June 18 (UPI) -- Electronic brain stimulation helped improve rats' mobility after debilitating strokes, offering hope for treatment in humans, researchers report in a new study.
University of California San Francisco scientists found the stimulation restored brain cell activity associated with efficient movement. Their findings were published Monday in the journal Nature Medicine.
"Our main impetus was to understand how we can develop implantable neurotechnology to help stroke patients," senior author Dr. Karunesh Ganguly, an associate professor of neurology at UCSF and a member of the UCSF Weill Institute for Neurosciences, said in a press release. "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."
He noted there's an "enormous field growing around the idea" of neural implants to help neural circuits recover and improve function.
Roughly one-third of patients recover fully after a stroke, one-third have significant lingering movement problems and one-third are virtually paralyzed, Ganguly said. Among those who experience partial recovery, some struggle with "goal-directed" movements of the arms and hands.
The only way to aid stroke victims now is physical therapy but it often offers no improvement for those whose stroke damage is too extensive.
In the past 20 years, neuroscientists have found that neural activity, known as oscillations, are the key to efficient brain function. Specifically, low-frequency oscillations -- or LFOs -- have helped organize the firing of neurons in the brain's primary motor cortex.
With the motor cortex controlling voluntary movement, LFOs place the cells' activity together to ensure that goal-directed movements are smooth and efficient.
UCSF researchers measured neural activity in rats as they reached out to grab a small food pellet. They detected LFOs before and during the action.
Researchers caused a stroke in rates that prevented movement. The LFOs diminished and when the LFOs returned, the animals were able to recover with faster and more precise movements.
Animals that fully recovered had stronger low-frequency activity than those that partially recovered. Those that didn't recover had virtually no low-frequency activity, the researchers report.
Next, the researchers used electrodes to deliver a mild electrical current to the rats' brains surrounding the center of the stroke damage.
This charge consistently enhanced LFOs in the damaged area and also appeared to improve motor function by up to 60 percent, helping them more accurately reach and grasp for a food pellet.
"Interestingly, we observed this augmentation of LFOs only on the trials where stimulation was applied," Gulati said. "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."
The researchers also recorded activity from the surface of the brain of an epileptic person who had a stroke and was left with impaired arm and hand movements. Like the rats, the recordings revealed significantly fewer LFOs than recordings of two epilepsy patients who hadn't had a stroke.
Electrical brain stimulation is already helping patients with Parkinson's disease and epilepsy, which makes Ganguly believe stroke patients could also benefit from its use.