The Human Connectome Project (HCP) has started trials on volunteers with a state-of-the-art scanner.

New maps of the networks of live brains could lead to better treatments for neurological disorders

Today’s technology allows neuroscientists to map the brain’s connections on an unprecedented level of detail. The ultimate goal of the HCP is to create a map, or connectome, of every neuron and synapse to better understand how the brain works. A better understanding of the brain means a better understanding of brain disorders like schizophrenia or autism, which in turn means better treatment.

The diffusion-imaging scanner is built by Siemens, a German engineering company. It works by tracking water molecules as they travel through nerve fibers. This imaging technique results in a more precise picture of the brain’s neuronal pathways. Van J. Wedeen, director of Connectomics at the Martinos Center for Biomedical Imaging at Massachusetts General Hospital (MGH), explains how the scanner works. “The diffusion image is a map of the water diffusion which we then convert into a marker for the fiber pathways, we then reconstruct it through computer algorithms that explain the water diffusion that we have observed.”

The scanner looks just like an MRI machine, but the new technology inside enables it to produce images that are ten times clearer. “It’s the difference between looking at the bonnet (of a car) and looking at the gears and belts inside,” Van J. Wedeen says. The idea behind the new technique is to look at the brain relative to a coordinate system. The idea is akin to the difference in making a map with longitude and latitude versus without.

Wedeen and his colleague Bruce Rosen are excited about the potential data collected by this machine. Rosen, the director of the Martinos Center for Biological Imaging at MGH, sees the future of the scanner, saying “Over time, it’s clear that in addition to scanning normal volunteers, we’d be very interested in scanning patients with disease.  The tools we are developing, as well as many other scientists around the world mapping these brain circuits, may be fundamental to how we understand and conceptualize diseases and treat them. Once you understand that it’s an abnormality of specific circuits, it gives you clues in terms of the pharmacology you want to use depending on the part of the brain.”

Diseases like autism that are not well understood could be the result of abnormal brain connections called connectopathies, which could be more easily diagnosed with the knowledge provided by a connectome. Rosen hopes that eventually “we’ll be in a position to see if that’s true or not. And if it is, try to understand where it came from and try to fix it.”

Source: Mapping out a new era in brain research – CNN.com
Connectome Scanner Progress Report 2011 – Human Connectome Project
Further Reading: Connectome: How the Brain’s Wiring Makes Us Who We Are – Sebastian Seung

There are numerous brain imaging techniques that allow us to gain insight into what damage the brain may have incurred after a patient has a traumatic injury. The ever popular fMRI measures blood flow to infer neural activity. Diffusion tensor imaging (DTI) uses the magnetic properties of water to look at white matter in the brain, while positron emission tomography (PET) uses radiolabeling to look for a specific chemical in the brain. All of these are important for possible disease diagnosis, however, there is skepticism around how dependent we should be on this technology, as the results should never be taken as the absolute truth.

Comparison of X-Ray to HDFT

Now, a new type of brain imaging developed by researchers at the University of Pittsburgh allows researchers to look for connections that have been broken as a result of traumatic brain injury, much like an X-Ray allows doctors to look for broken bones. It is called High Definition Fiber Tracking (HDFT). Although the technology is not specific at the cellular level, it is accurate in observing specific connections that have been lost as a result of injury. These lost connections act as a reliable predictor for  cellular information, such as the percentage of axons that have been lost.

The accompanying publication in the Journal of Neurosurgery focuses on a case study of a man who sustained severe brain damage after crashing an all-terrain vehicle (public service announcement: this is why we wear helments!!!). Initial MRI scans showed hemorrhaging in the right basal ganglia, which was confirmed by a later DTI. The patient  had extreme difficulty moving the left side of his body, and it was assumed to be a result of damage to the basal ganglia. It was not until the patient had a HDFT test that doctors could pinpoint the true problem: fiber tracts innervating the motor cortex had been lost.

Above is a comparison of the techniques that the researchers saw. The first column consists of scans from a normal patient, while the second two columns are the brain injury patient 4 and 10 months post injury. The imaging techniques used are MRI, DTI, and HDFT. The HDFT gives a clearer picture of what specific connections in the brain have been lost.

The following image comparing DTI with HDFT also shows the inaccuracies of the older technologies.

In healthy subjects, the DTI shows connections and fiber tracks which do not correspond with what we know about brain anatomy, including false turns (deviations from the pathway), false continuations (midline crossing), and looping (travel in random directions). The HDFT scan is consistent with brain anatomy. Thus, the use of HDFT was essential in pinpointing exactly what connections had been lost as a result of the patient’s traumatic brain injury (see Figs 5 and 6 in accompanying paper, linked below).

HDFT has the potential to become the future of diagnoses in patients who have sustained traumatic brain injury, thus revolutionizing how we can treat these patients.

The following video shows a summary of the new technology in addition to the patient in the research paper’s case study:

New Brain Imaging Technique Reveals Damage Caused by TBI … -YouTube

Further videos and news releases are available on the HDFT lab website, linked below.

References:

Concept | HDFT – High Definition Fiber Tracking – HDFT

High-definition fiber tracking for assessment of neurological deficit in a case of traumatic brain injury: finding, visualizing, and interpreting small sites of damage. – Journal of Neurosurgery

New High Definition Fiber Tracking Reveals Damage Caused by Traumatic Brain Injury -University of Pittsburgh Medical Center