MRI Sensor Detects Neural Activity Deep Within the Brain
A calcium-based MRI sensor enables more sensitive brain imaging and could reveal more about how the brain operates during different tasks.
Functional MRI measures blood flow in the brain as an indirect marker of neural activity. It’s a commonly used method for identifying parts of the brain that are active during particular behaviors, but it lacks specificity and detailed resolution.
Now, a team of scientists has developed a more direct way to image brain activity. The technique uses MRI to visualize the flow of calcium ions, a key part of the process that allows nerves to fire. As reported in the journal Nature Nanotechnology, the new technique can sense relatively subtle changes in extracellular calcium that are correlated with neural activity. It also allows much larger volumes of brain tissue to be analyzed than traditional MRI.
In tests in rats, the researchers demonstrated that their calcium sensor can accurately pick up changes in neural activity induced by chemical or electrical stimulation in a part of the brain called the striatum. Located deep within the brain, the striatum is involved in reward processing, planning movement and learning new behaviors.
Unlike blood flow, calcium ion flow is closely linked to the activity of individual neurons. Thus, this new type of imaging could allow more sensitive brain visualization than traditional functional MRI. The researchers hope that their new technique can be used to map patterns of neural activity with greater precision than is now possible and determine how distant brain regions communicate with one another during different tasks.