Having trouble paying attention?
MIT neuroscientists may have a solution for you: Turn down your alpha brain waves.
In a new study, the researchers found that people can enhance their attention by controlling their own alpha brain waves based on neurofeedback they receive as they perform a particular task.
The study found that when subjects learned to suppress alpha waves in one hemisphere of their parietal cortex, they were able to pay better attention to objects that appeared on the opposite side of their visual field.
This is the first time that this cause-and-effect relationship has been seen, and it suggests that it may be possible for people to learn to improve their attention through neurofeedback.
“There’s a lot of interest in using neurofeedback to try to help people with various brain disorders and behavioral problems,” says Robert Desimone, director of MIT’s McGovern Institute for Brain Research.
“It’s a completely noninvasive way of controlling and testing the role of different types of brain activity.”
It’s unknown how long these effects might last and whether this kind of control could be achieved with other types of brain waves, such as beta waves, which are linked to Parkinson’s disease.
The researchers are now planning additional studies of whether this type of neurofeedback training might help people suffering from attentional or other neurological disorders.
Desimone is the senior author of the paper, which appears in Neuron on Dec. 4. McGovern Institute postdoc Yasaman Bagherzadeh is the lead author of the study.
Daniel Baldauf, a former McGovern Institute research scientist, and Dimitrios Pantazis, a McGovern Institute principal research scientist, are also authors of the paper.
Alpha and attention
There are billions of neurons in the brain, and their combined electrical signals generate oscillations known as brain waves.
Alpha waves, which oscillate in the frequency of 8 to 12 hertz, are believed to play a role in filtering out distracting sensory information.
Previous studies have shown a strong correlation between attention and alpha brain waves, particularly in the parietal cortex.
In humans and in animal studies, a decrease in alpha waves has been linked to enhanced attention.
However, it was unclear if alpha waves control attention or are just a byproduct of some other process that governs attention, Desimone says.
To test whether alpha waves actually regulate attention, the researchers designed an experiment in which people were given real-time feedback on their alpha waves as they performed a task.
Subjects were asked to look at a grating pattern in the center of a screen, and told to use mental effort to increase the contrast of the pattern as they looked at it, making it more visible.
During the task, subjects were scanned using magnetoencephalography (MEG), which reveals brain activity with millisecond precision.
The researchers measured alpha levels in both the left and right hemispheres of the parietal cortex and calculated the degree of asymmetry between the two levels.
As the asymmetry between the two hemispheres grew, the grating pattern became more visible, offering the participants real-time feedback.
Although subjects were not told anything about what was happening, after about 20 trials (which took about 10 minutes), they were able to increase the contrast of the pattern.
The MEG results indicated they had done so by controlling the asymmetry of their alpha waves.
“After the experiment, the subjects said they knew that they were controlling the contrast, but they didn’t know how they did it,” Bagherzadeh says.
“We think the basis is conditional learning — whenever you do a behavior and you receive a reward, you’re reinforcing that behavior.
People usually don’t have any feedback on their brain activity, but when we provide it to them and reward them, they learn by practicing.”
Although the subjects were not consciously aware of how they were manipulating their brain waves, they were able to do it, and this success translated into enhanced attention on the opposite side of the visual field.
As the subjects looked at the pattern in the center of the screen, the researchers flashed dots of light on either side of the screen. The participants had been told to ignore these flashes, but the researchers measured how their visual cortex responded to them.
One group of participants was trained to suppress alpha waves in the left side of the brain, while the other was trained to suppress the right side.
In those who had reduced alpha on the left side, their visual cortex showed a larger response to flashes of light on the right side of the screen, while those with reduced alpha on the right side responded more to flashes seen on the left side.
“Alpha manipulation really was controlling people’s attention, even though they didn’t have any clear understanding of how they were doing it,” Desimone says.
After the neurofeedback training session ended, the researchers asked subjects to perform two additional tasks that involve attention, and found that the enhanced attention persisted.
In one experiment, subjects were asked to watch for a grating pattern, similar to what they had seen during the neurofeedback task, to appear.
In some of the trials, they were told in advance to pay attention to one side of the visual field, but in others, they were not given any direction.
When the subjects were told to pay attention to one side, that instruction was the dominant factor in where they looked.
But if they were not given any cue in advance, they tended to pay more attention to the side that had been favored during their neurofeedback training.
MIT neuroscientists have shown that people can enhance their attention by using neurofeedback to decrease alpha waves in one side of the parietal cortex. The image is credited to Yasaman Baghezadeh.
