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Flashcards in Limbic system Deck (40)
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1
Q

Describe a way to find the amygdala.

A

Simple: Find fornix, go to hippo, at distal end of temporal lobe you’ll run into amygdala.

Complicated: Beneath the uncus of the limbic lobe, at the anterior end of the hippocampus and the inferior horn of the lateral ventricle.

2
Q

What are the 3 major groups of nuclei in the amygdala?

Which is the biggest?

A
  • Medial
  • Central
  • Basolateral (biggest)
3
Q

What’s the role of the medial amygdalar nucleus?

A

Interconnected w/the olfactory system

small

4
Q

What is the central amygdalar nucleus important for? Connections to what brain centers make this so?

A

Emotional responses/*visceral sensory input

- Hypothalamus + all brainstem (e.g. PAG)

5
Q

What’s the main role of the basolateral amygdalar nuclei?

A

Key link of the experience of emotions and their expression.

6
Q

What cortical area is the amygdalar basolateral nuclei closely associated w/?

A

Parahippocampal cortex

7
Q

What general type of input do the amygdalar basolateral nuclei receive? (and from what 2 brain areas?)
What other part of the amygdala do they communicate w/?

A
  • Sensory (from cortex and thalamus)

- Central nucleus

8
Q

What type of cell would you find in the basolateral amygdalar nuclei that you’d also find in some layers of the cerebral cortex?

A

Pyramidal cells

9
Q

Where do the basolateral amygdalar nuclei get their input from regarding sights, sounds, touches, smells, and tastes?

A

Thalamus + unimodal visual, auditory, somatosensory, and gustatory association areas

10
Q

What 3 cortical areas do the basolateral amygdalar nuclei get their input from regarding levels of physical and emotional comfort and discomfort?

A

Orbital, anterior cingulate, and the insular cortices

11
Q

Fibers leave the amygdala through the ______________ and the _____________ to reach many of the same areas that send afferents to it.

A
  • Stria terminalis

- Ventral amygdalofugal pathway

12
Q

Efferents from the amygdala to the thalamus primarily terminate in the:

a. Anterior nucleus
b. Dorsomedial nucleus
c. Lateral geniculate nucleus
d. Pulvinar nucleus
e. Ventral lateral nucleus

A

b. Dorsomedial nucleus

13
Q

T/F - amygdala efferents can feed directly into the cortex. If false, what do they relay through?

A

True

14
Q

Explain, in detail, the different functions of the amygdala.

A
  1. While hippo remembers event, amygdala remembers whether it was “good” or “bad”
  2. Triggers appropriate responses to help decide what to do (“gut feelings”) for future similar events
  3. Conditioned responses
  4. Fear response
15
Q

Bilateral lesions to the tips of the temporal lobe would cause what syndrome?

A

Kluver-Bucy syndrome

16
Q

What are the sx that characterize Kluver-Bucy syndrome?

A
  1. Docility
  2. Hyperorality
  3. Hyperphagia
  4. Visual agnosia
  5. Hypersexuality
17
Q

What structures make up the hippocampus?

A
  • Dentate gyrus
  • Hippocampus proper
  • Subiculum
18
Q

What’s the subiculum of the hippocampus?

A

A transition zone between the hippocampus proper and temporal lobe neocortex.

19
Q

Describe the physical structure of the hippocampus.

How many layers it is?

A

2 interlocked letter C’s

- 3 layers (like cerebellum)

20
Q

The anterior part of the parahippocampal gyrus is the major interface between the hippocampus and vast areas of association cortex, allowing the hippocampus to serve as a key link underlying ________________.

A

Declarative memory (AKA explicit memory: long-term facts and verbal knowledge)

21
Q

What’s another name for the parahippocampal gyrus?

A

Entorhinal cortex

22
Q

Damage to the hippocampus and/or surrounding related areas could lead to what?

