Snapshot: What is Transcranial Direct Current Stimulation (tDCS)?

Transcranial Direct Current Stimulation (tDCS) is a non-invasive method of brain stimulation. It promotes or inhibits activities in specific parts of the brain. tDCS is an experimental treatment that has been shown to result in changes in motor, cognitive and behavioural activities. It may be a valuable tool for the treatment of neurological disorders including cerebellar ataxia.

How it works

Neurons communicate with each other is through an electrical event called the action potential. The cell membrane of neurons can create differences in the concentration of charged molecules, called ions, inside and outside the cell. This separation of ions creates a voltage called the membrane potential. When a signal needs to be transduced to other neurons, a series of voltage changes in the membrane potential called the action potential occurs. The action potential propagates along the arms of the neuron, like sending a message through the cell. Once the message reaches the end of the arm where it meets up with other neurons, the initial neuron releases its neurotransmitters that deliver the message to the next neuron. And thus, the cycle continues!

tDCS works by stimulating the neurons with a weak electrical current, through electrodes placed on the scalp of the patient. These electrodes can slightly increase or decrease the resting membrane potential. This process can make it easier or harder for an action potential to occur. This either promotes or inhibits activities in specific brain regions.

Artist's depiction fo the human brain. Electrical energy is swirling around it.
tDCS is a non-invasive method of brain stimulation that promotes or inhibits activities in specific parts of the brain. Photo used under license by Andrus Ciprian/Shutterstock.com.

Application in ataxia

Due to the ability of tDCS to reversibly modulate brain activity, clinical trials have been conducted in many neurological and psychiatric disorders. Notably, a randomized, double-blind trial in 61 patients with multiple subtypes of ataxia came to completion in March 2021. After treatment with tDCS, a significant improvement in both the motor and cognitive symptoms of ataxia was observed. Patients also self-reported improvement in quality of life. The clinical assessment for motor functions was done through the scale for the assessment and rating of ataxia and the international cooperative ataxia rating scale. Assessment for cognitive functions was done through the cerebellar cognitive affective syndrome scale.

The study found that patients who went through two repeated treatment sessions with ten weeks in between had significantly better improvement when compared to patients who went through only one session of treatment. Also, the improvements persisted on average 3 to 6 months post-treatment. This means that the benefits of tDCS might last longer than previously thought.

Risks and benefits

TDCS is considered non-invasive and since its initial application in 1998, no serious or ongoing side effects have been reported. Studies have also shown that the electrical current will not interfere with vital functions of the heart and the brain stem. However, tDCS is still in its infancy. More research needs to be conducted to improve our understanding of potential risks and benefits. Temporary side effects including a mild burning/itching sensation at the stimulation sites, headache, and moderate fatigue were reported in around 17% of the patients. On the flip side, the technique uses equipment that is available on the market for other medical purposes. This makes the procedure relatively inexpensive, easily administered, and using easily replaceable equipment. TDCS could also be used in combination with other treatment methods. However, more research on combination treatments needs to be conducted to test safety and effectiveness.

If you would like to learn more about Transcranial Direct Current Stimulation, take a look at these resources by Johns Hopkins Medicine and Neuromodec.

Snapshot written by Christina (Yi) Peng and edited by Dr. David Bushart.

Snapshot: What is Riluzole?

Riluzole, often sold under the trade name Rilutek, is a medication used for the treatment of amyotrophic lateral sclerosis (ALS). ALS is a fatal neurodegenerative disease that mainly affects neurons controlling muscle movements. The drug was approved by the FDA (1995), Health Canada (1997), and the European Commission (1996). It helps slow down disease progression and may extend patient survival. The medication is available in tablet and liquid form, generally well-tolerated. There are sometimes mild side effects, which may include loss of appetite, nausea, and abdominal pain.

