Brain probe that softens after insertion causes less scarring

November 3, 2011

A hard probe inserted in the cerebral cortex of a rat model turns nearly as pliable as the surrounding gray matter in minutes, and induces less of the tough scarring that walls off hard probes that do not change, researchers at Case Western Reserve University have found.

In the first test of the nanocomposite inspired by the dynamic skin of the sea cucumber, the immune response differed compared to that of a metal probe, and appeared to enable the to heal faster.

The findings, which provide insights to the brain's responses to the mechanical mismatch between tissue and probe, are described in the online edition of the .

Brain probes are used to study and treat neurological disorders. But, wires or silicon materials being used damage surrounding tissue over time and accumulate scarring, because they are far harder than brain matter.

In this test, "The scar wall is more diffuse; the nanocomposite probe is not completely isolated in the same way a traditional stiff probe is," said Dustin Tyler, a professor of biomedical engineering and leader of the experiment.

The result may prove beneficial. Studies by others in the field indicate the greater the isolation, the less effective the probe is at recording and relaying .

Tyler worked with James P. Harris, a graduate student in biomedical engineering and the lead author on the paper; Professor Jeffery Capadona; Stuart J. Rowan, professor of macromolecular science and engineering, and former graduate student Kadhiravan Shanmuganathan; Robert H. Miller, professor of neurosciences at Case Western Reserve School of Medicine; Christoph Weder, formerly a professor of and engineering at Case Western Reserve and now at the University of Fribourg; and Harvard Neurology Professor and Research Fellow Brian C. Healy.

The new probe material is inspired by the skin of the , which is normally soft and flexible, but becomes rigid for its own defense within seconds of being touched. These changing mechanical properties may improve our interaction with our brain, Tyler said.

In the nanocomposite, short polymer chains are linked together in a network mesh to make the material rigid, which is necessary for insertion into the cortex. In the presence of water, the mesh begin unlinking in seconds, changing to a soft, rubbery material designed to cause less damage to surrounding brain tissue over time.

To test the effects of the changing mechanical properties, metal probes were coated in a think layer of nanocomposite materal. When both were implanted into the brain, the chemical properties as seen by the brain were these same, but the were very different.

Four weeks after implantation, the density of neuronal nuclei adjacent to the new probe was significantly higher than surrounding the traditional probe.

At eight weeks, the density of nuclei had increased around the wire probe to equal the density around the flexible probe, which remained unchanged.

"One hypothesis is that the soft material allows the brain to recover more quickly," Tyler said. "Both probes cause the same insult to the tissue when inserted."

But, testing for scar components at 8 weeks showed that although the thickness of scar surrounding the metal probe had shrunk, the scar was denser and more complete than that around the nanocomposite probe. This dense scar separated the stiff probe from the brain more than the loose tissue around the more flexible probe.

The researchers are now comparing the impacts of the two probes at longer time intervals and testing for more indicators of the immune response, Harris said.

"We're trying to better understand the nuances regarding the response to the nanocomposite and how it would improve recordings."

More information: stacks.iop.org/1741-2552/8/066011

Related Stories

Recommended for you

The neural codes for body movements

July 21, 2017
A small patch of neurons in the brain can encode the movements of many body parts, according to researchers in the laboratory of Caltech's Richard Andersen, James G. Boswell Professor of Neuroscience, Tianqiao and Chrissy ...

Faulty support cells disrupt communication in brains of people with schizophrenia

July 20, 2017
New research has identified the culprit behind the wiring problems in the brains of people with schizophrenia. When researchers transplanted human brain cells generated from individuals diagnosed with childhood-onset schizophrenia ...

Scientists discover combined sensory map for heat, humidity in fly brain

July 20, 2017
Northwestern University neuroscientists now can visualize how fruit flies sense and process humidity and temperature together through a "sensory map" within their brains, according to new research.

Scientists reveal how patterns of brain activity direct specific body movements

July 20, 2017
New research by Columbia scientists offers fresh insight into how the brain tells the body to move, from simple behaviors like walking, to trained movements that may take years to master. The discovery in mice advances knowledge ...

Team traces masculinization in mice to estrogen receptor in inhibitory neurons

July 20, 2017
Researchers at Cold Spring Harbor Laboratory (CSHL) have opened a black box in the brain whose contents explain one of the remarkable yet mysterious facts of life.

Speech language therapy delivered through the Internet leads to similar improvements as in-person treatment

July 20, 2017
Telerehabilitation helps healthcare professionals reach more patients in need, but some worry it doesn't offer the same quality of care as in-person treatment. This isn't the case, according to recent research by Baycrest.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.