As a movie audience watches a frightening film, hearts race, palms sweat, and neck and shoulder muscles brace. Yet, no one was actually grabbed by the throat. Psychological activity affects the body. Conversely, physiological changes affect psychological activity. This powerful idea is Green and Green's psychophysiological principle.
Biofeedback therapists study the basic principles of psychophysiology to understand disease processes and health, and how clinical interventions achieve their results. The idiographic approach, which emphasizes individual differences, is critical to biofeedback practice. Each client's response to stressors is unique, specific, and often complex.
To effectively treat your client, you need to discover your client's characteristic responses to stressors during a psychophysiological profile administered during the assessment stage of treatment. For example, if during math and visual imagery stressors hand temperature falls and respiration rate increases, you might consider training your client to maintain hand temperature around 90o F while breathing under 7 breaths-per-minute. This approach may be superior to using a standard treatment protocol that disregards your client's unique response pattern or response stereotypy.
This unit covers Structure and function of the autonomic nervous
system (V-A1-2), and Psychophysiological Concepts (V-B).
Students completing this module will be able to discuss:
- Structure and function of the autonomic nervous system
A. Sympathetic and parasympathetic divisions
B. Anatomy and autonomic innervation of the cardiovascular, GI, and respiratory systems
- Psychophysiological concepts
A. Tonic and phasic activity
B. Orienting, arousal, and habituation
C. Situational specificity of physiological response
D. Individual response stereotypy
E. Physiological differentiation of emotional states
Green, Green, and Walters (1970)
proposed a revolutionary psychophysiological
principle of the bidirectional relationship between
physiological and psychological functioning:
"Every change in the physiological state is accompanied by an
appropriate change in the mental emotional state, conscious or
unconscious, and conversely, every change in the mental emotional state,
conscious or unconscious, is accompanied by an appropriate change in the
physiological state."
The central nervous system includes
the brain, spinal cord, and retina. The peripheral nervous system consists of the somatic nervous system
and three branches of the autonomic nervous system.
Caption: This image illustrates the three-quarter right anterior-lateral view of the male torso, with the nervous system highlighted. The central nervous system CNS (brain and spinal cord) is colored blue, and the peripheral nervous system PNS (major peripheral nerves) is colored yellow. Shown are the brain inside the cranium, spinal cord inside the vertebral column, and the spinal nerves exiting the intervertebral foramen.
The somatic nervous system controls the contraction of skeletal muscles
and transmits somatosensory information to the CNS. The
autonomic nervous
system regulates cardiac and smooth muscle, and glands, transmits sensory
information to the CNS, and innervates muscle spindles.
The autonomic nervous system is divided into three main systems: sympathetic division, parasympathetic division,
and enteric division.
The sympathetic division regulates activities that expend stored energy,
such as when we are excited. Sympathetic cell bodies are found in the
gray matter of the thoracic (from T1) and lumbar (to L2) segments of the
spinal cord. The sympathetic division is thoracolumbar.
Sympathetic preganglionic neurons exit the spinal cord via the ventral
root. Most of these axons synapse with the ganglia (collection of
neurons) of the sympathetic chain, which parallels the spinal cord on
each side. This produces mass activation since the ganglia are connected
to adjacent ganglia in the chain. The sympathetic chain’s postganglionic
neurons project axons to target organs, like the heart, lungs, and sweat
glands.
Sympathetic preganglionic axons directly innervate the adrenal medulla
(the central portion of the adrenal gland). The adrenal medulla releases
epinephrine and
norepinephrine when stimulated, which reinforces
sympathetic activation of visceral organs. Release of epinephrine and
norepinephrine increases muscle blood flow converts stored nutrients into
glucose for use by skeletal muscles.
Sympathetic preganglionic axons secrete acetylcholine while the
postganglionic axons secrete norepinephrine. Sweat glands and skeletal
muscle blood vessels are the exceptions to this rule. The postganglionic
axons that innervate them release acetylcholine.
The parasympathetic division regulates activities that increase the
body’s energy reserves: salivation, gastric and intestinal motility,
gastric juice secretion, and increased blood flow to the gastrointestinal
system.
