Thalamus and Hypothalamus

Question 1

What makes up the diencephalon?

Answer 1

thalamus, hypothalamus, sub thalamic nucleus

Question 2

structure of thalamus

Answer 2

• divided into left and right thalamus by the 3rd ventricle, under the lateral ventricles
• collection of individual nuclei
• the nuclei have separate function and ipsilateral connections to the forebrain
• separated from the caudate nucleus by the internal capsule

Question 3

function of the thalamus?

Answer 3

• relay centre of inputs and outputs between cortex and other CNS parts
• integrates/modulates information en route i.e. enhances or inhibits
• involved in all functions except olfaction i.e. smell(CN 1)
• some nuclei are part of the reticular activating system (RAS)

Question 4

classes of thalamic nuclei

Answer 4

specific- connected to primary cortical areas

association- to association areas

intralaminar- connected to all cortical areas

reticular- not connected to the cortex

Question 5

what nuclei connect parts of the limbic system?

Answer 5

anterior
lateral-dorsal
dorsomedial

Question 6

which nuclei connect with the association cortex at the junction of the parietal, occipital and temporal lobes and the prefrontal cortex?

Answer 6

lateral-posterior

pulvinar nuclei

Question 7

the Intra-laminar Nuclei (thalamus)

Answer 7

receive input from the Reticular Formation of the brainstem and project to cortical areas in the medial temporal lobe regions.

includes the hippocampus and amygdala (and basal ganglia)

Question 8

what are the hippocampus, amygdala and basal ganglia involved in?

Answer 8

hippocampus- short term memory

amygdala- fear, anxiety and emotions

basal ganglia- movement

Question 9

what type of neurones are in the intra-laminar nuclei?

Answer 9

glutaminergic neurones i.e, excitatory

Question 10

what is the consequence of the loss of the neurones in the intra-laminar nuclei?

Answer 10

association with motor disorders
progressive supranuclear palsy (problems with walking and balance)
Parkinsons

Question 11

what is the Reticular Nucleus (thalamic)?

Answer 11

outer covering of the thalamus
receives input from reticular formation but projects to other thalamic nuclei
only modulates thalamic activity to the cortex

Question 12

what types of neurones are involved in the Reticular Nucleus?

Answer 12

GABAergic i.e. inhibitory

Question 13

what is the overall function of the reticular activating system?

Answer 13

the reticular formation, intra-laminar and reticular nuclei form the RAS and control the level of arousal of the brain by modulating the level of activity in the cerebral cortex

Question 14

what make up RAS?

Answer 14

reticular formation
intralaminar nuclei
reticular nuclei

Question 15

what controls consciousness?

Answer 15

reticular formation projects through the brainstem and controls the level of consciousness
all parts of the cortex are affected by changes in consciousness as connections with the cortex are made with the intra-laminar nucleus

Question 16

what is thalamic syndrome?

Answer 16

• develops after thalamic stroke (posterior cerebral artery)
• pain and emotional disturbance
• change in sensation (Dejerine Roussey Syndrome)

Question 17

consequences of traumatic brain injury?

Answer 17

damage to brain axons (white matter)
neuroinflammation in thalamus
damage in white matter tracts travel down the axons into the thalamus which causes thalamus inflammation

Question 18

organisation of the hypothalamus

Answer 18

• below thalamus
• divided into left and right by 3rd ventricle
• largely a collection of individual nuclei with separate actions and ipsilateral connections with forebrain structures
• mammillary bodies lie directly bellow the hypothalamus

Question 19

function of the hypothalamus

Answer 19

coordinate homeostatic mechanisms by :

• regulating ANS via connections with the spinal cord
• acting as endocrine organ via pit. gland
• controlling behaviour via connections to the forebrain

Question 20

the 4Fs of the Hypothalamus

Answer 20

Fighting
Fleeing
Feeding
F***ing

Question 21

associate systems of the hypothalamus

Answer 21

• olfactory system
• limbic system (hippocampus, amygdala, cingulate cortex and septal nuclei)
• reward system (behaviour directed towards well-being)

Question 22

what control on behaviour does the hypothalamus exert?

Answer 22

• eating and drinking
• expression of emotion
• sexual behaviour
• circadian rhythm
• memory

Question 23

structural damage to the hypothalamus

Answer 23

• craniopharyngioma and other tumours: gliomas, meningioma, dermoid, chroma, hamarodoma
• inflammatory diseases: sarcoidosis, Langerhans cell histiocytosis

Question 24

what can patients with hypothalamic damage also have?

Answer 24

• hormone deficiencies
• DI and possible adipisa (no thirst at all)
• cannot regulate food intake (arcuate nucleus and PVN)
• forget things (mamillary bodies)
• temperature fluctuations (preoptic area)
• aggression (pre-frontal cortex)

Question 25

2 populations of nuclei in the infundibular nuclei

Answer 25

NPY- stimulates feeding
Alpha MSH- inhibits feeding
influenced by leptin

Question 26

what are the effects of PVN damage

Answer 26

MCR4 mutations

hyperphagia

Question 27

what is involved in the development in the hypothalamus and PVN

Answer 27

SIM1

a deficiency of SIM1 causes syndromic obesity

Question 28

Sexually Dimorphic Nucleus

Answer 28

 The sex of humans also influences the development of the hypothalamus as the structures and nuclei populations in the hypothalamus are different depending on gender.
 The “Bed nucleus of Stria Terminalis” is also important in gender differentiation.
 The supra-chiasmatic nucleus also differs between sexual identities.

Question 29

the thalamus is involved in all nerve functions except?

Answer 29

olfaction