Community Research and Development Information Service - CORDIS


INTERACTIONS — Result In Brief

Project ID: 331800
Funded under: FP7-PEOPLE
Country: Spain

External stimuli and their effect on brain activity

Neuroscientists have used classical electroencephalography (EEG) to register electrical activity in the brain and functional magnetic resonance imaging (fMRI) to look into the brain and detect where this activity occurs. With this information researchers were able to use computer models to investigate the communication pathways between distant regions of the brain.
External stimuli and their effect on brain activity
Studies of communication networks can help to increase our understanding of how the brain works. It has been discovered that regions of the brain are compartmentalised into modules, regions of densely interconnected groups, which are less connected with other regions in other groups. This division helps in segregating these parts of the brain with a specialised function, but does not explain where information from various senses is combined and integrated.

The presence of highly connected regions of the brain, known as hubs, may be the missing piece in the puzzle. These hubs, which span their connections across different specialised modules, could "listen" to the information from different sensory modalities and share it with the other hubs. The implications of this were investigated by the EU-funded INTERACTIONS (Investigation of the interaction between external stimulation and ongoing brain activity in cortical networks: analysis, modeling and empirical corroboration) project.

Researchers investigated the structural connectivity of the brains of cats, macaque monkeys and humans to develop dynamical models that simulate their activity. The results were compared with empirical observations of the human brain’s dynamics using fMRI data. It was found that the class of hierarchical structures to which the brain belong, in which both modular organization and hubs are combined, are the best structures for hosting complex dynamical processes in comparison with other hierarchical structures. In other words, a randomly connected brain would be unable to categorise the external information it receives, while a brain formed by perfect modules could not "make sense" of that information.

INTERACTIONS also set out to discover what kind of dynamical system the brain is. Researchers therefore investigated fMRI of healthy subjects at rest to determine if the brain's dynamical activity randomly wanders exploring the vast amount of states it can access, or if it limits itself to a finite set of states. The latter case is detectable if the system returns over time to states it has already visited before.

Results indicated that the brain dynamics are partially recurrent favouring a rich but finite set of states despite the almost infinite number of possible states it could set itself into. This robust, yet flexible dynamical behaviour, is supported by the underlying physical network of connections which is hierarchically organised into modules of specialised brain regions interconnected via hub regions.

INTERACTIONS developed computational tools to analyse complex networks. The project’s results will deepen our understanding about the organisation of the brain, its dynamical behaviour and how models are created to reproduce its activity.

Related information


Electroencephalography, brain, functional magnetic resonance imaging, communication pathways, multisensory integration, hierarchical networks, hubs
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