The parasympathetic division regulates activities that increase the
body’s energy reserves, including salivation, gastric (stomach) and
intestinal motility, gastric juice secretion, and increased blood flow to
the gastrointestinal system.
Parasympathetic cell bodies are found in the nuclei of four of the
cranial nerves (especially the vagus) and the sacral region (S2-S4) of
the spinal cord. The parasympathetic division is craniosacral.
Unlike the sympathetic division, parasympathetic ganglia are located near
their target organs. This arrangement means that preganglionic axons are
relatively long, postganglionic axons are relatively short, and
parasympathetic changes can be selective. Both parasympathetic
preganglionic and postganglionic axons release acetylcholine.
The enteric division ensures rhythmic and coordinated intestinal
contraction. While it can operate independently of the CNS, it is
innervated by both the sympathetic and parasympathetic divisions.
Berntson, Cacioppo, and Quigley (1993) challenge the concept of a
continuum ranging from sympathetic to parasympathetic dominance. They
argue that the two autonomic branches do not always act antagonistically
(reciprocally). They can also act independently or coactively (change in
the same direction),
The sympathetic and parasympathetic branches compete for control of
target organs, like the heart. Since these divisions generally produce
contradictory actions, like speeding and slowing the heart, their effect
on an organ depends on their current balance of activity.
Sympathetic and parasympathetic actions are complementary when they
produce similar changes in the target organ. Saliva production serves as
an example. Parasympathetic activation produces watery saliva and
sympathetic activation, which constricts salivary gland blood vessels,
produces thick saliva.
Sympathetic and parasympathetic actions are cooperative when their
different effects result in a single action. Sexual function provides an
example. Parasympathetic activation produces erection and vaginal
secretions and sympathetic activation produces ejaculation and orgasm.
Several organs are only innervated by the sympathetic division and are
controlled by increasing or decreasing firing of sympathetic
postganglionic fibers: adrenal medulla, arrector pili muscle, sweat
glands, and most blood vessels.
The medulla of the brainstem directly controls the autonomic nervous
system. The medulla is influenced by sensory input and the hypothalamus.
The hypothalamus is a forebrain structure located below the thalamus. The
hypothalamus is the body’s homeostat
(device that maintains homeostasis), and dynamically maintains balance through its
control of the autonomic nervous system, endocrine system, survival
behaviors (four F’s), and interconnections with the immune system.
The
hypothalamus is influenced by the cerebellum, cerebral cortex, and limbic
system.
Caption: This image illustrates the limbic system in the brain from a three-quarter superior view of the cerebrum. Cortical areas are semi-transparent so as to show the limbic system deep within the brain. Structures include the thalamus, hypothalamus, hippocampus, and amygdala.
Homeostasis is the maintenance of the body’s internal environment within
healthy physiological limits. Claude Bernard introduced the basic concept
of homeostasis and stated, "The stability of the internal environment is
the condition of a healthy life." Cannon (1939) introduced the term homeostasis in 1932 and elaborated on this
concept in The wisdom of the body.
The body achieves homeostasis for
specific variables, like blood pressure, through interlocking negative
and positive feedback systems.
Two important modifications to the principle of homeostasis are the boundary model and allostasis.
The boundary model challenges the maintenance of set points as rigid and proposes that physiological processes are maintained within acceptable ranges.
Allostasis means the maintenance of stability through change, and is a process that complements homeostasis. Allostasis is achieved by mechanisms that anticipate challenge and adapt through behavior (including learning) and physiological change. Therapists utilize allostasis when they teach patients to use an abbreviated relaxation exercise (QR) when they anticipate distress (traffic jams).
Wenger (1972) called the ratio of sympathetic to parasympathetic
excitation, autonomic balance. He proposed that resting individuals are
located along a continuum ranging from sympathetic to parasympathetic
dominance. Normally distributed A-bar scores, which measure location on
this continuum, are calculated from a battery of autonomic measurements.
Low A-bar scores indicate sympathetic dominance, while high A-bar scores
suggest parasympathetic dominance. Most subjects show intermediate
scores. Wenger and colleagues reported that individuals with low A-bar
scores, whom he called sympathicotonics, suffered an elevated incidence
of neurotic, psychotic, psychosomatic, and medical disorders.
