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

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 the thalamus is not involved in?

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 RETICULAR –not connected to the cortex

Question 8

What important system are the intralaminar and reticular nuclei connected to?

Answer 8

Ascending Reticular activating system – involved in maintaining WAKEFULNESS (not awareness)

someone can be awake but not aware of his surroundings ie vegetative state

ARAS is part of reticular formation which is located throughout the brainstem. Reticular formation has connections to thalamus

Question 9

Describe how the reticular nuclei affect cortical activity.

Answer 9

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 other nuclei to the cortex ie regulatory role

Question 10

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

Answer 10

Reticular formation

Question 11

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

Answer 11

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 12

What is thalamic syndrome?

Answer 12

Syndrome that develops after thalamic stroke

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

Question 13

What three main changes occur in thalamic syndrome?

Answer 13

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 14

Describe the location and structure of the hypothalamus.

Answer 14

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

Question 15

How is the hypothalamus involved in maintaining homeostasis?

Answer 15

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

Question 16

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

Answer 16

Olfactory system

Limbic system

Question 17

List some structures of the limbic system.

Answer 17

Hippocampus
Amygdala
Cingulate Cortex
Septal Nuclei

Question 18

What does the behavioural control exerted by the hypothalamus include?

Answer 18

Eating and drinking  
Expression of emotion 
Sexual behaviour  
Circadian rhythm  
Memory

4 Fs of life
Fighting, fleeing, feeding, fucking

Question 19

Which nucleus is involved in the circadian rhythm?

Answer 19

Suprachiasmatic nucleus- above optic chiasm. it is part of the hypothalamus

Question 20

How is our behaviour directed towards homeostatic goals?

Answer 20

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 21

Functions of hypothalamus?

Answer 21

1. Regulate ANS: Direct connections with autonomic nervous system, neurons from paraventricular nucleus of hypothalamus can go all the way down to the spinal cord to synapse with a preganglionic neuron that then leaves the spinal cord

2.Connection with endocrine system
3. Control of behaviour ie 4 F’s of life
Fighting
Fleeing
Feeding
Fucking

Question 22

Which nucleus in hypothalamus can send projections to endocrine and ANS systems ?

Answer 22

paraventricular nucleus (has MAGNOCELLULAR and PARVOCELLULAR neurons) - involved in feeding behaviour
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