ECG Archives - Page 2 of 3

Hitting the Mark: Using Event Markers to Improve Data Quality

Life is a series of events—some are planned while others catch us completely by surprise. This holds true in the lab where the quality of experiments and data depend on accurately identifying, tracking, and sorting key events as they occur. Events like the introduction of stimuli and a test subject’s reaction directly impact data.

In this context, we define an “event” as piece of information associated with a specific time in a waveform. An event can capture points of interest within a file (e.g., subject moved, dose added) or on a particular channel (e.g., T-wave onset).

Whether intentional or not, critical events need to be easily located and identified by those running an experiment. Event marking provides the key to this by helping researchers eliminate outlier data while making it possible to locate data that is significant to the experiment. Today’s researchers benefit from data acquisition software that offers some form of event marking functionality to easily identify, label, and categorize such events. BIOPAC’s latest build of AcqKnowledge, for example, integrates extremely easy-to-use event marking tools that enable users to mark “quick events” with a simple tap of a function/hotkey for 17 different event categories, each containing multiple types of events.

“I’m struggling to think of any time you wouldn’t be using these,” said BIOPAC Technical Support Manager David Pollock as part of the recent webinar AcqKnowledge Bootcamp: Set Up Experiments to Facilitate Data Analysis. “They are critical to being able to interpret your data after you acquire it.”

The benefits of event markers include:

Allowing researchers to differentiate stages of an experiment
Making it easy to eliminate outlier data
Allowing researchers to track and identify stimuli
Providing control over event tracking, thus eliminating errors

A Tale of Two Studies

A pair of recent studies illustrate how data acquisition software like AcqKnowledge can streamline event marking. The first sought to test the viability of various commercial-off-the-shelf ECG sensors for monitoring stress levels in participants. Test participants used a manual button to self-mark stress events triggered by mental arithmetic tasks, startle response tests, and a cold-water response test. A BIOPAC MP Research System data acquisition unit provided a clinical baseline for comparison with the pair of COTS ECG monitors. The limitations of self-reported events were revealed when participants were found to have accidentally activated the stress “clicker” about 60% of the time.

A similar 2018 John Hopkins University study avoided this problem through both automated and researcher-controlled event marking. When examining how military commanders maintain combat effectiveness while responding to a range of potentially stressful battlefield situations, researchers employed AcqKnowledge to record event marks at the onset and offset of various stimuli. Physiological data was fed to an AcqKnowledge-equipped computer via a BIOPAC DAQ connected to an STP100C digital interface module. Event markers generated by both AcqKnowledge and E-Prime allowed researchers to easily identify stimuli as well as each task the participants performed by name, start time, end time, and duration.

Not leveraging the power of event marking tools can result in key experimental events being lost in a flood of data, potentially corrupting results. Check out this video tutorial to learn more about event marking with AcqKnowledge.

THE BIG 3: Crucial Signals for Interdisciplinary Psychophysiology Research

This guest post was written by Michael Hogan, BIOPAC’s Southeast Regional Representative. Contact him at michaelh@biopac.com

Even trained psychologists can be daunted by the interdisciplinary applications involved with recording objective physiological data. However, it is not necessary to learn the intricacies of bio-medical engineering, physics, statistics and underlying physiological mechanisms of the body just to incorporate these objective measures into your research. With just a few key signals of interest, and a simple hardware and software setup, a trained researcher can record and interpret the objective physiological responses of participants in a physiology study.

How to get started? Begin with a protocol you are already studying and incorporate “THE BIG 3”

ECG: Electrocardiography is a biopotential, meaning direct measurement of the electrical voltage potential changes of the heart as it completes its “cardiac cycle.” Since we can record these voltage changes and graphically represent them as a waveform through analog to digital conversion, we are able to identify changes in the behavior of the heart in response to the presented stimulus. We can then establish a recurring reference point in the “R-Peak” of the QRS complex, we are able to measure the distance between these R-Peaks and establish an R-to-R interval, this measure tells us the time in-between cycles or “beats” of the heart. From one beat to the next, we can establish the participant’s heart rate. Once we have established a heart rate, we are able to extract valuable measures, such as Heart Rate Variability: how the heart rate changes over an observed set of time intervals or in response to the correlated stimulus.