Close up of a woman taking a pill with water
Riluzole has been used to treat ALS, and research has suggested it may also help with forms of ataxia. It is currently being tested in clinical trials. Photo used under license by fizkes/Shutterstock.com.

How does it work?

Exactly how Riluzole slows disease progression remains unknown. However, it is thought that its neuroprotective effects likely stem from reducing a phenomenon known as excitotoxicity.

Neurons communicate with each other through chemical messengers called neurotransmitters. The signalling of these messengers needs to be tightly controlled. Too little or too much signaling will disrupt normal functions of the brain and cause damage to cells. Excitotoxicity is the result of excessive signaling by glutamate, one of the most abundant neurotransmitters in the brain. Glutamate is also associated with many neurodegenerative diseases.

Riluzole prevents this excessive signaling through several mechanisms. It is hypothesized that the effectiveness of riluzole in ALS treatment is the result of this neuroprotective property.

Riluzole for Ataxia

The neuroprotective function of riluzole has been a point of interest for the treatment of other neurodegenerative diseases since its approval. Multiple clinical trials have been conducted for patients with neurodegenerative diseases including Parkinson’s disease, Huntington’s disease, multiple system atrophy, and ataxia.

In 2010, a pilot trial was conducted with 40 patients with cerebellar ataxia who showed a lower level of motor impairment, measured by the International Cooperative Ataxia Rating Scale. A follow-up trial was then performed in 2015 for 55 patients with spinocerebellar ataxia (SCA) or Friedreich’s ataxia. Similarly, patient impairment had improved by an alternative measurement using the Scale for the Assessment and Rating of Ataxia. These findings indicate the possibility of riluzole being an effective treatment for cerebellar ataxia. However, more long-term studies and ones that are specific to different types of SCA need to be conducted to confirm the results.

Riluzole in Development

Even though riluzole was discovered more than 25 years ago, variations of the drug are still under development. As ALS often affects a patient’s ability to swallow, a new formulation of riluzole that is absorbed by placing it under your tongue is being developed under the name Nurtec.

Another prodrug version of riluzole, named Troriluzole (BHV-4157), may be better absorbed by the body with fewer side effects. Troriluzole is currently in phase three clinical trial for patients with different types of SCA. The trial is expected to be complete by November 30, 2021, and will hopefully provide more insight into the effectiveness of Troriluzole in SCA patients.

If you would like to learn more about Riluzole, take a look at these resources by the ClinicalTrials.gov and the Mayo Clinic.

Snapshot written by Christina (Yi) Peng and edited by Terry Suk.

Snapshot: What is Cerebrospinal Fluid (CSF)?

Public transit may not be the first thing that comes to mind when we think about the brain, but it’s a great way to understand how all the parts of the central nervous system work together. Nutrients, hormones, and other important molecules (the passengers) need to get on and off at different stations to do their work. They might first stop at the large internal chambers within the brain, called ventricles. From the ventricles, they can get to the central canal in the spinal cord, as well as the subarachnoid space. The subarachnoid space is a space between two membranes that surround the brain and spinal cord. It provides a stable structure for a network of veins and arteries.

The passengers are shuttled from station to station by the cerebrospinal fluid (CSF), a clear, colourless fluid that provides the central nervous system with necessary nutrients and hormones while carrying away waste products. CSF also cushions the brain and spinal cord by circulating between layers of tissues surrounding them. The whole public transit system is enclosed: the subarachnoid space and the ventricles are connected to the central canal in the spinal cord, forming a single reservoir for CSF.

Cerebrospinal fluid written in colorful letters under a Stethoscope on wooden background
Photo used under license by Sohel Parvez Haque/Shutterstock.com.