Generally, both low and high A-bar scores seem to predispose individuals
to psychological and medical disorders. Where sympathetic dominance (low
A-bar scores) may result in cardiac arrhythmia and essential
hypertension, parasympathetic dominance (high A-bar scores) may be
associated with asthma, colitis, and hypotension. The healthiest pattern
of autonomic balance involves intermediate A-bar scores where neither the
sympathetic or parasympathetic branch overwhelms the other.
Clinicians can obtain both tonic and phasic autonomic measurements. A tonic measurement represents the background level of physiological
activity (a five-minute average of hand temperature). A phasic
measurement represents a brief change in physiological activity in
response to a discrete stimulus (a single skin potential response in
reaction to a sudden tone).
Psychophysiologists monitor tonic, phasic, and spontaneous
psychophysiological activity.
Tonic activity measures background activity and is the magnitude of
physiological activity over a specified period of time before stimulating
the subject.
Phasic activity is a discrete response evoked by a specific stimulus like
a tone or mild shock. Since subjects continuously react to environmental
stimuli and internal stimuli we cannot directly observe, interpreting
phasic activity can be a challenge.
Spontaneous responses are physiological changes in the absence of
detectable stimuli. These changes are important to researchers because
they can confound measurement of phasic activity. For example, if a
spontaneous increase in skin conductance occurs as a subject is shown an
emotionally-charged slide, the researcher could mistakenly conclude that
the slide increased conductance more than it did (Stern, Ray, & Quigley.
2001).
When we are exposed to a novel stimulus, an orienting response prepares
us to deal with this challenge. Pavlov's (1927) orienting response is a
"What is it?" reaction to stimuli like the sound of a vase crashing. The
orienting response includes (1) increased sensory sensitivity, (2) head
(and ear) turning toward the stimulus, (3) increased muscle tone (reduced
movement), (4) EEG desynchrony, (5) peripheral constriction and cephalic
vasodilation, (6) a rise in skin conductance, (7) heart rate slowing, and
(8) slower, deeper breathing. An orienting response rapidly habituates
since it is no longer needed once we respond to a novel stimulus.
In contrast, a defensive response is a very slowly habituating response
pattern that limits harm from intense stimulation. This pattern includes
(1) reduced sensory sensitivity, (2) a tendency to move away from the
stimulus, (3) heart rate increase, and (4) both peripheral and cephalic
vasoconstriction. For example, a defensive response might be elicited by
a loud work place environment.
Activation was
Duffy’s (1972) term for arousal. This concept originated
in Cannon's (1915) idea of the body's integrated preparation to fight or
flee a potential threat. Activation implies a unidimensional continuum
that ranges from low to high activation. For example, high activation
might be associated with elevated blood pressure, heart rate, and
respiration rate. Low activation might be associated with reduced
responses on these variables.
Duffy (1957) hypothesized that performance rises with increased
physiological arousal up to a level that is optimal for a specific task
and then declines with further arousal. This relationship is an
inverted
U-shaped curve. Task complexity and novelty may determine the optimal
level of arousal. The optimal level of arousal will be lower for more
complex and novel tasks.
Lacey (1967) and others have strongly criticized activation theory. Their
main concerns are that arousal is not a single dimension, different
stimuli elicit specific response patterns in most people, different
emotions are associated with unique physiological changes, and responses
can be complex.
First, Lacey argued that arousal is not a single dimension. He believed
that researchers should differentiate among autonomic, behavior, and
cortical arousal since these different forms of arousal are not
interchangeable. For example, when heterosexual men observe slides of
nude women, heart rate may increase while finger blood flow may not
change. If we only use finger blood flow as our index of arousal, we
might mistakenly conclude that the male subjects are not aroused (Stern,
Ray, & Davis, 1980).
Second, specific stimuli elicit a distinctive response pattern in most
subjects, instead of simply altering activation. This is the
principle of
stimulus-response specificity. For example, subjects may increase their
skeletal muscle tone when they are challenged to compete.
Third, primary emotions are associated with unique physiological changes.
This is the concept of emotional response specificity. Research with
facial expressions shows that (1) anger increases heart rate and skin
temperature, (2) fear increases heart rate and decreases skin
temperature, and (3) happiness increases heart rate, but does not affect
skin temperature.
