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Flashcards in Thalamus and hypothalamus Deck (37):
1

Where is the thalamus located?

Under the posterior half of the corpus callosum.
Bilateral separated by the third ventricle in the midline.
Collection of individual interconnected nuclei with different functions
Ipsilateral connections with the forebrain

2

What structures are part of the diencephalon?

Thalamus, hypothalamus and subthalamic nucleus

3

What is the function of the thalamus?

Acts as a relay centre between the cerebral cortex and CNS.
Intergates information to allow for modification.
Involved in all functional systems apart from olfaction.

4

What is the purpose of the internal capsule?

Connects the cerebral cortex to the brainstem

5

What are the classifications of thalamic nuclei?

Specific; connected to primary cortical areas
Association; connected to the association cortex
Reticular; not connected to the cortex
Intralaminar; connected to all cortical areas

6

What cortex is the ventral lateral and ventral anterior associated with?

Motor cortices (motor, supplementary and premotor)

7

What cortex is the ventral lateral and ventral anterior associated with?

Motor cortices (primary, supplementary and premotor)

8

Which thalamic nucleus is involved in info from the retina to primary visual cortex?

Lateral geniculate

9

Which thalamic nucleus is involved in relaying info from the retina to primary visual cortex?

Lateral geniculate

10

Which thalamic nucleus is involved in relaying info from the inner ear to the primary auditory cortex?

Medial geniculate

11

What are the anterior, lateral dorsal, dorsomedial nuclei involved with?

The limbic system; maxillary bodies, hypothalamus, cingulate + prefrontal cortex

12

Where do the lateral posterior and pulvinar nuclei join with the association cortex?

At the parieto-temporo-occipital junction and the prefrontal cortex

13

Which thalamic nuclei are involved with the reticular activating system?

Intralaminar; projects to all cortical areas
Reticular; intrathalamic projections
RAS involved in alertness, consciousness

14

What is thalamic syndrome?

Caused by a posterior cerebral artery stroke
[Dejerine-roussy syndrome]
Causes disturbance in nuclei involved in primary somatosensory cortex relay of info.
Sensation; reduced, altered, exaggerated
Pain; central, non-localised
Emotional disturbance; these nuclei are often involved with the limbic system

15

What occurs to the brain in traumatic brain injury?

Problems arise due to axonal damage, shearing forces to white matter tracts; thalamic cortical tract.
Thalamus shows high microglial activation indicative of neuroinflammation.
Anterograde tracking causes thalamic neuroinflammation

16

What are the borders of the hypothalamus?

Anterior is the optic chiasm
Posteriorly is the mamillary body
Lateral walls are the third ventricle
Inferior is the pituitary body

17

What important structure passes through the hypothalamus?

The internal carotid artery

18

What are the function of the hypothalamus?

Regulates the autonomic nervous system via connections with the brainstem and spinal cord
Endocrine system via pituitary
Controls behaviour via associated forebrain structures e.g. olfactory system, limbic system

19

Which structures are part of the limbic system?

Amygdala, hippocampus, cingulate cortex, septal nuclei

20

What behaviour systems are affected by the thalamus?

Eating and drinking
Expression of emotion
Sexual behaviour
Circadian rhythm
Memory

21

What causes hypothalamic structural damage?

Craniopharyngyomas
Other tumours e.g. gliomas, meningioma, dermoid, chordoma, hamartoma
Sarcoidosis
Langerhan cell hystiocytosis

22

What impact does a hypothalamic tumour have?

Presenting symptoms - polydipsia, polyuria, absent menses
Later - labile emotions, rage
?inappropriate sexual behaviour
memory lapses
temperature fluctuation
Unable to regulate food intake (infundibulum and PVN)
No inhibition of aggression from ventral median eminence
No compensation for sleep (loss of circadian rhythm from suprachiasmatic nucleus)
Thyroid, adrenal cortex, gonadal function decreases
Hyperphagia

23

What is the infundibular nucleus?

Part of dual hypothalamic circuitry involved in appetite
NPY/AGRP stimulates feeding
POMC/aMSH inhibits feeding
Hypothalamic nucleo project to PVN, dorso-medial hypothalamus (NPY), ventral-medial hypothalamus (BDNF), lateral hypothalamus (MCH and Orexin)

24

Which orexigenic neuropeptides inhibit feeding?

CRH, TRH and BDNF

25

How do hormones circulate to influence the feeding system?

Vagus nerve projects up to brainstem and then projects to hypothalamus.
There are BBB gaps in the brainstem and the hypothalamus where peripheral hormones can enter and influence appetite.
There are receptors on the vagus nerve to alter neuronal firing of the nerve, also altered by stretching of the stomach.

26

Where does circadian rhythm originate?

Suprachiasmatic nucleus

27

What is the clinical presentation of Alzheimer's?

Less AVP and melatonin

28

What is the clinical presentation of Alzheimer's?

Less AVP and loss of circadian efflux of melatonin

29

Describe the steps of fat leading to decreased appetite in monogenic causes of obesity

Leptin -> Leptin receptor in the hypothalamus -> POMC (a-MSH) -> binds to MC4 receptor -> projects to second order neurones (e.g. Sim 1 in PVN, BDNF in VMH)

30

What is the enzyme that produces a-MSH from POMC?

Pro-hormone converts 1

31

What is the enzyme that produces a-MSH from POMC?

Pro-hormone convertase 1

32

What is the clinical factor of narcolepsy?

Loss of the neuropeptide orexin in the lateral hypothalamus.
Production of orexin receives input from the limbic system, SCN, energy balance which stimulates NA or histamine involved in wakefulness.

33

What is the clinical presentation of depression?

Activation of HPA axis
Increased number of CRH
Chronic activation of CRH pathway -> cortisol
could be due to problem in hippocampus or hypothalamus

34

What part of the hypothalamus is involved in gender identity?

Bed nucleus of stria terminalis

35

What part of the hypothalamus is different between make and female?

Sexually dimorphic nucleus

36

What part of the hypothalamus is involved in determining sexuality?

Suprachiasmatic nucleus

37

Give examples of how the hypothalamus is involved in health and the areas it affects

Labour; interaction of maternal and fetal hypothalamus
Sexual differentiation
Infundibular nucleus; metabolism, eating
SCN; biological clock, melatonin
PVN; pituitary and autonomic regulation, depression-HPA axis
Disruption to PVN -> PWS, other genetic obesity syndromes
LH; cataplexy hypocretin-> orexin
Mamillary bodies; memory, cognitive function
Tuberomamillary nucleus (TMN); histamine awake state