Spring 2018

Cortical Spike Coding Using Gamma Frequency Latencies

Monday, Jun. 17, 2019 3:30 pm4:15 pm

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Dana Ballard (University of Texas at Austin)

Driven by advances in multi-cell spike recording technology, the statistics of action potential populations are revealing many new details of dynamic signals in the cortex. However, it is still difficult to integrate slow Poisson spiking with much faster spike timing signals in the gamma frequency spectrum. A potential way forward is being sparked by advances in patch clamping methodologies that allow the exploration of communication strategies that use millisecond timescales. The voltage potential of a cell's soma recorded at 20 kilohertz in vivo allows its high resolution structure to be correlated with behaviors. We show that this signal can be potentially interpreted by a unified model that takes advantage of a single cycle of cell's somatic gamma frequency to modulate the generation of its action potentials. This capability can be seen as organized into a general-purpose method of coding fast computation in cortical networks that has three important advantages over traditional formalisms: 1) Its processing speed is two to three orders of magnitude times faster than population coding methods, 2) It allows multiple, independent processes to run in parallel, greatly increasing the processing capability of the cortex and 3) Its processes are not bound to specific locations, but migrate across cortical cells as a function of time, facilitating the maintenance of cortical cell calibration.