The document summarizes the autonomic nervous system (ANS). It discusses that the ANS acts as an involuntary control system and is divided into the sympathetic, parasympathetic, and enteric nervous systems. The sympathetic "fight or flight" system is activated during stress and increases heart rate while the parasympathetic "rest and digest" system decreases heart rate. Dysregulation of the ANS is associated with psychiatric disorders like depression and anxiety. The ANS plays an important role in mood, stress response, and social behavior according to theories like the polyvagal theory.

1. AUTONOMIC
NERVOUS SYSTEM
- By Dr. SRIRAM. R

2. • This topic can be discussed under three sub-headings
• Introduction
• Evolutionary aspects of ANS
• Importance of ANS in psychiatry

3. INTRODUCTION

4. • The autonomic nervous system (ANS or visceral nervous
system or involuntary nervous system) is the
• part of the peripheral nervous system that acts as a
control system
• functions largely below the level of consciousness.
• Controls visceral functions, including heart rate,
digestion, respiratory rate, salivation, perspiration,
pupillary dilation, micturition (urination), sexual arousal,
breathing and swallowing

5. In the brain…
• ANS is located in the medulla oblongata in the lower
brainstem.
• The medulla's major ANS functions include respiration
(the respiratory control center, or "rcc"), cardiac
regulation (the cardiac control center, or "ccc"),
vasomotor activity (the vasomotor center or "vmc"),
and certain reflex actions (such as coughing,
sneezing, vomiting and swallowing).
• Those are then subdivided into other areas and are
also linked to ANS subsystems and nervous systems
external to the brain.

6. • The hypothalamus, just above the brain stem, acts
as an integrator for autonomic functions, receiving ANS
regulatory input from the limbic system to do so.
• The ANS is divided into three main sub-systems:
• the parasympathetic nervous system (PSNS),
• sympathetic nervous system (SNS), and the
• enteric nervous system (ENS)

7. • SNS is often considered the "fight or flight" system,
while the PSNS is often considered the "rest and digest"
or "feed and breed“ system. In many cases, PSNS and
SNS have "opposite" actions.
• A more modern characterization is that the sympathetic
nervous system is a "quick response mobilizing
system" and the parasympathetic is a "more slowly
activated dampening system", but even this has
exceptions, such as in sexual arousal and orgasm,
wherein both play a role.

8. Subdivisons of the ANS
• The sympathetic division has thoracolumbar
“outflow”, meaning that the neurons begin at the
thoracic and lumbar (T1-L2/3) portions of the spinal
cord.
• The parasympathetic division has craniosacral
“outflow”, meaning that the neurons begin at the
cranial nerves (Cranial nerves III, VII, IX, and X) and
sacral (S2-S4) spinal cord.
• Efferent pathway is 2 neuron - the preganglionic neuron
must first synapse onto a postganglionic neuron before
innervating the target organ.

10. SYMPATHETIC DIVISION
• The sympathetic division (thoracolumbar outflow)
consists of cell bodies in the lateral horn of the
spinal cord (intermediolateral cell columns) from T1 to
L2/3.
• These cell bodies are GVE (general visceral efferent)
neurons and are the preganglionic neurons.
• There are several locations upon which preganglionic
neurons can synapse for their postganglionic neurons:

11. • Paravertebral ganglia (3) of the sympathetic chain
(these run on either side of the vertebral bodies)
1. cervical ganglia (3)
2. thoracic ganglia (12) and rostral lumbar ganglia (2
or 3)
3. caudal lumbar ganglia and pelvic ganglia
• Prevertebral ganglia (celiac ganglion, aorticorenal
ganglion, superior mesenteric ganglion, inferior
mesenteric ganglion)
• Chromaffin cells of the adrenal medulla (this is the one
exception to the two-neuron pathway rule: the synapse
indirectly efferent onto the target cell bodies)

12. • These ganglia provide the postganglionic neurons
from which innervation of target organs follows.
Examples of splanchnic (visceral) nerves are:
• Cervical cardiac nerves & thoracic visceral nerves,
which synapse in the sympathetic chain
• Thoracic splanchnic nerves (greater, lesser, least),
which synapse in the prevertebral ganglion
• Lumbar splanchnic nerves, which synapse in the
prevertebral ganglion
• Sacral splanchnic nerves, which synapse in the inferior
hypogastric plexus
• These all contain afferent (sensory) nerves as well,
known as GVA (general visceral afferent) neurons.

