Mapping Serotonergic Dynamics using Drug-Modulated Molecular Connectivity

Understanding the complex workings of the brain is one of the most significant challenges in neuroscience, providing insights into the healthy brain, diseases, and the effects of potential therapeutics. A major challenge in this field is the limitations of traditional brain imaging techniques, which often deliver only a part of the complex puzzle of brain function. Our research employs a novel approach named “Molecular Connectivity” (MC), which merges the strengths of various imaging methods to offer a comprehensive view of how molecules interact within the brain and affect its function.

This innovative technique bridges the gap between functional magnetic resonance imaging (fMRI), known for its ability to monitor brain activity by tracking blood flow, and positron emission tomography (PET), which can depict specific molecular changes. By integrating these methods, we can better understand the far-reaching impacts of drugs on the brain. Our study focuses on the application of dynamic [ ¹¹ C]DASB PET scans to map the distribution of serotonin transporters, a key player in regulating mood and emotions, and examines how these are altered following the use of methylenedioxymethamphetamine (MDMA), commonly known as ecstasy.

Through a detailed analysis comparing MC with traditional measures of brain connectivity, we uncover significant patterns that closely align with physiological changes. Our results reveal clear changes in molecular connectivity after a single dose of MDMA, establishing a direct link between the drug’s effects on serotonin transporter occupancy and changes in the brain’s functional network.

This work not only offers a novel methodology for the in-depth study of brain function at the molecular level but also opens new pathways for understanding how drugs modulate brain activity.