PSYC06H3 Study Guide - Midterm Guide: Orbicularis Oris Muscle, Fast Fourier Transform, Muscle Contraction
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PSYC06 - Midterm 2 Review
Lecture 6 – Respiration
The respiration rate is the number of breaths you take in a minute (~12 – 16)
The tidal volume is the volume of air your lungs process per breath (~400 – 500mL)
Respiratory Sinus Arrhythmia (RSA) – the naturally occurring variation in heart rate that
occurs during a breathing cycle.
o Physiological basis: The Sinoatrial node fires faster than the heart rate; this
difference is the descending influence of the vagus nerve. Respiration interrupts
the vagal influence on heart rate. When you inhale, HR goes up; when you exhale,
HR goes down. The size of this oscillation reflects the strength of vagal influence.
RSA indexes parasympathetic activity.
o Calculation: It is calculated with the Fast Fourier Transform (FFT) that assesses
the degree of oscillation in HR that falls within certain (3) frequency bands of
respiration. RSA has a high frequency band of .15 - .4 Hz.
o Psychological correlates/meaning: Attention seems to be the key to the
relationship between the parasympathetic nervous system and social functioning.
When there is focused attention, there is a phasic decrease in RSA. When there is
divided attention, there is a phasic increase in RSA.
The vagus nerve controls attention, emotional expression, and communication. An
increase in RSA is associated with both good and bad forms of social
engagement. A high basal RSA is related to being more sensitive to social cues.
And both high basal and phasic RSA reactivity have been related to compassion.
Analysis and quantification
Scoring; onset of breath and onset of next breath, measuring the amplitude of the
Respiratory events: inspiratory time, inspiratory duty cycle (the ratio of inspiratory
duration to the total breathing cycle), tidal volume, respiration rate
Polyvagal Theory & the Social Engagement System: The parasympathetic nervous
system evolved to help us navigate complex social situations. The PNS is the newest
branch of the ANS. The size of the social groups across species corresponds with the
development of the PNS.
o 7 key points that summarize the theory
1. The vagal system does not represent a unitary dimension
2. There are two vagal motor systems
3. In mammals, the concept that vagal tone represents a single or summed
system may have limited physiological or heuristic value
4. The functional output on the heart by the vagal efferent pathways originating
in nucleus ambiguous may be monitored by RSA
5. The magnitude of neurogenetic bradycardia is mediated by the dorsal motor
6. There is a common cardiopulmonary oscillator
7. Primary emotions are related to autonomic function
o 8 key implications of the theory
1. The phylogenetic development of the neural regulation of the heart
2. The functional and structural distinction between the vagal efferent pathways
originating in the nucleus ambiguous and the dorsal motor nucleus of the
3. The identification and adaptive function of three phylogenetically-ordered
neural circuits regulating the heart
4. The application of the Jacksonian principle of “dissolution” to explain the
sequencing of the response hierarchy
5. A proposed neural process, neuroception that evaluates risk and modulates
vagal output via higher brain structures
6. The neuroanatomical and neurophysiological link between the vagal
regulation of the heart and the neural regulation of the striated muscles of the
face and head
7. The important role that physiological state, via afferent feedback to brain
structures, has on reactivity to environmental stimuli
8. The name polyvagal is used to emphasize the diverse features of the vagus
that include efferents originating primarily from two source nuclei in the
brainstem and the prevalence of afferents
o 4 principles that guide the theory on psychophysiological mechanisms of social
1. There is a phylogenetic shift in the regulation of the heart from endocrine
communication, to unmyelinated nerves, and finally to myelinated nerves
2. There is a development of opposing neural mechanisms of excitation and
inhibition to provide rapid regulation of graded metabolic output
3. A face-heart connection evolved as source nuclei of vagal pathways shifted
ventrally from the older dorsal motor nucleus to the nucleus ambiguous. This
resulted in an anatomical and neurophysiological linkage between the neural
regulation of the heart via the myelinated vagus and the special visceral
efferent pathways that regulate the striated muscles of the face and head
4. With increased cortical development, the cortex exhibits greater control over
the brainstem via direct (e.g., corticobulbar) and indirect (e.g.,
corticoreticular) neural pathways originating in motor cortex and terminating
in the source nuclei of the myelinated motor nerves emerging from the
brainstem (e.g., specific neural pathways embedded within cranial nerves V,
VII, IX, X, XI), controlling visceromotor structures (i.e., heart, bronchi,
thymus) and somatomotor structures (muscles of the face and head)
The “vagal brake” – The rapid inhibition and disinhibition of vagal tone to the heart that
can rapidly mobilize or calm an individual. This is the contribution of the myelinated
vagus. By assessing RSA during various challenges it is possible to measure the dynamic
regulation of the vagal brake.
Lecture 7 – Electrodermal Response
Electrodermal Measures – Skin conductance, finger temperature, finger pulse
Skin potential is found by measuring electrical activity at the surface of the skin, with no
externally imposed current. It is called the endosomatic technique
Skin conductance is the degree to which your skin conducts electricity. A small current
can be passed through the skin from an external source and the resistance to the passage
of the current then measured
o Physiology and interpretation: Normally, your skin resists electrical current, but
this resistance is less effective as sweat increases. It reflects sympathetic nervous
system activity but it‟s not a pure measure. It is stimulated by the neurotransmitter
o Skin conductance level (SCL): This is the tonic skin conductance, it has values of
2 – 20 microsiemens (µS)
o Skin conductance responses (SCR): This is the phasic skin conductance, it has
o Non-Specific Skin Conductance Responses (NSSCR): This is the spontaneous
skin conductance, there are about 1 – 3 per minute
o Eccrine sweat glands: These are the sweat glands on the palms of your hands and
feet. They are activated by sympathetic nervous system instead of heat
Finger temperature is the temperature of your finger tips, usually measured in Fahrenheit
o Physiology and interpretation: It is mostly affected by the amount of blood in the
fingers. It follows a circadian (diurnal) rhythm which fluctuates over the day.
Phasic: When the temperature increases it means relaxation, positive arousal;
when it decreases it means anxiety, threat, and negative arousal. Tonic: when the
temperature begins to fall it means 3.5 hrs before you feel sleepy at night and 5
hrs before your body is objectively sleepy
Finger pulse is measured with a photoplethysmograph (PPG).
o Finger pulse amplitude: The volume of blood at finger tips
The respiration rate is the number of breaths you take in a minute (~12 16) The tidal volume is the volume of air your lungs process per breath (~400 500ml) Respiration interrupts the vagal influence on heart rate. When you inhale, hr goes up; when you exhale, The size of this oscillation reflects the strength of vagal influence. Rsa indexes parasympathetic activity: calculation: it is calculated with the fast fourier transform (fft) that assesses the degree of oscillation in hr that falls within certain (3) frequency bands of respiration. Rsa has a high frequency band of . 15 - . 4 hz: psychological correlates/meaning: attention seems to be the key to the relationship between the parasympathetic nervous system and social functioning. When there is focused attention, there is a phasic decrease in rsa. When there is divided attention, there is a phasic increase in rsa. The vagus nerve controls attention, emotional expression, and communication.