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Quantifying Dynamics and Variability in Neural Systems
Committee
Robert J. Butera (advisor) - Georgia Institute of Technology and Emory University
Garrett Stanley - Georgia Institute of Technology and Emory University
Astrid Prinz - Emory University
Carmen Canavier - Louisiana State University Health Sciences Center
Robert Clewley - Georgia State University
Synchronized neural activity, in which the firing of neurons is coordinated in time, is an observed phenomenon in many neural functions. The conditions that promote synchrony, the dynamics of synchronized activity, and the dynamical effects of spike time variability on synchrony are active areas of investigation because they are incompletely understood.
Previous experiments revealed that irregularity in biological neuron spike timing could disrupt synchronization in neural circuits. In this work, we demonstrate that cycle-to-cycle characteristics of the coupled system can be used to infer dynamics of neural circuits, even if they are changing over time. Using this method, we can identify stable phase relationships in the presence of noise and resolve networks with similar phase but different underlying dynamics. The method is a valuable tool for distinguishing dynamics and describing robustness.
We also show that interspike interval (ISI) of invertebrate neurons recorded over hours can be represented as a process dependent on past history and a stochastic component with history. Integrate and fire model simulations reveal that stochastic activity in adaptation channels could contribute to the observed features of these neurons. This form of stochastic, history-dependent noise is not typically represented in network simulations; our understanding of network dynamics could be enhanced by incorporating more complex, but relevant, forms of noise in the simulation and interpretation of neural circuits.
Finally, some larger implications of neuroscience research are discussed. The use of neural interfaces for national security is a current interest. Because these technologies raise a number of unique ethical concerns and guidelines about which technologies should be developed are lacking, we discuss a two-step framework with 1) an initial screen to prioritize technologies that should be reviewed immediately, and 2) a comprehensive ethical review regarding concerns for individuals, operational norms, and multi-use applications in the case of transfer to civilian contexts.
