Diencephalon Flashcards

1
Q

What makes up the diencephalon?

A

Thalamus
Subthalamus (sub-thalamic nucleus)
Hypothalamus

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2
Q

What divides the thalamus and into what?

A

3rd ventricle

Into L and R thalamus

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3
Q

Where is the thalamus situated?

A

Sits ventral to the lateral ventricles (basal ganglia seen dorsally)

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4
Q

How is the thalamus organised?

A

Organised into a collection of discrete/individual nuclei

Each nuclei has a separate function & connection w ipsilateral forebrain structures

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5
Q

Internal capsule?

A

Separates thalamus from the caudate nucleus

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6
Q

Function of the thalamus?

A

Relay centre between cerebral cortex & other parts of the CNS

Integrates/modulates info. en route

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7
Q

What is an exception to thalamic function?

A

Involved in ALL sensory systems (except olfactory [smell])

Key relay centre to cortical sensory areas - enhances OR restricts signals

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8
Q

Where is the primary somatosensory cortex found?

A

Postcentral gyrus (just behind central sulcus) in the parietal lobe

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9
Q

E.g. specific thalamic nuclei involved in the somatosensory pathway?

A

Ventral posterior lateral nucleus

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10
Q

What can the thalamus nuclei be classed as?

A

SAIR

Specific - connected to 1o cortical areas

Association - connected to association cortex

Intralaminar - connected to ALL cortical areas

Reticular - NOT connected to the cortex

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11
Q

Structures associated with intralaminar nuclei?

A

Project to various medial temporal lobe structues

x Amygdala (inferior part of temporal lobe) - emotions, fear, anxiety
x Hippocampus (behind amygdala, lying on floor) - memory
x Basal ganglis (subcortical area) - movement
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12
Q

Type of neurones associated with intralaminar nuclei?

A

Glutamatergic neurones

i.e. excitatory!

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13
Q

What can a loss of neurones in the intralaminar nuclei cause?

A

Associated with
x PSP (progessive supranuclear pasly) - problems w. walking & balance
x Parkinsons disease

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14
Q

What is the reticular nucleus?

A

Forms the outer covering of the thalamus

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15
Q

Type of neurones associated with reticular nucleus?

A

GABAergic i.e. inhibitory

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16
Q

What is different about the reticular nucleus compared to other thalamic nuclei?

A

They do NOT connect w distal regions BUT with OTHER thalamic nuclei

17
Q

What is the function of the reticular nucleus?

A

Receives input from thalamic nuclei axons
SO
acts to modulate thalamic activity (-ve feedback)

18
Q

What is the reticular formation?

A

Set of interconnected pathways in the brainstem - sends ascending projections to the forebrain nuclei

19
Q

What is the reticular formation invovled in?

A

Consciousness and arousal

Degree of wakefulness depends on ARAS activity

20
Q

What is ARAS?

A

Ascending reticular activating system

21
Q

What makes up ARAS?

A

Reticular formation
Intralaminar nuclei
Reticular nucleus

22
Q

What divides the hypothalamus?

A

3rd ventricle - divided into L and R

23
Q

What is the hypothalamus?

A

Each side is a collection of individual nuclei with distinct functions

Largerly ipsilateral connection with other nuclei

24
Q

What are the hypothalamus involved in?

A

Fighting
Fleeing
Feeding
Mating

25
3 functions of the hypothalamus?
Coordinates homeostatic mechanisms by: x regulating ANS via connections w. spinal cord x connections w endocrine systems e.g. pg x controlling behaviours via connections w. forebrain structures
26
Paraventricular nuclei?
Involved in feeding behaviours - recieves input from the arcuate (infundibular) nuclei in the hypothalamus Sends projections to ANS and posterior P.G
27
What can PVN lesions cause?
Hyperphagia - abnormal increased desire for food Weight gain
28
Suprachiasmatic nucleus?
Directly above the optic chiasm Responsible for controlling circadian rhythm
29
Pineal gland?
Said to be invovled in the secretion of melatonin which helps regulate sleep patterns