Hippocampus: Memory And Amnesia

Question 1

What is lambic

Answer 1

It is an anatomical term, not really a functional term

Question 2

Limbic structures

Answer 2

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

Question 3

Limbic system

Answer 3

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

Question 4

Is the basal forebrain part of the limbic system

Answer 4

No

Question 5

Limbic structures in the medial temporal lobe

Answer 5

Uncus
Parashippocampal gyrus
Isthmus of cingulate gyrus

Question 6

Limbic structures in the subcortical medial temporal lobe

Answer 6

Amygdala, within uncus

Hippocampus (within PH gyrus)

Question 7

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

Answer 7

Medial and ventral

Question 8

Amygdala sits ______ to hippocampus

Answer 8

Mostly rostral

Question 9

Amygdala in relationship to the hippocampus

Answer 9

Amygdala extends caudally and just superior/dorsal to hippocampus

Question 10

Entorhinal cortex

Answer 10

Tail of the seahorse

• parahippocampal gyrus
• subiculum

Question 11

Hippocampus proper

Answer 11

• hippocampus

- dentate

Question 12

What is the hippocampal complex derived from

Answer 12

Folding of cortex

Question 13

What layers are the hippocampal complex made up of

Answer 13

• polymorphic layer
• pyramidal cell layer
• molecular layer

Question 14

How do signals travels in the hippocampal complex

Answer 14

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

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

Question 15

What is the tri synaptic circuit of the hippocampal complex

Answer 15

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

Long term memory

Question 16

What is the cellular/circuit basis of memory

Answer 16

Tri synaptic circuit of the hippocampal complex

Question 17

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

Answer 17

Tri synaptic circuit of the hippocampal complex

Question 18

What does the hippcampal complex receive input from

Answer 18

Amygdala and sensory/association neocortex

Question 19

Where does the hippocampal complex send projections to

Answer 19

Amygdala and sensory/association neocortex

Question 20

What is the output to the fornix from the hippocampal complex

Answer 20

Hypothalamic nuclei of all kinds

• behavioral
• hormonal
• unconscious involuntary responses

Question 21

Out put to fornix

Answer 21

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

Question 22

Memory consolidation

Answer 22

• 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

Question 23

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

Answer 23

Hippocampus

Hippocampus drives changes in wiring

Question 24

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

Answer 24

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

Question 25

Declarative long term memory

Answer 25

- Explicit=conscious/effortful - faces, events - hippocampus/cortex

Question 26

Non declarative long term memory

Answer 26

-implicit=unconscious/automatic

Question 27

Procedural non declarative long term memory

Answer 27

Skills/habits - basal ganglia - cerebellum

Question 28

Associative learning non declarative long term memory

Answer 28

Conditioning | -cortex and amygdala sometimes

Question 29

Examples of declarative memory

Answer 29

- 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

Question 30

Skills that become second nature or motor habits

Answer 30

Procedural memory

Question 31

Natural examples of procedural memory

Answer 31

- Tennis forehand/backhand volley - driving manual transmission - following a routine path through building

Question 32

Lab tests for procedural memory

Answer 32

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

Question 33

Procedural memory tasks in the lab

Answer 33

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

Question 34

Mirror drawing test

Answer 34

- tests procedural memory | - subject must trace between narrow lines

Question 35

Tower of hanoi puzzle

Answer 35

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

Question 36

Medial temporal lobe removal of HM

Answer 36

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

Question 37

Anterograde amnesia

Answer 37

Forgets everything after several minutes - cant recognize family or anyone - no recell or awareness of events more than several minutes ago

Question 38

Declarative memory loss

Answer 38

Retrograde/anterograde amnesia

Question 39

HM's procedural memory

Answer 39

- 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

Question 40

HM intact procedural memory and the tower of hanoi puzzle

Answer 40

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

Question 41

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

Answer 41

Dr. Brenda Milner | -mentee Suzanne Corkin also helped

Question 42

Is amygdala needed for memory

Answer 42

No

Question 43

Lesions of only hippocampus vs lesions of amygdala

Answer 43

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

Question 44

What does amygdala do

Answer 44

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

Question 45

Concept of memory storage

Answer 45

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

Question 46

Concept of memory consolidation

Answer 46

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

Question 47

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

Answer 47

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

Question 48

Lesion to hippocampus

Answer 48

Anterograde amnesia, retrograde amnesia | Sparing of oldest memories

Question 49

What is the hippocampus required for

Answer 49

- new infor to be stored in cortex (lesion=anterograde amnesia) - recent past info to be permanent stored in cortex (lesion=retrograde amnesia)

Question 50

What is hippocampus NOT required for

Answer 50

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