The cerebral cortex is a highly complex network comprised of billions of excitable nerve cells. Dynamic interactions among these cells underlie our thoughts, memories, and sensory perceptions. A healthy brain must carefully regulate its neural excitability to optimize information processing and avoid brain disorders. If excitability is too low, neural interactions are too weak and signals fail to propagate through the brain network. On the other hand, high excitability can result in excessively strong interactions and, in some cases, epileptic seizures. While it is commonly supposed that healthy neural excitability must lie between these extremes, the optimal degree of excitability is not known.
In this colloquium I will present new experimental evidence that brain dynamics undergo a phase transition as neural excitability is tuned from low to high. Importantly, the critical excitability at which the phase transition occurs also results in optimal information processing. These results suggest that the optimal excitability is that which places the brain closest to the phase transition. Moreover, many mental disorders such as epilepsy, Down syndrome, and autism may be caused by deviation from this optimal excitability.
Coffee: 3:45 pm, 241 Compton