CSF is made by the choroid plexus, a collection of tiny blood vessels called capillaries. Capillaries filter the blood and secrete it into the ventricles. When the pressure of CSF is less than the pressure in the capillaries, CSF flows out and into the ventricles. When the pressure of CSF is greater than that of the bloodstream, the extra fluid is absorbed from the subarachnoid space and into sinuses (large areas filled with blood), where it can flow into the surrounding veins. The blood supply in the central nervous system tightly regulates the movement of molecules or cells between the blood and brain. This blood-brain barrier is crucial for protecting the brain from toxins and pathogens. Dysfunction of this specific system contributes to the development of neurological diseases.

Anatomical labeled scheme with human head and inside of skull, including superior sigittal sinus, ventricles, arachnoid Villi and spinal cord central canal.
Structure of the ventricles and central canal components that contribute to the public transit system. Photo used under license by VectorMine/Shutterstock.com.

Why is CSF Important for Neurodegenerative Diseases?

In neurodegenerative diseases like Spinocerebellar Ataxias, CSF contains molecules that can be used as biomarkers. Biomarkers are disease-specific proteins that change in concentration depending on disease stages. Biomarkers provide information on disease progression, with or without the impact of therapeutics. They are also crucial for understanding how disease processes work and assist in developing treatments.

The development of intrathecal injections, injecting into the central canal for distribution to the central nervous system (for example, spinal anesthesia), has been monumental for administering drugs in neurodegenerative diseases. In other words, not only can the public transit system of the central nervous system be investigated to see what passengers are associated with the disease, but it can be used to deliver “medicine passengers” to the place where the disease occurs.

If you would like to learn more about Cerebrospinal Fluid, take a look at these resources by MedlinePlus and WebMD.

Snapshot written by Kaitlyn Neuman and edited by Dr. Tamara Maiuri.

Spotlight: The CMRR Ataxia Imaging Team

Location: University of Minnesota, MN, USA

Year Research Group Founded:  2008

What models and techniques do you use?

A photo of the CMRR Ataxia Imaging Team
A photo of the CMRR Ataxia Imaging Team in 2019. Front row, left to right – Diane Hutter, Christophe Lenglet (PI), Gulin Oz (PI), Katie Gundry, Jayashree Chandrasekaran Back row, left to right: Brian Hanna, James Joers, Pramod Pisharady, Kathryn France, Pierre-Gilles Henry (PI), Dinesh Deelchand, Young Woo Park, Isaac Adanyeguh (insert)

Research Group Focus

What shared research questions is your group investigating?

We use high field, multi-nuclear magnetic resonance imaging (MRI) and spectroscopy (MRS) to explore how diseases impact the central nervous system. These changes can be structural, functional, biochemical and metabolic alterations. For example, we apply advanced MRI and MRS methods in neurodegenerative diseases and diabetes.

We also lead efforts in research taking place at multiple different cities across the United States and the world. As you can imagine, studies spread out across such a big area require a lot of coordination and standardization. We design robust MRI and MRS methods to be used in clinical settings like these.

Another important question for our team is how early microstructural, chemical and functional changes can be detected in the brain and spinal cord by these advanced MR methods. We are interested in looking at these changes across all stages of disease.

Why does your group do this research?

The methods we use (MRI and MRS) can provide very helpful information to be used in clinical trials. These biomarkers we look at can provide quantitative information about how a disease is progressing or changing.

There is good evidence that subtle changes in the brain can be detected by these advanced MR technologies even before patients start having symptoms. If we better understand the earliest changes that are happening in the brain, this can in turn enable interventions at a very early stage. For example, we could treat people even before brain degeneration starts to take place.

Why did you form a research group connecting multiple labs?

We came together to form the CMRR Ataxia Imaging Team to benefit from our shared and complementary expertise, experience, and personnel. We can do more together than we could apart.

Are you recruiting human participants for research?

Yes, we are! We are looking for participants for multiple different studies. You can learn more about the research we are recruiting for at the following links: READISCA,  TRACK-FA, NAF Studies, and FARA Studies. More information is also available through the UMN Ataxia Center.

