Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Stroke: When the system fails for the second time

24.03.2020

It is now widely known that the brain is much more malleable than once thought. Even after stroke or brain injury the brain often succeeds finding a new balance between the failed regions and the functions they serve. Commonly, neighbouring regions are activated as well as homologues on the other side of the brain side. During language processing, the homologues of the left-dominant language areas are usually less active and are kept in check by the dominant half - until the emergency case occurs.

Until now, it was unclear whether these mechanisms also apply in the event of a second attack. Does the brain retain its capacity to adapt? This is important as up to 15 percent of those affected will have a second stroke. In addition, there was disagreement about whether an activated right brain is generally good for healing.


The second lesion, in which large parts of the left hemisphere are not working anymore (A, dark grey), increased the contribution of the right brain. The individual impairment predicted the activation on the right side (A, yellow). The stronger the fibre connection between the sister areas (B, red) on the right side, the less the patient was affected by the interruption on the left.

Credit: MPI CBS

Some studies suggest that involvement of the right hemisphere helps recovery, at least in the short term. Others had shown, however, that a loss of language areas in the left half can literally inhibit the right half. In that case the contribution of the right hemisphere has nothing to do with language and can cause confusion.

The brain gets out of step. Further, studies had also found that the patients are better off if the overactive half is restrained by inhibitory magnetic stimulation. The activity is more and more shifting back to the left hemisphere. It wins the upper hand again.

Scientists at the Max Planck Institute for Human Cognitive and Brain Sciences (MPI CBS) in Leipzig, Germany, have now found that the brain areas on the right side also become more active when there is a second injury in the left language areas.

"In the recovered brain, the right side's contribution was still little after the first impairment. After the second event, in which large parts of the left hemisphere are not working anymore, its role becomes much more important", explains Gesa Hartwigsen, research group leader at the MPI CBS and first author of the article, which has been published in the high-ranking, open access journal elife. "The second lesion increased the contribution of the right brain", Hartwigsen said.

The scientists examined these relationships using 12 patients in whom the regions for processing properties of sound in the left hemisphere were injured. The incident had happened to them at least six months prior. Their brain had the opportunity to regenerate and adapt to the new situation.

The researchers simulated the second disruption using so-called transcranial magnetic stimulation, which can be used to briefly halt certain areas of the brain through electrical stimuli. It can be used to simulate how the brain would react if certain areas actually fail due to a stroke or other events - and how this affects the ability to recognize sounds, for example. To do this, Hartwigsen and her team used a simple decision task. T

he participants heard the word "cat" and had to decide whether it consisted of one or two syllables. The individual impairment predicted the activation on the right side.The researchers also found that the stronger the fibre connection between the sister areas on the right side, the less the patient was affected by the interruption on the left.

"These results show that after large-scale disturbances, in which large parts of the left hemisphere no longer function as they should, the right hemisphere probably plays a beneficial role. Often, there is a lot of tissue in the left half of the brain that only works to a limited extent and needs support from the right side.

"Other studies show that recovery is helped when the activated right side later down regulates itself and thus contributes to normalization on the left side", said Hartwigsen. On the other hand, if the right half remains permanently up-regulated, healing is delayed.

Findings on how the damaged brain adapts to repeated injury could help to improve the therapy of stroke patients in the long term. "This may make it possible, at some point, to assess whether it would be more helpful to regulate specific areas up or down," says Hartwigsen, confidently.

Media Contact

Verena Mueller
verenamueller@cbs.mpg.de
49-341-994-02672

 @mpi_cbs

http://www.cbs.mpg.de/en 

Verena Mueller | EurekAlert!
Further information:
http://www.cbs.mpg.de/stroke-when-the-system-fails-for-the-second-time
http://dx.doi.org/10.7554/eLife.54277

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The spin state story: Observation of the quantum spin liquid state in novel material

New insight into the spin behavior in an exotic state of matter puts us closer to next-generation spintronic devices

Aside from the deep understanding of the natural world that quantum physics theory offers, scientists worldwide are working tirelessly to bring forth a...

Im Focus: Excitation of robust materials

Kiel physics team observed extremely fast electronic changes in real time in a special material class

In physics, they are currently the subject of intensive research; in electronics, they could enable completely new functions. So-called topological materials...

Im Focus: Electrons in the fast lane

Solar cells based on perovskite compounds could soon make electricity generation from sunlight even more efficient and cheaper. The laboratory efficiency of these perovskite solar cells already exceeds that of the well-known silicon solar cells. An international team led by Stefan Weber from the Max Planck Institute for Polymer Research (MPI-P) in Mainz has found microscopic structures in perovskite crystals that can guide the charge transport in the solar cell. Clever alignment of these "electron highways" could make perovskite solar cells even more powerful.

Solar cells convert sunlight into electricity. During this process, the electrons of the material inside the cell absorb the energy of the light....

Im Focus: The lightest electromagnetic shielding material in the world

Empa researchers have succeeded in applying aerogels to microelectronics: Aerogels based on cellulose nanofibers can effectively shield electromagnetic radiation over a wide frequency range – and they are unrivalled in terms of weight.

Electric motors and electronic devices generate electromagnetic fields that sometimes have to be shielded in order not to affect neighboring electronic...

Im Focus: Gentle wall contact – the right scenario for a fusion power plant

Quasi-continuous power exhaust developed as a wall-friendly method on ASDEX Upgrade

A promising operating mode for the plasma of a future power plant has been developed at the ASDEX Upgrade fusion device at Max Planck Institute for Plasma...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Contact Tracing Apps against COVID-19: German National Academy Leopoldina hosts international virtual panel discussion

07.07.2020 | Event News

International conference QuApps shows status quo of quantum technology

02.07.2020 | Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

 
Latest News

The spin state story: Observation of the quantum spin liquid state in novel material

09.07.2020 | Physics and Astronomy

New method for simulating yarn-cloth patterns to be unveiled at ACM SIGGRAPH

09.07.2020 | Information Technology

Stress testing 'coral in a box'

09.07.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>