Synchronization and Functional Connectivity Dynamics Across TC-CC-CT Networks: Implications for Clinical Symptoms and Consciousness

In this chapter, we argue that functional connectivity in the human brain is critical for the performance of cognitive processes, particularly consciousness, and its attendant phenomenology of subjective experience. We describe MEG (magnetoencephalography) and EEG (electroencephalography) work on the dynamics of functional connectivity in thalamocortical (TC), cortico-cortical (CC), and cortico-thalamic (CT) circuits, particularly emphasizing synchronization in various frequency bands. We then describe the cognitive consequences of various disruptions in these dynamics, from slight partial slowing, through severe slowing and selective loss, to the complete loss of functional network dynamics that can occur in traumatic brain injury. These consequences range from slight cognitive deficits through deficits that necessitate neurological or psychiatric treatment, to complete loss of consciousness and sometimes to paradoxical states such as “free-running cortex.”