Week 13: The Limbic System

Question 1

What are the functions of the limbic system?

Answer 1

control of memory and emotion and co-ordination of autonomic responses

Question 2

Which structures make up the limbic system?

Answer 2

limbic lobe
amygdala
hippocampal formation
circuit of papez

Question 3

How are the olfactory bulb and tract involved in the limbic lobe?

Answer 3

smell can trigger emotion and memory

Question 4

What structures are found in the limbic lobe?

Answer 4

• cingulate sulcus
• cingulate gyrus
• isthmus
• parahippocampal gyrus
• uncus

Question 5

what is the isthmus?

Answer 5

• narrowed region of the cingulate gyrus

- cingulate gyrus becomes continous with the parahippocampal gyrus at the isthmus

Question 6

Which structure is deep to the uncus?

Answer 6

the amygdala

Question 7

Which structure is deep to the parahippocampal gyrus?

Answer 7

hippocampus

Question 8

Which structure is deep to the cingulate gyrus?

Answer 8

cingulum

Question 9

What is the main function of the:

1. Hypothalamus
2. Paraolfactory area
3. Hippocampus
4. Amygdala

(HOME)

Answer 9

1. Homeostasis
2. Olfaction
3. Memory
4. Emotions

HOME

Question 10

What is the function of the cingulum?

Answer 10

• nerve tract of association fibres that receives information from pre-frontal, parietal, occipital and temporal gyri
• involved in the formation of memories and emotion

Question 11

Where is the amygdala?

Answer 11

• almond shaped nuclear (cell bodies) complex in the medial temporal lobe
• deep to the uncus

Question 12

What is the amygdala involved in?

Answer 12

• emotions and behaviour

- pain, pleasure, rage

Question 13

Where is the hippocampal formation?

Answer 13

• medial temporal bone

- deep to the parahippocampal gyrus

Question 14

What is the hippocampal formation involved in?

Answer 14

-memory (mainly short term)

Question 15

Why is a lesion to the brain more likely to affect short term memory than long term memory?

Answer 15

long term memory is more wide spread and involves other areas of the neocortex so one lesion is less likely to affect long term memory

Question 16

How is the amygdala connected to the hypothalamus?

Answer 16

via stria terminalis

Question 17

How is the hippocampus connected to the hypothalamus?

Answer 17

via the fornix

Question 18

Why can emotion trigger autonomic response e.g heart race increasing during stress

Answer 18

because the stria terminalis and fornix connect the amygdala and hippocampus respectively to the hypothalamus which is involved in homeostasis

Question 19

The fornix and stria terminalis follow the curves of which structure?

Answer 19

lateral ventricles

Question 20

Explain the 4 connections/links the amygdala has

Answer 20

1. Unprocessed visual, auditory, somatosensory, gustatory and olfactory stimuli
2. Cortex: cingulate and parahippocampal gyri - processed visual, auditory, somatosensory, gustatory and olfactory stimuli
3. Nuclei of ANS: brainstem and hypothalamus
4. Stria terminalis

Question 21

What are the two parts of the hippocampal formation?

Answer 21

• dentate gyrus

- hippocampus proper

Question 22

How do efferent fibres from the hippocampus reach the hypothalamus

Answer 22

• via the fornix
• fimbria of the fornix start to collect and leave the hippocampus formation
• the fornix becomes continous with the crus, body, columns of the fornix then the mamillary bodies to reach the hypothalamus

Question 23

What is the function of the hippocampal commissure?

Answer 23

allows for communication between the fornix on either side

Question 24

Where are mammillary bodies found?

Answer 24

• posterior to optic chiasma and infundibulum

- part of the hypothalamus

Question 25

What is the function of the circuit of papez?

Answer 25

reinforcement of emotion, memory, and olfaction with each other for survival responses

Question 26

What type of circuit is the circuit of papez

Answer 26

closed, bidirectional

Question 27

Explain the circuit of papez

Answer 27

hippocampus --> fornix --> mammillary bodies (ANS responses) --> anterior thalamic nuclei --> cingulate gyrus --> hippocampus cingulate fibres can be sent back to the hippocampus so we can memorise feelings and emotions

Question 28

The hippocampus receives all types of information via what structure?

Answer 28

the cingulum

Question 29

What happens when we try to learn specific items of important information?

Answer 29

- these items are rehearsed repeatedly until they are permanently stored in the areas of the cortex associated with long term memory - long term memory is less localised

Question 30

How does the hypothalamus have a role in endocrine function

Answer 30

- inputs to hypothalamus, modulatory role | - hypothalamus connected to pituitary

Question 31

What is the definition of memory?

Answer 31

the mental capacity to encode, consolidate, store and retrieve information

Question 32

What are the 4 different types of memory?

Answer 32

1. Sensory memory - what we see/ hear/ touch (visual/auditory/haptic) - quick and short lived 2. Working memory - stored in hippocampus - information we temporarily hold onto whilst we learn 3. Recent memory - stored in hippocampus 4. Remote memory - long term memory - stored in neocortex - maximum capacity

Question 33

How can we get information from our sensory memory into our remote memory?

Answer 33

sensory memory is sent to our working memory which encodes information to our recent memory, and if consolidated enough, will become part of our remote memory

Question 34

What is consolidation?

Answer 34

when we take new memories from the hippocampus and bring them to the neocortex for permanent storage