Better brain maps

August 15, 2011

Red and yellow indicate regions with high myelin levels; blue, purple and black areas have low myelin levels (credit: David Van Essen)

Researchers at the Washington University School of Medicine in St. Louis have developed a new technique that provides rapid access to brain landmarks formerly only available at autopsy.

Better brain maps will result in speeding up efforts to understand how the healthy brain works and potentially aiding in future diagnosis and treatment of brain disorders, the researchers said.

The technique combines data from two types of magnetic resonance imaging (MRI) scans.

It makes it possible for scientists to map myelination, the degree to which branches of brain cells are covered by a white sheath known as myelin, which speeds up long-distance signaling.

The technique was developed in part through the Human Connectome Project, a $30 million, five-year effort to map the brain’s wiring. Data on many subjects, acquired through many different analytical techniques, including myelination mapping, will help the resulting maps cover the range of anatomic variation present in humans.

Human Connectome Project (credit: Laboratory of Neuro Imaging, UCLA)

The researchers found that the highest myelination levels were in areas involved with early processing of information from the eyes and other sensory organs and with control of movement.

Many brain cells are packed into these regions, but the connections among the cells are less complex. Scientists suspect that these brain regions rely heavily on parallel processing: multiple separate teams of cells work simultaneously on different parts of a complex problem.

Areas with less myelin include brain regions are linked to speech, reasoning and use of tools. These regions have brain cells that are packed less densely, because individual cells are larger and have more complex connections with neighboring cells.

Myelin maps will provide important insights into where certain parts of the brain end and others begin. Easy access to detailed maps of myelination in humans and animals will also aid efforts to understand how the brain evolved and how it works, the researchers said.

Ref.: Glasser MF and Van Essen DC, Mapping human cortical areas in vivo based on myelin content as revealed by T1- and T2-weighted MRI, The Journal of Neuroscience, Aug. 10, 2011