Respiration: The respiration cycle is what is known as a transduced physiological signal. This means we utilize a mechanical apparatus to create a voltage potential in response to the inhalation and exhalation phases of the respiratory cycle. These voltage changes can then be measured and graphically represented as a waveform for further analysis. The respiratory cycle waveform can tell us the following:
- Respiratory rate: the number of cycles that occur within a given time interval or changes in response to a stimulus.
- Amplitude: What is the change in magnitude of the cycle, shallow vs. deep breathing.
- Respiratory Sinus Arrythmia (RSA): When collected along with an ECG signal, this analysis accounts for the changes in the participant’s heart rate as a response to the inhalation and exhalation phases of the respiratory cycle. For example, the heart rate elevates when the participant inhales and decreases when the participant exhales.

EDA: Electrodermal Activity has been adopted as the newest nomenclature for Galvanic Skin Response “GSR.” To this day EDA is touted as the best measure of sympathetic nervous system “activation.” As a derivative physiological measure, we pass a small, imperceptible current (0.5 V) into the participant’s body and measure the change from this known value as the participant responds.

As the autonomic nervous system responds to stimuli, it stimulates the eccrine glands to produce sweat. The sweat produced lowers the impedance to the current passing into the participant. We can then measure the change and extract meaningful data regarding how the participant responded to the chosen stimulus.

Skin Conductance Response (SCR): The magnitude of the response that occurred as a result of the stimulus from its onset to its peak.
Skin Conductance Level (SCL): How long it took for the response to occur following the chosen stimulus from its onset to its peak.
Recovery time: How long it takes the response to diminish and return to “baseline/normal” values.

With these “BIG 3” physiological measures we can perform hundreds of research protocols and objectively correlate patterns of behavior. Once these measures have been employed, we can integrate other measures for more comprehensive studies, such as:

EEG and fNIR for cognitive processing and learning metrics
Non Invasive Blood Pressure (NIBP) for stress and cardiovascular metrics
Facial EMG, fEMG, or Facial Coding Software for affective emotional states metrics

Visit us at www.biopac.com or click the following links for information on:

Signal-Specific Webinars
Detailed Application Notes
Signal Specific Analysis Video Tutorials
Physiological Recording Knowledge Base
Signal guides for ECG and EDA

BIOPAC Systems, Inc. provides life science researchers and educators with data acquisition and analysis systems that inspire people and enable greater discovery about life.

T4 Conference Wrap-up

August is a month of barbecues, baseball, and last-minute vacations against the backdrop of a fading summer, and the eighth month of 2019 proved to be an equally exciting time at BIOPAC, with something of a pleasant vacation thrown in. On August 12-14, BIOPAC hosted its 2nd Biennial “Tools, Trends, Techniques, and Technology” Human Physiology Conference, known as “T4” to our friends and partners around the world. This three-day event, first held in 2017, featured lively, informative sessions hosted by BIOPAC staff, partners, noted academics, and industry experts, and covered a wide range of physiological techniques and disciplines. Over 150 attendees joined BIOPAC at the 2019 T4 Conference staged once again at the beautiful University of California at Santa Barbara campus. Participants and instructors winged in from China, Australia, Germany, Sweden, Italy, Spain, U.K., Ireland, and Egypt, as well as from wide regions of the U.S and Canada to soak up the idyllic surroundings of this ocean-side campus.

The focus of BIOPAC’s T4 Conference was to provide a fun, relaxed environment while hosting nearly 40 hands-on, human physiology training workshops chaired by over 20 distinguished instructors from around the globe. One of the many conference highlights was the “Mindfulness, Meditation, and Measurement: Mindfulness Exercises in Physiological Monitoring” session, hosted by Dr. Allan Weiss of the University of Southern California and BIOPAC Co-founder and Director of R & D Alan Macy. These sessions, conducted in two parts over a two day period were booked beyond capacity, even though the early morning fog hadn’t yet lifted from the campus skyline.

