What is Biofeedback?

Biofeedback is also called biological feedback. It has different meanings on different occasions. It can refer to a process that occurs in the organism; it can also mean a method; it can also mean a special treatment.

Chinese name: Biofeedback
Foreign name: biofeedback

Also known as: Biological feedback
Types of: A special treatment

Introduction to Biofeedback

Biofeedback is the use of sophisticated specialized tools to explore and amplify various information generated by the human's inherent physiological changes. Through the display system, this information is converted into signals or readings that are easy for patients to understand, and guided by medical staff. The next training is to enable patients to learn to use the processed signals from themselves to consciously control various physiological and pathological processes in the body and promote functional recovery, so as to achieve the purpose of treating diseases ^[1] .

Biofeedback Research

Biofeedback research was initiated in the 1960s by five individuals (JVBasmajian, J. Kamiya, HDKimmel, NEMiller, and J. Olds). Basmajian believes that biofeedback is the use of instruments (usually electronic) to reveal normal or abnormal activities inside the human body through visual or auditory signals. The purpose is to control the internal activities of the body by manipulating physiological activities that are otherwise unconscious or invisible. Physiological activities in the body, such as how fast the heart beats, are generally unconscious and difficult to speed up or slow down at will. If we express the heartbeat with a certain sound height, we can increase or decrease the signal to achieve the purpose of making the heart rate faster or slower. In this way, tachycardia or bradycardia can be treated. This is what people usually call biofeedback. According to whether the role played by the organism is positive (positive or positive) or negative (negative or negative), it can be divided into positive feedback and negative feedback; according to whether there are external receptors in the feedback link, It can be divided into internal feedback and external feedback.

The study of biofeedback has both theoretical significance and practical value: it breaks the traditional framework that the organs governed by the autonomic nervous system cannot learn and cannot be controlled at will, opening up a new field of "visceral learning" ; Through biofeedback training, the internal environment of the organism can be changed, and the working states of the nervous, circulatory, respiratory, and digestive systems are changed. Therefore, it provides a new method for treating various diseases. In the early days of biofeedback research, scholars did a lot of research on the feedback training of EEG, EEG and sensorimotor rhythm, and also studied heart rate feedback, blood pressure feedback, skin temperature feedback, skin electrical feedback, myoelectric feedback, etc. And their practical application in the clinic. Among them, EMG feedback is the most widely used.

Compared with bio-feedback training, biofeedback is simple and easy to grasp, because it is supported by signals. However, due to the need for participants to pay attention to the signal continuously, some feedback training, such as muscle relaxation training, skin warming training, heart rate slowing training, etc., have adverse effects and hinder the further progress of these trainings. Although biofeedback has a good effect on certain diseases as a treatment, it is not a panacea.

Biofeedback Open-Loop Closed-Loop

Open / close loop

In the control system, a control system in which the output part no longer provides information to the input part is called an open-loop control system; a control system in which the output part can provide feedback information to the input part is called a closed-loop control system.

As far as humans are concerned, some of the reflexes that occur in the body are open-loop, such as knee-jump reflexes. When the tendon of the knee is stimulated, the quadriceps muscles contract, kicking on the calf, and the reflection ends here. Some reflexes are closed loops, such as the lung stretch reflex. When the inhalation reaches a certain level, the stretch receptors distributed on the bronchi and bronchioles are stimulated, sending excitement impulses into the brain, inhibiting the activity of the inhalation center, and making the inhalation Breath ceases and expiration occurs. When exhaling, the lungs shrink, the stimulation of the stretch receptors weakens, the afferent impulses decrease, the inhibition of the inhalation center is lifted, and the inhalation center is excited again.

Biofeedback positive and negative feedback

Positive / negative feedback

Refers to feedback that strengthens or weakens the physiological process that was originally performed. In a voltage feedback circuit, if the feedback voltage is in phase with the input voltage, the result is to strengthen it, which is called positive feedback. A similar situation occurs in the human body. When the bladder urinates, the urine stimulates the pressure-sensing devices in the bladder wall and urethra. Through reflexes, nerve impulses from the central nervous system strengthen the detrusor of the bladder. At this time, urine discharge is accelerated, and the stimulation of the bladder wall and the pressure-sensing device in the urinary tract is also strengthened, making the urination process more and more intense. This is the positive feedback phenomenon that occurs in the body.

