What is the brain state?

States of an organism, such as sleep, wakefulness, aphasia or attention have been intensively studied for years, but our understanding of the actual state of brain-networks related to them remains poor, despite of all developments in systems neuroscience. For that matter there is hardly any quantitative definition of a “brain-state”, let alone of its transitions and evolution reflecting both the underlying anatomy and the complexity if its dynamics. This should be hardly surprising, as brains have billions of neurons and trillions of synapses, nested recursive circuits at all possible spatiotemporal levels, massive connectivity, and initial condition dependent activity-evolution; all typical characteristics of so-called complex dynamic systems. Such systems can only be adequately investigated by using multimodal and multiscale methodologies, in studies combining theoretical and experimental approaches. An example is the combination of concurrent electrophysiological recordings of local, intrinsic neural events and imaging of brainwide activity patterns associated with them. In my talk, I’ll describe our observations related to various thalamic, hippocampal and pontine neural events, their interrelationship, and the multi-structure activity patterns offering some insights into the self-organization of networks, potentially related to learning and memory.