The varied additional sessions covered a range from the basics, “Setting Up Your Lab, Getting Great Data and Troubleshooting,” (hosted by Dr. Terry Blumenthal of Wake Forest University, and BIOPAC’s Alan Macy and Tim Cook), and “Creating Your Own Lessons Using BSL PRO,” (hosted by Dr. Taffeta Elliot of the New Mexico Institute of Mining and Technology), to exciting new technologies such as “Integrating Screen-based Eye Trackers with AcqKnowledge,” with Keith Jackson of BIOPAC partner company EyeTech, BIOPAC CEO Frazer Findlay, and BIOPAC Engineering Manager Ed Peterlin. Additional wide-ranging physiological disciplines were also covered, including MRI techniques, stimulation, and exercise physiology. All sessions were conducted using BIOPAC hardware and software systems, as well as platforms provided by BIOPAC partners such as Cedrus, fNIR, WorldViz, Psychology Software Tools, and CNSystems. At the end of each day, it was time to relax and unwind with a beverage of choice, a a walk along the beach, and some good conversation. Each evening featured excellent meals and camaraderie in the relaxed yet elegant environment of some of Santa Barbara and Goleta’s most stunning surroundings. After three great days of immersive sessions, it came time for everyone to part ways, having forged new collaborative partnerships and an enhanced knowledge about the full potential of BIOPAC and BIOPAC partner products.

You don’t have to wait for T4 2021 to learn more about life science data—watch Fundamentals of Physiological Data Recording now!

For a closer look at T4, and a preview of what is sure to be an exciting 2021 event, we invite you to visit our T4 Human Physiology Conference page.

Looking for additional resources, tips, tricks, and expert advice on BIOPAC and BIOPAC Partner products? Please also visit our Webinars and Video Tutorial pages.

BIOPAC offers a wide array of wired and wireless equipment that can be used in your research. To find more information on solutions for recording and analyzing signals such as ECG, heart rate, respiration and more using any platforms mentioned in this blog post, you can visit the individual application pages on the BIOPAC website.

ECG – The Little Wave You Can’t Live Without

For millennia, ancient healers across the globe long recognized the human heart as immeasurably vital to human life. Other organs may take an occasional time out, but not the heart. This sinewy fist-sized pump contracts and relaxes an average 60 to 80 beats per minute and faithfully repeats this cycle some two and a half billion times over an average human lifespan, constantly driving and recirculating lifeblood through 100,000 miles of veins, arteries, and capillaries. It’s a monumental task that we take for granted, but if the process stops for more than a few minutes, so will this mysterious force we call life.

It’s intriguing to consider the wonder with which the ancients must have contemplated this organ that thumps so audibly. They knew it was of critical importance, and over the centuries learned its form and surface physiology, but what did they imagine animated it? What force kept the heart moving so steadily and faithfully, while remaining implacably divorced from the consciousness of its host? (Go ahead. Try to stop your heart. On second thought, don’t.)

The answer, in a word, is electricity. Although the stethoscope, invented in 1816 by French physician René Laennec, augmented audible heart sounds, it wasn’t until 1901 that Dutch physician Willem Einthoven developed a “string galvanometer,” capable of reliably recording the heart’s electrical activity. Einthoven’s work established a standard configuration for recording the electrocardiogram (ECG) and garnered him the Nobel Prize in 1924. Because the ECG reflects electrical activity, it is a useful “picture” of heart normality or abnormality through the observation and analysis of various distinct components of the cardiac cycle. If there are interruptions of the electrical signal generation or transmission, the ECG changes. These changes can be useful in diagnosing changes within the heart.

The methods for recording ECG have become increasingly sophisticated with the advent of digital technology and have put state-of-the art acquisition and analysis of ECG within reach of not only clinicians, but also researchers and educators. Wired in-lab systems such as the BIOPAC MP160 System with AcqKnowledge software are widely used for Research applications, while the MP36 System with Biopac Student Lab software are the industry standard for physiology education around the globe. Wireless systems such as BioNomadix or BioNomadix Smart Center can be used to collect ECG and other body signals in an untethered environment and the BioNomadix Logger is a great solution for acquiring ECG and other body signals over extended periods outside the lab.

