Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Right side of brain learns language skills after stroke

26.09.2002


When a stroke affects the language areas in the left side of the brain, the right side takes over and learns how to perform language tasks, according to research at Washington University School of Medicine in St. Louis. The study found that patients’ right side of the brain is more active than normal during a verbal language task, and that the right side’s activity decreases with practice, similar to what happens on the left side of the brain in healthy individuals.



"This is the first demonstration that learning and, by extension, speech therapy change the way compensatory pathways in the brain work," says Maurizio Corbetta, M.D., head of stroke and brain injury rehabilitation. "This study supports the hypothesis that brain pathways in the right hemisphere are directly involved in the recovery of language after stroke."

The study appears in the Sept. 26 issue of the journal Neuron. Corbetta, the study’s senior author, also is associate professor of neurology, of radiology and of anatomy and neurobiology. The first author is Valeria Blasi, M.D., a former post-doctoral fellow in neurology at the School of Medicine, who now is at the San Raffaele Scientific Institute in Milan, Italy.


Each year, about 750,000 Americans suffer a loss of blood flow to the brain, a condition known as an ischemic stroke. Since the left side of the brain houses most of the areas responsible for speech and language, a left-sided stroke often causes language problems, a condition known as aphasia. About 1 million people in the United States have aphasia, resulting in an estimated $1.5 billion of lost productivity and other costs each year.

Remarkably, many of those who initially lose language abilities after a stroke significantly recover these abilities within six to 12 months. Several studies suggest that language recovery occurs because the right hemisphere of the brain compensates for the loss of the left hemisphere. For example, language abilities recovered after a stroke to the left hemisphere are lost again if the individual later has a stroke to the right hemisphere.

To test whether there is a direct link between recovered language abilities and activity in the right hemisphere, Corbetta’s team compared performance scores and brain images from 14 healthy individuals with those of eight stroke patients. The patients all had experienced a stroke at least six months before participating in the study and still had damage near a brain region called Broca’s area, located towards the front of the brain and thought to be involved in speech.

The team first measured the two groups’ performance while they learned a word-stem completion task. Participants saw three letters at a time and were asked to say a word that began with those three letters. For example, if they saw the letters "COU" they might say "cougar." Each word stem appeared several times during the experiment.

The patient group was slower and less accurate, but both groups learned and improved at the same rate. For example, each group was about 400 milliseconds faster on the seventh block of trials than on the first. Participants in each group also repeated the same answer for a given word stem about 20 percent of the time, a sign that they remembered the word and learned the answer.

The participants then performed the same task while the researchers took brain images using functional magnetic resonance imaging (fMRI). These images identify which brain regions are active during a given task.

The brain normally becomes less active as subjects practice. Because the task becomes familiar and easier, the brain does not have to work as hard. Brain activity decreases in areas that are important for performing the task. In this study, as healthy participants’ performance improved, language areas on the left side of the brain, including Broca’s area, became less active with practice. In addition, areas towards the back of the brain that are involved in vision became less active in both the left and right hemispheres.

Brain images from stroke patients revealed several differences. Language areas damaged by the stroke were not active during the language task. However, areas on the right side of the brain opposite the damaged areas on the left did become active during the task, and that activity decreased with practice. Visual areas on the right side also decreased with practice.

The team also noticed that patients with smaller lesions had slightly different patterns of brain activity. In addition to learning-related changes on the right side of the brain, the areas near the lesion on the left side also improved with practice. These patients also were better at learning the task and ultimately recovered more than the other stroke patients.

According to Corbetta, these results indicate that a stroke produces complex changes in the way both sides of the brain perform during language tasks. "The good news is that these new patterns of brain activity can change through practice, and that this correlates with improved performance," he says. "This information has direct implications for optimizing rehabilitation and pharmacological treatment after stroke."

Gila Z. Reckess | EurekAlert!
Further information:
http://medinfo.wustl.edu/

More articles from Health and Medicine:

nachricht Correct connections are crucial
26.06.2017 | Charité - Universitätsmedizin Berlin

nachricht One gene closer to regenerative therapy for muscular disorders
01.06.2017 | Cincinnati Children's Hospital Medical Center

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: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Study shines light on brain cells that coordinate movement

26.06.2017 | Life Sciences

Smooth propagation of spin waves using gold

26.06.2017 | Physics and Astronomy

Switchable DNA mini-machines store information

26.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>