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Brainwave Abnormality Could Be Common to Parkinson’s Disease, Tinnitus, Depression

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A brainwave abnormality could be a common link between Parkinson’s disease, neuropathic pain, tinnitus, and depression—a link that authors of a new study suggest could lead to treatment for all four conditions.

Dr Sven Vanneste, an associate professor in the School of Behavioral and Brain Sciences at The University of Texas at Dallas, is one of three authors of a paper in the journal Nature Communications regarding thalamocortical dysrhythmia (TCD), a theory that ties a disruption of brainwave activity to the symptoms of a wide range of neurological disorders, The University of Texas announced.

Dr Sven Vanneste, associate professor in the School of Behavioral and Brain Sciences.

Dr Sven Vanneste, associate professor in the School of Behavioral and Brain Sciences.

Vanneste and his colleagues—Dr Jae-Jin Song of South Korea’s Seoul National University and Dr Dirk De Ridder of New Zealand’s University of Otago—analyzed electroencephalograph (EEG) and functional brain mapping data from more than 500 people to create what Vanneste believes is the largest experimental evaluation of TCD, which was first proposed in a paper published in 1996.

“We fed all the data into the computer model, which picked up the brain signals that TCD says would predict if someone has a particular disorder,” Vanneste said. “Not only did the program provide the results TCD predicted, we also added a spatial feature to it. Depending on the disease, different areas of the brain become involved.”

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The strength of our paper is that we have a large enough data sample to show that TCD could be an explanation for several neurological diseases.

Brainwaves are the rapid-fire rhythmic fluctuations of electric voltage between parts of the brain. The defining characteristics of TCD begin with a drop in brainwave frequency—from alpha waves to theta waves when the subject is at rest—in the thalamus, one of two regions of the brain that relays sensory impulses to the cerebral cortex, which then processes those impulses as touch, pain, or temperature.

A key property of alpha waves is to induce thalamic lateral inhibition, which means that specific neurons can quiet the activity of adjacent neurons. Slower theta waves lack this muting effect, leaving neighboring cells able to be more active. This activity level creates the characteristic abnormal rhythm of TCD.

“Because you have less input, the area surrounding these neurons becomes a halo of gamma hyperactivity that projects to the cortex, which is what we pick up in the brain mapping,” Vanneste said.

While the signature alpha reduction to theta is present in each disorder examined in the study—Parkinson’s, pain, tinnitus, and depression—the location of the anomaly indicates which disorder is occurring.

“If it’s in the auditory cortex, it’s going to be tinnitus; if it’s in the somatosensory cortex, it will be pain,” Vanneste explained. “If it’s in the motor cortex, it could be Parkinson’s; if it’s in deeper layers, it could be depression. In each case, the data show the exact same wavelength variation—that’s what these pathologies have in common. You always see the same pattern.”

EEG data from 541 subjects was used. About half were healthy control subjects, while the remainder were patients with tinnitus, chronic pain, Parkinson’s disease, or major depression. The scale and diversity of this study’s data set are what set it apart from prior research efforts.

“Over the past 20 years, there have been pain researchers observing a pattern for pain, or tinnitus researchers doing the same for tinnitus,” Vanneste said. “But no one combined the different disorders to say, ‘What’s the difference between these diseases in terms of brainwaves, and what do they have in common?’ The strength of our paper is that we have a large enough data sample to show that TCD could be an explanation for several neurological diseases.”

With these results in hand, the next step could be a treatment study based on vagus nerve stimulation—a therapy being pioneered by Vanneste and his colleagues at the Texas Biomedical Device Center at UT Dallas. A different follow-up study will examine a new range of psychiatric diseases to see if they could also be tied to TCD. Tinnitus, is thought to be connected.

For now, Vanneste is glad to see this decades-old idea coming into focus and suggest that Tinnitus is getting better understood,.

“More and more people agree that something like thalamocortical dysrhythmia exists,” he said. “From here, we hope to stimulate specific brain areas involved in these diseases at alpha frequencies to normalize the brainwaves again. We have a rationale that we believe will make this type of tinnitus therapy work.”

The research was funded by the National Research Foundation of Korea(NRF) and the Seoul National University Bundang Hospital.

Original Paper: Vanneste S, Song J-J, De Ridder D. Thalamocortical dysrhythmia detected by machine learning. Nature Communications. 2018;9(1103)

Source: Nature Communications, University of Texas at Dallas, Tinnitus.

Image: University of Texas at Dallas

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Neurofeedback May Reduce Severity of Tinnitus, Study Shows

Neurofeedback May Reduce Severity of Tinnitus, Study Shows

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Researchers using functional MRI (fMRI) have found that neurofeedback training has the potential to reduce the severity of tinnitus or even eliminate it, according to a study presented at the annual meeting of the Radiological Society of North America (RSNA), the international society of radiologists, medical physicists, and other medical professionals announced on its website.

sherwood_fig_1

The standard approach to fMRI neurofeedback.

