Levy walk dynamics explain gamma burst patterns in primate cerebral cortex

Levy walks describe patterns of intermittent motion with variable step sizes. In complex biological systems, Levy walks (non-Brownian, superdiffusive random walks) are associated with behaviors such as search patterns of animals foraging for food. Here we show that Levy walks also describe patterns of oscillatory activity in primate cerebral cortex. We used a combination of empirical observation and modeling to investigate high-frequency (gamma band) local field potential activity in visual motion-processing cortical area MT of marmoset monkeys. We found that gamma activity is organized as localized burst patterns that propagate across the cortical surface with Levy walk dynamics. Levy walks are fundamentally different from either global synchronization, or regular propagating waves, because they include large steps that enable activity patterns to move rapidly over cortical modules. The presence of Levy walk dynamics therefore represents a previously undiscovered mode of brain activity, and implies a novel way for the cortex to compute. We apply a biophysically realistic circuit model to explain that the Levy walk dynamics arise from critical-state transitions between asynchronous and localized propagating wave states, and that these dynamics yield optimal spatial sampling of the cortical sheet. We hypothesise that Levy walk dynamics could help the cortex to efficiently process variable inputs, and to find links in patterns of activity among sparsely spiking populations of neurons. Liu et al used a combination of empirical observation and modeling to investigate high-frequency (gamma band) local field potential activity in visual motion-processing cortical area MT of marmosets. They found that gamma bursts are organised as localised patterns that propagate across the cortical surface with Levy walk dynamics and hypothesized that such dynamics could help the cortex to efficiently process variable inputs.

Automated summary

Levy walks describe patterns of intermittent motion with variable step sizes, different from global synchronization or regular propagating waves. Levy walk dynamics in the primate cerebral cortex result in localized burst patterns of gamma activity, representing a previously undiscovered mode of brain activity.