Cognitive recovery after brain damage more complex than realized

January, 2011

Two new studies show us that recovery after brain damage is not as simple as one region ‘taking over’ for another, and that some regions are more easily helped than others.

When stroke or brain injury damages a part of the brain controlling movement or sensation or language, other parts of the brain can learn to compensate for this damage. It’s been thought that this is a case of one region taking over the lost function. Two new studies show us the story is not so simple, and help us understand the limits of this plasticity.

In the first study, six stroke patients who have lost partial function in their prefrontal cortex, and six controls, were briefly shown a series of pictures to test the ability to remember images for a brief time (visual working memory) while electrodes recorded their EEGs. When the images were shown to the eye connected to the damaged hemisphere, the intact prefrontal cortex (that is, the one not in the hemisphere directly receiving that visual input) responded within 300 to 600 milliseconds.

Visual working memory involves a network of brain regions, of which the prefrontal cortex is one important element, and the basal ganglia, deep within the brain, are another. In the second study, the researchers extended the experiment to patients with damage not only to the prefrontal cortex, but also to the basal ganglia. Those with basal ganglia damage had problems with visual working memory no matter which part of the visual field was shown the image.

In other words, basal ganglia lesions caused a more broad network deficit, while prefrontal cortex lesions resulted in a more limited, and recoverable, deficit. The findings help us understand the different roles these brain regions play in attention, and emphasize how memory and attention are held in networks. They also show us that the plasticity compensating for brain damage is more dynamic and flexible than we realized, with intact regions stepping in on a case by case basis, very quickly, but only when the usual region fails.

Reference: 

[2034] Voytek, B., Davis M., Yago E., Barcel F., Vogel E. K., & Knight R. T.
(2010).  Dynamic Neuroplasticity after Human Prefrontal Cortex Damage.
Neuron. 68(3), 401 - 408.

[2033] Voytek, B., & Knight R. T.
(2010).  Prefrontal cortex and basal ganglia contributions to visual working memory.
Proceedings of the National Academy of Sciences. 107(42), 18167 - 18172.

Related News

Do older adults forget as much as they think, or is it rather that they ‘misremember’?

A small study has tested the eminent Donald Hebb’s hypothesis that visual imagery results from the reactivation of neural activity associated with viewing images, and that the re-enactment of eye-movement patterns helps both imagery and

A British study using data from 475,397 participants has shown that, on average, stronger people performed better across every test of brain functioning used.

In a series of experiments involving college students, drawing pictures was found to be the best strategy for remembering lists of words.

A study involving 18 volunteers who performed a simple orientation discrimination while on a stationary bicycle, has found that low-intensity exercise boosted activation in the visual cortex, compared with activation levels when at rest or during high-intensity exercise.

A small study involving 50 younger adults (18-35; average age 24) has found that those with a higher BMI performed significantly worse on a computerised memory test called the “Treasure Hunt Task”.

A small study that fitted 29 young adults (18-31) and 31 older adults (55-82) with a device that recorded steps taken and the vigor and speed with which they were made, has found that those older adults with a higher step rate performed better on memory tasks than those who were more sedentary.

The number of items a person can hold in short-term memory is strongly correlated with their IQ. But short-term memory has been recently found to vary along another dimension as well: some people remember (‘see’) the items in short-term memory more clearly and precisely than other people.

Organophosphate pesticides are the most widely used insecticides in the world; they are also (according to WHO), one of the most hazardous pesticides to vertebrate animals.

Spatial abilities have been shown to be important for achievement in STEM subjects (science, technology, engineering, math), but many people have felt that spatial skills are something you’re either born with or not.

Pages

Subscribe to Latest newsSubscribe to Latest newsSubscribe to Latest health newsSubscribe to Latest news