Featured Research

from universities, journals, and other organizations

Stroke Recovery Might Be Speeded By Electrical Stimulation Of The Brain

Date:
March 17, 1998
Source:
University Of California, San Francisco
Summary:
The schoolchild's fantasy of learning without really paying attention might not be so farfetched after all, although recovering stroke patients, not schoolchildren, may be the most likely to ultimately benefit from a technique that could potentially make such learning possible.

The schoolchild's fantasy of learning without really paying attention might not be so farfetched after all, although recovering stroke patients, not schoolchildren, may be the most likely to ultimately benefit from a technique that could potentially make such learning possible.

In a study appearing in the March 13 issue of Science, researchers with the W. M. Keck Center for Integrative Neuroscience at the University of California San Francisco used mild electrical stimulation in mature rats to quickly bulk up brain regions that perceive and interpret sounds. They suggest that a similar strategy might help stroke patients recover lost brain functions such as speech, accurate hearing, and movement.

Michael Merzenich, PhD, the Francis A. Sooy Professor of Otolaryngology at UCSF, has for almost two decades studied the ability of the brain to learn and in so doing to form new networks of nerve connections. Merzenich pioneered the new idea, now well accepted, that adults as well as growing children exhibit these brain changes. In his research into this phenomenon, termed "brain plasticity," Merzenich has concentrated on refining maps of the brain regions that represent sensory and motor stimuli.

Both children and adults rely on plasticity to remodel the detailed connections in the brain during learning. Brain plasticity underlies the progressive development of all of our behavioral skills and abilities, Merzenich explains, and it contributes critically to the maintenance of our abilities to recognize and discriminate among incoming stimuli and to respond appropriately. Brain plasticity also contributes to progressive recovery from brain trauma such as stroke.

Thanks to brain plasticity, stroke patients often regain a substantial amount of the brain function lost after brain cells die. Exercises to regain control over movements or to recover the ability to speak or to understand language, for example, often lead to significant post-stroke recovery.

However, for psychological and neurological reasons, stroke patients often lack the will to participate vigorously in rehabilitation programs. And because brain resources are more limited after a stroke, it is often difficult for a patient to voluntarily and reliably produce normal movements or speech.

Experiments conducted by Merzenich and graduate student Michael Kilgard on the auditory cortex, the brain region responsible for sound processing, now have revealed a greater degree of brain reorganization than has ever previously been observed in mammals.

To spur accelerated brain reorganization in normal adult rats, Kilgard and Merzenich electrically stimulated an area called the nucleus basalis, which is located at the front of the brain below the cerebral cortex.

"Just as direct electrical stimulation in the basal ganglia now is used as a treatment for Parkinson's disease, stimulation of the nucleus basalis to coincide with an important-to-remember stimulus or movement might serve as a means to overcome motivational problems in the early epoch of stroke recovery," Merzenich says. "In extension, this strategy could quickly maximize the full potential for recovery of function in a damaged brain," he adds.

If we regarded all incoming stimuli as equally important, we would not learn successfully to adapt and respond to our surroundings, and normal mental development would not be possible, Merzenich points out. In a person engaged in learning, brain structures, including the relatively primitive limbus and paralimbus, help weigh the importance of stimuli to the more evolved cerebral cortex, the "thinking" brain that must further process stimuli during learning. If stimuli are deemed important, these brain structures activate the nucleus basalis.

The nucleus basalis is a gatekeeper. To bring about brain reorganization, it relays commands to the auditory cortex or other brain regions by secreting the neurotransmitter acetylcholine. The amount of this vital signaling molecule released corresponds to the speed of learning and the strength of memory, Merzenich says. Indeed, in Alzheimer's disease, treatment aims to boost the supply of acetylcholine available within the brain, without focusing on a particular brain region.

Although paying close attention to stimuli and the brain's recognition of the stimuli's behavioral importance play a critical role in activating brain regions during learning, direct stimulation of the nucleus basalis may bypass this requirement, according to Merzenich.

"Our strategy has been to trick the brain into sending a message that says 'save this,' and thereby to maximize and accelerate brain plasticity. In our experiments, electrical stimuli of the nucleus basalis clearly magnified and accelerated plasticity changes in the brain related to the progression of learning.

"These changes closely paralleled those that we previously recorded in skill-learning, except that in this case changes were especially large and rapid, and were achieved in a non-attending brain. These changes are similar to some of those that must occur during successful recovery from brain injury," he says.

To explore and map out in detail the learning-related changes in the auditory cortex, Kilgard exposed normal rats to sounds of assorted frequencies and bandwidths, about 300 times a day for 20 days.

The experimental group of 21 rats received auditory stimuli coinciding with mild electrical stimulation of the nucleus basalis. Another group received the auditory stimuli but no electrical stimulation. In the electrically stimulated rats, the auditory cortex became dramatically rearranged to respond to the specific frequencies used as sound stimuli. The researchers recorded no changes in rats that were not electrically stimulated.

Brains of humans and other mammalian species have been trained to distinguish sound frequencies, but according to Merzenich, "The extent of reorganization in the auditory cortex generated by activating the nucleus basalis that we saw in the rats is substantially larger than the reorganization that is typically observed after several months of intensive behavioral training."

The brain is a highly sophisticated, self-organizing system, but additional experiments similar to those described in the Science article should lead to much more precise brain maps and to better models for explaining how reorganization of nerve networks occurs, Merzenich says.


Story Source:

The above story is based on materials provided by University Of California, San Francisco. Note: Materials may be edited for content and length.


Cite This Page:

University Of California, San Francisco. "Stroke Recovery Might Be Speeded By Electrical Stimulation Of The Brain." ScienceDaily. ScienceDaily, 17 March 1998. <www.sciencedaily.com/releases/1998/03/980317070802.htm>.
University Of California, San Francisco. (1998, March 17). Stroke Recovery Might Be Speeded By Electrical Stimulation Of The Brain. ScienceDaily. Retrieved July 29, 2014 from www.sciencedaily.com/releases/1998/03/980317070802.htm
University Of California, San Francisco. "Stroke Recovery Might Be Speeded By Electrical Stimulation Of The Brain." ScienceDaily. www.sciencedaily.com/releases/1998/03/980317070802.htm (accessed July 29, 2014).

Share This




More Mind & Brain News

Tuesday, July 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Losing Sleep Leaves You Vulnerable To 'False Memories'

Losing Sleep Leaves You Vulnerable To 'False Memories'

Newsy (July 27, 2014) A new study shows sleep deprivation can make it harder for people to remember specific details of an event. Video provided by Newsy
Powered by NewsLook.com
University Quiz Implies Atheists Are Smarter Than Christians

University Quiz Implies Atheists Are Smarter Than Christians

Newsy (July 25, 2014) An online quiz from a required course at Ohio State is making waves for suggesting atheists are inherently smarter than Christians. Video provided by Newsy
Powered by NewsLook.com
Beatings and Addiction: Pakistan Drug 'clinic' Tortures Patients

Beatings and Addiction: Pakistan Drug 'clinic' Tortures Patients

AFP (July 24, 2014) A so-called drugs rehab 'clinic' is closed down in Pakistan after police find scores of ‘patients’ chained up alleging serial abuse. Duration 03:05 Video provided by AFP
Powered by NewsLook.com
New Painkiller Designed To Discourage Abuse: Will It Work?

New Painkiller Designed To Discourage Abuse: Will It Work?

Newsy (July 24, 2014) The FDA approved Targiniq ER on Wednesday, a painkiller designed to keep users from abusing it. Like any new medication, however, it has doubters. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins