Lesson 14 BIOFEEDBACK Relaxation and Arousal

Transcription

1 Physiology Lessons for use with the Biopac Student Lab Lesson 14 BIOFEEDBACK Relaxation and Arousal Manual Revision EDA/GSR Richard Pflanzer, Ph.D. Associate Professor Indiana University School of Medicine Purdue University School of Science J.C. Uyehara, Ph.D. Biologist BIOPAC Systems, Inc. William McMullen Vice President BIOPAC Systems, Inc. BIOPAC Systems, Inc. 42 Aero Camino, Goleta, CA (805) , Fax (805) Web: BIOPAC Systems, Inc.

2 Page 4 II. EXPERIMENTAL OBJECTIVES 1) Introduce the concept of biofeedback training for relaxation. 2) Measure levels of arousal via heart rate and electrodermal activity (EDA). Biopac Student Lab III. MATERIALS BIOPAC disposable vinyl electrodes (EL503), 3 electrodes per Subject Electrode lead (SS2L) BIOPAC EDA setup o Disposable Setup: EDA/GSR Lead (SS57L) and EDA Gelled Electrodes (EL507 x 2) o Reusable setup: EDA/GSR transducer (SS3L) and Electrode gel (GEL1) Computer system Biopac Student Lab 3.7 BIOPAC data acquisition unit (MP36, MP35, or MP30 with cable and power) IV. EXPERIMENTAL METHODS For further explanation, use the online support options under the Help Menu. A. SET UP FAST TRACK Set Up DETAILED EXPLANATION OF SET UP STEPS 1. Turn the computer ON. The desktop should appear on the monitor. If it does not appear, ask the laboratory instructor for assistance. 2. Make sure the BIOPAC MP3X unit is turned OFF. 3. Plug the equipment in as follows: EDA setup (SS3L or SS57L) CH 1 Electrode lead set (SS2L) CH 2 4. Turn the MP3X Data Acquisition Unit ON. EDA Setup to CH 1 BIOPAC MP3X unit SS3L shown or SS57L EDA/GSR Lead SS2L Electrode Lead Set 5. Select a Subject (who has not exercised within the last hour). Set Up continues Fig Subject must not have done any rigorous exercise within the last hour. For optimal adhesion, electrodes should be placed on the skin at least 5 minutes before the start of Calibration

3 Lesson 14: Biofeedback Page 5 6. Place three electrodes on the Subject (Fig. 14.2). one on right forearm (just above wrist) right forearm WHITE lead 7. Attach the electrode lead (SS2L) to the Subject following the color code (Fig. 14.3). When the electrode cable is connected properly, the LEAD II electrode configuration will be established. one on inside right leg (just above ankle bone) right leg one on inside left leg BLACK lead (just above ankle bone) (ground) Fig Fig left leg RED lead medial surface of right leg, just above the ankle bone medial surface of left leg, just above the ankle bone right anterior forearm at the wrist (same side of arm as the palm of hand). Each of the pinch connectors on the end of the electrode cable needs to be attached to a specific electrode. The electrode cables are each a different color, and you should follow Fig to ensure that you connect each cable to the proper electrode. The pinch connectors work like a small clothespin, but will only latch onto the nipple of the electrode from one side of the connector. 8. Setup the EDA. HINT For a good signal to be picked up, it helps if the subjects have a little sweat on their hands (not a lot, but enough so that their hands are not completely smooth or cold). If subjects wash their hands just prior to the recording or if they have been sitting in a cold room, then they must do something to activate the sweat glands before beginning calibration or recording. If subjects begin with colder hands, the scale will be diminished and the signal will be easily saturated once they warm up during the lesson. SS57L and EL507 Attach two EL507 electrodes to the subject s fingertips and connect the SS57L lead, as shown in Fig. 14.4a. Fig. 14.4a SS57L and EL507 Setup Set Up continues

4 Page 6 SS3LA and GEL1 Fill both cavities of the EDA/GSR transducer (SS3L/SS3LA) with gel and attach to the Subject (Fig. 14.4b). IMPORTANT You must fill both SS3L sensor cavities with electrode gel (GEL1) before attaching to the fingers. 9. Start the Biopac Student Lab Program. 10. Choose Lesson 14 (L14-Biofbk-1). 11. Type in your filename. 12. Click OK. You must fill the each cavity of the SS3L/SS3LA EDA/GSR transducer with electrode gel to obtain accurate recordings. The SS3L and SS3LA attach to the fingertips in an identical manner (Fig. 14.4b) and should be in place for at least five minutes prior to the start of recording. The SS3L/SS3LA is typically placed on the index and middle finger of the left hand. Position the transducer so that the sensor is on the bottom of your fingertip (the part without the fingernail) and wrap the Velcro tape around the finger so the transducer fits snugly but not so tight that blood circulation is cut off. It s a fine line between tight and too tight. Use a unique identifier. This ends the Set Up procedure. Sensors attach to bottom of fingertips Biopac Student Lab Velcro strap wrap around fingers Fig. 14.4b SS3L/SS3LA attachment and connection END OF SET UP

