Browsing by Subject "Physiology and Neuroscience"

The Critical Brain -hypothesis proposes that the brain operates in a phase transition between ordered and disordered state, in the vicinity of the critical point. The hypothesis has its roots in statistical physics and thermodynamics that aim to explain the emergent complexity of the nature and the behaviour of physical systems by investigating their statistical collective properties instead of looking solely at the micro level. Physical criticality can be seen as a fundamental phenomenon where the collective action of systems becomes independent of their microscopical details and many seemingly unrelated systems are characterised by same macro level attributes. Operation at the critical point maximises many attributes beneficial to the information processing capability of the brain such as information capacity, dynamic range and information transfer. Within the past 25 years, the criticality hypothesis has progressed from a theoretical framework to a convincing explanation for the operation of the brain. There’s cumulating evidence from computer simulations, in vitro experiments, animal experiments and from human MEG- and EEG-data. The mathematical background and the path from the depolarization of neurons to statistical inference has been perceived as abstract and difficult. The criticality hypothesis shares moderate attention in clinical use and teaching compared to its possible explanatory power. In this study, basic concepts and history of criticality are introduced by reviewing the relevant literature and showing examples. There’s a chapter for clinical applications. A nested, hierarchical model was built to explore the functional and structural dimensions of the brain. Common algorithms for computing outcome measures were implemented in-house. Under a linear topology, the model functioned as a non-nested model which complied with the hypothesis. The results suggest that the model is a viable platform for exploring the contribution of structure to brain dynamics. Biologically motivated structural modeling can have possible future clinical application for the understanding, diagnosis and the assessment of treatment outcomes in neurological and psychiatric disorders. This study can possibly raise awareness for the criticality hypothesis as there’s a limited number of reviews that go through the mathematical concepts, basic research and clinical examples.