A photo of the CMRR Ataxia Imaging Team in 2016
A photo of the CMRR Ataxia Imaging Team in 2016, in front of the historic 4T scanner where the first functional MR images were obtained, in CMRR courtyard. Left to right – Christophe Lenglet (PI), Sarah Larson, Gulin Oz (PI), Dinesh Deelchand, Pierre-Gilles Henry (PI), James Joers, Diane Hutter

What Labs Make Up the CMRR Ataxia Imaging Team?

The Oz Lab

Principal Investigator:  Dr. Gulin Oz

Year Founded:  2006

Our focus is on MR spectroscopy, specifically neurochemistry and metabolism studies. We focus on spinocerebellar ataxias. Also, we have been leading MRS technology harmonization across different sites and vendors.

The Henry Lab

Principal Investigator: Dr. Pierre-Gilles Henry

Year Founded:  2006

We develop advanced methods for MR spectroscopy and motion correction. Then apply these new methods to the study of biochemistry and metabolism in the brain and spinal cord in various diseases. We have been working on ataxias since 2014.

Fun Fact about the Henry Lab: The French language can often be heard in discussions in our lab!

The Lenglet Lab

Principal Investigator:  Dr. Christophe Lenglet

Year Founded:  2011

We develop mathematical and computational strategies for human brain and spinal cord connectivity mapping. We do this using high field MRI. Our research aims at better understanding the central nervous system anatomical and functional connectivity. We are especially interested in looking at this in the context of neurological and neurodegenerative diseases.

Fun Fact

Members of our team have their roots in 7 countries (US, Turkey, France, India, Mauritius, South Korea, Ghana) and 4 continents (North America, Europe, Asia, Africa)

For More Information, check out the Center for Magnetic Resonance Research (CMRR) Website!


Written by Dr. Gulin Oz, Dr. Pierre-Gilles Henry, and Dr. Christophe Lenglet, Edited by Celeste Suart

Spotlight: The Kuo Lab

Principal Investigator: Dr. Sheng-Han Kuo

Location: Columbia University, New York, NY, United States

Year Founded:  2012

What disease areas do you research?

What models and techniques do you use?

Kuo Lab group photo.
This is a group picture of the Kuo Lab. From the left to right: Nadia Amokrane, Chi-Ying (Roy) Lin, Sara Radmard, Sheng-Han Kuo (PI), Chih-Chun (Charles) Lin, Odane Liu, Chun-Lun Ni , Meng-Ling Chen, Natasha Desai, David Ruff.

Research Focus

What is your research about?

We study how mishaps and damage in the cerebellum lead to the symptoms experienced by ataxia and tremor patients. By looking at human brains, as well as brains from mouse models, we study how different changes in brain structure can lead to symptoms. This includes how well different parts of the brain can communicate with each other.

Why do you do this research?

When you ask patients about the challenges living with ataxia or tremor, they will talk to you about their symptoms. Symptoms can make different activities of daily living very challenging! By connecting specific brain changes to specific symptoms, we want to develop treatment options that target specific diseases. By doing this, we hope to improve patient’s quality of life. 

Initiative for Columbia Ataxia and Tremor Logo. It is a circle containing a lion with its whiskers to look like a neuron

The Kuo lab is part of the Initiative for Columbia Ataxia and Tremor. It’s a new Initiative at Columbia University to bring a group of physicians, scientists, surgeons, and engineers to advance the knowledge of the cerebellum and to develop effective therapies for ataxia and tremor.

Are you recruiting human participants for research?

Yes, we are! We are looking for participants for clinical research and trials. You can learn more about the studies we are currently recruiting for at this link.

Fun Fact

In the Kuo Lab, we call ourselves “the Protector of the Cerebellum in New York City”.

For More Information, check out the Kuo Lab Website!

We are looking for new graduate students and postdoctoral researchers to join our team. If you are interested in our work, please reach out to us


Written by Dr. Sheng-Han Kuo, Edited by Celeste Suart