limbic system

Question 1

What are the core components of the limbic system?•

Answer 1

• Amygdala
• Hipocampus
• Limbic cortex

Question 2

Where is the amygdala?

Answer 2

• Anterior temporal lobe
• Tail of the caudate nucleus
• Rostral to the hippocampus

Question 3

What are the nuclei of the amygdala?

Answer 3

• Central
• Corticomedial
• Basolateral (basal and lateral)

Question 4

Kluver Bucy

Answer 4

• Associated with damage to the anterior temporal lobes
• Common symptoms: 
- Hyperorality 
- Placidity 
- hyper sexuality 
- visual agnosia 
- memory loss 
- hyper metamorphosis 
- enhanced aggression and anger 
- seizures 
- anger 
- dementia

Question 5

What are the causes of kluver bucy syndrome?

Answer 5

• herpes encephalitis
• Trauma
• Tumours
• hypoxia
• Pick’s disease

Question 6

What happens when there is damage to the amygdala specifically?

Answer 6

Abrogates fear

Question 7

Urbach Wiethe disease

Answer 7

• Calcificaiton in the temporal lobes
• Without fear
• Defecrs in judgment of emotion present in facial expression
• Poor performance in odour-figure association test
• Defects in remembering positive and negative emotional content of pictures

Question 8

What happens when the amygdala is electrically stimulated?

Answer 8

• Anxiety and fear

Question 9

What nucleus is activated by fear?

Answer 9

Central (and the bed of the stria terminalis BST)

Question 10

What are the outputs of the amygdala?

Answer 10

• Central nucleus 
• Output to hypothalamus via the stria terminalis 
• Output to brainstem structures: 
- Locus ceruleus 
- parasympathetics 
- ventral tegmental area 
- periaqueductal grey matter

Question 11

What are the inputs to the amygdala?

Answer 11

• Can be extant objects, imagined or contextual
• Can be from inside or outside of the CNS
• Inputs go to the lateral nucleus
• Fast track via the thalamus
• Longer route via the cerebral cortex (+ hippocampus_)

Question 12

Which part of the amygdala is responsible for comparing the incoming sensory stimuli to previous stimuli?

Answer 12

The basolateral amygdala

Question 13

What makes up the limbic cortex?

Answer 13

Anterior and anterior portion of the middle cingulate gyrus

Question 14

What is the role of the anterior cingulate gyrus?

Answer 14

• Encodes basic emotion: happiness, sadness, fear
• Encodes emotional memory
• has a top down influence and works to recode the amygdala

Question 15

Describe the top down influence of the amygdala

Answer 15

• Computes relevance/outcomes and drives appropriate behaviour
• Provides conflict resolution
• Part of the pain network

Question 16

What are the effector pathways of the anterior cingulate gyrus?

Answer 16

• Motor reactions
• Specific zone for driving face muscles
• Direct outputs to the autonomic NS and indirect via the amygdala

Question 17

What is the role of the insula?

Answer 17

• Works with the ACC to evaluate emotional contexts
• Role in empathy
• Encodes emotional awareness

Question 18

PTSD

Answer 18

• Hyporesponsive and decreased volume ACC
• Amygdala becomes hyperresponsive to. trauma related stimuli
• Top down control of the amygdala is therefore missing in PTSD

Question 19

What are the effectors of the limbic system?

Answer 19

• Hypothalamus
• Locus coeruleus
• Periaqueductal grey
• Dorsal raphe nucleus

Question 20

What are the inputs to the hypothalamus

Answer 20

• Limbic cortex
• Amygdala
• Olfactory systems
• Viscera
• Pain
• Internal signals

Question 21

What are the outputs of the hypothalamus?

Answer 21

• Neuronal to the brainstem and spinal cord

* Hormonal

Question 22

What is the locus coeruleus?

Answer 22

Midbrain nucleus involved in physiological responses to panic and stress

Question 23

What are the inputs to the locus coeruleus?

Answer 23

• Cingulate gyrus
• Amygdala
• PAG
• Hypothalamus

Question 24

What is the function of the locus coeruleus

Answer 24

• Promotes alertness and wakefulness
• Promotes anxiety and the formation and retrieval of emotional memories
• Projections to the hypothalamus maintains arousal and effects autonomic nervous system output
• Projections from the APG select fight or flight mode

Question 25

What is the dorsal raphe nucleus?

Answer 25

* Midbrain nucleus that projects on ascending system * Projects to and receives from the amygdala and aCC * Serotonin

Question 26

What is the function of the dorsal raphe nucleus?

Answer 26

* Determines tonic limbic activity and dynamic mood state | * Processes descending pain paths from he periaqueductal grey to the dorsal raphe nucleus to the spinal cord

Question 27

Depression

Answer 27

* Reduced metabolism in the ACC * Reduced size of the ACC * Amygdala is reduced in size and hyperactive * Highest density of 5HTT in the ACC

Question 28

Function of the hippocampus

Answer 28

* Indirect influence on emotion | * Important in forming episodic memories

Question 29

Where is the hippocampus?

Answer 29

* Deep in the temporal lobe * Floor of the lateral ventricle * Rolled appearance

Question 30

What is the hippocampal formation?

Answer 30

Hippocampus and associated cortex

Question 31

What is the parahippocampal gyrus

Answer 31

Perirhinal cortex, entorhinal cortex and parahippocampal cortex

Question 32

Entorhinal area

Answer 32

Main gateway for communication with the neocortex

Question 33

Subiculum

Answer 33

Most inferior part of the hippocampus, connected to the entorhinal areas, amygdala and nucleus accumbent

Question 34

What is declarative memory?

Answer 34

Episodic and semantic memory

Question 35

What is episodic memory?

Answer 35

Recollection of events in a person's past

Question 36

What is semantic memory?

Answer 36

General knowledge about the world

Question 37

Early damage of the hippocampus

Answer 37

* Difficult to remember events of daily lives | * Intact semantic memory- can gain factual knowledge

Question 38

Adults with hippocampal damage

Answer 38

* Can retain memories of events that occurred years before the onset of the damage * difficult to remember events of daily life