 image analysis while receiving transcranial direct current stimulation (TDCS) to accelerate learning.){kind=spacer}
Air Force operator performing synthetic aperture radar (SAR) image analysis while receiving transcranial direct current stimulation (TDCS) to accelerate learning.
Image: Courtesy of Richard A. McKinley, USAF
WASHINGTON, D.C.—One of the most difficult tasks to teach Air Force pilots who guide unmanned attack drones is how to pick out targets in complex radar images. Pilot training is currently one of the biggest bottlenecks in deploying these new, deadly weapons.
So Air Force researchers were delighted recently to learn that they could cut training time in half by delivering a mild electrical current (two milliamperes of direct current for 30 minutes) to pilot's brains during training sessions on video simulators. The current is delivered through EEG (electroencephalographic) electrodes placed on the scalp. Biomedical engineer Andy McKinley and colleagues at the Air Force Research Laboratory at Wright–Patterson Air Force Base, reported their finding on this so-called transcranial direct current stimulation (TDCS) here at the Society for Neuroscience annual meeting on November 13.
"I don't know of anything that would be comparable," McKinley said, contrasting the cognitive boost of TDCS with, for example, caffeine or other stimulants that have been tested as enhancements to learning. TDCS not only accelerated learning, pilot accuracy was sustained in trials lasting up to 40 minutes. Typically accuracy in identifying threats declines steadily after 20 minutes. Beyond accelerating pilot training, TDCS could have many medical applications in the military and beyond by accelerating retraining and recovery after brain injury or disease.
The question for the Air Force and others interested in transcranial stimulation is whether these findings will hold up over time or will land in the dustbin of pseudoscience.
"There is so much pop science out there on this right now," says neurobiologist Rex Jung of the University of New Mexico Health Sciences Center in Albuquerque, referring to sensational media reports, the widely varying protocols and sometimes lax controls used in different studies of brain stimulation to power learning or elevate mood.
Indeed, electrical stimulation for therapeutic effect has a long and checkered history extending back to the 19th century when "electrotherapy" was the rage among adventurous medical doctors as well as quacks. Pulses of electric current were applied to treat a wide range of conditions from insomnia to uterine cancer. The placebo effect might have been at work in the case of those historical results, and although the experiments were carefully controlled, it is unclear to skeptics if it is a factor in the case of the Air Force's research on transcranial stimulation and learning.
Subjects definitely register the stimulation, but it is not unpleasant. "It feels like a mild tickling or slight burning," says undergraduate student Lauren Bullard, who was one of the subjects in another study on TDCS and learning reported at the meeting, along with her mentors Jung and Michael Weisend and colleagues of the Mind Research Network in Albuquerque. "Afterward I feel more alert," she says. But why?
Bullard and her co-authors sought to determine if they could measure any tangible changes in the brain after TDCS, which could explain how the treatment accelerates learning. The researchers looked for both functional changes in the brain (altered brain-wave activity) and physical changes (by examining MRI brain scans) after TDCS.
They used magnetoencephalography (MEG) to record magnetic fields (brain waves) produced by sensory stimulation (sound, touch and light, for example), while test subjects received TDCS. The researchers reported that TDCS gave a six-times baseline boost to the amplitude of a brain wave generated in response to stimulating a sensory nerve in the arm. The boost was not seen when mock TDCS was used, which produced a similar sensation on the scalp, but was ineffective in exciting brain tissue. The effect also persisted long after TDCS was stopped. The sensory-evoked brain wave remained 2.5 times greater than normal 50 minutes after TDCS. These results suggest that TDCS increases cerebral cortex excitability, thereby heightening arousal, increasing responses to sensory input, and accelerating information processing in cortical circuits.
Remarkably, MRI brain scans revealed clear structural changes in the brain as soon as five days after TDCS. Neurons in the cerebral cortex connect with one another to form circuits via massive bundles of nerve fibers (axons) buried deep below the brain's surface in "white matter tracts." The fiber bundles were found to be more robust and more highly organized after TDCS. No changes were seen on the opposite side of the brain that was not stimulated by the scalp electrodes.
The structural changes in white matter detected by the MRI technique, called diffusion tensor imaging (DTI), could be caused by a number of microscopic physical or cellular alterations in brain tissue, but identifying those is impossible without obtaining samples of the tissue for analysis under a microscope.
