Mind mapping: White's what matters

The white stuff

 

Researchers in Europe have used an advanced MRI technique to build the first atlas of the microstructure of the white-matter of the human brain. The project has the potential to revolutionise neuroscience, medicine and our understanding of the human brain in the coming decades.

Participants in the CONNECT project from Denmark, France, Germany, Israel, Italy and the United Kingdom worked under the European Union's future and emerging technologies program and a grant of 2.4 million Euros during a three-year period and have now announced their conclusions. The team explains that the new atlas, which takes the notion of a mind map to a whole new material level, combines three-dimensional images from magnetic resonance imaging scans of one hundred volunteers with unprecedented detail and precision.

The work of computer scientist Daniel Alexander of University College London's Centre for Medical Image Computing (CMIC) was key to the development of modelling algorithms and using hardware (state-of-the-art parallel computing hardware, such as the Legion cluster (basically a farm of over 5000 computer processors) that allowed new imaging techniques to emerge from the project to facilitate the atlas' construction. "The imaging techniques reveal new information about brain structure that helps us understand how low-level cellular architecture relates to high-level thought processes," Alexander says.

Until now, biomedical researchers across the globe have relied on a brain atlas produced by painstaking and destructive histological methods on the brains of a few individuals who donated their bodies to science. The new atlas simulates the impossible process of painstakingly examining every square millimetre of brain tissue of which there are around 100 million per brain with a microscope, without requiring the brain to have been removed from the skull of the "volunteer".

Of particular note in the new atlas is that the mapping of microscopic features, such as average cell size, packing density, fibre diameter, within the brain's so-called white matter reveals details of the neuronal fibres that transmit information from region to region within the living brain. The team points out that the atlas will be useable even by non-experts so that physicians and medical researchers alike might exploit the wealth of knowledge contained within. Historically, one might say that neuroscience has focused on understanding the brain's grey matter and neurons. The grey matter is a major component of the central nervous system (CNS) and consists of neuronal cell bodies, dendrites and unmyelinated axons as well as glial cells and capillaries. The white matter contains mostly myelinated axon tracts and accounts for almost half the volume of the brain but has only recently become the subject of increased research interest as scientists recognise that it is anything but a passive component of the CNS but is actively involved in learning and brain function.

Mind map with a difference

Part of the reason white matter was less of a focus for research was perhaps more technical than a lack of interest. "MRI methods for probing white matter started to appear in the mid-1990s and have revealed a wealth of new information about brain anatomy and operation," Alexander told SpectroscopyNOW". However, the methods emerging from CONNECT take those techniques to a new level by allows scientists to probe specific features of cellular architecture that were not previously accessible through non-invasive techniques, he adds.

Time dependence of microstructures will now be a focus of research as neuroscientists search for the signature changes imprinted in the white matter microstructure by particular stimuli and experiences. There is also now the potential for studying how Alzheimer's disease or schizophrenia alter the microstructure of the white matter with a view to developing MRI as a diagnostic tool for such disorders and putatively discriminating between changes that are cause or effect and so perhaps allowing biomedical research to posit new ways to treat such problems.

The CONNECT coordinator is Yaniv Assaf of Tel-Aviv University, Israel, the three steering committee members are Yaniv, Alexander and Derek Jones of Cardiff University, UK.