Fourth, responses to a stimulus can be complex with some physiological
indices increasing and others decreasing. This builds on the principle of
stimulus-response specificity. Specific stimuli elicit a distinctive
response pattern and this pattern is often complex. Lacey called
this complex pattern directional fractionation. For example, when a NATO
solider on guard duty in the Balkans hears a noise, EEG and
skin conductance may show arousal while heart rate decreases.
Habituation is the opposite of arousal. A person gradually ceases to
respond or reduces his or her response to a constant stimulus. For
example, after 15 trials of listening to a moderate intensity tone, heart
rate might no longer increase. Predictable, low-intensity stimuli that
convey no new information and require no response readily produce
habituation. Habituation is inhibited when a stimulus is intense,
complex, and unique, and the subject must respond to it (rate its
unpleasantness).
The orienting response and defensive response differ in their speed of
habituation. Orienting responses rapidly habituate while defensive
response habituate very slowly .
Situational specificity means that a
physiological response (blood pressure elevation) does not occur randomly
and is most likely in situations with special characteristics. A
situation's properties may include physical location (office), time of
day (morning), activity (conference), individuals present (employer), and
personal emotional state (anxiety). A client's hypertensive response may
be classically or operantly conditioned, which means that he or she may
be unaware of learning this response since its symptoms are largely
"silent" and both processes involve implicit learning. Due to associative
learning, the presence of one or more situational cues may elicit the
complete physiological response.
Clinicians investigate the situational specificity of presenting
complaints when they conduct a history, perform a psychophysiological
profile (PSP), ask the client to maintain a symptom journal, and monitor
the client in multiple real-world settings (blood pressure measurement in
the office and while stalled in traffic). Situational information is
crucial to the creation of stimulus hierarchies when using systematic
desensitization to treat phobia.
Clients may show consistent physiological responses when they encounter
stimuli that share the same intensity and elicit similar emotions. For
example, a client
may raise heart rate and blood pressure when delivering a
report during a business meeting or completing an assignment under time
pressure, Individual response stereotypy
occurs because our clients possess different
diatheses (vulnerabilities) and enter treatment with unique
learning histories. During assessment, a clinician conducts a
psychophysiological profile (PSP) to determine a client's response
stereotypy by presenting several mild stressors.
The six primary facial expressions
are surprise, anger, sadness, disgust, fear, and happiness. The concept
of emotional response specificity
proposes that primary emotions are associated with unique physiological
changes.
Research by Ekman and colleagues with
facial expressions showed that anger increases heart rate and skin
temperature, fear increases heart rate and decreases skin temperature,
and happiness increases heart rate, but does not affect skin temperature.
Schwartz, Weinberger, and Singer (1981)
studied cardiovascular patterning in six emotions using imagery,
nonverbal expression, and exercise tasks. Their dependent variables were
diastolic and systolic blood pressure, and heart rate. Participants'
cardiovascular responses discriminated anger from fear (blood pressure),
and anger and fear from happiness and sadness (all three variables).
Ax (1953) reported that 7 of 14
autonomic measures discriminated between fear and anger.
Malta et al. (2001) reported that
aggressive drivers significantly increased muscle tension and blood
pressure during driving vignettes compared with controls. Aggressive
drivers also responded differently to a fear vignette and mental
arithmetic than controls: they increased muscle tension and blood
pressure, but showed lower heart rate and electrodermal reactivity.
Wilder (1967) argued that the size of our response to a stimulus depends
on a physiological variable's starting value. Wilder’s
law of initial
values (LIV) predicts that the higher the initial value of a
physiological variable, the lower its tendency to change. For example, a
subject who normally breathes rapidly should only slightly increase his
or her respiration rate when exposed to a loud sound. Homeostatic
mechanisms (negative feedback) are responsible for this phenomenon.
Hord, Johnson, and Lubin (1964) found that the LIV applies to heart rate
and respiration rate, but not to skin conductance or skin temperature.
Stern, Ray, and Quigley (2001) reported that studies support the LIV for
heart rate and skin resistance, but not skin conductance.