5 Lesson 14: Biofeedback Page 7 B. CALIBRATION The Calibration procedure establishes the hardware s internal parameters (such as gain, offset, and scaling) and is critical for optimum performance. Pay close attention to the Calibration procedure. FAST TRACK Calibration DETAILED EXPLANATION OF CALIBRATION STEPS 1. Subject should sit in a relaxed state, breathing normally. 2. Click Calibrate (then YES, then OK). When you click Calibrate, two dialog boxes will pop-up to make sure you are ready for the calibration procedure. Click YES for the first box and click OK for the second box. 3. After the beep, inhale and exhale deeply once. You should see three tracings on the screen: the EDA recording, the ECG recording, and the Heart Rate (ECG Rate). A beep should occur four seconds into the recording. The Subject should take one deep inhale and exhale, and then return to normal breathing. The program needs to see some variation in the EDA and BPM data. Note: The Subject should inhale and exhale without tensing the chest muscles too much, as this may cause excessive EMG artifact. 4. Wait for the Calibration to stop. The Calibration will run for 20 seconds and then stop automatically, so let it run its course. 5. Check your calibration data. If similar, proceed to the Data Recording section. If different, Redo Calibration. At the end of the 20-sec calibration recording, your screen should resemble Fig EDA/GSR Figure 14.5 Both recording channels should show some fluctuation. If there is not any fluctuation, then it is possible that a transducer is not connected properly and you must redo calibration. If the display of Heart Rate shows large fluctuations (20 BPM or more) during the interval from 4-20 seconds, then it is possible that excessive EMG artifact during inhale and exhale caused loss of BPM tracking and you should redo the calibration and have the Subject breathe less deeply. If you did not hear a beep during the calibration, then you should make sure your computer volume is turned up and redo calibration. Redo by clicking Redo Calibration and repeating the entire calibration sequence. END OF CALIBRATION

6 Page 8 Biopac Student Lab C. RECORDING LESSON DATA FAST TRACK Recording DETAILED EXPLANATION OF RECORDING STEPS 1. Prepare for the recording. In order to work efficiently, read this entire section so you will know what to do for each recording segment. This lesson requires that the Subject concentrate on the monitor display of Heart Rate and Arousal (EDA) and try to change the reading(s) without physical movement. Heart Rate and level of arousal (EDA) are independent, so the Subject may be able to change one or the other or both. Check the last line of the journal and note the total amount of time available for the recording. When you begin recording, your Heart Rate and your EDA (Fig. 14.6) will be plotted in a thermometer style bar chart. Fig Heart Rate and Arousal (EDA) The Heart Rate will be displayed to the left and will increase (rise) as the heart rate increases. Arousal (EDA) will be displayed on the right, and will increase (rise) as the body resistance decreases, indicating a higher level of arousal. The upper and lower range of each reading was set with your calibration data. Both readings should begin with values in approximately the center of the display. If your reading for either bar begins beyond the mid-range, you may want to consider redoing calibration. The bar chart display only works while data is being recorded. The display will change to a standard data plot when recording is complete. 2. Click Record. The recording will begin and will run continuously until you click Stop or the time indicated runs out. 3. For the first 90 seconds of the recording, Subject should try to relax so that both bars move down. 4. After 90 seconds, Subject should try to move the bars up by increasing arousal and Recorder should insert an event marker. Recording continues Hints for achieving relaxation: a) Relax your posture. b) Breathe in and out very slowly. c) Imagine yourself at a warm, relaxing seashore. d) Smile. e) Close your eyes. To move the bars up, you need to become more aroused. Recorder should insert an event marker 90 seconds into the recording to indicate that the Subject is now attempting arousal versus relaxation. To insert an event marker, press the F9 key once. (As you are viewing the bar chart display, you will not see the marker as it is entered. A marker can also be entered after the data is recorded.)

