Nav: Home

New brain mapping tool produces higher resolution data during brain surgery

May 24, 2017

Researchers have developed a new device to map the brain during surgery and distinguish between healthy and diseased tissues. The device provides higher resolution neural readings than existing tools used in the clinic and could enable doctors to perform safer, more precise brain surgeries.

The device is an improved version of a clinical tool called an electrode grid, which is a plastic or silicone-based grid of electrodes that is placed directly on the surface of the brain during surgery to monitor the activity of large groups of neurons. Neurosurgeons use electrode grids to identify which areas of the brain are diseased in order to avoid damaging or removing healthy, functional tissue during operations. Despite their wide use, electrode grids have remained bulky and have not experienced any major advances over the last 20 years.

The new electrode grid, developed by a team of researchers at the University of California San Diego and Massachusetts General Hospital, is about a thousand times thinner -- 6 micrometers versus several millimeters thick -- than clinical electrode grids. This allows it to conform better to the intricately curved surface of the brain and obtain better readings. The new electrode grid also contains a much higher density of electrodes -- spaced 25 times closer than those in clinical electrode grids -- enabling it to generate higher resolution recordings.

"Our goal is to develop a tool that can obtain more reliable information from the surface of the brain," said electrical engineering professor Shadi Dayeh, who co-led the study with neuroscience professor Eric Halgren and electrical engineering professor Vikash Gilja, all at UC San Diego. The project was funded by the Center for Brain Activity Mapping (CBAM) at UC San Diego and brought together experts from multiple fields, including neurosurgeons, neuroscientists, electrical engineers, materials scientists and experts in systems integration. Researchers published their work on May 12 in Advanced Functional Materials.

"By providing higher resolution views of the human brain, this technology can improve clinical practices and could lead to high performance brain machine interfaces," Gilja said.

To make their high resolution electrode grid, researchers had to find a way to shrink the size of the electrodes to pack them closer together. But with metal electrodes, which are typically used to make these grids, there is a tradeoff -- shrinking their size increases their electrical resistance, resulting in more noisy readings.

To overcome this problem, the team switched out the metal electrodes with ones made of a conductive polymer called PEDOT:PSS. The material is transparent, thin and flexible. Using this material enabled researchers to make smaller electrodes without sacrificing electrochemical performance. It also enhanced the richness of the information measured from the surface of the brain.

"These electrodes occupy minuscule volumes -- imagine Saran wrap, but thinner. And we demonstrate that they can capture neural activity from the human brain at least as well as conventional electrodes that are orders of magnitude larger," Gilja said.

Researchers worked with neurosurgeons at Thornton Hospital at UC San Diego and Brigham Women's Hospital in Boston to test their grid on four patients. The PEDOT:PSS electrode grid and a standard clinical electrode grid were compared side by side. In standard clinical recordings, the PEDOT:PSS electrode grid either performed similarly or slightly better than the standard electrode grid, recording with lower noise and higher resolution.

"In order to introduce a new electrode grid for clinical use, we first need to show that the device can yield the same information as that used in the clinic. Then we can build upon that work to make an even better product that can improve patient care," Dayeh said.

In one test, the team performed background readings of a patient's brain waves both while the patient was awake and unconscious. The PEDOT:PSS electrode grid produced similar readings as the standard clinical electrode grid. In another test, the team monitored the brain activity of a patient undergoing epilepsy surgery. Both electrode grids identified normal functioning areas of the brain versus where the seizures were happening. The main difference is that the PEDOT:PSS electrode grid produced more detailed and higher resolution readings than the clinical electrode grid.

Other tests monitored the brain activity of patients performing cognitive tasks. Patients were either shown a particular word or a picture illustrating that word. The word was afterwards recited to the patients. In the readings from both the PEDOT:PSS and standard electrode grids, researchers could differentiate between when the patients were hearing the word versus when they were seeing it (or a picture). "This experiment shows we can resolve functional and cognitive activity from the surface of the brain using these electrodes," Dayeh said.

The team's next steps are to make higher density electrode grids for improved resolution and biocompatibility tests to see how long they can stay in the body before they experience biofouling.
-end-
Paper title: "Development and Translation of PEDOT:PSS Microelectrodes for Intraoperative Monitoring," by Mehran Ganji*, Erik Kaestner*, John Hermiz*, Nick Rogers, Atsunori Tanaka, Daniel Cleary, Sang Heon Lee, Joseph Snider, Bob S. Carter, David Barba, Vikash Gilja, Eric Halgren and Shadi A. Dayeh at UC San Diego; Milan Halgren at Massachusetts General Hospital; Garth Rees Cosgrove and Sydney S. Cash at Brigham and Women's Hospital, Boston, Massachusetts; and Ilke Uguz and George G. Malliaras at CMP-EMSE, Gardanne, France.

