title: The Foraging Brain: Evidence of Lévy Dynamics in Brain Networks.
abstract: In this research we have analyzed functional magnetic resonance imaging (fMRI) signals of different networks in the brain under resting state condition. To such end, the dynamics of signal variation, have been conceived as a stochastic motion, namely it has been modelled through a generalized Langevin stochastic differential equation, which combines a deterministic drift component with a stochastic component where the Gaussian noise source has been replaced with α-stable noise. The parameters of the deterministic and stochastic parts of the model have been fitted from fluctuating data. Results show that the deterministic part is characterized by a simple, linear decreasing trend, and, most important, the α-stable noise, at varying characteristic index α, is the source of a spectrum of activity modes across the networks, from those originated by classic Gaussian noise (α = 2), to longer tailed behaviors generated by the more general Lévy noise (1 ≤ α < 2). Lévy motion is a specific instance of scale-free behavior, it is a source of anomalous diffusion and it has been related to many aspects of human cognition, such as information foraging through memory retrieval or visual exploration. Finally, some conclusions have been drawn on the functional significance of the dynamics corresponding to different α values.
authors: Focus Lab, Department of Psychology, University of Turin, Turin, Italy.|GCS-fMRI, Koelliker Hospital, Turin, Italy.
authors: Tommaso
authors: T
authors: Costa
authors: PHuSe Lab, Department of Computer Science, University of Milan, Milan, Italy.
authors: Giuseppe
authors: http://orcid.org/0000-0002-5572-0924
authors: G
authors: Boccignone
authors: Focus Lab, Department of Psychology, University of Turin, Turin, Italy.|GCS-fMRI, Koelliker Hospital, Turin, Italy.
authors: Franco
authors: F
authors: Cauda
authors: Department of Physics, University of Turin, Turin, Italy.
authors: Mario
authors: M
authors: Ferraro
mesh_terms: D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008959:Models, Neurological; D009415:Nerve Net / Q000000981:diagnostic imaging / Q000502:physiology*; D012146:Rest / Q000502:physiology