We have come a long way since our forebears contemplated the mysteries of the vital mechanical wonder that beats in every chest, and we now have a myriad of accessible options for unlocking its secrets.

For further exploration of ECG, we invite you to enjoy the following comprehensive free ECG webinars:

Recording Great ECG

HRV & RSA – Fundamental ECG Analysis Techniques

Stressing over the effects of stress

Several studies show chronic stress is typically detrimental to health, while acute stress may be linked to positive effects in addition to the negative counterparts

With April comes National Stress Awareness Month, and it bears noting that different types of stress have varying effects. Where chronic stress is typically detrimental to health, acute stress may be linked to positive effects in addition to the negative counterparts. But is this trade-off worth it?

In a biological psychology experiment testing the effect of oxytocin on acute social stress, researchers found different results between men and women. Subjects underwent several stress tasks while their electrocardiography and impedance cardiography were recorded with a BIOPAC MP Research System and amplifiers. The researchers found that after being given oxytocin during the stressful event, men had less negative affect and women had greater math performance (compared to the control group).

A neurobiology study examined the effect stress had on an extinction memory process when a competing association was paired with a previously aversive cue. To test this, participants were presented with two images, one that was paired with a shock from a BIOPAC bar electrode, and one that was not. Extinction memory training immediately followed this stimulus, with extinction retrieval testing following a day later. Data gathered by a BIOPAC data acquisition system suggested significantly lower retrieval in the group that experienced the acute stress stimulus.

Another biopsychology experiment measured the effect of acute stress on pro-inflammatory cytokine levels in the blood. BIOPAC equipment was used to measure ECG while participants were given the Trier Social Stress Test. After reviewing the data and blood samples, the researchers determined that levels of the cytokine cell, interleukin-1β, increased significantly immediately after the stress test.

The physiological and psychological impacts of stress are clearly multifaceted with many potential results. In some situations, a heightened positive affect or greater analytical thinking may be beneficial. But is this boost in mental performance worth the increase of inflammatory cells and lower memory retention? As with many aspects of life, moderation is the safest answer, ensuring the negative effects do not become chronic problems.

For more information on BIOPAC’s wide range of tools for recording, displaying, and analyzing ECG measurements from human and animal subjects including respiration, heart rate variability, and RSA, visit BIOPAC’s electrocardiography pages and view BIOPAC’s full line of electrodes, amplifiers, and wearable, wireless transmitters and loggers.

BIOPAC Systems, Inc. provides life science researchers and educators with data acquisition and analysis systems that inspire people and enable greater discovery about life. Visit us at www.biopac.com.

Holiday Happiness Part 2: Sounds, Smells, and Self-Reflection

In a previous post, we discussed the stress-reducing benefits of loving interactions with close friends and family during the holiday season. In addition to family, there are many mood-shaping habits and activities that characterize the holidays: the smell of home-cooked meals, seasonal music, and reflection on the past year, to name a few. But do these have a real impact on happiness?

In a psychophysiology study, Matsunaga, et al., tested odor effects on autobiographical memory recall. The researchers introduced several odor stimuli to participants and measured their psychological and physiological reactions. Heart rate and skin conductance were recorded throughout the experiment with a BIOPAC data acquisition system. The odor stimuli resulted in decreased heart rate, increased skin conductance level, and an increase in positive mood states.

Another article tested the effects of meditation on emotional regulation. Participants completed emotional measures before and after a meditation intervention, and had their ECG, respiration, and blood pressure recorded using a BIOPAC MP unit. The meditation correlated with greater participant emotional regulation, as suggested by lower heart rate and respiration.

In addition to meditation and smell, Harmat and Eerola have found music to also be emotionally significant. Participants listened to a musical piece, and then responded to a questionnaire about their emotional state. In addition to measuring pulse rate and facial expressions, the BIOPAC Research System and EDA Amplifier were used to record skin conductance while participants listened to the stimulus. The results found that music samples evoked several emotions, including nostalgia and happiness.

This research suggests that we can affect happiness using subtle techniques that are part of everyday living. To read more studies about psychophysiology and stress reduction, visit the BIOPAC publication page.

