WHEN LIGHTNING STRIKES THE BRAIN: INTEGRATED INFORMATION THEORY AND THE CAUSAL PERSPECTIVE

Experience and experiments offer two complementary lenses through which to approach the natural world and consciousness. On one side, subjective experience inaugurates the realm of sensations, thoughts and feelings, striving to go beyond itself and touch upon the mind-independent realities of the world, objectivity and science. On the other side, the interventional perspective provided by scientific experimentation has long sought to penetrate the elusive reality of consciousness, subjectivity and ideas. Through an interdisciplinary approach, this thesis comprises four studies that explore the interplay between first-person experience and third-person experimentation as two distinct yet interconnected perspectives for understanding consciousness and the brain. The first two studies focus on Integrated Information Theory (IIT), a theory of consciousness which takes subjective experience as its starting point and develops a physical account of consciousness based on the notion of cause-effect power. The first study presents a new perspective on IIT, reviewing its engagement by neuroscientists, theoreticians, and philosophers. Rather than starting with its notorious phenomenology-to-physical approach, this study presents IIT’s main ideas as unique solutions to general problems faced by theories of consciousness. The second study applies IIT to the experience of time, demonstrating that directed 1D grid, which are conjectured to constitute the neural substrate of temporal experience, yield a cause–effect structure that can account for how time feels—namely, flowing. In this account, temporal experience does not correspond to a process extending in “clock time”, but to a cause–effect structure specified by a system in its current state. The next two studies employ a perturbational perspective to investigate the emergence (and breakdown) of complexity and causality across a system’s different scales and states. The third study is an empirical investigation comparing two brain stimulation techniques used to probe the properties of brain circuits: Transcranial Magnetic Stimulation (TMS) and Intracranial Electrical Stimulation (IES). In this study, the effects of TMS and IES are for the first time compared using hd-EEG scalp recordings acquired during single-pulse stimulation delivered during wakefulness and NREM sleep. The fourth study is a computational work that investigates the concept of causal emergence, surveying different measures of causation in the literature. Using simulated toy systems, the study demonstrates that, contrary to reductionism, causal emergence can be observed across all the measures of causation examined. Together, these four studies provide a comprehensive analysis of how experiential and experimental approaches can jointly contribute to a deeper understanding of consciousness and causality, bridging the gap between first-person experience and third-person scientific inquiry.