Hippocampus: Memory And Amnesia Flashcards

1
Q

What is lambic

A

It is an anatomical term, not really a functional term

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2
Q

Limbic structures

A

Structures bordering the ventricular system and midline, including cingulate cortex, primary olfactory cortex, parahippocampal gyrus, amygdala, hippocampus, septum

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3
Q

Limbic system

A

Phrase commonly used to refer to lambic regions and related tracts, but often used incorrectly to suggest a single functional system or to include regions that are not limbic

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4
Q

Is the basal forebrain part of the limbic system

A

No

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5
Q

Limbic structures in the medial temporal lobe

A

Uncus
Parashippocampal gyrus
Isthmus of cingulate gyrus

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6
Q

Limbic structures in the subcortical medial temporal lobe

A

Amygdala, within uncus

Hippocampus (within PH gyrus)

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7
Q

How does the hippocampus sits _______ to inferior horn of the lateral ventricle

A

Medial and ventral

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8
Q

Amygdala sits ______ to hippocampus

A

Mostly rostral

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9
Q

Amygdala in relationship to the hippocampus

A

Amygdala extends caudally and just superior/dorsal to hippocampus

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10
Q

Entorhinal cortex

A

Tail of the seahorse

  • parahippocampal gyrus
  • subiculum
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11
Q

Hippocampus proper

A
  • hippocampus

- dentate

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12
Q

What is the hippocampal complex derived from

A

Folding of cortex

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13
Q

What layers are the hippocampal complex made up of

A
  • polymorphic layer
  • pyramidal cell layer
  • molecular layer
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14
Q

How do signals travels in the hippocampal complex

A

Cortex-entorhinal-dentate-hippocampus(CA2)-CA1-subiculum-cortex

Comes in through cortex and back out to different part of cortex

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15
Q

What is the tri synaptic circuit of the hippocampal complex

A

Takes info from the cortex and back out to the cortex.

Long term memory

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16
Q

What is the cellular/circuit basis of memory

A

Tri synaptic circuit of the hippocampal complex

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17
Q

Promotes long term memory of information for single sensory modality or can promote multi sensory memories

A

Tri synaptic circuit of the hippocampal complex

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18
Q

What does the hippcampal complex receive input from

A

Amygdala and sensory/association neocortex

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19
Q

Where does the hippocampal complex send projections to

A

Amygdala and sensory/association neocortex

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20
Q

What is the output to the fornix from the hippocampal complex

A

Hypothalamic nuclei of all kinds

  • behavioral
  • hormonal
  • unconscious involuntary responses
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21
Q

Out put to fornix

A

Mediated hippocampal regulation of feeding, reproductive behavior, stress hormone release

22
Q

Memory consolidation

A
  • when first meeting a future friend, reciprocal connections between cortical regions processing faces and voices are initially very weak, unlikely to activate each other
  • repeated meetings with friend repeatedly strengthens reciprocal connections. Hippocampus is required for this strengthening of synspases
  • after memory consolidation, exposure to voice alone will re-activate memory of face without hippocampal participation
23
Q

What is required for strengthen of synapses when repeatedly meeting a friend and becoming familiar with their face

A

Hippocampus

Hippocampus drives changes in wiring

24
Q

After you have seen your friend so many times, what role does the hippocampus play in recognition of friend

A

None. After memory consolidation, exposure to voice alone will reactivate memory of face without hippocampal participation

25
Q

Declarative long term memory

A
  • Explicit=conscious/effortful
  • faces, events
  • hippocampus/cortex
26
Q

Non declarative long term memory

A

-implicit=unconscious/automatic

27
Q

Procedural non declarative long term memory

A

Skills/habits

  • basal ganglia
  • cerebellum
28
Q

Associative learning non declarative long term memory

A

Conditioning

-cortex and amygdala sometimes

29
Q

Examples of declarative memory

A
  • who is US president
  • what is your home address
  • how did you get here for your appointment
  • what did you do yesterday? On your last birthday
30
Q

Skills that become second nature or motor habits

A

Procedural memory

31
Q

Natural examples of procedural memory

A
  • Tennis forehand/backhand volley
  • driving manual transmission
  • following a routine path through building
32
Q

Lab tests for procedural memory

A
  • read backwards text as if viewed in mirror; copy test backwards (does not require hippocampus)
  • Mirror drawing
  • tower of hanoi disk puzzle
33
Q

Procedural memory tasks in the lab

A

Normal subjects show improved performance with training and long term memory (they retain good performance later)

34
Q

Mirror drawing test

A
  • tests procedural memory

- subject must trace between narrow lines

35
Q

Tower of hanoi puzzle

A

Sequential moves of disks with a goal of re-stacking them in same order on a different peg

36
Q

Medial temporal lobe removal of HM

A
  • had extensive medial temporal lobe removed to help seizures
  • immediate anterograde amnesia
  • retrograde amnesia
  • preserved general intelligence
  • no changes in personality or motivation
37
Q

Anterograde amnesia

A

Forgets everything after several minutes

  • cant recognize family or anyone
  • no recell or awareness of events more than several minutes ago
38
Q

Declarative memory loss

A

Retrograde/anterograde amnesia

39
Q

HM’s procedural memory

A
  • was intact because you don’t need hippocampus for that
  • during each days training, HM shows steady reduction in errors. Also when returning the next day to continue trading in, the Indian error rate is still low, indicating intact long term procedural memory, despite no episodic memory training
40
Q

HM intact procedural memory and the tower of hanoi puzzle

A

HM has to move 31 discs instead of just 3, and reaches top score after just 2 days and still good at it one year later

41
Q

First to study HM and gain insight into neural basis of declarative memory

A

Dr. Brenda Milner

-mentee Suzanne Corkin also helped

42
Q

Is amygdala needed for memory

A

No

43
Q

Lesions of only hippocampus vs lesions of amygdala

A

Lesions of only hippocampus Reproduce amnesic syndrome, whereas lesions only of amygdala do not proceed amnesia

44
Q

What does amygdala do

A

Can enhance or impair declarative memory for information from emotionally charged events. Amygdala also mediates simpler forms of learning/memory

45
Q

Concept of memory storage

A

Consensus is that storage and recall of information occurs in same region of cortex as original sensory processing. Recall of visual info occurs in visual cortex, auditory recall in auditory cortex, verbal recall in Wernicke’s speech comprehension area, etc

46
Q

Concept of memory consolidation

A

Hippcampal function and connectivity with cortical areas is required to induce changes in cortex that allow for memory storage and retrieval. Later hippocampus is no longer needed to recall information: cortical regions can ref-activate each other without help from the hippocampus

47
Q

What does hippocampus specialize in and is an exception to the rule for memory consolidation

A

Specializes in spatial information processing and is required for storage and retrieval f spatial information (navigating to parked car, to home, etc)

48
Q

Lesion to hippocampus

A

Anterograde amnesia, retrograde amnesia

Sparing of oldest memories

49
Q

What is the hippocampus required for

A
  • new infor to be stored in cortex (lesion=anterograde amnesia)
  • recent past info to be permanent stored in cortex (lesion=retrograde amnesia)
50
Q

What is hippocampus NOT required for

A

Memory storage or recall for remotes (older) events (lesion=sparing of oldest memories)