BIOPAC offers a variety of equipment that can be used in studies similar to the ones presented. To find more information on solutions for recording and analyzing signals such as skin conductance, ECG, heart rate, respiration, and EDA using the MP160/MP150, and other platforms, you can visit the individual application pages on the BIOPAC website.

Holiday Happiness: Gratitude or Gifts?

Studies investigated the anxiety of gift-giving, the effects of social support in stressful situations, and what impact meditation has on heart rate, ECG, and blood pressure.

December has arrived, and for many the holidays bring a rush to check items off of a long shopping list for parents, siblings, friends, in-laws, and many more. Often we struggle to find that “perfect” gift, but are the physical goods we exchange the true source of the warmth and happiness that characterizes the season?

An article by Nomura investigated anxiety induced by gift-giving. To test this, EDA data was recorded with a BIOPAC data acquisition system and STP100 while participants responded to stimuli. The participants visualized a specific relative while being presented with potential gift options, and were asked how likely they were to purchase the potential gift for that relative. The data found that people who self-reported thinking of in-laws were the most stressed, while those who reported thinking of children or same-gender friends were least stressed.

A psychosomatic study by Inagaki and Eisenberger found that mental and physical well-being benefit from forms of social support. They tested this by administering mild shocks with the BIOPAC STMISOLA to male patients who held the hand of a female partner lying in an fMRI. The results suggest that this support (hand-holding) provided possible stress-reduction for both the male and female participants.

Another article on nonverbal communication and well being by Shaltout, et al. tested the effects of meditation and the subsequent ECG, blood pressure, and heart rate effects. The BIOPAC ambulatory BioHarness and NIBP Blood Pressure System gathered data while participants underwent several mediation episodes, during which they were instructed to focus on loving kindness towards a subject. The results found that participants had decreased heart rate.

Research suggests direct, loving interactions with those who are close to us have many stress-reducing benefits. So when you are shopping for gifts, remember that spending time is more important than spending money. To read more studies about love and stress reduction, visit the BIOPAC publication page.

BIOPAC offers a variety of equipment that can be used in studies similar to the ones presented. To find more information on solutions for recording and analyzing signals such as EEG, EMG, respiration, and EDA using the MP160/MP150, MP36, and other platforms, you can visit the individual application pages on the BIOPAC website.

The Physiology of Consumer Buying Habits

On “Black Friday” in the US, shoppers will come out in search of great deals, and researchers can measure the many physiological factors that motivate shoppers other than deals and price cuts.

Black Friday is one of the most exciting days for consumers in the United States. With the holidays right around the corner, significant deals and price cuts incentivize people to do bulk gift shopping. But is price the only factor influencing shoppers to dedicate hours waiting in line for a product?

In a neurophysiology study by Alexander et al., researchers found that participants who received a coupon while shopping online had a significant increase in oxytocin and a decrease in cortisol. A BIOPAC research system was used to gather ECG, respiration, and skin conductance data while the participants browsed a commerce website.

Another article by Ha-Brookshire and Bhaduri measured ECG response to stimuli that tested consumers’ perceived trust of businesses. The BIOPAC MP36R was used to record participants’ heart rates while they read negative reviews of an apparel business. The results found lower heart rate and less trust were correlated with the less favorable comments.

Conversely, a consumer research study by Langner et al. found that consumers’ love of brands is similar to their love of friends. Signals measured included EDA, EMG, ECG, and BPV, and were recorded by BIOPAC MP160/MP150 hardware to measure arousal levels while participants viewed different brand and interpersonal stimuli.

BIOPAC offers a variety of equipment that can be used in studies similar to the ones presented. To find more information on solutions for recording and analyzing signals such as EEG, EMG, respiration, skin conductance using the MP160/MP150, MP36, and other platforms, you can visit the individual application pages on the BIOPAC website. If you are interested in reading other related studies, visit the publications page on the BIOPAC website.

The Physiology of Election Decision-Making

The psychophysiological factors of stress, the behaviors of others, and of introception can play major roles in decision-making, and BIOPAC systems provide measurements of how physiological factors such as these influence decisions.

