BrainHub scientists visualize basal ganglia pathway

Carnegie Mellon researchers have used neuro-imaging to show the major pathways of the basal ganglia, a portion of the brain responsible for motion.  (credit: Patrick Beukema) Carnegie Mellon researchers have used neuro-imaging to show the major pathways of the basal ganglia, a portion of the brain responsible for motion. (credit: Patrick Beukema)

Neurological diseases, such as Parkinson’s and Huntington’s disease, affect millions of people worldwide, making them ideal targets for future research. In the United States alone, Huntington’s disease affects nearly 30,000 people, according to the Family Caregiver Alliance, while Parkinson’s affects approximately one million, according to the Parkinson’s Disease Foundation. The prevalence of these diseases provides a clear motive for understanding the neurology behind the disorders. BrainHub researchers from Carnegie Mellon University and the University of Pittsburgh have developed a way to visualize parts of the basal ganglia, which could eventually help track the progression of diseases like Parkinson’s or Huntington’s.

The basal ganglia, the part of the brain that is responsible for movement, is made up of four interconnected sections that, when damaged, can lead to diseases such as Parkinson’s or Huntington’s. “For reasons that are not fully understood, these connections are highly susceptible to damage and, because they are important for motor control, this damage can result in substantial motor deficits,” said Patrick Beukema, a graduate student in the Center for Neuroscience at the University of Pittsburgh (CNUP) and the Center for the Basis of Neural Cognition (CNBC), a joint program between Carnegie Mellon and the University of Pittsburgh. The research team also included Timothy Verstynen, an assistant professor of psychology at Carnegie Mellon and CNBC faculty member, and Fang-Cheng Yeh, a postdoctoral researcher in Carnegie Mellon’s psychology department and the CNBC.

These basal ganglia pathways have traditionally been challenging to study. “Clinically, it is difficult to see the pathways within the basal ganglia with neuroimaging techniques, like the ever popular MRI, because many of the fiber bundles that make up key parts of this circuit are very small and buried within areas of dense cell bodies,” Beukema said. “Specifically, many of these fibers are nestled within a set of nuclei that are known collectively as the globus pallidus, or just the pallidum for short.” In order to combat this issue, the team turned to diffusion MRI, a non-invasive neuro-imaging technique that measures the movement of water molecules and creates a visual depiction of the brain’s physical connections, called axons. Two types of diffusion imaging, diffusion spectrum imaging and multi-shell imaging, were used to scan the brains of healthy individuals. The team found that not only could they detect the small fibers of the basal ganglia using diffusion imaging, but they could also distinguish between small components of the brain, specifically the internal and external global pallidus.

“Both of these findings suggest that the diffusion signal might serve as a marker of the collective health of key basal ganglia pathways and potentially be used to track the progression of diseases like Parkinson’s or Huntington’s disease,” Beukema said.

He also noted the potential for future research stemming from their results. “This work, of course, raises more questions than it answers. One question is whether or not this technique is sensitive enough to be used as the foundation for a novel in-vivo biomarker of the health of these pathways in disease,” Beukema said. He also noted the necessity of testing new techniques in patient populations, as opposed to healthy individuals. “The pathways that Patrick has been able to visualize are critical to so many functions, yet we haven’t been able to see them in the living human brain before,” Verstynen said in a university press release. “This opens the door to so many research and clinical opportunities.”

The team’s research, which was published in NeuroImage, was funded by a National Science Foundation BIG DATA grant, the Army Research Laboratory, and the CNUP. The research also benefitted from open access data provided by Washington University, the University of Minnesota, and Oxford University, known as the WU-Minn HCP consortium.