14. STRESS RESPONSE SYSTEM
• The Locus Ceruleus in the brainstem is the "start" button
for the fight or flight system. It releases
norepinephrine/noradrenalin anytime stress of any kind
is detected. All of this takes place in the limbic system.
• This triggers the amygdala which triggers the
hypothalamus. The amygdala prompts feelings of
anxiety and fear.
• The hypothalamus then releases CRH, which stimulates
the pituitary.
• The pituitary release ACTH to stimulate the adrenal
glands.
• The adrenal glands release adrenalin and cortisol.

16. FUNCTION OF SNS
• Diverts blood flow away from the gastro-intestinal (GI) tract and skin
via vasoconstriction
• Blood flow to skeletal muscles and the lungs is enhanced (by as
much as 1200% in the case of skeletal muscles)
• Dilates bronchioles of the lung, which allows for greater alveolar
oxygen exchange
• Increases heart rate and the contractility of cardiac cells (myocytes),
thereby providing a mechanism for enhanced blood flow to skeletal
muscles
• Dilates pupils and relaxes the ciliary muscle to the lens, allowing
more light to enter the eye and far vision
• Provides vasodilation for the coronary vessels of the heart
• Constricts all the intestinal sphincters and the urinary sphincter
• Inhibits peristalsis
• Stimulates orgasm

18. PARASYMPATHETIC DIVISON
• The parasympathetic division (craniosacral outflow)
consists of cell bodies from one of two locations:
• the brainstem(Cranial Nerves III, VII, IX, X) or the
• sacral spinal cord (S2, S3, S4).
• These are the preganglionic neurons, which synapse
with postganglionic neurons in these locations:

19. • Parasympathetic ganglia of the head: Ciliary (Cranial
nerve III), Submandibular (Cranial nerve VII),
Pterygopalatine (Cranial nerve VII), and Otic (Cranial
nerve IX)
• In or near the wall of an organ innervated by the Vagus
(Cranial nerve X) or Sacral nerves (S2, S3, S4)
• These ganglia provide the postganglionic neurons
from which innervations of target organs follows.
Examples are:
• The postganglionic parasympathetic splanchnic
(visceral) nerves
• The Vagus Nerve, which wanders through the thorax
and abdominal regions innervating, among other
organs, the heart, lungs, liver and stomach

20. FUNCTIONS OF PSNS
• Promotes a "rest and digest" response, promotes calming of the
nerves return to regular function, and enhances digestion
• The parasympathetic nerves dilate blood vessels leading to the GI tract,
increasing blood flow (this is important following the consumption of food,
due to the greater metabolic demands placed on the body by the gut)
• The parasympathetic nervous system can also constrict the bronchiolar
diameter when the need for oxygen has diminished
• Dedicated cardiac branches of the vagus and thoracic spinal accessory
nerves impart parasympathetic control of the heart (myocardium)
• During accommodation, the parasympathetic nervous system causes
constriction of the pupil and contraction of the ciliary muscle to the lens,
allowing for closer vision
• The parasympathetic nervous system stimulates salivary gland secretion,
and accelerates peristalsis, mediating digestion of food and, indirectly, the
absorption of nutrients
• Involved in the erection of genital tissues via the pelvic splanchnic nerves
2–4.
• Stimulating sexual arousal

22. Neurotransmitters and pharmacology
• At the effector organs, sympathetic ganglionic
neurons release noradrenaline (norepinephrine),
along with other cotransmitters such as ATP, to act
on adrenergic receptors, with the exception of the sweat
glands and the adrenal medulla:
• Acetylcholine is the preganglionic neurotransmitter for
both divisions of the ANS, as well as the postganglionic
neurotransmitter of parasympathetic neurons.
• Nerves that release acetylcholine are said to be
cholinergic.

23. • In the parasympathetic system, ganglionic neurons use
acetylcholine as a neurotransmitter to stimulate
muscarinic receptors.
• At the adrenal medulla, there is no postsynaptic neuron.
Instead the presynaptic neuron releases acetylcholine to
act on nicotinic receptors. Stimulation of the adrenal
medulla releases adrenaline (epinephrine) into the
bloodstream, which acts on adrenoceptors, producing a
widespread increase in sympathetic activity.

24. EVOLUTIONARY ASPECTS OF ANS

26. SOCIAL ENGAGEMENT SYSTEM
• Focuses only on the neural regulation of the
striated muscles of the face and head and the
specific autonomic functions mediated by the
myelinated vagus.
• Conceptualized to emphasize a system that has
a common neural substrate composed of
several cranial nerves that develop
embryologically together.

