55.2 Hypothalamic Control of the Autonomic Nervous System

Question 1

Which three major pathways connect the hypothalamus to the brainstem autonomic network?

Answer 1

Dorsal longitudinal fasciculus
Medial forebrain bundle
Mammillotegmental tract

Question 2

Which pathway is shown in blue?

Answer 2

Medial forebrain bundle

Question 3

Which pathway is shown in green?

Answer 3

Dorsal longitudinal fasciculus

Question 4

Which pathway is shown in pink?

Answer 4

Mammillotegmental tract

Question 5

Which is the principal pathway of the hypothalamus in the central autonomic network?

Answer 5

Dorsal longitudinal fasciculus

Question 6

What is the origin of the DLF?

Answer 6

Hypothalamus, in region of PVN

Question 7

Which central structures does the DLF innervate?

Answer 7

Periaqueductal gray
Parabrachial nucleus
Raphe nuclei
Locus coeruleus
Dorsal motor nucleus of vagus
Nucleus ambiguus

Question 8

What does the DLF synapse with below the brainstem?

Answer 8

Autonomic nuclei (parasympathetic and sympathetic) nuclei in the spinal cord

Question 9

What are the roles of the PAG?

Answer 9

Origin of descending autonomic fibres
Influences pain signals

Question 10

What are the roles of the parabrachial nucleus?

Answer 10

Integration of taste/appetite signals
Regulation of breathing rate

Question 11

What are the roles of the raphe nuclei?

Answer 11

Release of enkephalins for pain inhibition
Feedback to SCN for circadian rhythms
Thermoregulation

Question 12

What are the roles of the locus coeruleus?

Answer 12

Principal site of NA synthesis
–> arousal, attention, memory, cognition, sleep, etc

Question 13

What is the role of the dorsal motor nucleus of vagus?

Answer 13

Parasympathetic innervation to viscera of thorax and abdomen
–> feeding, digestion, energy/glucose metabolism

Question 14

What are the roles of the nucleus ambiguus?

Answer 14

Motor innervation of ipsilateral muscles of soft palate, pharynx, larynx, upper eosophagus
–> Speech and swallowing
Also contains preganglionic parasympathetic neurons –> innervate heart

Question 15

What are the influences of the hypothalamus on the eye?

Answer 15

Pupillary dilation (ventromedial part)
Pupillary constriction (lateral area)
Lacrimation (anterior nucleus)

Question 16

How is the hypothalamus involved in osmotic regulation?

Answer 16

Controls ADH secretion
Boosts SNS linked aldosterone secretion

Question 17

How is the hypothalamus involved in the cardiovascular system?

Answer 17

Autonomic outflows - vascular constriction/dilation, or modulation of heart rate, contractility, and AV conductance

Question 18

Which two functions of the hypothalamus in the alimentary tract are highlighted in the spec?

Answer 18

Salivation
Peristalsis

Question 19

How is the hypothalamus involved in salivation?

Answer 19

Receives signals (smell, taste, touch etc)
Signals to salivary centres (superior salivatory nucleus, inferior salivatory nucleus)
–> Salivary glands

Question 20

How is the hypothalamus involved in peristalsis?

Answer 20

Stimulation of SNS by hypothalamus –> peristalsis

Question 21

What are the roles of the hypothalamus for the genital system?

Answer 21

Induces parasympathetic erection (S2-S4 nerves) and sympathetic emission (hypogastric nerve) for ejaculation

Question 22

Which higher functions is the hypothalamus involved in?

Answer 22

Sleep-wake cycles
Emotions

Question 23

How is the hypothalamus involved in sleep-wake cycles?

Answer 23

Retinal inputs provide light info
SCN controls biological clock

Question 24

What kind of behaviour has been exhibited when particular sites in the hypothalamus have been excited?

Answer 24

Aggressive behaviour

Question 25

What are the neuroanatomical pathways for aggression?

Answer 25

Multisensory inputs processed by thalamus
Prefrontal areas can modulate aggressin
Mainly: amygdala activates hypothalamus –> activates VTA to promote learned aggressive actions, PAG controls motor execution of aggression

(CAC = core aggression circuit)

Question 27

Where does the hypothalamus have neural outputs to?

Answer 27

Brainstem and spinal tract (amongst others)