With nearly 100 billion neurons and 10,000 billion synapses per square centimeter, the brain defies science with its complexity. After centuries of thinking about the brain with nothing but their own, today researchers call increasingly upon technology. Progress in our understanding has been swift. The Fundamental Research Division develops imaging methods and animal models to visualize the brain, both healthy and diseased, particularly using positron emission tomography (PET) and magnetic resonance imaging (MRI), supported by the physical phenomenon of nuclear magnetic resonance (NMR).
Valette is one of CEA’s neuroscience explorers, but this “technophile” never imagined himself as one. “I was headed for industry, probably aerospace,” he says. So what explains his arrival at CEA? “My goal was to find a line of work that called on cutting-edge physics, mathematics and abstraction.” Also interested in the complexity of the brain’s twists and turns, he took an internship at the Service Hospitalier Frédéric Joliot in Orsay.
“That internship, which involved applying NMR to study the brain’s metabolism, stirred something in me,” he says. “I abandoned industry to work on a thesis because NMR spectroscopy brings together everything I like, plus the adventure of research.”
Today in charge of an NMR group at the Fontenay-aux-Roses center, Valette thinks the technique has enormous potential. “We can innovate constantly, change the machine’s parameters to adapt it to what we want to observe. Depending on how we prepare the magnetization, we have access to different physical phenomena: diffusion, chemical exchanges, etc.” In this way, RMN allows researchers to determine the number, nature and properties of molecules present in a predetermined part of the brain, and in a noninvasive way, in a live, conscious organism.
Scientists use this technique to better understand the development of neurodegenerative diseases. “We’ve perfected an original method for characterizing viscosity in neurons, a parameter susceptible to change in patients afflicted with Alzheimer’s or Huntington’s disease,” explains Valette. “This change appears to be due to an accumulation of proteins that slows intracellular diffusion.” His team also works on neuron morphology, which changes when cells are suffering. “While we may be far from applications for the ill, we would like to detect ‘neuronal suffering’ in order to, one day, be able to make early diagnosis of neurodegenerative diseases, well before the appearance of clinical symptoms.” The road ahead is still long, but the development of high-field devices will increase result precision and accuracy. It is one step closer to finding the “Holy Grail” of diagnostics.