Smooth-gradient fMRI technique could improve brain mapping during behavior

Researchers at the University of North Carolina at Chapel Hill (UNC-CH) have developed a new functional magnetic resonance imaging (fMRI) technique called SORDINO that could provide clearer and more precise brain mapping during behavior. Unlike conventional fMRI approaches that use the blood-oxygenation-level-dependent (BOLD) signal, which reflects changes in blood oxygen levels following neural activity, SORDINO spreads out the rapid gradient changes that occur in conventional methods over time.

This allows for a smoother gradient direction change, minimizing noise and interference that can compromise fMRI data. By collecting signals continuously during these gradual gradient changes, SORDINO reduces the time needed to prepare the functional contrast, increasing the amount of data collected. Researchers successfully used SORDINO to map brain-wide activity in rodents performing various behavioral tasks, such as reaching movements and social interactions.

Compared to conventional gradient-echo EPI and standard ZTE imaging, SORDINO showed several advantages, including being silent, sensitive, and specific while also overcoming common fMRI artifacts. The technique was shown to provide better sensitivity than gradient-echo EPI at matched spatiotemporal resolution and was compatible with multimodal experiments, such as electrode-based recordings and calcium imaging at cellular resolution.

Researchers also used SORDINO to track cerebrospinal fluid influx associated with glymphatic activity. The approach could be improved further and tested on larger animals or even humans. The researchers are actively sharing SORDINO with other neuroscientists and medical scientists for further testing and development.