Lecture 5 - Memory and Learning

Question 1

What is amnesia

Answer 1

The amnesic syndrome refers to a permanent, stable and global disorder of memory due to organic brain dysfunction, which occurs in the absence of other extensive perceptual or cognitive disturbance.

Question 2

what did HM have lesioned

Answer 2

 medial temporal pole cortex
most of the amygdala
entorhinal cortex
more than half of the hippocampus
 subiculum
some debate about temporal stem and perirhinal cortex

Question 3

What happened to HM after the surgery?

Answer 3

• declarative amnesia
• got not recall anything that happened after the surgery
• brief retrograde amnesia
• perceptual tasks intact, childhood memories intact.
• implicit memory was intact

Question 4

What are the neural systems underlying explicit and implicit memory?

Answer 4

medial temporal region:

• hippocampus
• amygdala
• entorhinal cortex
• parahippocampal cortex
• preirhinal cortex

Question 5

What is the entorhinal cortex

Answer 5

• located on medial surface of temporal lobe
• major route for neocortical input into the hippocampal formation
• ento= interior rhinal=nose
• role in declarative memory and LTP

Question 6

Describe the parahippocampal cortex

Answer 6

• along the dorsal medial surface of temporal lobe
• receives connection sto the parietal cortex
• involved in VISUOSPATIAL processing

Question 7

perirhinal cortex?

Answer 7

• next to rhinal fissure on base of brain - medial temporal lobe
• receives connections from the visual regions of the ventral stream
• receives sensory information from all sensory areas
• involved in VISUAL OBJECT MEMORY
• also involved in recency of objects

Question 8

what are the 3 types of amnesia

Answer 8

hippocampal or medial temporal lobe (MTL) amnesia,

diencephalic amnesia

and basal forebrain amnesia.

Question 9

Neuropsychologically, how does MTL amnesia look

Answer 9

amnesia for all modalities of memory input (visual, verbal.. etc)

• impaired episodic memory
• impaired semantic, but less than EM
• retrograde amnesia - variable length
• implicit memory, working memory is unimpaired

transfer fro wm to long term is impaired

Question 10

What does the MTL include

Answer 10

hippocampus
parahippocampal region
amygdala
entorhinal cortex

Question 11

what did Eichenbaum, Otto & Cohen (1994) find about functional distinctions between components of MTL

Answer 11

parahippocampal region - representation of isolated items, and intermediate term memory for these items

hippocampus - relational representations - processes relationships among multiple items and content rich episodic memories

Question 12

what did aggleton & brown (2005) find about mTL memory

Answer 12

• doesnt function as a unitary system
• hippocampal region - anteror thalamic system - recall and recognition of EM
• perirhinal - medial dorsal thalamic system - familiarity based memory system (recognition) —> problem can cause deja vu

Question 13

What is the role of the hippocampal formation in memory

Answer 13

• binds different features into an episodic representation in encoding
• uses retrieval cues and compares to stored memories
• processes spatial localisation in the hippocampus
• recognises object identity in the rhinal cortex - longer term association
• consolidates memories in the cortex - if memories are old enough, it is not necessary in retrieval

Question 14

what is the circuit of papez

Answer 14

ring around the top of the brainstem, mamillary, hippo, thalamus, cingulate…

all work together as the circuit of papez.

Question 15

examples of MTL amnesia syndromes

Answer 15

• cerebral ataxia
• early AD
• CNS infection
• MTL sclerosis and epilepsy

Question 16

examples of diencephalic amnesia

Answer 16

• AlcoholicWKS
• Thalamic stroke - vascular disease
• Thalamic trauma

Question 17

examples of basal forebrain amnesia

Answer 17

• ACoA aneurysm

* Cholinergic deficit in AD??

Question 18

describe korsakoff’s syndrome

Answer 18

diencephalic

due to alcohol

mamillary body degeneration

severe anterograde amnesia, variable retrograde amnesia, confabulations, and a disorientation with respect to time and place

intelligence and short-term memory are frequently preserved

encoding deficits

Question 19

what are the diencephalic structures

Answer 19

• basal forebrain
• thalamus
• mamillary bodies
• hypothalamus

posterior part of forebrain

Question 20

What does a basal forebrain amnesia look like?

Answer 20

• ACoA - anterior communicating artery infarctions
• disruption of cholinergic projections from basal forebrain to hippocampus and cortex
• anterograde amnesia
• variable retrograde
• ## confabulation

Question 21

how does Ach affect memory

Answer 21

• affects basal forebrain area
• contains many cholinergic neurons
• projects to cortical and subcortical areas

disruptions to these projections will lead to amnesia

Question 22

what brain reigon does working memory rely on

Answer 22

• involves maintenance and processing of info
• PFC:
• maintenance (episodic buffer) –> ventrolateral PFC
• manipulation –> dorsolateral PFC

contributes to stratgies in memory - organisation, selection, monitoring, evluation and retrieval.

Question 23

How will a frontal lesion affect memory

Answer 23

• a working memory / executive function type memory deficit
• problems in maintenance and manipulation of memory
• strategies for memory, such as planning and organising will be impaired

Question 24

how does MTL and frontal lobe interact in memory

Answer 24

The frontal lobes control the information delivered to the medial temporal and diencephalic regions at encoding and initiate, guide and monitor retrieval and help interpret and organise the information retrieved, conferring a measure of intelligence and direction of the process

Question 25

what is the role of frontal lobes in memory

Answer 25

- temporal order of events - working memory - mediates general intelligence - controls different but connected abstract supervisory operations

Question 26

What are the neural systems underlying working memory?

Answer 26

phonological loop: - rehearsing numbers and letters - prefrontal (DLPFC) - articulatory distraction - parietal - central executive - executive prefrontal visuospatial sketchpad - right prefrontal occipital parietal cortex

Question 27

What is the circuit of papez?

Answer 27

initially thought it was for emotion, now moreso for MEMORY cortical association areas --> hippocampus --> mammilary bodies --> anterior nucleus of thalamus --> cingulum, entorhinal cortex --> Hippocampus

Question 28

which area of the brain is responsible for information maintenance

Answer 28

VLPFC - maintenance

Question 29

which area of the brain is responsible for manipulating information

Answer 29

DLPFC

Question 30

how was the DLPFC been found to be engaged

Answer 30

there was no difference in organisation/activation between spatial or non-spatial information there was a distinction between maintenance or Maintenance plus work!! plus work was more anterior. level of processing matters.

Question 31

What are the locus' of processing deficits for the three amnesias

Answer 31

MTL - consolidation - rapid forgetting Basal forebrain - executive stuff - strategic planning, techniques Diencephalic - encoding

Question 32

In which of three amnesias does confabulation happen

Answer 32

not MTL YES IN BASAL FOREBRAIN sometimes in diencephalic

Question 33

what is the pattern of memory disturbance in diencephalic and temporal amnesia

Answer 33

temporal - time dependant diencephalic - temporally graded

Question 34

Describe HERA

Answer 34

Hemispheric Encoding Retrieval Asymmetry model THAT DIFFERENT HEMISPHERES DO DIFF THINGS - Left prefrontal activation when encoding memory, especially when must organise meaningful information - Right prefrontal activation when retrieving from episodic memory so the circuitry involving encoding and retrieval are different from each other

Question 35

explain spontaneous or persistent confabulation

Answer 35

- spontaneous or persistent - usually extensive frontal damage and basal forebrain damage (for the executive component) -Severe anterograde amnesia + dysexecutive syndrome

Question 36

Explain transient or provoked confabulation

Answer 36

- just in basal forebrain : no amnesia  no confabulation - can also get it from orbitofrontal lesions