When people's blood pressure rises temporarily due to increased activities, emotional fluctuations, etc., the receptors in the aortic arch area generate more afferent impulses due to changes in pressure. Through reflection, the center sends out "commands" to weaken the contraction of the heart and dilate some blood vessels, limiting the originally rising blood pressure and stabilizing blood pressure. When the originally increased blood pressure gradually decreased, the stimulation of the receptors was weakened, and the impulse to the center was relatively weakened. The "decompression instruction" issued by the center also decreased accordingly, and the blood pressure stabilized. This is the negative feedback phenomenon.

Internal and external feedback

Internal / external feedback

Feedback in the feedback loop including external receptors (such as vision, hearing, etc.) is called external feedback. For example, when training subjects to lower their blood pressure, they need to raise and lower their blood pressure and feedback them to the subjects through visual or auditory channels. This feedback requires the participation of external receptors, which is external feedback. In contrast, feedback that is performed in vivo without the involvement of external receptors is called internal feedback. For example, lung reflex (see open / closed loop) is an internal feedback. (Yan Kele)

Biofeedback feedforward

Feedforward

In contrast to feedback, feedback refers to later activities that in turn act on previously occurring activities, while feedforward refers to the impact of previous activities on subsequent activities.

Feedforward control in cybernetics refers to a type of process control. That is to say, changes occurring in the subsequent process are detected at the input of the process and compared with predetermined instructions. If there is a deviation, an instruction is issued before the output is affected, and the deviation is corrected. To ensure that the original instructions issued are accurately implemented. Feed-forward also refers to a balanced system that accepts multiple inputs of information. The higher-level system can change the output information of the latter without waiting for the feedback from the subsystem. Most of the advanced psychological activities of humans are carried out according to the feedforward principle. People do not need to try and error everything, but directly compare the current situation with the information that has been stored in the advanced nervous system in the past. Proper response.

The ultimate goal of biofeedback training is to achieve feedforward through feedback. Only in this way can we exercise arbitrary control over the organs dominated by the autonomic nervous system.

Biofeedback false feedback

Pseudofeedback

In order to check the effect of feedback or to achieve special experimental purposes, the feedback information provided by the main test to the test subject is not the actual reaction of the test subject at the time, but the reaction of others or the reactions he made in the past. This practice is called false feedback. In alpha feedback training, in order to test whether the subjective factor "expectation" will affect how much alpha waves are generated, researchers have adopted a method of false feedback: "expectation" to obtain the feedback signal obtained by a successful group of participants More than the alpha waves that they actually generate in the brain, and encourage them with language; the feedback signals obtained by the other group of subjects were given in the normal way, while emphasizing that it is very important to generate more alpha waves difficult. The previous set of feedback is called false feedback.

Biofeedback Alpha Experience

Alpha experience

It refers to the subjective feeling when alpha waves appear in the brain of the subject. In the experimental study of increasing the EEG alpha wave, many subjects reported that they entered a pleasant, relaxed state of quietness, a state of lost body and time perception, and a state of empty mind and self. , A general state of psychological balance. Participants also reported that when in this state, they thought very little about external things, rarely thought about how the experiment was conducted, and rarely thought about what they were doing.

At first, some researchers believed that the alpha experience was related to the number of alpha waves in the subject's EEG. Later research proved that there is no necessary connection between the two. Researchers have further determined that alpha experience is closely related to certain socio-psychological variables (such as cues, expectations, and the degree of success experienced by participants). Alpha experience is quite similar to what Chinese Chinese qigong practitioners say when they enter the "Qigong state" or "Get Qi". Some people think that the stronger the "Qigong", the better the effect of Qigong in curing diseases. Based on. (Yan Kele)

Biofeedback EEG alpha feedback

EEGfeedback

It refers to a method of feeding back the 8-13 Hz component of the EEG activity to the subject. The specific methods are: ask the subject to guess whether an alpha wave appears in their brain; use the EEG alpha wave generated by the subject to control the flash or picture to display feedback; use the alpha wave generated in the brain Control sound for feedback.