27. • The social engagement system has a control component
in the cortex (upper motor neurons) that regulates
brainstem nuclei (i.e. lower motor neurons controlling
special visceral efferent pathways) to control:
• eyelid opening (e.g. looking)
• facial muscles (e.g. emotional expression) ;
• middle-ear muscles (e.g. extracting human voice from
background noise) ;
• muscles of mastication (e.g.ingestion) ;
• laryngeal and pharyngeal muscles (e.g.vocalization
and language) ; and
• head-turning muscles (e.g. social gesture and
orientation)

28. • The social nervous system functions from birth and
rapidly develops to support communication with the
environment.
• For example, when a healthy infant encounters the
caregiver’s face, the infant will attempt to engage via
facial expression and vocalizations. The infant may use
vocalizations (cry) and facial expressions (grimace) to
signal negative states to the caregiver.
• Or, to signal more positive states, a wide-eyed,
smilinginfant would attempt to elicit positive vocalizations
and smiles from the caregiver.

29. POLYVAGAL THEORY
• Derived from investigations of the evolution of the
autonomic nervous system.
1. Evolution has modified the structures of the autonomic nervous system.
2. The mammalian autonomic nervous system retains vestiges of
phylogenetically older autonomic nervous systems.
3. Emotional regulation and social behavior are functional derivatives of
structural changes in the autonomic nervous system due to evolutionary
processes.
4. In mammals, the autonomic nervous system response strategy to challenge
follows a phylogenetic hierarchy, starting with the newest structures and,
when all else fails, reverting to the most primitive structural system.
5. The phylogenetic stage of the autonomic nervous system determines
affective states and the range of social behavior.

30. • In the ANS, the parasympathetic system is the oldest,
reflecting the survival needs of a primitive passive
feeders.
• The sympathetic nervous system is a later development,
adding mobility, mobilization and a wider range of
possible survival responses.
• Porges has shown clear evidence of a third, more
modern branch of the ANS, with a survival value specific
to more sophisticated animals especially primates.
“Social Nervous System” is the proposed term for this
third branch of the ANS.

31. • Drawing on the “Theory of Dissolution” (J.H. Jackson,
ca.1910), Porges also shows that under stress, the
human system tries its newest, most sophisticated and
efficient equipment first.
• If that doesn’t work, older strategies are attempted, and if
they don’t work, the oldest resources are employed.
• Therefore under stress, the human first uses its
social/relational tactics, then fight/flight, then immobility,
as survival strategies

32. • The theory proposes that physiological state limits the
range of behavior and psychological experience
• The theory proposes that the different branches are
related to unique, adaptive behavioral strategies and
articulates three phylogenetic stages of the development
of the mammalian autonomic nervous system -

33. HEIRARCHIAL RESPONSE STRATEGY
1. The ventral vagal complex VVC : a mammalian signaling
system for motion, emotion, and communication.
2. The sympathetic nervous system SNS : an adaptive
mobilization system supporting fight or flight behaviors.
3. The dorsal vagal complex DVC : a vestigial
immobilization system.
The polyvagal theory proposes a hierarchical response strategy to
environmental challenges, with the most recent modifications (1)
employed first and the most primitive (3) last. However, the
response strategy is not all-or-none, and may include transitional
blends between the boundaries of the three hierarchical stages.

34. IMPORTANCE OF ANS IN PSYCHIATRY

35. • Dysregulation of the autonomic nervous system (ANS) is
a common characteristic of a variety of psychiatric
disorders, including depression, schizophrenia, and
panic disorder (Friedman and Thayer, 1998a; Karavidas
et al., 2007; Valkonen-Korhonen et al., 2003)
• Heart rate variability (HRV) represents a sensitive
measure of autonomic system function (Low and Pfeifer,
1997) and can be utilized as a tool to assess the effect of
psychopathology and disease on the balance between
sympathetic and parasympathetic input to the heart.

36. • Mood disorders are strongly associated with changes in
cardiovascular function (Johnson and Grippo, 2006) and
alterations in HRV.
• Cardiac patients with more severe depression exhibit
less HRV compared to those with less severe
depression (Krittayaphong et al., 1997) and successful
treatment of depression tends to be accompanied by an
increase in HRV (Balogh et al., 1993; Chambers and
Allen, 2002)
• Vagal nerve stimulation (VNS) has been reported to
successfully improve affect in treatment-resistant
depression (George et al., 2005), suggesting a strong
link between sympathovagal dysregulation and
symptoms of depression

37. • Anxiety disorders have long been associated with autonomic
abnormalities, including low HRV, decreased cardiac vagal tone,and
elevated sympathetic heart rate control (Friedman and
Thayer,1998b)
• A growing number of reports have also observed HRV dysfunction
in schizophrenia (SCZ) (Bar et al., 2005; Boettger et al., 2006;
Valkonen-Korhonen et al., 2003). There is a decrease in
parasympathetic activity independent of medication effects in
schizophrenia.
• Manic BD patients demonstrated a significant reduction in HRV,
parasympathetic activity, compared to control subjects, while SCZ
patients demonstrated a similar, but non-significant, trend towards
lower HRV. Reduction in parasympathetic tone was significantly
correlated with higher YMRS scores and the unusual thought
content subscale on the BPRS (Brook et al, 2009).

