Milan)
Consciousness is the biggest unsolved problem of modern science because no one has successfully explained how the concerted firing of brain cells is able to produce our subjective experience of the world. It has been argued that in order to understand this phenomenon better we must first identify the neural correlates of consciousness – those neural events which are jointly sufficient for producing a specific conscious experience. The present thesis was set to contribute to this research effort by investigating the neural correlates and markers of conscious visual perception. It is likely that previous studies have failed to identify the true correlates of consciousness because their results also contain processes that systematically precede or follow conscious experience, but do not directly reflect consciousness itself. Thus, the current aim was to study these additional processes in more detail or to even avoid their contribution is some studies. To that end more carefully designed experimental paradigms and more realistic stimulus material was employed. Furthermore, the ongoing state of more global neural networks and its influence on conscious perception was taken into account. Together the results demonstrate that neural markers of conscious visual perception begin to arise about 200 ms after the visual image reaches our eyes. It is however possible that conscious perception is a gradual phenomenon proceeding step-by-step, because another marker also reliably correlates with conscious visual perception around 100 ms later. Furthermore, some results indicate that the complex dynamics of our visual system are best observable with realistic images and not to the same extent with simple and artificial figures. The brain retains a lot of prior knowledge about the natural visual world and its regularities. This information influences the processes of conscious perception early on by complementing and correcting them.