Control L20 Limbic System

Question 1

What is the role of the cingulum (underlying the cingulate gyrus) ?

Answer 1

Receiving information from pre-frontal, parietal, occipital and temporal gyri to form memories and emotions.

Question 2

What structures make up the limbic system?

Answer 2

Paraolfactory area
Hypothalamus
Amygdala
Hippocampus

Question 3

What are the roles of each of the structures which comprise the limbic system? What mneumonic can be used to remember them?

Answer 3

HOME

H= homeostasis by hypothalamus
O= olfaction by paraolfactory area
M= memory by hippocampus
E= emotions by amygdala

Question 4

Why is the amygdala termed the emotional brain?

Answer 4

As it is involved in the emotional and motivational aspects of behaviour and provides the emotional component to learning.

Question 5

What is the main function of the limbic system as a whole?

Answer 5

To regulate drive and affective behaviour + has a crucial role in memory and learning.

Question 6

What are the anatomical characteristics of the amygdala?

Answer 6

An almond shaped nuclear complex
Found in the medial temporal lobe deep to the uncus

Question 7

What are the anatomical characteristics of the hippocampus?

Answer 7

Nuclear complex found in the medial temporal lobe
Sits deep to the parahippocampal gyrus

Question 8

What connects the amygdala and hippocampus to the hypothalamus?

Answer 8

The fornix and stria terminalis (which follow the curves of the lateral ventricles.

Question 9

What structures does the amygdala connect to?

Answer 9

Unprocessed special sensory stimuli (e.g. visual, somatosensory, auditory etc…)
The cingulate and parahippocampal gyri (processed sensory stimuli)
Nuclei of the autonomic nervous system in the brainstem and hypothalamus
The stria terminalis connecting the amygdala to the hypothalamus

Question 10

What is the hippocampus formed of?

Answer 10

Dentate gyrus
Hippocampus proper

Question 11

What connects the hippocampus to the hypothalamus?

Answer 11

The fornix

Question 12

What is the fornix?

Answer 12

Main efferent fibres of the hippocampus which travels over the thalamus in a C shape to connect to the hypothalamus with some fibres extending to the mammillary bodies.

Question 13

What is the role of the circuit of papez?

Answer 13

A closed, bidirectional circuit which reinforces emotion, memory and olfaction with eachother for survival responses

Question 14

Describe the flow of the circuit of papez.

Answer 14

Hippocampus —> fornix —> mammillary bodies —> anterior thalamic nuclei —> cingulate gyrus —> hippocampus

Question 15

What are the roles of the hippocampus?

Answer 15

Formation of short term memories
Vital in learning
Has an endocrine function as inputs into the hypothalamus which is connected to the pituitary gland.

Question 16

What is the role of the mammillary bodies?

Answer 16

Recollective memory

They receive fibres from the hippocampus via the fornix and fibres ascend into the anterior nucleus of the thalamus.
Fibres project from the thalamus to the cingulate gyrus.
Fibres are then distributed to cortical areas including pre-frontal, posterior parietal and temporal association via the cingulum.

Question 17

What brain areas are involved in memory?

Answer 17

Sensory memory = visual auditory haptic (haptic = sense of touch)
Working memory = hippocampus
Recent memory = hippocampus
Remote/long term memory = neocortex