What is Biofeedback?Biofeedback is the process of obtaining information about psychophysiological or mind-body interactions and “feeding it back” for training. These interactions are measured via heart rate, breathing, CO2 breath measurement, skin temperature, sweat gland activity, muscles tension and brain wave activity.
Information is received by noninvasive surface electrodes (sensors) and electronically amplified to provide feedback, usually in the form of an audio tone and/or visual feedback.
Biofeedback uses the information that has been monitored from the sensors to help train the client to learn how to make voluntary changes in those biological functions and enhance self-regulation.
This training helps to increase the client’s awareness first of their body and second, of the mind-body connection. For example, pain, stress and anxiety management increases as self-regulation skills are learned and then applied to daily life.
Description of Biofeedback Modalities:
Psychophysiological Stress Profile: The PPSP is an assessment of physiological response during stress. A baseline measurement is obtained with respiration, sEMG, GSR, skin temperature, EEG and/or heart rate. (Other modalities may also be used) After the baseline, the client is given an appropriate stressor, such as Serial 7s (counting backwards by 7’s from 100), invoking an emotional event or math or reading task and recorded. The stressor is discontinued and the client rests. Stress recovery time and physiologic “hot spots” are isolated and targeted for future training.
Skin/Surface EMG (sEMG): activity is a measure of the number of muscle motor units firing under the sensor and is measured in microvolts (uV). It is reflective of the client’s level of tension and motor control over a muscle or region. Ideally the muscle should both relax and contract quickly and efficiently. A baseline is established at each session.
Basal Skin Response (GSR, Skin conductance): is a phasic measure of electrical resistance in the epidermis and is measured in ohms. This resistance is created by autonomic activity in the eccrine sweat glands, which is easily measured on the fingers. In general, the higher the reading, the lower the sympathetic activity or arousal taking place. “Higher is drier” with this measure.
Heart Rate (HR): is measured using a photoplythsmograph (PPG) and should be variable. In general, we should see an increase in HR as the client inhales and a decrease as the client exhales. This is known as normal respiratory sinus arrhythmia (RSA). It is a reflection of the sympathetic and parasympathetic nervous systems correct signals to the sino-artrial node in the heart. Working with the RSA pattern, we generalize the readings to sympathetic and parasympathetic activity throughout the body.
Heart Rate Variability (HRV): is a measure of heart rate using a Fourier Transform analysis to generate spectral display from the raw PPG tracing. It reflects sympathetic and parasympathetic influences on the heart. When the influences on the heart are balanced, a spike appears around the .1Hz area of the spectrum.
Blood Volume Pulse (BVP): is extracted from the raw data present in the PPG tracing. It is an indirect measure of blood pressure and blood flow. As the signal increases we can extrapolate that the blood pressure is dropping.
Skin Temperature: is a measure of surface skin temperature and is measured on the fingers and/or toes. Skin temperature is related to vasodilatation and vasoconstriction. It is a measure of sympathetic or arousal activation or deactivation.
Respiration: is a measure using a strain gauge positioned across the abdomen and/or chest. Diaphragmatic breathing is encouraged, depending on the client’s medical history and capnometry readings. Limited amount of upper chest and trapezius movement is encouraged. However, the emphasis is on effortless breathing. Signs of hyperventilation and over-breathing are monitored and clients are educated regarding these breathing problems. Diaphragmatic breathing decreases arousal and is very helpful for any condition exacerbated by stress, anxiety and pain.
Capnometry: training with a simple breath analyzer called a capnometer. A capnometer measures the amount of CO2 exhaled at the end of the breath, called end tidal CO2. (The amount of infrared light absorbed by the CO2 in the sample is displayed by a wave form or capnograph). If the capnometer reading is low, it may indicate that the client is over breathing during the session or they have been over breathing for awhile. The goal in training is to work with the breathing to normalize O2 and CO2 levels which in turn normalizes blood pH and other body chemistries.
EEG: is a measure of various brain frequencies, specifically frequencies referred to as delta, theta, alpha and beta. EEG training is done for a variety of conditions in which the clients can benefit from uptraining or downtraining certain frequencies.
HEG: Hemoencephalography measures blood flow in cortical areas of the brain. The premise is that if there is blood flow, the glucose and oxygen metabolism occurs. This occurs when there is brain activity and is encouraged for optimal function.
qEEG: The quantitative electroencephalogram measures the brain's electrical activity and is used as a diagnostic tool for determining brain function and to aide in developing neurofeedback (EEG) training protocols.