Sunday, 3rd October, 2010, 12h - 13h

How Local Network Oscillations lead to Functional Networks during Rest (workshop on multiscale simulations - 2nd Barcelona School on Biomedical Informatics)

Spatiotemporally organized spontaneous low-frequency (< 0.1 Hz) fluctuations have been revealed by the blood-oxygenation level-dependent (BOLD) fMRI signal during rest. Indeed, in the absence of a task, significant correlations between distinct anatomical regions are found. These correlations, referred to as functional connectivity (FC), yield large-scale maps constituting so-called resting-state networks (RSNs). Furthermore, direct measurements of the neuronal activity have revealed similar large-scale correlations, particularly in the slow fluctuations of the power of local field potential gamma frequency range oscillations. Nevertheless, the origin of this highly structured slow dynamics and its relationship with neural activity, particularly in the gamma frequency range, remains largely unknown. To address these questions, we defined a model of brain neural activity taking into account the long range connectivity together with their corresponding conduction delays and instantiating sustained gamma oscillations in the dynamics of its local nodes. We apply the model to the macaque and human measured structural connectivity. In the human case, we search for parameters such that the model best reproduces the human empirical FC obtained at the same nodes. The best agreement is found in a region of the parameter space where the network is globally in an incoherent state but where partial clusters of nodes tend to synchronize. Inside such clusters, the BOLD signal between nodes is found to be correlated, instantiating then RSNs. Between clusters, patterns of positive and negative correlations are found, as in experiments. These results are found to be robust to a number of model parameters.

Speaker: Gustavo Deco (Universitat Pompeu Fabra)

Room PRBB Auditorium