Quantifying high-order interdependencies via multivariate extensions of the mutual information

Rosas, Fernando; Mediano, Pedro A. M.; Gastpar, Michael; Jensen, Henrik Jeldtoft

doi:10.1103/physreve.100.032305

Cited by 127 publications

(174 citation statements)

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“…Here we are describing in the connectome an organization that cannot be explained in terms of node-to-node relationships, similar to the description of interactions between more than a pair of nodes (high order interdependencies) using information theory tools [40,41].…”

Section: Discussionmentioning

confidence: 99%

Cortical ignition dynamics is tightly linked to the core organisation of the human connectome

Castro

El-Deredy

Battaglia

et al. 2020

Preprint

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The capability of cortical regions to flexibly sustain an "ignited" state of activity has been discussed in relation to conscious perception or hierarchical information processing. Here, we investigate how the intrinsic propensity of different regions to get ignited is determined by the specific topological organisation of the structural connectome. More specifically, we simulated the resting-state dynamics of mean-field whole-brain models and assessed how dynamic multistability and ignition differ between a reference model embedding a realistic human connectome, and alternative models based on a variety of randomised connectome ensembles.We found that the strength of global excitation needed to first trigger ignition in a subset of regions is substantially smaller for the model embedding the empirical human connectome.Furthermore, when increasing the strength of excitation, the propagation of ignition outside of this initial core -which is able to self-sustain its high activity-is way more gradual than for any of the randomised connectomes, allowing for graded control of the number of ignited regions. We explain both these assets in terms of the exceptional weighed core-shell organisation of the empirical connectome, speculating that this topology of human structural connectivity may be attuned to support an enhanced ignition dynamic. Author summaryThe activity of the cortex in mammals constantly fluctuates in relation to cognitive tasks, but also during rest. The ability of brain regions to display ignition, a fast transition from low to high activity is central for the emergence of conscious perception and decision making. Here, using a biophysically inspired model of cortical activity, we show how the structural organization of human cortex supports and constrains the rise of this ignited dynamics in spontaneous cortical activity. We found that the weighted core-shell organization of the human connectome allows for a uniquely graded ignition. This graded ignition implies a smooth control of the ignition in cortical areas tuned by the global excitability. The smooth control cannot be replicated by surrogate connectomes, even though they conserve key local or global network properties. Indeed, the first trigger of ignition in the human cortex has the lowest global excitability and corresponds with the strongest interconnected areas, the ignition core.Finally, we suggest developmental and evolutionary constraints of the mesoscale organization that support this enhanced ignition dynamics in cortical activity.

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Section: Discussionmentioning

confidence: 99%

Cortical ignition dynamics is tightly linked to the core organisation of the human connectome

Castro

El-Deredy

Battaglia

et al. 2020

Preprint

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“…Together, these results show that, once the receptor distribution is fixed, the network strength distribution is both necessary and sufficient to explain the entropic effects of 5HT2A-R activation. Of course, this is not to say that strength explains every aspect of 5HT2A-R action -other topological network features are known to mediate transitions of consciousness in other contexts, 24 and investigating which network properties explain high-order dynamical signatures 25 of psychedelics remains an exciting avenue of future work.…”

Section: The Specific Connectivity Strength Distribution Explains Relmentioning

confidence: 99%

“…However, it is known that some high-level subjective effects of psychedelics (such as complex imagery 7 and ego dissolution 28 ) are related to network, as opposed to single region, dynamics. Therefore, building a richer statistical description of the brain's dynamics using recent information-theoretic tools (such as multivariate extensions of mutual information 25 ) remains an exciting open problem.…”

Section: Current Limitations and Future Researchmentioning

confidence: 99%

A mechanistic model of the neural entropy increase elicited by psychedelic drugs

Herzog

Mediano

Rosas

et al. 2020

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Psychedelic drugs, including lysergic acid diethylamide (LSD) and other agonists of the serotonin 2A receptor (5HT2A-R), induce drastic changes in subjective experience, and provide a unique opportunity to study the neurobiological basis of consciousness. One of the most notable neurophysiological signatures of psychedelics, increased entropy in spontaneous neural activity, is thought to be of relevance to the psychedelic experience, encoding both acute alterations in consciousness and mediating long-term effects. However, no clear mechanistic explanation for this 'entropic' phenomenon has been put forward so far. We sought to do this here by building upon a recent whole-brain model of serotonergic neuromodulation, to study the entropic effects of 5HT2A-R activation. Our results reproduce the overall entropy increase observed in previous experiments in vivo, providing the first model-based explanation for this phenomenon. We also found that entropy changes were not uniform across the brain: entropy increased in some regions and decreased in others, suggesting a topographical reconfiguration mediated by 5HT2A-R activation. Interestingly, at the whole-brain level, this reconfiguration was not well explained by 5HT2A-R density, but related closely to the topological properties of the brain's anatomical connectivity. These results help us understand the mechanisms underlying the psychedelic state and, more generally, the pharmacological modulation of whole-brain activity.

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“…More formally, we say that [21]: Definition: A system of random variables is redundancydominated if Ω( 1 , … , ) > 0 and synergy-dominated if Ω( 1 , … , ) < 0.…”

Section: Definitionmentioning

confidence: 99%

“…[20] and study the effects of aging on the high-order interactions in the human brain, with a special focus on interdependencies between four or more brain regions. To this end, we employ the recently proposed O-Information [21], which can be considered to be revision of the measure of neural complexity proposed by Tononi, Sporns and Edelman [22] under the light of Partial Information Decomposition [23]. In particular, the O-Information captures the balance between redundancies and synergies in arbitrary sets of variables, thus extending the properties of the interaction information of three variables to larger sets [24].…”

Section: Introductionmentioning

confidence: 99%

High-order interdependencies in the aging brain

Gatica

Cofré

Mediano

et al. 2020

Preprint

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Brain interdependencies can be studied either from a structural/anatomical perspective ("structural connectivity", SC) or by considering statistical interdependencies ("functional connectivity", FC). Interestingly, while SC is typically pairwise (white-matter fibers start in a certain region and arrive at another), FC is not; however, most FC analyses focus only on pairwise statistics and neglect highorder interactions. A promising tool to study high-order interdependencies is the recently proposed O-Information, which can quantify the intrinsic statistical synergy and redundancy in groups of three or more interacting variables. In this paper we used the O-Information to investigate how high-order statistical interdependencies are affected by age. For this, we analised functional magnetic resonance imaging (fMRI) data at rest obtained from 164 healthy participants, ranging from 10 to 80 years old. Our results show that older subjects (age ranging from 60 to 80 years) exhibit a higher predominance of redundant dependencies than younger subjects; moreover, this effect seems to be pervasive, taking place at all interaction orders. Additionally, we found that these effects are highly heterogeneous across brain regions, and suggest the existence of a "redundancy core" formed by the prefrontal and motor cortices -thus involving functions such as working memory, executive and motor functions. Our methodology to assess high-order interdependencies in fMRI data has unlimited applications. The code to calculate these metrics is freely available.

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Quantifying high-order interdependencies via multivariate extensions of the mutual information

Cited by 127 publications

References 50 publications

Cortical ignition dynamics is tightly linked to the core organisation of the human connectome

Cortical ignition dynamics is tightly linked to the core organisation of the human connectome

A mechanistic model of the neural entropy increase elicited by psychedelic drugs

High-order interdependencies in the aging brain

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