 Tinnitus is the perception of noise, often ringing, in the ear. The condition is very common, affecting approximately one in five people. As sufferers start to focus on it more, they become more frustrated and anxious, which in turn makes the noise seem worse. The primary auditory cortex, the part of the brain where auditory input is processed, has been implicated in tinnitus-related distress.

For the study, researchers looked at a novel potential way to treat tinnitus by having people use neurofeedback training to turn their focus away from the sounds in their ears. Neurofeedback is a way of training the brain by allowing an individual to view some type of external indicator of brain activity and attempt to exert control over it.

“The idea is that in people with tinnitus there is an over-attention drawn to the auditory cortex, making it more active than in a healthy person,” said Matthew S. Sherwood, PhD, research engineer and adjunct faculty in the Department of Biomedical, Industrial, and Human Factors Engineering at Wright State University in Fairborn, Ohio. “Our hope is that tinnitus sufferers could use neurofeedback to divert attention away from their tinnitus and possibly make it go away.”

Matthew S. Sherwood, PhD

Matthew S. Sherwood, PhD

To determine the potential efficacy of this approach, the researchers had 18 healthy volunteers with normal hearing undergo five fMRI-neurofeedback training sessions. Study participants were given earplugs through which white noise could be introduced for periods of time. The earplugs also served to block out the scanner noise.

sherwood_fig_2

Overview of the experimental design. Each participant completed 5 sessions.

To obtain fMRI results, the researchers used single-shot echo planar imaging, an MRI technique that is sensitive to blood oxygen levels, providing an indirect measure of brain activity.

“We started with alternating periods of sound and no sound in order to create a map of the brain and find areas that produced the highest activity during the sound phase,”  Sherwood said. “Then we selected the voxels that were heavily activated when sound was being played.”

The volunteers then participated in the fMRI-neurofeedback training phase while inside the MRI scanner. They received white noise through their earplugs and were able to view the activity in their primary auditory cortex as a bar on a screen. Each fMRI-neurofeedback training run contained eight blocks separated into a 30-second “relax” period followed by a 30-second “lower” period. Participants were instructed to watch the bar during the relax period and actively attempt to lower it by decreasing primary auditory cortex activity during the lower phase.

Neurofeedback training paradigm.

Neurofeedback training paradigm.

The researchers gave the participants techniques to help them do this, such as trying to divert attention from sound to other sensations like touch and sight.

“Many focused on breathing because it gave them a feeling of control,” Sherwood said. “By diverting their attention away from sound, the participants’ auditory cortex activity went down, and the signal we were measuring also went down.”

A control group of nine individuals were provided sham neurofeedback—they performed the same tasks as the other group, but the feedback came not from them but from a random participant. By performing the exact same procedures with both groups using either real or sham neurofeedback, the researchers were able to distinguish the effect of real neurofeedback on control of the primary auditory cortex.

Control over the primary auditory cortex (A1 control) separated by group and session. The experimental group was found to have significantly higher control, averaged across training, than the control group.

Control over the primary auditory cortex (A1 control) separated by group and session. The experimental group was found to have significantly higher control, averaged across training, than the control group.

Whole brain effects of neurofeedback training.

Whole brain effects of neurofeedback training.

Effect of emotion on attention. Emotional distractors resulted in a significantly larger change in response latency in the experimental group when compared to the control group. However, the impact of emotion on attention was not found to change significantly between the groups across training.

Effect of emotion on attention. Emotional distractors resulted in a significantly larger change in response latency in the experimental group when compared to the control group. However, the impact of emotion on attention was not found to change significantly between the groups across training.

Activation of the primary auditory cortex in response to binaural stimulation. Activation significantly decreased from session 1 to session 5.

Activation of the primary auditory cortex in response to binaural stimulation. Activation significantly decreased from session 1 to session 5.

Improvements in control over the primary auditory cortex were found to be significantly related to decreases in the effect of emotion on attention.

Improvements in control over the primary auditory cortex were found to be significantly related to decreases in the effect of emotion on attention.

The study reportedly represents the first time fMRI-neurofeedback training has been applied to demonstrate that there is a significant relationship between control of the primary auditory cortex and attentional processes. This is important to therapeutic development, Sherwood said, as the neural mechanisms of tinnitus are unknown but likely related to attention.

The results represent a promising avenue of research that could lead to improvements in other areas of health like pain management, according to Sherwood.

“Ultimately, we’d like take what we learned from MRI and develop a neurofeedback program that doesn’t require MRI to use, such as an app or home-based therapy that could apply to tinnitus and other conditions,” he said.

Co-authors are Emily E. Diller, MS; Subhashini Ganapathy, PhD; Jeremy Nelson, PhD; and Jason G. Parker, PhD. This material is based on research sponsored by the US Air Force under agreement number FA8650-16-2-6702. The views expressed are those of the authors and do not reflect the official views or policy of the Department of Defense and its Components. The US Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright notation thereon. The voluntary, fully informed consent of the subjects used in this research was obtained as required by 32 CFR 219 and DODI 3216.02_AFI 40-402.

Source: RSNA

Images: RSNA