Brain-scale emergence of slow-wave synchrony and highly
responsive asynchronous states based on biologically realistic
population models simulated in The Virtual Brain.
Jennifer S. Goldman, Lionel Kusch, Bahar H. Yalcinkaya, Damien
Depannemaecker, Trang-Anh Nghiem, Viktor Jirsa and Alain Destexhe.
Understanding the many facets of the organization of brain dynamics
at large scales remains largely unexplored. Here, we construct a
brain-wide model based on recent progress in biologically-realistic
population models obtained using mean-field techniques. We use The
Virtual Brain (TVB) as a simulation platform and incorporate
mean-field models of networks of Adaptive Exponential (AdEx)
integrate-and-fire neurons. Such models can capture the main
intrinsic firing properties of central neurons, such as adaptation,
and also include the typical kinetics of postsynaptic conductances.
We hypothesize that such features are important to a biologically
realistic simulation of brain dynamics. The resulting ``TVB-AdEx''
model is shown here to generate two fundamental dynamical states,
asynchronous-irregular (AI) and Up-Down states, which correspond to
the asynchronous and synchronized dynamics of wakefulness and
slow-wave sleep, respectively. The synchrony of slow waves appear
as an emergent property at large scales, and reproduce the very
different patterns of functional connectivity found in slow-waves
compared to asynchronous states. Next, we simulated experiments
with transcranial magnetic stimulation (TMS) during asynchronous
and slow-wave states, and show that, like in experimental data, the
effect of the stimulation greatly depends on the activity state.
During slow waves, the response is strong but remains local, in
contrast with asynchronous states, where the response is weaker but
propagates across brain areas. To compare more quantitatively with
wake and slow-wave sleep states, we compute the perturbational
complexity index and show that it matches the value estimated from
TMS experiments. We conclude that the TVB-AdEx model replicates
some of the properties of synchrony and responsiveness seen in the
human brain, and is a promising tool to study spontaneous and
evoked large-scale dynamics in the normal, anesthetized or
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