Week 5-Memory

Question 1

According to the Atkinson–Shiffrin model (1968)

what are the 3 different types of memory models

Answer 1

Sensory store: modality-specific (auditory; visual; tactile) information held in sensory memory for a few milliseconds. [environmental stimuli]

Short-term store: information held for a few seconds (up to 20s), the duration can be extended via active rehearsal, limited capacity

Long-term store: nearly limitless in its duration and capacity

Question 2

Limited Capacity for Visual Short Term Memory (STM)

Vogel & Machizawa (2004) study -Electrophysiology

Answer 2

Visual cue- and which visual hemifield becomes relevant for memory storage. Displaying an array of the colours to be retained. Whether test array matches with a memory array. Recorded ERP responses from opposite hemisphere from visual LEFT hemisphere.

Electric brain activity reaches its maximum when about 3 – 4 items have to be stored in STM. –>There seems to be a limit to the storage capacity!

Going beyond 6 items. Increase 34 and 4-8. Indeed a maximum to storage capacity in visual short term memory.
-ve
Limit due to experimental design

Question 3

Paulesu et al. (1993)-The syllabus has to be retained with a probe

Answer 3

• More left-hemispheric activity during verbal STM task compared to the right
• BA 44 (Broca area) involved in the rehearsal. Rehearsal can increase the duration of short-term storage by several seconds.
• BA 40 involved in the storage(Prosterial area ACTIVATED)

Question 4

What is CHUNKING?

Bor et al., (2003)

Answer 4

Task: Memorise Structured and Unstructured Patterns
Memory patterns Structured remembered larger > Unstructured
Prefrontal Cortex (PFC) involved in chunking

Question 5

What is declarative long term memory?

Answer 5

• Semantic LTM(Facts)

- Episodic LTM(Events)

Question 6

Where in the brain are Declarative memories stored?

Answer 6

The volume of brain tissue destroyed was correlated with attenuated memory performance – independent of location!!

Lashley: There is no specific memory area in the brain; the whole brain is involved in learning and memory

• Memories are stored in brain areas involved in original sensory processing; e.g. visual information stored in higher visual cortex. Ventral(what) and Dorsal(when) pathway.
• Spatial information stored in parietal cortex; inferior temperal lobe.

Question 7

What does epilepsy (half brain)do to declarative memory?

Answer 7

Shows no memory deficits

Question 8

Explain Lashley’s mouse maze results for LTM

Answer 8

Worst possible laboratory task to study, maze running involves many senses
-vision (remembering the sight of correct pathways), -spatial sense (remembering the direction to turn),

• olfaction (smelling the cheese and moving toward the more powerful odour)
• kinesthesis (the feeling of arms and legs running a certain direction)

Eliminating one type –>others were spared to enable maze running
Memory is not unitary and different types of memory are relying on different brain structures

Brain-like vision (remembering the sight of correct pathways), spatial sense (remembering the direction to turn), olfaction (smelling the cheese and moving toward the more powerful odour), and kinesthesis (the feeling of arms and legs running a certain direction). If one type of clue is eliminated, there are many others remaining, allowing the rat to guide itself to the end of the maze. So Lashley was half right: memory is widely distributed. He was also half wrong because he assumed memory was unitary and there was one type of memory trace stored all over the brain.

Question 9

Where are memories stored? Inferior Temporal Cortex Roll’s study of facial processes

Answer 9

Specific memory advantage and visual perception

People with expertise in recognising cars show stronger area IT response to cars than birds, and people with expertise in recognition of birds vice versa
=> But is it correlate of memory traces or of sole visual perception? CORRELATE visual perception than of memory

Spiking of a neuron-memory trace of the specific face. Tuned to represent face 1

Inferior Temporal Cortex stores specific information

Question 10

Where are memories stored? Hippocampus

Answer 10

Hippocampus is located inside medial temporal lobes in each hemisphere

Question 11

Role of Hippocampus in animal (mice) studies

Answer 11

Radial arm maze-Mouse must remember from which arms it has already eaten reward–>episodic memory task
With hippocampal lesion NOT successful in this task

Morris water maze-Experience-based spatial memory relies on intact hippocampal activity

Question 12

Hippocampal Place Cells(2014)

Answer 12

Place cells are hippocampal neurons that spike when the rat is in a particular location in the environment which has been explored previously by the rat

Grid cells-Fire when the animal is approaching the neuron’s place field (similar to the perceptive field in sensory perception) Expand the space animal can explore. Unlimited spatial environment