In another task, participants were asked to look at an image such as a natural outdoor scene, urban scene, or computer-generated fractal shape.
By tracking subjects’ eye movements, the researchers found that people spent more time looking at the side that their alpha waves had trained them to pay attention to.
“It is promising that the effects did seem to persist afterwards,” says Desimone, though more study is needed to determine how long these effects might last.
“It would be interesting to understand how long-lasting these effects are, and whether you can use them therapeutically, because there’s some evidence that alpha oscillations are different in people who have attention deficits and hyperactivity disorders,” says Sabine Kastner, a professor of psychology at the Princeton Neuroscience Institute, who was not involved in the research.
“If that is the case, then at least in principle, one might use this neurofeedback method to enhance their attention.”
Funding: The research was funded by the McGovern Institute.
Brain–computer interface (BCI) provides a promising technology that allows humans to control their brain waves through an external device.1–4 BCI may be employed to improve neurocognitive functions, such as attention span and working memory.5–8 The neurofeedback training (NFT) system acquires brain wave activities from an electroencephalogram (EEG) amplifier and then extracts EEG features to define states of cognition.
The system visualizes the estimated cognitive state of the subjects who are able to recognize their own current state of cognition. Consequently, participants may learn how to modulate their brain EEG activities to meet the goals of the training protocol in each training session.
Knowledge of NFT systems has undergone considerable developments by studying how to improve the cognitive state and attention using NFT in, for example, children with Attention-Deficit Hyperactivity Disorder (ADHD).9–12 Some studies delineated the association between learning problems or sustained attention and cognitive performance in ADHD.13,14 Moreover, NFT systems were designed with the aim to improve cognitive performance not only in children with ADHD but also in elderly individuals.
For example, Becerra et al examined the effect of NFT, which targeted theta reduction, on neurocognitive performance in healthy elderly people.15 They randomly assigned 14 subjects to either active NFT or sham treatment and found that subjects in the experimental group exhibited greater improvement in EEG and behavioral measurements. Zoefel et al used an NFT system that targets the amplitude of the upper alpha frequency band by playing mental rotation games.16
The authors found that 11 of 14 undergrad students who had attended five NFT sessions in 1 week significantly improved their cognitive performance when compared with non-NFT control group. Haddadi et al examined an NFT system to enhance learning and memory in patients with cognitive impairment.17
Their NFT protocol (40 sessions, 45 minutes/day, and 3 sessions a week) increased beta wave frequency and decreased theta wave frequency in association with improved scores on the Wechsler Intelligence Scale for Children and Child Behavior Checklist. Engelbregt et al evaluated short- and long-term effects of frontal beta EEG-NFT in healthy subjects and found that frontal beta activities increased after 15 sessions of 45-minutes NFT intervention and that these effects remained stable for at least 3 years.18
Gruzelier provided an intensive review of cognitive and affective outcomes of EEG-NFT in healthy subjects and showed that outcome gains included memory, executive functions, and sustained attention.19
There are also some studies that evaluated the effects of NFT in patients with Alzheimer’s Disease (AD). Luijmes et al examined positive outcomes of theta-decreased NFT in patients with AD by performing 30 intervention sessions and found improved recall of information and recognition,20 although other cognitive functions did not change. Hohenfeld et al studied cognitive functions in association with brain activity and found that NFT improved visuospatial memory performance; however, no significant changes in brain activities were found.21
Recently, it was shown that NFT may improve memory performance in association with peak alpha frequency in patients with mild cognitive impairment (MCI).22 Nevertheless, there are no data whether, in amnestic MCI (aMCI), NFT has an effect on other cognitive functions including spatial working memory (SWM), strategy, visual pattern recognition and memory, sustained attention, and attention span.
Hence, the main aim of this study was to examine whether a newly developed game-based NFT system may enhance neurocognitive performance in healthy elderly subjects and patients with aMCI. To evaluate the effects of NFT, we examined the tests scores of key cognitive domains as measured with the Cambridge Neuropsychological Test Automated Battery (CANTAB) both before and after NFT and compared the results with exergame-based cognitive training and care as usual (CAU). We decided to use exergame as a control treatment because the latter is a popular treatment that may enhance cognition and may help some patients with MCI.23
The major finding of this study is that NFT significantly decreased SWM_BER and SWM_STR tests scores and increased RVP_A′ scores. This shows that NFT, but not exergame treatment or CAU, improves working memory, the ability to retain spatial information, and strategy for completing a task, as well as visual sustained attention capability. Importantly, there were no significant differences in the effects of NFT on cognitive functions between healthy elderly and aMCI subjects; both groups improved their working memory, strategy, and sustained attention during NFT treatment.