*These authors contributed equally to this work.

This work was supported by the Center for Brain Activity Mapping (CBAM) at UC San Diego. The authors acknowledge faculty start-up support from the Department of Electrical and Computer Engineering at UC San Diego. Partial support is also acknowledged from the National Science Foundation (grant no. ECCS-1351980), the University of California Multicampus Research Programs and Initiatives (UC MRPI, grant no. MR-15-328909), and the Office of Naval Research (grant no. N00014-13-1-0672). This work was performed in part at UC San Diego's Nano3 nanofabrication cleanroom facility, part of the San Diego Nanotechnology Infrastructure, a member of the National Nanotechnology Coordinated Infrastructure, which is supported by the National Science Foundation.

University of California - San Diego

Related Brain Activity Articles:

Studies of brain activity aren't as useful as scientists thought
Hundreds of published studies over the last decade have claimed it's possible to predict an individual's patterns of thoughts and feelings by scanning their brain in an MRI machine as they perform some mental tasks.
A child's brain activity reveals their memory ability
A child's unique brain activity reveals how good their memories are, according to research recently published in JNeurosci.
How dopamine drives brain activity
Using a specialized magnetic resonance imaging (MRI) sensor that can track dopamine levels, MIT neuroscientists have discovered how dopamine released deep within the brain influences distant brain regions.
Brain activity intensity drives need for sleep
The intensity of brain activity during the day, notwithstanding how long we've been awake, appears to increase our need for sleep, according to a new UCL study in zebrafish, published in Neuron.
Do babies like yawning? Evidence from brain activity
Contagious yawning is observed in many mammals, but there is no such report in human babies.
Understanding brain activity when you name what you see
Using complex statistical methods and fast measurement techniques, researchers found how the brain network comes up with the right word and enables us to say it.
Your brain activity can be used to measure how well you understand a concept
As students learn a new concept, measuring how well they grasp it has often depended on traditional paper and pencil tests.
Altered brain activity in antisocial teenagers
Teenage girls with problematic social behavior display reduced brain activity and weaker connectivity between the brain regions implicated in emotion regulation.
Gender impacts brain activity in alcoholics
Compared to alcoholic women, alcoholic men have more diminished brain activity in areas responsible for emotional processing (limbic regions including the amygdala and hippocampus), as well as memory and social processing (cortical regions including the superior frontal and supramarginal regions) among other functions.
Light, physical activity reduces brain aging
Incremental physical activity, even at light intensity, is associated with larger brain volume and healthy brain aging.
More Brain Activity News and Brain Activity Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Meditations on Loneliness
Original broadcast date: April 24, 2020. We're a social species now living in isolation. But loneliness was a problem well before this era of social distancing. This hour, TED speakers explore how we can live and make peace with loneliness. Guests on the show include author and illustrator Jonny Sun, psychologist Susan Pinker, architect Grace Kim, and writer Suleika Jaouad.
Now Playing: Science for the People

#565 The Great Wide Indoors
We're all spending a bit more time indoors this summer than we probably figured. But did you ever stop to think about why the places we live and work as designed the way they are? And how they could be designed better? We're talking with Emily Anthes about her new book "The Great Indoors: The Surprising Science of how Buildings Shape our Behavior, Health and Happiness".
Now Playing: Radiolab

The Third. A TED Talk.
Jad gives a TED talk about his life as a journalist and how Radiolab has evolved over the years. Here's how TED described it:How do you end a story? Host of Radiolab Jad Abumrad tells how his search for an answer led him home to the mountains of Tennessee, where he met an unexpected teacher: Dolly Parton.Jad Nicholas Abumrad is a Lebanese-American radio host, composer and producer. He is the founder of the syndicated public radio program Radiolab, which is broadcast on over 600 radio stations nationwide and is downloaded more than 120 million times a year as a podcast. He also created More Perfect, a podcast that tells the stories behind the Supreme Court's most famous decisions. And most recently, Dolly Parton's America, a nine-episode podcast exploring the life and times of the iconic country music star. Abumrad has received three Peabody Awards and was named a MacArthur Fellow in 2011.