An expert on brain imaging, Robert Turner of the Department of Neurophysics at the Max Planck Institute for Human Cognitive and Brain Sciences, in Leipzig, Germany, who was not involved in the study, speculated that the changes detected by DTI could represent an increase in insulation on the fibers (myelin) that would speed transmission of information through the fibers. "In my present view, the leading hypothesis for the observed rapid changes…is that previously unmyelinated axonal fibers within white matter become rapidly myelinated when they start to carry frequent action potentials," he says. There are, however, several other possible explanations, he cautions.
Matthias Witkowski, now at the Institute for Medicine, Psychology and Behavioral Neurobiology at the University of Tübingen in Germany, described the rapid changes in white matter in these experiments as "incredible." "That [white matter changes] would not have been my first guess," he said. "It will be very interesting to see if there are cellular changes." This is the next step in research planned by Jung and colleagues. They hope to obtain brain tissue from patients who would be willing to participate in TDCS studies prior to undergoing necessary brain surgery in which tissue would be removed as a required part of their treatment.
Witkowski is convinced by these new studies and his own research that transcranial stimulation can accelerate many kinds of learning, and research on brain–machine interfacing, which he presented at the meeting, demonstrates the potential for TDCS in speeding patient rehabilitation after injury. People with paralyzed limbs can be taught to control a robotic glovelike device that will move their fingers in response to the patient's own thoughts. Electrodes on the person's scalp pick up brain waves as the person imagines moving his or her hand. The brain waves are analyzed by a computer to control the robotic artificial hand. But learning to generate the proper brain waves to control the artificial hand through thought alone requires considerable training. Witkowski found that if patients received 20 minutes of TDCS stimulation once during five days of training, they learned to control the hand with their thoughts much more rapidly.
The new studies reported at this meeting suggest that there is far more to speed learning produced by TDCS than can be explained by the placebo effect. And the evidence now shows that TDCS produces physical changes in the brain's structure as well as physiological changes in its response. TDCS increases cortical excitability, which can be measured in recordings of brain waves, and it also causes changes in the structure of the brain's connections that can be observed on an MRI. By using electricity to energize neural circuits in the cerebral cortex, researchers are hopeful that they have found a harmless and drug-free way to double the speed of learning.
Rights & Permissions
See what we're tweeting about
25 Comments
Add CommentWow.
Reply | Report Abuse | Link to this"...researchers are hopeful that they have found a harmless and drug-free way to double the speed of learning."
Reply | Report Abuse | Link to thisRight. Look, if it was easy for the brain to learn twice as fast without any downside I'm just going to venture a WILD guess and imagine there would be HEAVY selective advantage to that. Thus it would already be the normal way our brains operate.
The FAR more likely situation IMHO is that there are corresponding costs or disadvantages to whatever the underlying process is. It may be considered worth the cost, but there is very likely to be one and who really knows WHAT the downsides are or how obvious they will be? The consequences could be quite subtle and very long-term.
There is ALWAYS as downside when you tamper with your body. It can be the most subtle thing we don't even KNOW about the brain yet but it will happen..
Reply | Report Abuse | Link to thisPerhaps there are costs to it which make natural electrical self-stimulation too costly if done on a continual basis, but not if only done occasionally.
Reply | Report Abuse | Link to thisCome to think of it, have there been studies comparing human brain activity with other animals to see if maybe we already do have this going on naturally, but maybe only do so to the extent that we can afford the energy/side effects? Perhaps we have not yet evolved a sufficient regulatory system for it that would let us kick it into high gear during important learning situations, but keep it moderated the rest of the time.
Transcranial...transcranial...transcranial...That would mean from left to right or right to left, wouldn't it? Heck, I been doing that since I was a kid. My folks called it in one ear and out the other, and walloped me for it. And your and my's tax money is going into this stuff?
Reply | Report Abuse | Link to thistharter, you are right, but *evolution does not work fast*. We are not in anything close to the evolutionary environment where (more) rapid learning apparently was not that useful.
Reply | Report Abuse | Link to thisNotice one of the explanations offered was additional myelination - well, where do you get the fats and proteins for that? In the evolutionary environment, maybe nowhere; in the modern environment, you just pigged out on fatty stuff at McDonald's and you have so much fat and protein that you're poisoning yourself with it.
See http://www.gwern.net/Drug%20heuristics#eoc for other loopholes.
I only suggest that these researchers be required to identify potential side effects of this type of 'shotgun' electrical stimulation. For example, does the use of TDCS inhibit learning ability without stimulation? If axon growth is selectively enhanced there could be complex secondary effects...
