Hierarchical distribution of connections represented in colours on the surface of a human brain. Credit: Varga, L et al & Cell Systems. License: CC BY.
A new study has paved the way for identifying more precise and sensitive brain biomarkers using advance MRI techniques.
Researchers from the Institute for Neurosciences (IN), a joint centre of the Spanish National Research Council (CSIC) and the Miguel Hernández University (UMH) of Elche, along with a team from the Transylvanian Institute of Neuroscience (Romania), and in collaboration with experts from the Universitat Politècnica de València, have developed an innovative approach to studying brain connections using functional magnetic resonance imaging (fMRI).
The work introduces a new way of understanding brain architecture through dynamic functional networks, challenging the traditional static approach.
The study has revealed that delays in communication between brain regions are crucial to understanding the organization of functional networks.
Unlike conventional methods that average a single static network, the team used an approach that studies the temporal evolution of connection strength, analysing their statistical distribution rather than their average activation. This has allowed them to discover a brain architecture that is both robust and dynamic.
Santiago Canals, who leads the Brain Networks Plasticity laboratory at the IN, said: “The connection speed between brain regions and integration times are variable, which introduces communication delays.
“Our objective has been to incorporate these delays into the analysis of functional connectivity to develop a more precise and sensitive method.”
Flexibility
The results of this research reveal the existence of a functional backbone formed by robust, delay-free interactions, complemented by a large number of weaker connections whose strength fluctuates over time, adding flexibility to the brain’s functional architecture.
Canals added: “This dynamic approach better captures the brain’s constantly changing reality. It has enabled us to obtain comparable results in rats, marmosets, and humans, with extraordinary consistency when the same subject is scanned repeatedly over time, which is uncommon in the field of magnetic resonance.”
One of the most significant discoveries of the study is the identification of the ‘backbone’ – a set of robust and stable functional connections that serve as the core of communication in the brain.
Although these connections represent less than 10% of all those studied, they play a crucial role in the overall cohesion of brain networks, maintaining robust connectivity that ensures efficient communication between different regions.
Canals stated: “Efficiency in network communication is dramatically reduced when these connections are compromised, underscoring their importance in the brain’s functional structure.
“Meanwhile, the weaker and more dynamic connections amplify the system’s potential functional states, providing flexibility.”
To conduct this study, scientists used fMRI data from rats, non-human primates, humans, and patients with alcohol use disorder. These findings open new avenues for identifying more precise and sensitive brain biomarkers capable of detecting subtle alterations in neuronal networks, which could have significant implications for diagnosing neuropsychiatric diseases.
The study is published in Cell Systems.
