Brain connectomics: time for molecular imaging?
Brain connectomics is a major concept in the field of neuroscience. According to this concept, cognitive functions can be understood by studying communication between different elements of the brain, such as brain regions. In an opinion of the Molecular Connectivity Working Group (MCWG), an international consortium of neuroimaging scientists, this communication, or connectivity, can be effectively investigated with a molecular imaging technique called positron emission tomography.
Connectomics studies how brain regions communicate with one another. Communication, or connectivity, between brain regions can be estimated using neuroimaging. Now, an opinion paper by an international consortium of researchers from Belgium, Germany, Italy, Sweden, UK, USA and Australia, argues for the need of a paradigmatic shift within the field.
Arianna Sala, a post-doctoral researcher at GIGA Consciousness (University of Liège) and Centre du Cerveau2 (University Hospital of Liège, CHU) who is leading the study, explains: “Brain activity emerges from a complex interplay of biochemical and electrical signaling, so that one method cannot completely characterize the diversity of the inter-regional brain communication. Still, around 2/3 of the connectome studies rely on a single method of functional magnetic resonance imaging.”
The opinion paper calls neuroscientists to action, arguing for the need of integrating measures of positron emission tomography into the discipline of connectomics. This molecular imaging technique allows to measure dozens of different molecules that are important for the brain, like, for example, chemical messengers called neurotransmitters . “Currently, we know very little about chemical substrates of the brain communication.” The biological information derived from positron emission tomography would change this situation. “For example, we could potentially tell which brain region is initiating communication with the other, if the communication is stimulatory (activating) or suppressing (deactivating), and we could point at a responsible neurotransmitter. This would allow us to get to an unprecedented level of biological detail in characterizing the human connectome.”
To facilitate this line of research, referred to as ‘molecular connectivity’, the article includes additional resources for the scientific community. “It took several months to summarize information on suitable programs, publicly accessible data sets including images from 33.063 subjects, and studies on molecular connectivity.” The resources will be kept up to date and made available soon on the website of the MCWG.
“We hope this paper and these resources will boost the interest in ‘molecular connectivity’. Many things need to be done to bring this approach to maturity, an effort that our working group will keep promoting with standardization and validation initiatives, open science practices and educational activities”.
Applications to join the initiative as a volunteer are still open.