Reply | Report Abuse | Link to thisIt seems that additional myelination would be unlikely to occur as an immediate response to electrical stimulation. Unless the insulating myelin sheaths are damaged, resulting in signal loss, it seems unlikely that additional insulation would improve performance. Increased myelination over time might be a side effect of excessive electrical stimulation. If only axons activated during electrical stimulation received increased myelin the inactive axons' myelin sheaths might become diminished or damaged in some way...
There seems to be great potential for unintended negative effects as a result of these kinds of learning and development interventions.
What about the positioning of the TDCS device? In the picture it seems to be at least on the right frontotemporal region. Damage to frontotemporal areas is known to sometimes cause aquired savant abilities and I remember at least one study (http://www.centreforthemind.com/images/savantskills.pdf) in which TMS to left frototemporal region had similar, although much milder, effects. The rationale was that the TMS turned off some inhibitory network thus enabling learning trough disinhibition.
Reply | Report Abuse | Link to thisI recall decades ago when they were training Rhesus monkeys or chimpanzees, and to teach them faster they'd zap them with an unpleasant electric current jolt when they made a mistake. Does this research imply the hapless monkeys and great apes learned faster, not because they were avoiding the unpleasant shock but because their learning capacity was boosted by the current?
Reply | Report Abuse | Link to this*Warning: tongue-in-cheek comments follow
I wonder if some enterprising college students begin marketing an IQ cap, claiming to boost learning capacity, to allow fellow students to cram for exams more efficiently? Or sell something possibly called Alert Caps, to help long distance truck drivers stay awake for longer, allowing them to drive at night without having to take illegal stimulants?
I recall that episode in Futurama where Dr. Farnsworth invented an "electronium" hat for a monkey named Guenter that became super-intelligent, and was enrolled into Mars University - is this a potential case of life imitating art?
Some of us Electrical/Electronic Engineers humorously refer to ourselves as "bright sparks"; looks like there may be a scientific vindication here somewhere...?
Could this research eventually lead to the evolution of Homo Sapiens Sapiens into Homo Sapiens Electrocephalus?
*End of tongue-in-cheek remarks
This 'comment' should be reported as a marking blurb from a commercial enterprise that has nothing to do with the subject of this article, but the two highlighted customer reviews of SA are quite accurate. Even the most favorable review is critical of the now diminished depth of reporting...
Reply | Report Abuse | Link to thisThis 'comment' should be reported as a marking blurb from a commercial enterprise that has nothing to do with the subject of this article, but the two highlighted customer reviews of SA are quite accurate. Even the most favorable review is critical of the now diminished depth of reporting...
Reply | Report Abuse | Link to thisWhat's the probability here for a useful therapy for Parkinson's Disease, dementia, Alheimer's, and other neuro-degenerative conditions? Also, is there a ceiling threshold for this stimulation beyond which harmful effects accrue? In addition, what about nerve growth factor at the site where stimulation is applied? Would this increase neural entanglement of host with special design AI interfaces?
Reply | Report Abuse | Link to thisClearly, this is not a substitute for student effort applied to the college lesson. It is presented as augmentation only... Nowhere did I read the suggestion it will replace the need for the fuddy duddy university Don. So, you can relax, guys. Tenure is safe so far.
Reply | Report Abuse | Link to thisThis would be great for special perk time during extended space flight, or life/work on Lunar surfaces.
I wanna go!!!!
I hope this has no porn industry application, or America is doombed.
Reply | Report Abuse | Link to thisDear jtdwyer, I asked Bullard if she was concerned about possible negative side effects and she said she is not concerned at all.
Reply | Report Abuse | Link to thisFrom White Matter Matters, R.D. Fields, Scientific American, March 2008
Reply | Report Abuse | Link to this******
Is myelin formation totally programmed, or do our life experiences alter the degree of wrapping and thus how well we learn? Does myelin actually build cognitive ability, or is cognition simply limited in regions where it has not yet formed?
Piano virtuoso Fredrik Ullén decided to find out. Ullén also happens to be an associate professor at the Stockholm Brain Institute in Sweden. In 2005 he and his colleagues used a new brain-scanning technology called diffusion tensor imaging (DTI) to investigate the brains of professional pianists.
Information must travel enormous distances between brain centers. Each center carries out its particular function and sends the output to another region for the next step of analysis. For complex learning, such as learning the piano, information must be shuttled back and forth among many regions; information flowing over different distances must arrive simultaneously at one place at a certain time. For such precision to occur, delays are necessary. If all axons transmitted information at the maximum rate, signals from distant neurons would always arrive later than signals from neighboring neurons. An impulse typically takes 30 milliseconds to travel from one cerebral hemisphere to the other through myelinated axons in the corpus callosum, compared with 150 to 300 milliseconds through unmy¬elinated axons. None of the corpus callosum’s axons are myelinated at birth, and by adulthood 30 percent remain that way. The variation helps to coordinate transmission speeds.
