Brain waves are easy to read and difficult to understand

Brain waves can be roughly divided into α wave, β wave, γ wave, δ wave and θ wave Different waves correspond to different brain states Although different brain waves have roughly one representative direction, the actual situation is much more complicated In fact, the decoding of EEG signals is still a "blue ocean" Not long ago, a primary school in Zhejiang province put on a "smart head ring" to test brain waves to determine whether students are focused Brain wave testing is a common technology in the field of medical treatment and research, because the dazzle of science fiction movies always makes people feel very mysterious So what is brain wave? Can it be detected and interpreted? The activity of neurons forms brain waves, which do exist despite the illusion that the brain's "bareness" discharge will look funny It's hard to detect because it's only 200 microvolts strong When the brain is active, a large number of neurons synchronously produce postsynaptic potentials which form brain waves after summation The essence of postsynaptic potentials is the entry and exit of charged ions in the synapses The so-called "spark of thought" is the "crackling" sound left by the charged ions in the body passing through the channels on the nerve cell membrane (such as chemical gated channels) and the potential difference in different regions of the brain after passing through It is the general reflection of the electrophysiological activity of brain nerve cells on the surface of cerebral cortex or scalp recorded by EEG Generally speaking, brain waves can be roughly divided into α wave, β wave, γ wave, δ wave and θ wave Different waves correspond to different brain states "Brain waves exist all the time, but different waves will become the main body in different states For example, when the eyes are closed, the alpha wave will be activated immediately." Huang Zhili, a professor at Fudan University, said that when the brain is full of theta waves, people's conscious activities are obviously inhibited, unable to carry out logical thinking and reasoning activities At this time, the brain receives and transmits information by intuition, inspiration, imagination, etc Scientists also found that when people wake up and focus on something, they often see a higher frequency of γ wave than β wave The frequency is 30-80 Hz, and the amplitude range is uncertain There is a hypothesis that gamma wave may be related to the establishment of a unified and clear cognition It can enhance consciousness and generate attention by attracting synchronization of different neural circuits The brain wave itself is an electrical signal It's really difficult to measure microvolts, but there's no problem in the detection At least there's no problem in the laboratory Thunderbolt, a research fellow at Peking University, said that the advanced nature of EEG measurement equipment, the degree of cohesion, the measurement method and the implantation are all factors that can influence the accuracy of EEG measurement It is understood that at present, there are brain computer interface, electrode patch, head ring or helmet and so on In theory, the method of obtaining brain wave through brain computer interface has the highest efficiency, the best recognition rate, and can be used continuously for a long time, but the disadvantage is that brain computer interface is needed, which has a high risk Electrode patch is a typical way to obtain brain waves In the field of medicine and some scientific experimental scenes, we can often see the scene of sticking dense electrodes on the outside of the brain Li Luqun, a professor of Shanghai Normal University, and others introduced in detail the way to obtain brain wave through electrode patch in the article "analysis of human fatigue test model based on brain wave signal": through two dry electrodes, the chip is connected with the tester's head, one of which is attached to the tester's forehead, the other is clamped in the tester's left ear; then the biosensor Connected with the computer terminal, the chip sends the collected brain wave signal to the biosensor through Bluetooth, and the computer terminal will display the characteristic value of the brain wave signal Although the cost of this method is much lower than that of BCI, it does not need to be implanted, and it has high security In addition, its signal recognition rate is relatively guaranteed But the disadvantage is that the operation cost of this method is high, and it needs the help of professionals, and it can not be carried out at any time, so it is difficult to popularize in daily life scenarios In addition, the head ring or helmet is also one of the ways to obtain brain waves The head ring or helmet has the advantages of simple wearing, continuous use and convenient productization Its disadvantage is that the acquisition signal is easy to be interfered by the background noise signal, and the accuracy and efficiency of recognition are obviously lower than the former two The decipherment of EEG signal is still "blue ocean", which is free from any restriction and profound in wisdom People's thinking is so rich and colorful There are many kinds and tens of millions of combinations of brain waves How to decipher these signals? "Different cognition can be judged by the change of EEG, but it is very complicated." Zhang Yunhong, a researcher at China Institute of standardization, said that although different brain waves have roughly one representative direction, the actual situation is much more complicated In order to find out the relationship between driver fatigue and brain wave signal, Li Luqun et al Once established a model, through multi-step processing of complex data, such as noise reduction, reconstruction, modeling, fitting, etc., after multi-step calculation, and then carried out reverse verification, obtained a relatively accurate calculation method, so that the characteristic values of α, β, θ waves can be calculated, and then the fatigue state can be obtained Judgment expression to judge whether fatigue or not "The main question is whether the EEG is accurate and whether the data is valuable." Thunderbolt believes that if the accurate mathematical model is not obtained in the stage of basic research, the subsequent software design and application development are all groundless In fact, the decoding of EEG signals is still a "blue ocean" "Using the eigenvalues of α, β and θ waves for calculation is only one part of it, and there are many other influences." Zhang Yunhong said that at present, there is no consensus such as guidelines in the scientific community The basis of life activities in the field of biology is still an unsolved mystery The expression of transforming it into a mathematical model is a reflection of thick lines Even if the EEG capture is accurate and the subsequent software development is appropriate, it can not reflect the current situation of thinking highly accurately For example, from the paper "the effect of EEG biofeedback on the attention of normal primary school students" by Li Xuefei and Xu Chaojin of Southwest University of science and technology, we can see that 8 Five grade primary school students used EEG biofeedback training system for two months of attention training After comparison, it was found that although the overall effect was improved, there was inconsistency between EEG data and the results of the scale In other words, EEG data shows concentration, while the scale item bank shows lack of attention It is still difficult to judge whether the EEG data is close to the reality or whether the subjective question bank is more accurate Related link regulation of brain waves is expected to interfere with cognitive impairment The reporter learned that the American Academy of Pediatrics regards brain wave neural feedback training as one of the interventions for ADHD Chinese scientists are also developing a kind of wearable helmet, hoping to realize the feedback regulation of human brain function enhancement technology by monitoring and regulating brain waves and combining with artificial intelligence algorithm This kind of wearable helmet is based on the non-invasive brain stimulation control technology which appears in recent years Its principle is: through the flexible electrode sensor, recognize the changes of brain wave when the brain performs different tasks, release weak current pulse stimulation through the electrode combination, reach the specific area of the brain, change the activity of brain wave, regulate the activity of brain neuron cells State According to the research team leader, this technology is expected to be applied to the skill training and rapid improvement of learning and memory ability of special personnel in the future, as well as the intervention and relief of anxiety and tension caused by high pressure environment In the field of medical treatment, this technology is expected to intervene children with ADHD, depression, Alzheimer's disease, aphasia, Parkinson's disease and other functional abnormalities, limb motor disorders, cognitive disorders Through the experimental study, the research team analyzed the specific brain areas related to attention cognition, emotional regulation, anxiety, drug addiction, stress and epilepsy, hoping to implement effective intervention in these specific brain areas in the future But the relevant person in charge also said frankly that the current data is only the results of some population tests Before the helmet is put into the market on a large scale, a large number of double-blind experiments need to be conducted for different age groups to accumulate enough convincing data