Question 13

London Taxi Driver Study and Hippocampal Place Cells

Maguire et al. (2000)

Answer 13

HIPPOCAMPUS INVOLVED IN SPATIAL MEMORY
Compared to controls London taxi drivers show larger posterior part of the hippocampus

The longer the drivers are on their job the larger posterior part of hippocampus (and the smaller anterior part)
-Size of posterior and anterior hippocampus correlates to the duration of a taxi driver. The longer —Larger posterior hippocampus
(remembering routes/sites etc. enormous spatial memory)

Question 14

The role of the hippocampus in episodic memory

Ranganath et al study of coding - remember words and context

Answer 14

episodic memory = memory for events and their context (when, where, how?)

when the context of the studied material is recollected correctly–>stronger activity of the hippocampus and parahippocampal gyrus

More activity in the POSTERIOR hippocampus- storing contextual episodic memory

Question 15

Patient H.M

What happens when there is damage to the hippocampus?

Answer 15

Very severe anterograde amnesia(No memory from the time of surgery onwards)

Could not store any new episodic memories and hardly any new semantic long-term memories

Intact procedural memory (old semantic memories what happened before the surgery)
Intact short-term memory

Hippocampus not directly involved in the storage of semantic memories but in the formation of episodic memories

Question 16

Episodic memories-The Thalamus

Answer 16

Lesion in the diencephalon (thalamus)
Severe anterograde and retrograde amnesia(can't remember anything new or the past from the point of time)
preserved procedural memory
Thiamine deficit (vitamin B1: helps brain cells produce energy from sugar)
Causes:
alcohol abuse;
anorexia and overly-stringent dieting;
AIDS; kidney dialysis; chronic infection

Question 17

What is Korsakoff’s Syndrome?

Answer 17

Korsakoff’s Syndrome: A deficit of the thalamus

Question 18

How are memories stored in the brain(e.g. inferior temporal cortex)?

Answer 18

Grandmother cells-Memory entries (like memory about your granny) are stored by single neurons

Distributed Representations-Memory entries are stored by many neurons which form distributed networks

Question 19

Donald Hebb- How memories are stored?

Answer 19

Neurons which fire together wire together
Neurons which fire out of synch lose their link

EXTERNAL STIMULUS ACTIVATES SEVERAL NEURONS WITHIN THE HIPPOCAMPUS. All these neurons form strong synaptic links with each other. Activation of networks and activity spreading to all these cells.

Memories stored in distributed networks (cell assemblies) which are set up by simultaneous activation during learning sub-population of the assembly can reactivate the whole assembly!
Strengthening memory during learning

Question 20

Evidence for Grandmother Cells or rather for Distributed Representations?

Answer 20

Coding is relatively sparse but memories still would be implemented in distributed networks/cell assemblies. Overlapping neural networks

Unlikely that complex memory traces are stored by only one single cell

How would this cell e.g. code for Halle Berry at the red carpet as well as in a Catwoman costume?

What when we lost this cell? Would we lose Halle Berry?

How could complexity of memory entries (different sensory impressions…) be coded by only one cell?Unlikely

Question 21

How the brain is involved in the long-term storage of information?

Answer 21

Distributed representations, strengthened through

• Hebbian modification including inferior temporal and parietal cortex (semantic memories), and
• Hippocampus and thalamus (episodic memories)

Question 22

Procedural Long Term Memory (LTM)

Answer 22

Double dissociation between patients with Parkinson’s -Disease (PD) and with Amnesia (hippocampal lesion)-> Evidence for separated memory systems for declarative and procedural memory

-procedural LTM –> Basal ganglia crucially involved

Question 23

How has procedural memory been investigated?

Memory: weather prediction task

Answer 23

Compared to healthy controls and amnesic patients only patients with Parkinson’s Disease (PD) show attenuated implicit memory formation.

A patient’s with Parkinson-Impaired procedural memory; Intact declarative memory

Patient with amnesia- Impaired declarative; intact procedural

NEURAL BASIS for declarative and procedural memory are MUTUALLY EXCLUSIVE.

But Parkinson Disease patients perform normally in a declarative memory task. ( Can’t perform weather memory task)- there is a disassociation between PD and Huntington’s Disease patients

Question 24

H.M & Amnesia- Severe deficit in declarative memory

Answer 24

H.M. showed severe anterograde amnesia

But good learning in the Mirror Drawing Task
–>normal procedural memory