Clearly, the speed of impulse transmission is a vital aspect of brain function. We know that memory and learning occur when certain neuronal circuits connect more strongly. It seems likely that myelin affects this strength, by adjusting conduction velocity so that volleys of electrical impulses arrive at the same neuron simultaneously from multiple axons. When this convergence occurs, the individual voltage blips pile up, increasing the strength of the signal, thus making a stronger connection among the neurons involved.
Much more research must be done to explore this theory, but there is no doubt that myelin responds to the environment and participates in learning skills.
******
Interesting that TDCS causes myelin to grow so quickly. The general idea is that differential myelination of axon populations causes "volleys of electrical impulses to arrive at the same neuron simultaneously from multiple axons". How does TDCS cause that to happen?
Another question:
Reply | Report Abuse | Link to this"By using electricity to energize neural circuits in the cerebral cortex, researchers are hopeful that they have found a harmless and drug-free way to double the speed of learning."
If training involved discrimination of targets from radar returns, would only that activity be learned? Or, would learning be improved in general? Ullen studied piano players, presummably due to their skill and the fairly unique nature of piano playing. So, would what was learned in the TDCS training process matter to the eventual improvement in learning speed?
Sounds like this is stopping the "mind from wandering"...very interesting.
Reply | Report Abuse | Link to thisAs with other posters, I would be interested to see how it applies to other learning.
And as always...what are the downsides 1,10,50 years later...
Can we now look whether TDCS might be useful in improving autism spectrum or Alzheimer's/dementia or eliminate the possibility?
Reply | Report Abuse | Link to thisDear R. Douglas Fields - Thanks, but the researchers not concerning themselves with possible negative side effects is the greatest cause for concern of all...
Reply | Report Abuse | Link to thisDear Dr. Fields,
Reply | Report Abuse | Link to thisI know this is off topic but I would like to know your personal opinion about so called "mirror neurons". As far as I know the whole "mirror neuron" concept is highly controversial among mainstream neuroscientists. Some neuroscientists even say that the "mirror neuron" theory is not a scientific theory at all because it is unfalsifiable:
http://www.talkingbrains.org/2010/03/mirror-neurons-unfalsifiable-theory.html
http://www.newscientist.com/article/dn17192-role-of-mirror-neurons-may-need-a-rethink.html
I think your amazing discoveries about the "real" cellular mechanisms of learning (myelination of axons) actually falsifies the whole "mirror neuron" concept. I am very interested to hear your personal opinion about "mirror neurons".
Sorry for this late reply. I have been out of the country at a couple of scientific meetings for the last 8 days.
Reply | Report Abuse | Link to thisMany interesting questions: First, we do not know if this has anything to do with myelin. This is just a theory that will be answered once tissue can be collected.
There are other data to suggest that this technique would improve learning in other tasks as well; not just this task.
Yes, the researchers are very interested in applying this technique to patients with dementia or other learning disorders. This is in fact one of their primary motives.
jtdwyer--Bullard was a subject in the study. She eagerly allowed her own brain to be stimulated for these experiments. This is why I thought you would be interested in her view on your question.
Thanks for clarifying undergraduate student Lauren Bullard's role as both a researcher and subject of experimentation, but her lack of concern for potential side effects is highly disconcerting. I have experimented on myself with interferon injections to treat basil cell carcinoma and understand both researchers' and subjects' enthusiasm, but in any case responsible research should also include investigation of potential side effects.
Reply | Report Abuse | Link to thisDoes the use of TDCS inhibit learning ability without stimulation? If axon growth is selectively enhanced there could be complex secondary effects...
A study that applied TDCS during non-learning tasks would be useful. It would be most interesting to determine if subjects were required to learn two very different skills and TDCS was applied during only one, how would the learning of other task fare compared to a baseline group?
There certainly seems to be potential for unintended detrimental effects, regardless of how enthusiastic researchers and subjects might be in their evaluation of positive effects!
Don't know about the downsides, but I'm interested. Looks like the effects are transitional. Here I've found some more information: <a href="http://www.trans-cranial.com/howitworks/"> Trans-Cranial.com </a>
Reply | Report Abuse | Link to thisFor readability: www.trans-cranial.com
Reply | Report Abuse | Link to this