Using a portable device developed at Drexel University, researchers at Albert Einstein College of Medicine have identified differences in brain activation patterns associated with postural stability in people with Parkinsonian syndromes and healthy adults. The findings, published recently in Brain Research, describe the critical role of the prefrontal cortex in balance control and may have implications with respect to detecting and treating Parkinsonian symptoms in the elderly.
Parkinson’s disease is a neurological disorder that arises when brain cells that control movement die, leaving many patients in the late stages of the disease unable to take a few steps before falling. Parkinsonian syndromes, which are common in older adults, are conditions that do not rise to a Parkinson’s diagnosis but encompass many symptoms of the disease, like rigidity, tremor and difficulty walking.
Past attempts to compare brain activity and stability in people with Parkinsonian syndromes have been limited, because neuroimaging tools could only be used when a study participant was lying flat, rather than walking or standing. In these cases, the person undergoing the brain scan could only imagine that he or she was performing the tasks.
A portable system created by researchers in Drexel’s School of Biomedical Engineering and Health Systems overcomes this challenge. It has allowed scientists, for the first time, to better understand the role of the brain’s prefrontal cortex during standing and walking.
The device employs functional near-infrared, or fNIR, spectroscopy, which uses light to monitor changes in blood oxygenation in the brain as individuals perform tasks, take tests or receive stimulation. The prefrontal cortex is the area responsible for higher-level processing, such as memory, attention, problem solving and decision-making. When a person is learning a new skill, for instance, neural activity is greater in this region.
Unlike fMRI (functional magnetic resonance imaging), the fNIR system is fully portable: Participants wear a headband, allowing them to talk and move around while a computer collects data in real time.
“Postural instability is a major risk factor for older adults. If we can monitor the cognitive component of staying balanced, then this could eventually lead to better treatment options for people with Parkinsonian syndromes or even Parkinson’s disease,” said Meltem Izzetoglu, PhD, an assistant research professor of biomedical engineering at Drexel who co-authored the study.
Researchers at Albert Einstein College of Medicine used the fNIR technology to compare 126 healthy adults to 117 individuals with mild Parkinson’s symptoms and 26 with more severe symptoms. While wearing the fNIR headband, the participants were asked to stand and look straight ahead while counting for 10 seconds. They then walked on a mat that captured their gait speed, pace and stride length. The fNIR system recorded their brain oxygen levels during the entire testing period.
The researchers found that those with Parkinsonian symptoms demonstrated significantly higher prefrontal oxygenation levels to maintain stability when standing than participants with mild and no symptoms.
“In fact, brain activity in the frontal brain region was nearly twice as large,” said Jeannette R. Mahoney, PhD, assistant professor of neurology at Einstein and the study’s lead author.
The prefrontal cortex, highlighted in red, is responsible for high-level functions like memory, attention and problem solving. Credit: Life Science Databases.
“This initial study allowed us to measure brain activity in real-time, in a realistic setting. It shows that there are indeed differences in the prefrontal cortex of healthy and Parkinsonian syndrome patients, and those differences relate to their performance in maintaining stability while standing,” Izzetoglu said. “It opens up new fields of research.”
In an upcoming clinical trial, the researchers will use a computerized cognitive training program and the fNIR system to identify how cognitive training affects brain activation during walking.
The portable technology could aid in diagnosing Parkinsonian syndromes or developing interventions.
“Our goal is to be able to intervene with Parkinsonian symptoms and develop novel remediation in the not-so-distant future to improve elders’ quality of life,” Mahoney said.
About this neurology research
Funding: This research was supported with funding from the National Institute of Aging.
Source: Lauren Ingeno – Drexel University
Image Source: The image is credited to Life Science Databases
Original Research: Abstract for “The role of prefrontal cortex during postural control in Parkinsonian syndromes a functional near-infrared spectroscopy study” by Jeannette R. Mahoney, Roee Holtzer, Meltem Izzetoglu, Vance Zemon, Joe Verghese, and Gilles Allali in Brain Research. Published online November 6 2015 doi:10.1016/j.brainres.2015.10.053
The role of prefrontal cortex during postural control in Parkinsonian syndromes a functional near-infrared spectroscopy study
Postural instability represents a main source of disability in Parkinsonian syndromes and its pathophysiology is poorly understood. Indirect probes (i.e., mental imagery) of brain involvement support the role of prefrontal cortex as a key cortical region for postural control in older adults with and without Parkinsonian syndromes. Using functional near infrared spectroscopy (fNIRs) as a direct online cortical probe, this study aimed to compare neural activation patterns in prefrontal cortex, postural stability, and their respective interactions, in (1) patients with Parkinsonian syndromes; (2) those with mild parkinsonian signs; (3) and healthy older adults. Among 269 non-demented older adults (76.41±6.70 years, 56% women), 26 individuals presented with Parkinsonian syndromes (Unified Parkinson’s disease rating scale (UPDRS): 11.08±3.60), 117 had mild parkinsonian signs (UPDRS: 3.21±2.49), and 126 individuals were included as a healthy control group. Participants were asked to stand upright and count silently for ten seconds while changes in oxygenated hemoglobin levels over prefrontal cortex were measured using fNIRs. We simultaneously evaluated postural stability with center of pressure velocity data recorded on an instrumented walkway. Compared to healthy controls and patients with mild parkinsonian signs, patients with Parkinsonian syndromes demonstrated significantly higher prefrontal oxygenation levels to maintain postural stability. The pattern of brain activation and postural control of participants with mild parkinsonian signs were similar to that of normal controls. These findings highlight the online role of the prefrontal cortex in postural control in patients with Parkinsonian syndromes and afford the opportunity to improve therapeutic options for postural instability.
“The role of prefrontal cortex during postural control in Parkinsonian syndromes a functional near-infrared spectroscopy study” by Jeannette R. Mahoney, Roee Holtzer, Meltem Izzetoglu, Vance Zemon, Joe Verghese, and Gilles Allali in Brain Research. Published online November 6 2015 doi:10.1016/j.brainres.2015.10.053
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