Early researchers thought that they could train subjects to randomly increase or decrease their EEG alpha waves. Later, they learned that through training, they only learned some methods, removing those factors that inhibit alpha rhythm, and produced greater levels than baseline. EEG alpha density. It is hoped that the alpha waves in the subjects 'brains will increase through training, so that the subjects' attention and memory conditions will be improved. The research results cannot convincingly confirm this assumption.

Biofeedback EEG feedback

EEG theta feedback

It refers to a feedback method that feedbacks EEG signals of 4-6 Hz to subjects through audiovisual methods to increase or decrease theta activity. The specific method is: when the average number of waves in a period of time decreases or remains the same as before, if the subject is being trained at this time to increase the waves, the sound (such as 400 Hz) will be louder than before Stronger, with encouragement; On the contrary, if the subject is training to reduce theta wave, and the subject's wave is reduced or remains the same as before, let the sound sound for one second to strengthen. Through the method of biofeedback, subjects can generate more waves, and the opposite training can be used to suppress the generation of waves. Theoretically speaking, training of waves can be used to improve the performance of subjects' perceptual signals. However, due to the need for individual training and complex equipment and conditions, its widespread use is limited. Some experiments have proven that the participants are effective in laboratory training, but the actual work performance is not necessarily high. Therefore, the theoretical significance of EEG feedback research is greater than its practical value.

Slow cortical feedback

Slow cortical potential feedback of the cerebral cortex

It is a feedback method that feeds back the slow potential generated by the cerebral cortex to the subject. The method of slow potential feedback of the cerebral cortex is to take a signal from the center of the head (Cz), place the reference electrode on the ear lobe, use a computer to generate stimuli and collect and calculate materials. Use a rocket moving laterally on the screen as the cortex Signal of continuous feedback of slow potential. Changes in the direction of the rocket represent changes in the cortical slow potential relative to the baseline level before the measurement. The slow potential transition recorded from the surface of the scalp is regarded as the process of adjusting the excitability of the cerebral cortex under the location of the recording electrode. After a healthy person is stimulated, the slow potential of the cerebral cortex will return to the baseline level within 300-500 seconds. In patients with schizophrenia and anhedonia, their ability to regulate excitability in the cerebral cortex is impaired. Their cerebral cortex can generate negative potentials, but this potential cannot be changed during the first few training sessions. Using biofeedback and operating conditioned reflexes, the slow cortex potentials of schizophrenia can be changed through training.

Biofeedback EEG sensory motor rhythm training

EEG sensorimotor rhythm training

In the study of animal EEG, it was found that when a cat learns to suppress movement, a 12--15 Hz sinusoidal rhythm can be recorded in the cortex of its sensorimotor area, because this activity occurs in the cerebral cortex. The sensory motor area is named sensory motor rhythm (SMR). The emergence of sensorimotor rhythms, whether in sleep or awake state, is closely related to lack of exercise. To this end, researchers have adopted biofeedback methods to increase patients' sensory motor rhythms to treat epilepsy. However, this treatment method has not been widely used because it requires complex equipment and longer training.

EMG feedback

It is a feedback method that amplifies the weak EMG signal and feedbacks it to the subject in the form of sound or light. The subject manipulates muscle activity based on this feedback signal to relax or strengthen the muscle. EMG feedback can be divided into three cases: one is to feedback the changes in the potential of a few muscle fibers to the subject. This feedback is performed using a needle electrode inserted into the muscle. The advantage of this feedback method is that it can make subjects increase their EMG potential in just a few minutes. The disadvantage is that the effect is not consolidated. The second case is the use of surface electrodes for feedback training on muscle contraction. The purpose is to relax muscles or increase muscle contraction strength; the third is position feedback. Through this feedback training, participants can learn to control a part of the body, keep it in a certain position, or make it Muscle movements are more coordinated and accurate. The placement of the electrodes depends on the needs. When using surface electrodes for relaxation training, two signal-taking electrodes are usually placed two centimeters above the eyebrow arch, facing the two pupils, and the reference electrode is placed between the two electrodes. When performing feedback training on a certain muscle, if a needle electrode is used, the electrode should be inserted on this muscle. If surface electrodes are used, the positions of the two electrodes on the surface of the skin should be directly opposite the abdomen of the muscles to be trained. Sound is usually used as a signal for EMG feedback. When the EMG level rises (muscle tension increases) reaches a predetermined value, the sound can be heard (or the original sound disappears). As the muscle tension increases, , The louder the sound (or the higher the pitch), and vice versa.

