A novel calcium-based MRI sensor will allow for more sensitive brain imaging by tracking calcium ions to monitor deep neural activity, according to research out of the Massachusetts Institute of Technology (MIT).
Research led by MIT professor Alan P. Jasanoff, PhD, found that because calcium ions are linked to neuronal firing, tracking their movement could help clinicians link specific brain functions to their neuronal activity patterns. This is unlike traditional MRI, Jasanoff said in a release, which relies on an indirect signal detected by changes in blood flow.
“Concentrations of calcium ions are closely correlated with signaling events in the nervous system,” Jasanoff said. “We designed a probe with a molecular architecture that can sense relatively subtle changes in extracellular calcium that are correlated with neural activity.”
The sensor Jasanoff’s team designed comprises two types of particles—the calcium-binding protein synaptotagmin and a magnetic iron oxide nanoparticle—that cluster together when near calcium, according to the release. The nanoparticle can only bind to synaptotagmin in the presence of calcium, and calcium binding ultimately clumps the particles together, making them appear darker on an MRI scan. Clinicians can then identify physical areas with high and low calcium to determine where in the brain neurons are firing electric impulses.
Jasanoff and his colleagues tested their method in rats, injecting the calcium sensors into the rodents’ striatum and following that with a chemical stimulus to induce short bouts of neural activity. Within seconds of initial brain stimulation, the researchers reported, the calcium sensors reflected activity. The sensor also picked up activity induced by stimulation in parts of the brain involved in reward, they said.
The technique shows promise in mapping neural activity in the brain with more precision than ever before, but Jasanoff and his team want to speed up the process in the future. They said they’re also working to modify the sensor so it can cover more of the brain and pass through the blood-brain barrier.
“You could imagine measuring calcium activity in different parts of the brain and trying to determine, for instance, how different types of sensory stimuli are encoded in different ways by the spatial pattern of neural activity that they induce,” Jasanoff said.
After graduating from Indiana University-Bloomington with a bachelor’s in journalism, Anicka joined TriMed’s Chicago team in 2017 covering cardiology. Close to her heart is long-form journalism, Pilot G-2 pens, dark chocolate and her dog Harper Lee.