Hope for stroke survivors? Implant that electric shocks the brain restored movement in rats’ arms and legs – paving the way to human trials
- Brain cells communicate with each other via electrical signals to control functions throughout the body
- The signals can become damaged after a stroke because blood flow to the brain is cut off
- Low-frequency brainwaves, which help fire neurons that control movement, were found to decrease after a stroke
- When scientists delivered an electric shock to rats, it activated the brainwaves that were in the area damaged by the stroke and improved movement
Stroke victims may be able to regain the use of their arms and legs from an implant that delivers electric shocks to the brain.
Using this technique, scientists from the University of California, San Francisco, were able to restore movement to rats struck down by the devastating condition.
Most stroke patients never fully recover with physical therapy being the only available treatment and one-third of all patients remaining virtually paralyzed.
The discovery could open the door to a new therapy that will give stroke patients the opportunity to avoid suffering potentially life-long disabilities including difficulty walking and communicating.
Stroke victims could soon get back the use of their arms and legs thanks to an implant that delivers electric shocks to the brain, a study from the University of California, San Francisco, has found
The brain cells communicate with each other via electrical signals to control functions throughout the body.
During a stroke, blood flow to an area of the brain is cut off. When this occurs, brain cells are deprived of oxygen and begin to die.
Every year, more than 795,000 Americans suffer a stroke, which is the leading cause of serious, long-term disability in the US.
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After suffering a stroke, those electrical signals can become damaged – leading to major movement and balance problems.
According to Dr Karunesh Ganguly, an associate professor of neurology at UC San Francisco, only about one-third of patients fully recover from a stroke.
WHAT IS A STROKE?
There are two kinds of strokes:
1. Ischemic Stroke
An ischemic stroke – which accounts for 75 percent of strokes – occurs when there is a blockage in a blood vessel that prevents blood from reaching part of the brain.
2. Hemorrhagic stroke
The more rare of the two, a hemorrhagic stroke occurs when a blood vessel bursts, flooding part of the brain with too much blood while depriving other areas of adequate blood supply.
The two types of hemorrhagic strokes are intracerebral (within the brain) hemorrhage or subarachnoid (area around the brain) hemorrhage.
Hemorrhagic strokes are responsible for about 40 percent of all stroke deaths.
These include: age, high blood pressure, smoking, obesity, sedentary lifestyle, diabetes, atrial fibrillation (irregular and rapid heart rate), family history and history of a previous stroke.
Signs and symptoms:
- Sudden numbness or weakness of the face, arm or leg, especially on one side of the body
- Sudden confusion, trouble speaking or understanding
- Sudden trouble seeing or blurred vision in one or both eyes
- Sudden trouble walking, dizziness, loss of balance or coordination
- Sudden severe headache with no known cause
Only about one-third of patients fully recover from a stoke.
One-third will have lifelong disabilities including difficulty walking, communicating, eating and completing everyday tasks or chores.
The last third will be practically paralyzed.
Once the clots are removed, physical therapy is the only form of treatment to help stroke patients recover more quickly.
However, if the brain damage is too substantial, it is not a viable option.
Source: American Stroke Association
One-third will have lifelong problems moving their limbs and the other third will be practically paralyzed.
For the last 20 years, neuroscientists have determined that patterns of neural activity in the central nervous system – called oscillations or brainwaves – are essential for healthy brain function.
In recent studies, low-frequency oscillations (LFOs) were found to help neurons fire in the brain’s primary motor cortex, which controls movement.
LFOs group the cells’ activity together to make sure that the execution of movement is efficient.
For the study, the scientists measured the brainwaves of rats as they reached out to take a food pellet. LFOs were detected before and as the action was performed.
The researchers stimulated a stroke within the rats, which impaired their movement, and found that LFOs decreased.
For the rats who recovered, gradually gaining back their movement, the LFOs increased, showing a correlation between recovery of function and the reemergence of LFOs.
Fully-recovered rats had stronger LFOs than those who partially recovered while the rodents that didn’t recover had almost no such activity.
‘There’s an enormous field growing around the idea of neural implants that can help neural circuits recover and improve function,’ said Dr Ganguly.
In fact, stimulating neurons is already widely used in Parkinson’s disease, to correct impulses that cause motor control loss, and epilepsy, to prevent seizures.
‘We were interested in trying to understand the circuit properties of an injured brain relative to a healthy brain and to use this information to tailor neural implants to improve motor function after stroke.’
The team used electrodes to record brain activity as well as send a light electrical current to the rats’ brains.
Stimulating the area where the stroke damage happened appeared to activate LFOs in that area.
When the researchers sent an electrical current to the rats’ brains right before they made a movement, the rodents were 60 percent more accurate in reaching and obtaining the food pellet.
‘We are not creating a new frequency – we are amplifying the existing frequency,’ said Dr Ganguly.
‘By amplifying the weak low-frequency oscillations we are able to help organize the task-related neural activity. When we delivered the electrical current in step with their intended actions, motor control actually got better.’
Currently, physical therapy is the only form of treatment to help stroke patients recover more quickly. However, if the brain damage is too substantial, it is not a viable option.
Dr Ganguly says she hopes this technique offers an alternative for patients with extensive damage.
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