The purpose of EMG feedback is to help patients (or subjects) to relax training and reduce their arousal level, as an auxiliary method for treating various psychogenic disorders, to help patients restore the strength of a certain part of the muscle (such as facial or other paralysis Muscles) to achieve the purpose of curing diseases.

Control of a single motion unit for biofeedback

Single motor unit control

Skeletal muscle is dominated by motor neurons in the anterior horn of the spinal cord. All muscle fibers dominated by a single anterior horn cell and its efferent nerves are collectively referred to as motor units. Experimental research shows that it is very easy to control this kind of movement unit by using biofeedback method. It only takes about 5 minutes to make the movement unit that was basically out of control and strengthen the activity at will. It should be noted that this regained control disappears quickly, and the control of a single motion unit does not equal the restoration of complex motor functions. Therefore, we cannot draw the conclusion that the motor function is easy to recover.

Biofeedback Epilepsy Feedback

GSR feedback

It refers to a feedback method that presents the subject's skin electrical activity to himself. It is generally believed that skin electrical activity is generated by sweat gland activity, so it is also called sweat gland potential. There are two methods for measuring skin electrical activity: one is Charles Fere's method with the help of an external power source. This method measures the skin resistance between two electrodes (the unit of measurement is ohms or its reciprocal number) (European) changes are commonly expressed by EDR (F); the other is J. Tarchanoff's method, which measures the skin's potential (the unit of measurement is the consumption voltage), Expressed as EDR (T). There are two corresponding feedback methods. One reflects changes in the skin resistance level and resistance response of the subject, and the other reflects the potential level and potential response. It is simple and easy to use the fluorescent screen of the eight-channel recorder for feedback. OK method. The room temperature is below 20 degrees, which is not suitable for skin electrical feedback training. Electrocutaneous feedback is often used to reduce a person's arousal level, promote relaxation, or as an aid to treat mental illness.

Biofeedback Skin Temperature Feedback

Skin temperature feedback

It refers to a feedback method that presents the skin temperature change of the subject to the subject, and the subject manipulates the perceived temperature change to change the temperature of a part of his body. The main components and functions of the skin temperature feedback instrument are: The temperature change is converted into an electrical signal by a sensor (thermistor), amplified by an amplifier, and finally the change is presented to the subject in the form of a number or a curve. The lower the skin temperature before training, the higher the temperature that the training may rise, and vice versa. This situation is called the initial law. Participants' calm mood and relaxed muscles helped the skin temperature rise faster and more steadily. The more eager the subjects were to increase the skin temperature, the less satisfactory the effect was. In the feedback training that raises the temperature of the finger, the skin temperature can be gradually increased in the first 15 minutes, and then it will often decrease. Trainees to raise their finger temperature are often used to treat headaches, especially migraines, and also to treat other conditions caused by vasomotor disorders, such as Raynaud's disease.

