Toward in vivo nano-scale imaging of the brain

Fluorescence microscopy is an extremely powerful tool that has enabled scientists to study the dynamics of biological processes in vivo with molecular specificity. However, many important cellular and subcellular structures (such as synapses and spines in the brain) are not resolvable with traditional fluorescence techniques.


As it turns out, the so-called diffraction barrier of far-field (lens-based) optical microscopes can be overcome for nano-scale resolution. However, the usefulness of the methods was limited in the past by insufficient image quality deep inside living tissues. The EU-funded project 'Intravital optical super-resolution imaging in the brain' (BRAIN STED) developed a novel strategy for fluorescence imaging of nano-scale structures and dynamics of living cells and inside tissues, particularly in the brain.


The super-resolution microscope developed by BRAIN STED scientists was tested on living cell culture samples. It demonstrated competitive resolution, high image quality and capability of repeated imaging (to compare tissue changes after experimental manipulations). When tested on neuronal cells in cultured brain tissue and after compensation for optical aberrations, the technique produced high-resolution images of neurons deep within the tissue. Importantly, it enabled decoding the intricate three-dimensional structure of neurons in living tissue samples.


With resolving power not limited by the diffraction barrier the technology paves the way to observation of brain function and nano-scale structures also in living animals. It might in the future be incorporated in a miniaturized imaging device for in-vivo nanoscopy. The technology is likely to shed light on the molecular mechanisms of learning and memory. More generally, it could reveal important links between structure and function in virtually all cells and tissues in the body in health and disease. Further, the super-resolution technology will put the EU at the forefront of an important global market sector.