Criticality in Neural Systems

Neuroscience is currently experiencing a revolution in the area of monitoring brain activity at ever higher spatial and temporal resolutions. The simultaneous recording of the activity of hundreds or thousands of nerve cells and the observation of averaged activity of large fractions of the whole human brain with ever-increasing precision is leading to a new generation of Big Data. The complexity of the myriads of observed neuronal interactions promises deep insights into how real brains work - how brains assure the survival of the species in highly complex and dynamically changing environments. At the same time, this complexity poses an enormous challenge to our analytical skills and our willingness to break traditional approaches to explore and explain brain function. The nearly century-old and still highly successful approach to neuroscience that maps single neuron responses to select sensory, motor, or associative processes is challenged by the view that it is activity from wide-spread organized neuronal populations that underlies the computational operations of the brain. The view that brain circuits are analogous to both precisely and permanently wired electronic circuits is making way to a picture in which circuit elements continuously change affiliations leading to the emergence of complex spatio-temporal patterns. Yet, will these metaphors provide us with the precision and manipulative potential that is ultimately required to understand brain functions? Are we forced to leave the realm of precise biophysical laws at the single neuron level to enter a level of description in which insights can be expressed only in terms of probabilistic patterns that loosely correlate with brain operations?.