New noninvasive neuroimaging method for direct mapping of neuronal activity in a living mouse's brain

A new noninvasive neuroimaging method dubbed DIANA (direct imaging of neuronal activity) allows direct mapping of neuronal activity in a living mouse's brain at high resolution, researchers report.

According to the study authors, the ability to image neuronal activity directly and at such high spatial and temporal resolutions could open new avenues in brain science by providing a deeper understanding of the brain's functional organization at scales relevant to natural mental processes. The development of functional magnetic resonance imaging (fMRI) using the blood oxygenation level-dependent (BOLD) effect revolutionized our understanding of how the human brain and its cognitive functions operate.

However, like looking through a blurry lens, this noninvasive technique is limited by its ability to pinpoint the time and location of specific neuronal activation, largely due to its reliance on changes in blood oxygenation in the brain's complicated vascular architecture as an underlying proxy for neuronal activity. Phan Tan Toi and colleagues present DIANA, a method that allows for direct imaging of neuronal activity for fMRI.

According to Toi et al., DIANA provides a signal that reflects the intracellular voltage of a population of activating neurons with millisecond precision, thus overcoming the indirect physiological limitations of BOLD-fMRI. To demonstrate their approach, Toi et al. performed in vivo mouse imaging during whisker-pad stimulation in anesthetized mice, which allowed the detection of rapid sequential propagation of neuronal activity across functionally-defined neural pathways. In a related Perspective, Timo van Kerkoerle and Martijn Cloos highlight the potential and limitations of the new approach as well as the technical challenges that remain. "The ability of DIANA to lift the temporal and spatial hurdles that now limit BOLD-fMRI holds the exciting potential to reveal the detailed computational mechanisms of mental processing at the fast pace at which it unfolds," write Kerkoerle and Cloos.