Researchers studying
phasic (rapidly changing) measures may consider
employing statistical methods to control for the influence of prestimulus
values on the size of physiological responses.
The LIV is a principle—not a law—and does not apply to all subjects and
response systems. Jamieson (1993)
questioned the LIV’s value for psychophysiological research since it can
be influenced by several factors (measurement errors, reactivity or
response to the measurement process, skew or asymmetrical distribution
of scores, and variance or score differences).
Researchers can determine whether the LIV is relevant by computing the
correlation between prestimulus and poststimulus values.
Geenen and van
de Vijver (1993) suggested that the LIV may be less common than perceived
and that correction methods may be more harmful to the data than the
phenomenon itself.
Thompson (2005) has recently reported
that the human cortex contains
mirror neurons that may help us
understand others' intentions and emotions.
Mirror neurons fire weakly when we see another person perform a movement
(reaching for a glass) and fire rapidly when the action implies
intention (reaching for a glass as if to drink from it). Neurons
responsible for somatosensations like touch fire when we see others
touched. Similarly, neurons responsible for feelings of fear and disgust
are activated by others' expressions of these emotions. Mirror neurons
may trigger "empathic emotions" through their connections with the
limbic system's emotional circuitry (Begley, 2005).
The mirror neuron system has important implications for applied
psychophysiology since it may be responsible for the generation of
conditioned emotional reactions, including distress and relaxation, and
provides a mechanism through which clients may model a clinician's
non-verbal behaviors like muscle bracing and thoracic breathing.
Two issues, the key muscle hypothesis and hand-warming specificity, have
important implications for biofeedback training.
The
key muscle hypothesis is the belief that a single muscle indexes
activity in other muscle groups. Research strongly contradicts this view:
(1) SEMG values across different sites are uncorrelated, (2) single site
SEMG values are not correlated with generalized tension or autonomic
arousal, and (3) SEMG reductions at one site (frontalis) do not
automatically generalize to other sites.
The key muscle hypothesis is invalid because there is no key upper body
or lower body muscle group. The musculoskeletal system functions very
specifically--we simultaneously contract and relax adjacent
agonist-antagonist muscle pairs at a joint. This belief has resulted in
clinicians mistakenly training the frontalis muscle to lower autonomic
arousal or relax muscles on the upper trunk.
The cardiovascular system can function very specifically just like the
musculoskeletal system. Temperature training can produce extremely
site-specific changes. For example, vasodilation in the left hand need
not generalize to the right hand or to the feet.
Clinicians should never expect hand-warming to generalize beyond the
actual site (digit) trained. Depending on training procedure and
individual differences, hand-warming will generalize to other digits on
the same hand or to the digits of the other hand for some clients but
not for others.
The temperature map below shows mean undergraduate finger and web dorsum temperatures
detected using infrared temperature scanning (White & Lammy, 2004).
Placebos are pharmacologically inert substances that can
produce a significant clinical response. In a
placebo response, both the symptoms and therapeutic response
are real and measurable. Placebos produce the greatest effects in
symptoms or disorders that wax and wane over time. The placebo response
may increase the client’s therapeutic response to a drug. Client
response to a placebo is about 30%, active
placebo (placebo combined with an additive that produces a side effect), 60%,
and medication, 70%.
Placebos seem to trigger a homeostatic response via stimulus-response
learning, expectancy, and self-liberation of endogenous neurotransmitters
like endorphins and adrenaline-like catecholamines. This may mirror
changes (therapeutic effects, time course, and duration of effect)
produced by prescription drugs.
Petrovic and colleagues (2002) showed
that opioid analgesia and placebo analgesia both increased
activity in the rostral anterior cingulate cortex and the brainstem.
Wager et al. (2004) used the
functional MRI (fMRI) to
study the placebo effect. They exposed volunteers to painful shocks or
heat. Subjects told that an "anti-pain" had been applied to their arms
reported less pain than those who were not told about the cream. The
fMRI showed that subjects in the "anti-pain" cream condition increased
activity in the prefrontal cortex and decreased activity in
pain-processing regions of the thalamus, the somatosensory cortex, and
cerebral cortex.
Now that you have completed this module, think of how you measure tonic
and phasic activity when your conduct a psychophysiological profile.
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