A

Anterograde amnesia (can’t form new memories)

23
Q

Since retrograde amnesia following damage to the hippocampus only lasts a few hours/days, what does that mean about the storage of long-term memories?

A

They are stored outside the hippo

24
Q

What are the major inputs to the entorhinal cortex on their way to the hippo?
What about those that bypass the entorhinal cortex and go straight to hippo?

A
  • Unimodal areas, multimodal areas, limbic areas

- Septal nuclei and amygdala

25
Q

How do modulatory cholinergic inputs from septal nuclei reach the hippocampus?

A

Travel back through the fornix, a major output route from the hippo

26
Q

What’s the reason memories receive input from the amygdala?

A

*Amygdala affects probability of whether or not something will be remembered as a declarative memory based on our emotional reaction to it.

27
Q

What are the major cortical “areas” that receive output from the hippocampus, by way of the entorhinal cortex?

A

Unimodal areas, multimodal areas, limbic areas

28
Q

Besides the entorhinal cortex, what’s another major efferent projection for the hippocampus?

A

*Projections to the mammillary body through the fornix

29
Q

The fornix curves around with the lateral ventricle; it separates from the hippocampus near the __________________________, travels forward along the inferior edge of the septum pellucidum, turns downward in front of the interventricular foramen, and enters the __________________.

A
  • Splenium of the corpus callosum

- Hypothalamus

30
Q

Recall: Which part of the thalamus do the mammillary bodies project to?
How do they get there?

A
  • Anterior nucleus

- Mammillothalamic tract (part of Papez circuit)

31
Q

What common, commonly age-related disease affects the hippocampus?
What are other ways to dmg the hippo?

A
  • AD

- Oxygen starvation (hypoxia), encephalitis, or medial temporal lobe epilepsy

32
Q

Bilateral temporal lobe lesions cause anterograde amnesia, as well as retrograde amnesia to semantic memories immediately prior to the event. Would this apply to declarative memories, nondeclarative memories (skills/procedures), or both?

A

Declarative only

  • Patients could learn to assemble a puzzle with greater skill on each attempt, but not remember having ever seen the puzzle before.
  • The function of laying down or consolidating memories has been attributed, therefore, to the hippocampus (but stored elsewhere)
33
Q

Besides acting like a memory “index” (keeping track but not storing them), what other areas does the hippo appear to play a role? (just read it)

A

Aging, stress, epilepsy, schizophrenia and transient global amnesia.

34
Q

What type of memory are the mammillary bodies critical for?

A

*Spatial memory (position of head in space)

35
Q

What’s Wernicke-Korsakoff’s syndrome?
What are the causes of it?
What are the sx?

A
  • Disabling degenerative brain disorder
  • Lack of thiamine (vitamin B1) due to alcohol abuse, dietary deficiencies, prolonged vomiting, eating disorders, or chemo
  • Mental confusion, confabulation, attention deficit, memory impairment (both anterograde and retrograde), vision impairment, stupor, coma, hypothermia, hypotension, and ataxia.
36
Q

Regarding Wernicke-Korsakoff’s syndrome, what’s the name of the acute phase of the disorder?
What’s the name of the chronic phase of the disorder?

A
  • Wernicke’s encephalopathy

- Korsakoff’s amnesiac syndrome (memory disorder, confabulation)

37
Q

What are the functions of the septal nuclei?

A
  • Regulates gonadal hormone secretion and various reproductive/sexual behaviors
  • Facilitates memory formation (projects to hippo)
38
Q

What are the 3 afferents and 5 efferents of the septal nuclei?

A

Afferents: Hippocampus, Amygdala & Preoptic area of hypothalamus
Efferents: Hippocampus, Amygdala, Preoptic area of hypothalamus, Mammillary body & Median eminence

39
Q

Lesioning the septal nuclei would result in what?

A
  • General behavioral overreaction, particularly evident as “septal rage.”
40
Q

What type of seizure disorder is closely associated w/the limbic system?

A

Temporal lobe epilepsy