People experienced varying stress levels because of the 2016 US presidential election. There are a variety of factors that can impact voting behaviors and decision-making. Several recent studies using BIOPAC systems investigated the psychophysiological effects of stress, the behaviors of others, and introception on decision-making.

Stress has been shown to be very influential in decision-making. In their study, Yamakawa, Ohira, and Mastunga Isowa (2016) investigated effects of acute stress and risk taking in decision-making. Participants were asked to perform a decision-making choice where they either kept or bet the money they were given. Cardiodynamic activity was measured with ECG using a BIOPAC MP system. Results suggest that with an increase in cortisol, adrenaline, heart rate, and subjective stress, participants were likely to make fewer risky choices. So, high levels of stress may be key in helping make better decisions when selecting a future president.

Perhaps it’s not stress that will influence the choice of the next POTUS (President of the United States), but rather the behaviors of others. Work by Bault, Joffily, Rustichini, and Coricelli (2011) sought to compare private and social decision-making to discover the effect of social comparison on risky choices. The objective of the study was to understand more about how individuals evaluated the outcomes of their decisions in private as opposed to in a social context. Combining data from functional MRI (FMRI) and skin conductance recordings, subjects’ reactions were measured using a BIOPAC MP150 System. Researchers found that participants took significantly longer to make a decision in a social setting than in a private one.

In the end, many feel that it is important to listen to your heart when deciding who you find qualified to be the next president. A study by Dunn et al. (2010) examined whether introception moderates the coupling of bodily responses to emotional experience and intuitive decision-making. Bodily response and heart rate were recorded using a BIOPAC Research System and electrodes to measure introception through changes in heart rate. Researchers found that introception was not related to arousal, valence ratings, or heart rate response to images.

For more information on BIOPAC’s wide range of tools for recording, displaying, and analyzing physiological measurements from human and animal subjects including respiration, heart rate variability, ECG and EDA, visit BIOPAC’s psychophysiology page and view BIOPAC’s full line of electrodes, amplifiers, and wearable, wireless transmitters and loggers.

Respiration and ECG

By Alan Macy, BIOPAC Systems, Inc. The mechanical relationship between the diaphragm and heart and Respiratory Sinus Arrhythmia (RSA). are two influences of respiratory activity on the electrocardiogram (ECG).

By Alan Macy, BIOPAC Systems, Inc.

There are two influences of respiratory activity on the electrocardiogram (ECG). The first influence is characterized by the mechanical relationship between the diaphragm and heart. The second influence is a consequence of respiratory action on the vagus nerve and is known as Respiratory Sinus Arrhythmia (RSA).

The position and movement of the diaphragm determine the position of the heart because the pericardium is firmly attached to the central tendon of the diaphragm. With deep inspiration, the diaphragm contracts and becomes flatter and less dome-shaped. As it does, the heart descends, moves backward, and rotates to the right so that it becomes narrower and more vertical. The apex beat is lower and more medial. During deep expiration, the diaphragm relaxes, elevates, and becomes more dome-shaped, and movements of the heart are the converse of those that occur during deep inspiration. The degree of the directional movements of the heart during quiet breathing is similar, but reduced, compared to deep breathing and, in some persons, may be hardly noticeable. Diaphragmatic breathing cyclically affects the position of the heart, thus modifying the ECG.
Heart rate increases during inhalation and decreases during exhalation. Heart rate is normally controlled by centers in the medulla oblongata. One of these centers, the nucleus ambiguus, increases parasympathetic nervous system input to the heart via the vagus nerve. The vagus nerve decreases heart rate by decreasing the firing rate of the sinoatrial (SA) node. The SA node is the “pacemaker” of the heart. Upon expiration, the cells in the nucleus ambiguus are activated and heart rate slows down. In contrast, inspiration triggers inhibitory signals to the nucleus ambiguus and consequently the vagus nerve remains unstimulated. When recording the ECG, this phenomenon is experienced as subtle changes in the R-R interval that appears synchronized with respiration. This is the time period between two “R” waves on an electrocardiogram. The R-R interval associated with the ECG is shortened during inspiration and prolonged during expiration.