7 Lesson 14: Biofeedback Page 9 Insert event marker at 90 seconds. (No marker label is needed.) Hints for achieving arousal: a) Think of a stressful situation. b) Have the Director clap behind you. c) Make a scowl with your face. d) Hold your breath. 5. Click Stop. When you click Stop, the data window will change to display a standard three-channel recording with ECG, Heart Rate, and EDA. This data represents the entire recording. 6. Review the data on the screen. If correct, go to Step 7. If all went well, your data should look similar to Fig and you can proceed to Step 7. Note: The recording will vary greatly from person to person, and it is hard to generalize about the results. Hopefully, you were able to manipulate your physiological responses to some degree. This may take some practice, as many people are not used to thinking that they have some control over things like their heart rate and nervous system. If incorrect, click Redo. Fig Sample data The data would be incorrect if: a) The BPM data fluctuates excessively, indicating that an electrode may have peeled up. b) The EDA signal goes outside of its plotting region, indicating that one of the EDA transducers may not have had good contact. If incorrect, you should redo the recording by clicking Redo and repeating Steps 2-6. Note that once you press Redo, the data you have just recorded will be erased. 7. Click Done. A pop-up window with options will be generated. Make your choice, and continue as directed. 8. Remove the electrodes and transducers. If an SS3L transducer was used, clean the gel cavities. If choosing the Record from another Subject option: a) Attach the electrodes and transducer to the new Subject per Set Up Steps 5 and 6, and continue the entire lesson from Set Up Step 9. b) Each the new Subject will need to use a unique file name. Remove the electrode cable pinch connectors, and peel off the electrodes. Throw out the electrodes (BIOPAC electrodes are not reusable). Wash the electrode gel residue from the skin, using soap and water. The electrodes may leave a slight ring on the skin for a few hours. This is normal, and does not indicate that anything is wrong. END OF RECORDING If an SS3L transducer was used, use alcohol to clean out the electrode gel cavities.

8 Page 10 V. DATA ANALYSIS FAST TRACK Data Analysis DETAILED EXPLANATION OF DATA ANALYSIS STEPS Biopac Student Lab 1. Enter the Review Saved Data mode. Enter the Review Saved Data mode. Note Channel Number (CH) designation: Channel CH 2 CH 41 CH 42 Displays ECG Heart Rate EDA The data window should come up the same as Fig Fig Turn OFF Channel 2, ECG. To turn a channel OFF, click on the channel number box while holding down the Ctrl key. 3. Setup your display window for optimal viewing of the data interval when the Subject was trying to relax. 4. Set up the measurement boxes as follows: Channel CH 41 CH 42 Measurement value value Data Analysis continues Fig Channel 2 turned off This is the data that represents Subject trying to relax between Time 0 and the event marker you inserted at 90 seconds. The following tools help you adjust the data window: Autoscale horizontal Horizontal(Time) Scroll Bar Autoscale waveforms Vertical (Amplitude) Scroll Bar Zoom Tool Zoom Previous The measurement boxes are above the marker region in the data window. Each measurement has three sections: channel number, measurement type, and result. The first two sections are pull-down menus that are activated when you click on them. Brief definition of measurements: value: displays the amplitude value for the channel at the point selected by the I-beam cursor. If a single point is selected, the value is for that point, if an area is selected, the value is the endpoint of the selected area. Note: The selected area is the area selected by the I-beam tool (including the endpoints).

9 Lesson 14: Biofeedback Page Measure the EDA and heart rate values about 10 seconds into the recording. A It takes a few heart rate cycles for the BPM data to be correct, so measuring data 10 seconds into the record will be an accurate baseline. Simply clicking the cursor at Time = 10 seconds will update the value measurements. 6. Scroll to the point of maximal relaxation. Fig Use the horizontal scroll bar to move through the data. Select a point at the end of the first interval (before the marker) representing the point of maximal relaxation. 7. Take the measurements on this point as needed. A Fig Scroll to the point of maximal arousal. Scroll to the second interval (after the marker). Select a point at the end of the interval representing the point of maximal arousal. 9. Take the measurements on this point as needed. A 10. Save or print the data file. You may save the data to a drive, save notes that are in the journal, 11. Exit the program. END OF DATA ANALYSIS or print the data file. END OF LESSON 14 Complete the Lesson 14 Data Report that follows.

10 Page 12 L14: Biofeedback Data Report starts on next page.

11 Biopac Student Lab Page 13 BIOFEEDBACK Relaxation and Arousal DATA REPORT Student s Name: Lab Section: Date: I. Data and Calculations Subject Profile Name Height Age Weight Gender: Male / Female A. Measurement CH. # Heart Rate (BPM) CH 40 value Table 14.1 Baseline (10 sec.) Condition Maximal Relaxation Maximal Arousal EDA (ΔμMHO) CH 41 value II. Questions B. Based on the data from Table 14.1, did the effects of the parasympathetic nervous system change with biofeedback? Explain the physiological mechanisms causing the results. C. Describe a biofeedback program for stress management. Include details such as the physiological variable(s) you would measure, the transducers needed, and your criterion for a successful training program.

12 Page 14 L14: Biofeedback D. Name the branches of the autonomic nervous system and explain their function. E. Define Biofeedback and explain in general terms how it works. F. What change, if any, did your EDA recording show when you were aroused? Relaxed? G. Why is EDA a useful measure for biofeedback training? End of Lesson 14 Data Report