Biofeedback blood pressure feedback

Blood pressure feedback

It refers to a feedback method that presents the changes in the blood pressure of the subject to the person through the instrument. The purpose is to make the participants learn to control their changes in blood pressure, so as to stabilize the blood pressure at a certain level. The specific methods of blood pressure feedback are: arterial intubation (only for animals), B. Tursky method and pulse wave velocity method. The method used by Tursky et al. Is to place a microphone on an artery at the elbow socket instead of a stethoscope and secure it with an inflatable cuff. When blood flows through the arteries, the microphone is vibrated, and the loudspeaker is amplified to make a sound. This sound is called Korotkoff sound (Ks). When the heart beats, if 50% of the heart is accompanied by Ks sound, then the cuff pressure is equal to the average systolic pressure. If 25-75% of the heartbeat is accompanied by Ks sound, the cuff pressure is 2 mm Hg higher or lower than the mean systolic pressure. In order to better change the blood pressure of the subject in the direction expected by the experimenter, the blood pressure value as a feedback signal is presented to the subject through such processing: If the subject appears in a one-minute test, Ks is equal to or higher than 75%, then in the next test, the stable cuff pressure will increase by 2 mm Hg; on the contrary, if it is lower than 25%, the cuff pressure will be decreased by 2 mm Hg. In order for the subjects to obtain intuitive feedback signals, three lights of red, green, and yellow can be presented in front of the subjects, and the subjects were given three different prompts: systolic blood pressure decreased, increased, and met the requirements.

The pulse wave velocity method is a method in which the length of the pulse wave transmission time is used as an analog quantity for blood pressure feedback. The transit time of the pulse wave refers to the time between the R wave in the electrocardiogram and the start point of the pulse wave. The feedback method is to display the pulse wave transmission time on the fluorescent screen with a horizontal line. A longer horizontal line indicates a decrease in blood pressure, and a shorter line indicates an increase in blood pressure. Although this method can give the participants intuitive and timely feedback, they do not know the absolute value of blood pressure. The blood pressure feedback has a certain therapeutic effect on the initial essential hypertension.

Biofeedback pulse blood volume feedback

Blood volume pulse feedback

When the heart contracts, the capillaries on the body surface fill up. At this time, the light transmittance increases. During the diastole, the capillaries on the body surface are in a relatively contracted state, and the light transmission performance decreases. Pulse blood volume feedback is based on this situation. The feedback sensor is composed of a luminous electric bead and a photoresistor, and the light emitted by the electric bead passes through the body surface tissue and then acts on the photoresistor. Due to the different light transmission of body surface during systole and diastole, there will be a curve on the screen that fluctuates with the pulse and reflects the change in blood volume of peripheral blood vessels (this method is a step forward from the previous plethysmography). Because it reflects the blood filling in the body's surface capillaries, it can be used for feedback training related to the body's capillaries, and it can also be used to monitor the heart rate and cardiac force. The heavy wave in the pulse blood volume curve can also reflect the elasticity of the aortic arch, so it can be used to roughly observe the changes in the elasticity of the arteries.

Biofeedback Heart Rate Feedback

Heart rate feedback

It is the kind of feedback that provides the subject with the change of heart rate to himself so as to change his heart rate accordingly. There are many ways of heart rate feedback: first, let the participant guess his heart rate is fast and affirm if he guesses correctly; the second method is to ask the subject to press the electric key whenever the heart rate increases or decreases; the third is , Asked participants to control their heart rate based on the size of the heart rate simulation. The specific method is: the subject looks at the screen of the computer monitor. Whenever the subject's heart beats once, a horizontal line is drawn from left to right on the screen. The length of the line indicates the time between the two R waves of the heart beat. (In median size). The longer the time between the R waves of the two heartbeats, the longer the horizontal line appears on the screen, indicating that the subject's heart rate is slower, and vice versa. There is also a vertical target line on the screen. Participants are required to keep the horizontal line on the screen as long as possible. If the participant can successfully cross the target line more than 10 times, a new line will appear on the screen. Target line, the position of this target line is based on the median of the previous heart rate and the current heart rate of the participant. After the new target line appeared, the participants were required to make efforts to keep the horizontal line indicating the slow heart rate longer. This method can reduce the heart rate of the subjects 4 times per minute, and the maximum can reduce 19 times per minute. The fourth method is to control the sharpness of the image on the TV screen based on the speed of the subject's heart rate. The participant watched a pre-recorded video tape, and told the participant that when the experimenter walked into the room, the TV set started to play, and after a while (the time was 10 minutes, it was used to record the participant's heart rate and breathing. (Baseline level) The image and sound of the TV will start to blur. If your heart activity can slow down, the image and sound will become clear again. This TV is controlled by a computer. When the subject's heart rate is larger than the predetermined, the image and sound of the TV are more unclear, otherwise it is clear. When there is no difference, there is no noise interference. When the subject's heart rate decreases to a predetermined standard, a new standard is scheduled to continue to reduce the heart rate. Experimental results show that subjects can manipulate the TV's image and sound by changing their heart rate. Heart rate feedback can be used to change the speed of a patient's heart activity.

