How do cortical neurons collectively interact to process information? A new hypothesis, supported by recent multielectrode recordings in brain tissue samples and in the intact brain, suggests that local cortical networks self-organize to operate near a critical point. At this point, interactions across all spatial and temporal scales can occur, and avalanches of neural activity are generated at all sizes, resulting in approximately power law distributions. Very generic neural network models suggest that information processing will be optimal at this point. This "criticality hypothesis" has significant implications for computation in cortical circuits, and ultimately, for human health. Despite the potential importance of this hypothesis, it has remained untested in local cortical networks consisting of 100 or more synaptically connected neurons. Previous work has relied on local field potential recordings, which do not reveal the number or location of individual neurons generating signals. Previous work also has relied on relatively few (~60-100) broadly-spaced recording sites, which are insufficient to adequately sample a population of synaptically connected neurons. Here, the PI will record from 512 closely spaced electrodes, allowing us to monitor the spiking behavior of hundreds of neurons, many of which are expected to share synaptic connections. The tests the PI will perform of the criticality hypothesis will allow him, for the first time, to determine if networks of cortical neurons are critical or not.
Scientific education and outreach is another vital component of this proposal. The PI will engage thousands of children from economically disadvantaged areas in the development and use of an interactive exhibit for WonderLab, a popular local science museum for K-middle school children. This exhibit is based on electroencephalogram (EEG) recordings and will display children's brain waves, allowing them to modify these waves by biofeedback. This exhibit will be placed in WonderLab museum, which serves 78,000 visitors each year. WonderLab has been named by Parent's magazine as one of the "Top 25 Science Centers in the United States."
