Lévy walk dynamics explain gamma burst patterns in primate cerebral cortex

Area of Science:

• Neuroscience
• Computational Neuroscience
• Complex Systems

Background:

• Lévy walks are characterized by intermittent motion with variable step sizes, observed in animal foraging and other biological systems.
• Non-Brownian, superdiffusive random walks, Lévy walks differ from standard diffusion models.

Purpose of the Study:

• To investigate whether Lévy walk dynamics describe oscillatory activity patterns in the primate cerebral cortex.
• To explore the implications of Lévy walk dynamics for cortical computation and information processing.

Main Methods:

• Empirical observation of high-frequency (gamma band) local field potential activity in the visual motion-processing area MT of marmoset monkeys.
• Biophysically realistic circuit modeling to explain the emergence of Lévy walk dynamics.

Main Results:

• Gamma band activity in the primate cortex is organized into localized burst patterns that propagate across the cortical surface with Lévy walk dynamics.
• These dynamics involve large steps, enabling rapid movement of activity patterns across cortical modules, distinct from global synchronization or regular waves.
• The observed dynamics arise from critical-state transitions between asynchronous and localized propagating wave states.

Conclusions:

• Lévy walk dynamics represent a previously undiscovered mode of brain activity in the primate cortex.
• This mode implies a novel mechanism for cortical computation, potentially enabling efficient spatial sampling and processing of variable inputs.
• The findings suggest Lévy walk dynamics may facilitate the cortex's ability to link activity patterns across sparsely spiking neuronal populations.