Biofeedback

Respiratory feedback

It is a feedback method to provide the subject's breathing condition to himself. Respiration feedback can take two forms: one is to present the breathing curve to the subject, and the other is to show the inspiratory volume to the subject. When using the breathing curve for feedback, there are two ways to pick up the signal: one is to place the thermistor on the subject's nostril, and the other is to place the sensor (which can be a flexible tube filled with conductive fluid ) Tied to the chest or abdomen, then the breathing signal is amplified and presented to the subject through an oscilloscope or a tracing device. The subject can adjust his breathing according to the curve. Respiratory feedback training can be used to treat asthma. Patients are required to increase their maximum forced expiratory volume for one second. After a period of training, the onset of asthma can be significantly reduced. Respiration feedback can be used to train subjects to learn abdominal or other forms of breathing.

Biofeedback inspiratory volume feedback

Inspirometer feedback

It is a feedback method that presents the amount of gas inhaled to a subject each time he breathes. There are two specific methods: one is to use an inspiratory meter with a capacity of 4,000 milliliters. An inspiratory volume is predetermined for the subject in advance, and the subject is required to inhale three times in a row. If it can meet the predetermined requirements, The predetermined standard is increased by 500 ml. If the subject reaches this new standard in three inhalations, the standard of inspiratory capacity is increased by one level until it cannot be increased. The other method is described in the respiratory feedback item, the second method using the breathing curve for feedback. Inspiratory volume feedback is often performed simultaneously with myoelectric feedback to increase the inspiratory volume of asthmatic patients and overcome their bronchospasm.

Biofeedback biofeedback treatment mechanism

Myoelectric biofeedback therapy is through the regulation of the central nervous system, endocrine system, and immune system. Under the conscious guidance, it uses psychological processes to affect physiological processes. On the basis of relaxation, train and control your own physiological activities, adjust and correct various autonomic dysfunctions, and promote the recovery of the body from the state of balance to the level of balance. The biofeedback signal itself can be very effective in teaching you how to direct functional activities in the body. When biofeedback signals transmit what is happening in your body to the brain, this unconscious psychological process will work to change this functional activity in the body. In the process, your brain will distinguish biofeedback information and make new cognitive evaluations in time, and then send signals along the nerve to change the level of muscle tension. In general, the skin surface potential is in equilibrium with the isotonic tension potential, and the degree of muscle tension is positively related to the level of emotional anxiety. The forehead skeletal muscle is the most representative and is used for relaxation training. It can represent the tension of the whole body muscles and can monitor the patient's mood fluctuations. It can effectively help patients relax and relieve anxiety and achieve the purpose of treatment ^{[1 ]} .

Establishment of self-confidence in biofeedback biofeedback therapy

The establishment of self-confidence is the basis for improving the cure rate. In the course of treatment, it is necessary to help patients fully understand the purpose of biofeedback therapy and affirm the treatment effect. Once successful, taste the sweetness and be confirmed, it will promote the next use, create a virtuous circle, and enable patients to accept and With treatment. When the patient is receiving treatment, the patient's intentional concentration should be implied according to the condition in order to obtain good results. For example, when a patient with concentration of mind learns to control his muscle tension level, his brain obtains information about the muscle tension state that he could not feel from biological feedback signals, and uses these to relieve muscle tension. In addition, watching or listening to this biofeedback signal can also direct a person's attention away from the problem that they are annoying, so as to reduce this muscle tension and frequent alertness, reduce psychological stress, and get relaxed. sense. It can be seen that it is a prerequisite for patients to establish self-confidence before treatment.