Heart rate variability
Heart rate variability (HRV) is the variation in the time interval between heartbeats, measured by the change in beat-to-beat intervals.
The parasympathetic nervous system is the branch of the autonomic nervous system that is not under conscious control. (i.e. the “rest and digest” system)
Para-sympathetic Nervous System
Polyvagal Theory
Polyvagal Theory, developed by Dr. Stephen Porges, is a theory that utilizes the evolution of the mammalian autonomic nervous system to explain and understand social behavior. It emphasizes the importance of physiological state in the expression of behavioral problems and psychiatric disorders.
To learn more about Polyvagal Theory, click here to read an interview with Dr. Porges from the Guardian.
Respiratory Sinus Arrhythmia is the fluctuation in heart rate variability caused by inhalation and exhalation in each breath cycle. The heart rate increases upon inhalation and decreases during exhalation. This fluctuation is typically normal and benign. RSA is often used as a noninvasive way to explore vagal tone.
Respiratory Sinus Arrhythmia (RSA)
The sympathetic nervous system is the branch of the autonomic nervous system that responds to danger cues and triggers the release of adrenaline. This causes an individual to take action in unsafe situations (i.e. the “fight or flight” response).
Sympathetic Nervous System
Trauma
Psychological trauma occurs as a result of an overwhelmingly stressful event or series of events. The extent and severity of stress from these events exceeds an individual’s personal ability to cope with the situation physically, mentally, and emotionally. Trauma often results in lasting negative effects on the mind and body and may even result in the development of Post-Traumatic Stress Disorder (PTSD). Our lab seeks to explore how the lasting effects of trauma affect the body’s natural autonomic function.
Vagal tone is the nature of the continuous output of parasympathetic action from the vagus nerve. These changes are not under conscious control.
Vagal Tone
Vocal Prosody
Vocal prosody is the content of speech (pitch, rhythm, intensity, etc.) that is not individual phonetic elements such as vowels and consonants. It can convey otherwise unspoken meaning such as a person’s emotional state. Vocal prosody is controlled by the same nerves that control breathing and heart rate.
Vagal Efficiency is a measurement of the heart’s change in beating rate in response to changes in respiratory sinus arrhythmia (RSA), a measure of ventral vagal mediated cardiac inhibition. When RSA increases, and the vagus nerve is more active, heart rate drops. But, the amount of change in heart rate for a standardized change in RSA is highly variable, both between people and even across time for a person. Vagal Efficiency is measured by looking at the covariation between short-time estimates (around 15 seconds) of RSA and heart rate. When the sympathetic, or fight-flight, system is active, we expect lower vagal efficiency (i.e., the heart rate response to changes in RSA will be small). Thus, vagal efficiency is a novel approach to estimating the activity of the sympathetic system using only heart rate information. Typically, we measure vagal efficiency during a controlled protocol of posture changes, such as sitting and standing from a chair in one-minute intervals, or shifting from laying down, to sitting, and then to standing. We use these posture shifts to standardize the external influences on the autonomic nervous system across members of our studies.