Our results in normal volunteers are in agreement with a review published by Gruzelier showing that NFT may improve cognitive functioning in healthy elderly participants, including memory, executive functions, and sustained attention.19 Moreover, the current study shows that NFT resulted in the same effects in participants with aMCI, indicating that these subjects may also benefit from NFT.
Previously, it was shown that some of the NFT effects in MCI on memory performance may be associated with peak alpha frequencies.22 All in all, the results show that it is possible to train healthy elderly and aMCI individuals with NFT to enhance specific domains of their cognitive performance.
Most previous research examining the effects of NFT training on CANTAB test results focused on cognitive training in children, especially those with ADHD.40–42 The results of these studies indicate improvements mainly in SWM and RVP areas, which is in agreement with our findings in healthy elderly subjects and aMCI patients.
Karbach and Verhaeghen reported that NFT may improve working memory executive control in elderly participants.43 Enriquez-Geppert et al found that neurocognitive modulation (including NFT) of brain regions, which are crucially involved in specific executive functions, can lead to behavioral benefits in response inhibition, task switching, and memory updating.44
The second major finding of this study is that women with aMCI showed disorders in SWM, including strategy, PRM, and short-term visual memory when compared with age-matched healthy elderly women. This indicates that NFT improved some, but not all, features of aMCI such as impairments in PRM and short-term visual memory.
On the other hand, NFT significantly improved impaired SWM_STR thereby normalizing the scores to values observed in healthy elderly women. Phrased differently, NFT may be used clinically in aMCI to normalize strategy and improve SWM and sustained attention, which may result in beneficial effects on overall cognitive functions. Therefore, deficits in strategy may be a new indication to treat aMCI patients with NFT.
It is interesting to note that NFT did not have any significant effect on the SSP CANTAB test, which probes the subject’s attention span and ability to assess working memory, while exergame treatment, but not CAU, significantly improved the SSP test outcome. This suggests that exergame significantly improves attention span and the ability to assess working memory in both healthy elderly and aMCI patients.
Previously, it was shown that exergame may improve cognitive functioning, in particular, executive control skills.45,46 These beneficial effects may be explained by recent knowledge that aerobic fitness improves cognitive performance via increased cerebral circulation, increased neurotransmitter availability, and enhanced physiological and neurological processes.47
Exergames may also improve cognitive control of attention, which in turn could improve cognitive functioning.48 Other cognitive functions that could benefit from exergaming include visual–spatial skills including spatial relations, visualization, perceptual speed, and 3D rotation skills.49
All in all, our exergame intervention approach potentially improved speedy reaction and decision-making capability of both aMCI and healthy elderly women. Therefore, it may be speculated that a combined treatment of NFT + exergame may result in a better response than each treatment alone. In this regard, it is interesting to note that some researchers examined the combined effects of cognitive and physical training.50–52
The results of the present study should be interpreted with reference to its limitations and strengths. Firstly, the main purpose of the current study was to examine a new game-based NFT system for cognitive enhancement with a consumer-grade EEG acquisition device, called “Emotiv EPOC”, one of the low-cost EEG headsets available on the market. However, there are some clinicians and researchers in the field who are concerned about the quality of consumer-grade EEG devices for clinical use.
In this respect, several studies compared the EEG signal quality of Emotiv EPOC with that of medical- and research-grade devices. Badcock et al showed that the morphology of ERP signals of Emotiv EPOC devices was very similar to that of the signal acquired from a research-grade EEG system (Neuscan).53
There were only few differences of peak amplitude and latency estimates between the two systems. Duvinage et al found that the EEG signal quality of Emotiv EPOC is somewhat less than that of a medical-grade system (ANT Neuro System), although the results show that the Emotiv headset can be used in noncritical applications such as games for rehabilitations.54
Secondly, our interventional study was performed on women only, and therefore a follow-up study should be performed to examine the effects of NFT in elderly healthy males and males with aMCI.
Thirdly, it would have been even more interesting if we had used more cognitive tests, for example, using the Consortium to Establish a Registry for AD tests to probe semantic and episodic memory, and word recall and recognition.55
The strengths of this study are that we examined the efficacy of NFT in a large study sample and compared NFT with CAU and exergame and adjusted for possible effects of age and education.
Anne Trafton – MIT
The image is credited to Yasaman Baghezadeh.
Original Research: Closed access
“Alpha Synchrony and the Neurofeedback Control of Spatial Attention”. Yasaman Baghezadeh et al.