Thalamus and Hypothalamus

Question 1

Where is the thalamus found within the brain?

Answer 1

It is right in the middle the brain just under the posterior half of the corpus callosum and lateral ventricles

Question 2

What separates the two halves of the thalamus?

Answer 2

3rd ventricle

Some people have a bridge connecting the two halves

Question 3

Describe the connections of the thalamus with the forebrain.

Answer 3

Each half of the thalamus has ipsilateral connections with the forebrain

Question 4

What is the main function of the thalamus?

Answer 4

It is a relay centre between the cerebral cortex and the rest of the CNS

Question 5

What is the only function that is not represented within the thalamus?

Answer 5

Olfaction

Question 6

Describe how thalamic nuclei are named.

Answer 6

They are named based on their location within the thalamus

Question 7

What is the classification of thalamic nuclei based on and what are the four different classes?

Answer 7

The classification is based on the connections of the thalamic nuclei with the cortex

SPECIFIC – connected to primary cortical areas
ASSOCIATION – connected to association cortex
INTRALAMINAR – connected to ALL cortical areas (mostly glutamatergic nuclei) Loss of neurones here causes progressive nuclear palsy
RETICULAR –not connected to the cortex (mostly GABA-ergic nuclei) Project to other thalamic nuclei

Question 8

Which nuclei connect with the motor cortex (primary, premotor and supplementary)?

Answer 8

Ventral lateral

Ventral anterior

Question 9

Which nuclei relay sensory information from different parts of the body?

Answer 9

Head – Ventral posteromedial

Below the neck – Ventral posterolateral

Question 10

Which nucleus is connected to the primary visual cortex?

Answer 10

Lateral geniculate nucleus

Question 11

Which nucleus is connected to the primary auditory cortex?

Answer 11

Medial geniculate nucleus

Question 12

The association cortex can be divided into three areas based on thalamic function. What are these three areas?

Answer 12

Prefrontal Cortex
Parieto-tempero-occipital Cortex
Cingulate Cortex

Question 13

What do the anterior, lateral dorsal and dorsomedial nuclei connect with?

Answer 13

Prefrontal and Cingulate Cortex

Question 14

What do the lateral posterior and pulvinar nucleus connect with?

Answer 14

Prefrontal

Parieto-tempero-occipital Cortex

Question 15

What important system are the intralaminar and reticular nuclei a part of?

Answer 15

Reticular activating system (RAS) – involved in maintaining consciousness

Question 16

Describe how the reticular nuclei affect cortical activity.

Answer 16

The reticular nuclei don’t have any direct connections with the cortex, but they do have widespread intrathalamic connections with all other thalamic nuclei, so it can influence the flow of information from the othernuclei to the cortex

Question 17

What is the core of grey matter that runs through the brainstem involved in the reticular activating system?

Answer 17

Reticular formation (Reticular formation + Intralaminar nuclei + Reticular nuclei = RAS)

Question 18

How do the intralaminar nuclei modulate the activity of the cortex?

Answer 18

The reticular formation projects up to the thalamus to the intralaminar nuclei and the intralaminar nuclei, because of their diffuse cortical projections, can modulate the activity of the cortex

Question 19

What is thalamic syndrome?

Answer 19

Syndrome that develops after thalamic stroke

The symptoms depend on which part of the thalamus has been affected

Question 20

What three main changes occur in thalamic syndrome?

Answer 20

CHANGE IN SENSATION – reduced, exaggerated, altered
PAIN – central, non-localised (not easily treated because normal analgesics have no effect – may need to use opioids or anti-convulsants/anti-depressants)
EMOTIONAL DISTURBANCE – the nuclei that transmit information to and from the association cortex are associated with the limbic system

Question 21

Describe the location and structure of the hypothalamus.

Answer 21

The hypothalamus is just below the thalamus and is divided by the 3rd ventricle
It also has ipsilateral connections with the forebrain

Question 22

How is the hypothalamus involved in maintaining homeostasis?

Answer 22

It coordinates these different mechanisms to maintain homeostasis:
Autonomic nervous system
Behaviour
Endocrine system

Question 23

What does the behavioural control exerted by the hypothalamus include?

Answer 23

Eating and drinking 
Expression of emotion 
Sexual behaviour 
Circadian rhythm 
Memory

Question 24

State some forebrain structures that the hypothalamus has very close connections with.

Answer 24

Olfactory system

Limbic system

Question 25

List some structures of the limbic system.

Answer 25

Hippocampus - memory
Amygdala -emotion response, decision making
Cingulate Cortex - processing, learning
Septal Nuclei - Reward nuclei

Question 26

Which nucleus is involved in the circadian rhythm?

Answer 26

Subrachiasmatic nucleus

Question 27

How is our behaviour directed towards homeostatic goals?

Answer 27

There is a pleasure centre within the limbic system, which, whenever you’ve achieved homeostasis (e.g. eating food when you’re hungry), the activity of the pleasure centre increases

Question 28

What are the presenting symptoms of hypothalamic tumour?

Answer 28

Polydipsia
Polyuria
Absent menses

Question 29

What are some later symptoms of hypothalamic tumour?

Answer 29

Labile emotions, rage 
Inappropriate sexual behaviour 
Memory lapses 
Temperature fluctuation 
Thyroid, adrenal cortex and gonadal function decreases 
Hyperphagia