Brain songs framework used for discovering the relevant timescale of the human brain

Abstract

A key unresolved problem in neuroscience is to determine the relevant timescale for understanding spatiotemporal dynamics across the whole brain. While resting state fMRI reveals networks at an ultraslow timescale (below 0.1 Hz), other neuroimaging modalities such as MEG and EEG suggest that much faster timescales may be equally or more relevant for discovering spatiotemporal structure. Here, we introduce a novel way to generate whole-brain neural dynamical activity at the millisecond scale from fMRI signals. This method allows us to study the different timescales through binning the output of the model. These timescales can then be investigated using a method (poetically named brain songs) to extract the spacetime motifs at a given timescale. Using independent measures of entropy and hierarchy to characterize the richness of the dynamical repertoire, we show that both methods find a similar optimum at a timescale of around 200 ms in resting state and in task data.

Resolving the connectome – Spectrally-specific functional connectivity networks and their distinct contributions to behaviour

“…The difference in the modulation of envelope dynamics and the absence of clear spectrally confined effects also touches upon another recent discussion -the debate of dominant neuronal time scales in the human brain. One of the studies supporting such a view suggests that there is evidence for the existence of neuronal processes with life-times on the order of 200 milliseconds 46 , using computational modelling of the neuronal responses underlying the relatively sluggish fMRI time-series. Other studies, using temporally highly resolved MEG data used statistical models such as Hidden-Markov-Modeling to infer life-times of neuronal states hidden in resting state time-series 47,48 .…”

Revisiting the Global Workspace: Orchestration of the functional hierarchical organisation of the human brain

“…The transition to this state of high correlated activity is very fast and leads to amplification of local neural activation and the subsequent ignition of multiple distant areas. We have not studied ignition here since the fast timescale (typically about 100-200 ms) is difficult to capture with fMRI -although we have recently shown that such fast timescales can be reconstructed using appropriate whole-brain modelling (Deco et al, 2019b). Yet, the potential role of ignition in initiating and sustaining FRIC and the global workspace should clearly be further investigated in future studies using for example MEG.…”

“…Traditionally, whole-brain models have been relatively successful in linking structural connectivity with functional dynamics (Breakspear, 2017;Deco and Kringelbach, 2014). This has revealed important new mechanistic principles of brain function (Deco et al, 2018;Deco et al, 2019a;Deco et al, 2019b;Deco et al, 2017e;Honey et al, 2007). Nevertheless, the present causal characterisation of whole-brain information flow offers a new avenue for generating even more useful models.…”

Making of the mind

“…Conscious awareness is associated with the increased ability of the brain to sustain a rich repertoire of dynamic neural patterns and maximise the global entropy rate. A resting‐state study by Deco et al found that the optimal timescale for brain processing, namely broadcasting and the availability of information, was around 200 milliseconds. This is sustained by a set of brain regions or dynamical workspace of binding nodes which is also in line with other theories of consciousness, such as the integrated information theory of consciousness.…”