Lecture 11 - Limbic system Flashcards

1
Q

The hippocampal formation consists of

A

Dentate gyrus
Entorhinal cortex
Subiculum
Hippocampus proper

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2
Q

The hippocampus consists of

A

Hippocampus proper + Dentate gyrus

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3
Q

Broca’s Limbic LOBE is purely an ___ term and is composed of _____ , and does not contain any ___structures

A
  • anatomical
  • Fornicate gyrus (cingulate + parahippocampal)
  • subcortical
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4
Q

describe Maclean’s Limbic SYSTEM

A
  • the TRIUNE BRAIN THEORY
  • consists of 3 distinct brain layers:
    1. Primitive brain (archipallium) - survival, action brain
    2. Intermediate brain (paleopallium, limbic brain) - emotional brain
    3. Rational brain (neopallium) - the logical/thinking brain
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5
Q

what are the functions of the Limbic System?

A
  • learning & memory

- control of emotion & instinctive behaviour

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6
Q

What are widely accepted concepts of the Limbic system? (x3)

A
  • analyses sensory stimuli for emotional significance
  • stores emotionally significant memory
  • impacts cognitive responses required for normal social behaviour/survival
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7
Q

What are the major cortices involved in the LIMBIC SYSTEM? (x5)

A
  • hippocampal formation (D.E.S.H)
  • Parahippocampal gyrus
  • Cingulate Gyrus
  • Oribto-frontal cortex
  • subcallosal area
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8
Q

What are the nuclei involved in the LIMBIC SYSTEM? (x3)

A
  • Amygdala
  • hypothalamus
  • anterior nucleus of Thalamus
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9
Q

What are the fibre tracts involved in the LIMBIC SYSTEM? (x4)

A
  • fornix
  • fornical commissure
  • cingulum
  • uncinate fascicle
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10
Q

The cingulum connects ____

the uncinate fascicle connects ____

A
  • cingulate and parahippocampal gyri

- temporal and frontal lobes (orbitofrontal cortex)

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11
Q

memory is defined as (x3)

A
  • acquisition
  • storage
  • retrieval

of information

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12
Q

Short-term memory is also know as? it is important for ___

A
  • working, transient, online memory

- performing daily acitivities

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13
Q

Describe the mechanisms of Short-term memory

A
  • > sensory stimulus = < 1s
  • > forget stimulus
  • > attention + sensory stimulus = few seconds
  • > peformance in daily activity
  • > forget stimulus
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14
Q

Short-term memory is mediated by

A

the PFC

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15
Q

short-term memory is encoded into long-term memory by

A

the hippocampus

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16
Q

Long-term memory can be divided into (x2)

A
  • Explicit memory
    • declarative
    • conscious processing
  • Implicit memory
    • non-declarative
    • unconscious processing
17
Q

Explicit memory is divided into __and stored in __

A
  • semantic (Basic knowledge)
  • episodic (personal events)
  • most higher association cortices
18
Q

Implicit memory is divided into ___ and stored in (respectively)

A
  • memories of skills and habits (stored in Basal ganglia, cerebellum, motor cortex)
  • emotional memories (stored in amygdala)
19
Q

Which cortical structure is the “door/gate” to the Limbic Loop?

A

the entorhinal cortex

20
Q

Describe the features and functions of the Entorhinal cortex (x5)

A
  • rostral most part of parahippocampal gyrus
  • door to limbic loop
  • contains grid cells for spatial navigation
  • first site to be affected in Alzheimer’s disease
  • important for learning, memory and spatial nav.
21
Q

Describe the functions and features of the hippocampus (x4)

A
  • contains TIME NEURONS (for order of events)
  • contains PLACE NEURONS (spatial navigation)
  • deals with EXPLICIT memory
  • converts short-term into long-term memory (specifically “where” & “when” of events)
22
Q

What is retrograde and anterograde amnesia?

A

retrograde - unable to retrieve information from long-term memory

anterograde - unable to encode/store new information to long-term memory

23
Q

What type of amnesia will result from a lesion of the hippocampus?

A

profound anterograde amnesia where one is unable to store new information into long-term memory and is unable to spatially navigate, but skilled memory and short-term memory are still intact.

24
Q

The hippocampus Proper is also know as ___. It is divided into ____.

A
  • cornu ammonis
  • CA1
  • CA2
  • CA3
  • CA4
25
Q

Which hippocampal portion is sensitive to low levels of oxygen (Hypoxia)?

A

CA1

26
Q

Which hippocampal portion is involved in seizure generation?

A

CA2

27
Q

What is the name of the fibre tract within the hippocampus?

A

Alveus

28
Q

Fibres of the alveus become the ___ which become the __.

A
  • fimbria of the hippocampus

- fornix

29
Q

Where in the cortex does adult neurogenesis occur?

A

dentate gyrus

30
Q

The limbic/Papez Circuit is believed to

A

underlie the connection between emotion and memory

31
Q

The papez ciruit involves

A

Entorhinal cortex -> dentate gyrus -> hippocampus -> mammillary bodies –> ant. nucleus of Thalamus -> cingulate gyrus - - - - - -> (back to entorhinal cortex via cingulum)

32
Q

The amygdala is contained within the ___ gyrus of the ___

A

semilunar

uncus

33
Q

What causes Wernicke-Korsakoff Syndrome ?

What are the symptoms?

A
  • damage to the mamillary bodies caused by Vitamin B1 deficiency caused by severe malnutrition or chronic alcoholism
  • Memory loss, disturbance of Papez circuit
34
Q

What are the functions of the amygdala? (x3)

A
  • stores emotional memories of fear
  • analyses environmental stimuli for emotional significance (hostility/friendliness)
  • initiates attachment (if friendly) or fear response (fight or flight response via hypothalamus) (if hostile)