38. HPA axis in psychiatry
• The HPA axis is involved in the neurobiology of mood
disorders and functional illnesses, including anxiety
disorder, bipolar disorder, insomnia, posttraumatic stress
disorder,borderline personality disorder, ADHD, major
depressive disorder, burnout, chronic fatigue
syndrome, fibromyalgia, irritable bowel syndrome,
and alcoholism.
• Antidepressants, which are routinely prescribed for many
of these illnesses, serve to regulate HPA axis function
(Pariante, 2003)

39. • Prolonged maternal stress during gestation is
associated with mild impairment of intellectual activity
and language development in their children, and with
behaviour disorders such as attention
deficits, schizophrenia, anxiety and depression;
• Self-reported maternal stress is associated with a higher
irritability, emotional and attentional problems
• A 2010 literature review article regarding
neurophysiological findings in Borderline PD noted
several studies supporting at least the potential of
abnormal HPA axis sensitivity and function.

40. • Preliminary studies found that individuals diagnosed with
Borderline PD tend to have:
1) an exaggerated response to HPA activation;
2) increased basal cortisol levels; and
3) reduced feedback system, which impairs the brains
ability to know when to “shut off” the cascade of events
leading to cortisol secretion, when compared with
psychiatric controls (Wingenfeld, Spitzer, Rullkotter, &
Lowe, 2010)

41. • Most people with PTSD also show a low secretion
of cortisol and high secretion
of catecholamines in urine, with a norepinephrine/cortisol
ratio consequently higher than comparable non-
diagnosed individuals.
• This is in contrast to the normative fight-or-flight
response, in which both catecholamine and cortisol
levels are elevated after exposure to a stressor.
• Brain catecholamine levels are high, and corticotropin-
releasing factor (CRF) concentrations are high.
• Together, these findings suggest abnormality in
the hypothalamic-pituitary-adrenal (HPA) axis

42. SKIN CONDUCTANCE TESTING
• Skin conductance, also known as galvanic skin
response (GSR), electrodermal response (EDR),psychogalvanic
reflex (PGR), skin conductance response (SCR), or skin
conductance level (SCL), is a method of measuring the electrical
conductance of the skin, which varies depending on the amount of
sweat-induced moisture on the skin.
• Sweat is controlled by the sympathetic nervous system, so skin
conductance is used as an indication of psychological or
physiological arousal.
• If the sympathetic branch of the autonomic nervous system is highly
aroused, then sweat gland activity also increases, which in turn
increases skin conductance

43. • SCR is used widely in psychological research due to its
low cost and high utility.
• Many biofeedback therapy devices utilize skin
conductance to measure and display an individual's
stress response with the goal of helping the user to
control anxiety.
• Skin conductance measurement is also becoming more
popular in hypnotherapy and psychotherapy practices
where it can be used as a method of detecting depth of
hypnotic trance prior to the commencement
of suggestion therapy.

44. DEPRESSION
• Depressed patients are twice as likely as nondepressed
patients to have a major cardiac event within 12 months
of the diagnosis of coronary artery disease (Carney et al,
1988) and they are significantly more likely to die in the
years following the diagnosis (Barefoot et al, 1996)

45. ANXIETY DISORDER

46. • The ANS of some patients with anxiety disorder,
especially those with panic disorder, exhibits increased
sympathetic tone, adapt slowly to repeated stimuli and
respond excessively to moderate stimuli.
• Affected patients may have poorly regulated NA system
with occasional bursts of activity.
• Patients with anxiety disoders, have elevated CSF or
urinary levels of 3-methoxy-4-hydroxyphenylglycol
(MHPG), a NA metabolite
• In patients with panic disorder, blunted ACTH responses
to CRF has been reported in some studies

47. SCHIZOPHRENIA
• Balance in the autonomic nervous system is altered in
schizophrenic patients with a hyperexcitability in both the
sympathetic and the parasympathetic division (Nielsen et
al, 1988)
• Heart-rate response to standing was used as a measure
of sympathetic function.
• Heart-rate response to inspiration was greater in non-
medicated schizophrenics compared to normal subjects.

48. THANK YOU