My bioengineering lab last week was about biofeedback. This is basically the idea that you can control bodily functions that are usually automatic. By looking at some sort of visual display which shows measurements of physiological function you can consciously control unconscious behaviors. For example, heart rate is controlled unconsciously by the body. There are numerous controls so that the heart rate can be increased during exercise or as part of the flight or fight response and decreased when the body is less active, but these controls are not conscious (you can’t just decide to raise or lower your heart rate). But, using biofeedback, you can learn how things like breathing deeply and smiling can lower your heart rate and eventually train yourself to control your heart rate. In our experiment one of my group members was hooked up with electrodes that measured her heart rate and something called electro-dermal activity (EDA). EDA is the electrical activity of the skin, the EDA on the palms of your hands increases when you sweat. Both EDA and heart rate increase during periods of stress and decrease during relaxation. The computer displayed these measurements in a thermometer type fashion with bars that went up when the EDA and heart rate went up.
It was surprising to see how easily my partner was able to control her heart rate and EDA just by trying to be relaxed or stressed. The green line in the middle shows heart rate and the blue line at the bottom shows EDA. The red line at the top is an EKG showing the electrical activity of the heart. During the first half of the recording my partner was trying to relax, lowering her heart rate and EDA. For the second half she was trying to increase both heart rate and EDA. It is clear that for the second half of the recording the heart rate and EDA are both significantly higher showing increased stress. It is impressive that all of this could be done while simply sitting in a chair trying to be relaxed or stressed.
This same technique is used to help treat a number of medical problems. High blood pressure can be lowered using biofeedback and it has also been shown to be helpful in pain management, especially for headaches. I had heard about biofeedback before without really understanding how it worked, so I liked being able to see it work first hand.