Long term memory and the brain- Lecture 5

Question 1

HM case study

Answer 1

Suffered severe epilepsy
Abnormal electricity in temporal lobes
Surgery to remove parts of left n right medial temporal lobes
Developed issues retaining new information more than seconds or minutes.

Question 2

Evaluation of HM case as evidence for locating memory in the brain

Answer 2

• Revolutionary at the time- well documented
• Locates specific memory functions in the brain
• Lead to Milner’s work on patients with unilateral MTL lobectomies- revealed content specific memory deficits

Question 3

Causes of Amnesia

Answer 3

• Anoxic or ischaemic episodes
• Progressive disorders
• Chronic Alcoholism
• Viral or bacterial infections
• Brain Tumours
• Head injury

Question 4

Areas of damage typical in amnesia

Answer 4

Medial temporal lobes
Thalamus
Fornix & Mammillary bodies
Basal Forebrain
Interconnected structures

Question 5

Anterograde Amnesia

Answer 5

Impaired memory for events and facts learned experienced after onset of amnesia

Question 6

Retrograde Amnesia

Answer 6

Impaired memory for events and facts before onset of amnesia

Question 7

Things that are unaffected by organic amnesia

Answer 7

Intelligence
perception
attention
language
short term memory (to extent)
Working memory

Question 8

Organisation of Long-term memory

Answer 8

• Memory is related but distinct from info processing
• LTM exists in multiple forms, anatomically dissociable
• New classification of LTMs

Question 9

Explicit memories

Answer 9

Conscious retrieval of information

-Involves structures damaged in amnesia

Question 10

Implicit memories

Answer 10

Do not require consciousness
Like learned procedures
-Involves structures non damaged by amnesia

Question 11

Skill Learning- Knowlton, Mangels & Squire (1996)

Implicit/procedural memories

Answer 11

Probabilistic learning (learning to associate specific combinations of cards with a specific outcome)

• Damage to basal ganglia (like in Parkinson’s) are impaired in this
• When task made implicit> basal ganglia is engaged
• When explicit> medial temporal lobe is inactive

Question 12

Eye- blink conditioning & the cerebellum

Bracha et al (2000)

Answer 12

NOT IN AMNESIA -Cerebellum is linked with creating the eye-blink reflex- when damaged, they do not respond to the neutral stimulus (tone) that is associated with the puff of air.
AMNESIC’S HAVE IMPLICIT MEMORY INTACT

Question 13

Priming

Implicit memory

Answer 13

Change in the ability to identify or produce an item as a result of a specific prior encounter with the item

Question 14

Priming in Amnesics

Warrington & Weiskrantz, 1968;1970

Answer 14

-Used fragmented versions of words- start with most fragmented and asked if the ppt can identify
-When this task is repeated over and over, will see that amnesics and controls show learning and become better
Priming is preserved in amnesics

Question 15

Neuroimaging studies of Priming

Perceptual and conceptual priming

Answer 15

Perceptual priming activates areas in extrastriate cortex

Conceptual priming activates an area in the inferior frontal gyrus (dorsal & inferior prefrontal cortex)

Question 16

Wig et al. (2005)

Answer 16

Investigated areas of haemodynamic response of conceptual priming using TMS

• When TMS applied in the front left area of brain (the inferior frontal gyrus) didn’t interfere with task itself
• but did effect haemodynamic response- was as if novel items

Question 17

Functional deficit of Anterograde amnesia

Explicit memories

Answer 17

> Impairment in creating associations between separate items of information (Eichenbaum & Cohen, 1991)
impairment of episodic memory (Aggleton & Brown, 1999)
Affects both episodic and semantic memory (Squire, 2009)

Question 18

Episodic Memory deficits

Declarative Memories

Answer 18

Memory for events containing contextual information (TULVING, 1983)
-semantic memories start as components of episodes but surrounding episode is forgotten

Question 19

Aggleton & Brown (1999)

Episodic memory deficit

Answer 19

There is 2 systems that are implicated in Episodic memory deficits, both the MTL and diencephalic structures
-Two systems are independent but interacting

Question 20

Episodic Memory Deficit

Recollection System

Answer 20

Involves the hippocampus, anterior thalamus , fornix and mammillary bodies
Ability to remember episodes

Question 21

Episodic memory deficit

Familiarity system

Answer 21

Sense of familiarity, the feeling that something has been experienced before in the absence of additional information.
Involves the rhinal cortex (entorhinal and perirhinal), parahippocampal cortex and dorsomedial thalamus (MTL)

Question 22

Tsivilis et al (2008)

Answer 22

Damage to the fornix creates wasting of Mammillary bodies Patients with large mammillary body volumes tended to do better at recall (recollection network) than patients with small mammillary body volumes
-no effect on familiarity network

Question 23

The role of the Perirhinal cortex

Answer 23

Bowles (2008)

When damage to the Perirhinal cortex- the familiarity memory is impaired but not recollection

Question 24

Remote memories

Answer 24

Memory of events from the distant past

Question 25

Ribot’s Law

Remote Memory

Answer 25

The older the memory, the less likely it is to be effected in the event of memory damage

Question 26

Remote memories

ECT therapy

Answer 26

ECT used for depression
BUT causes both anterograde and retrograde amnesia for events around the treatment
However, older memories appeared intact

Question 27

ECT Therapy studies

Criticisms

Answer 27

Not all studies have replicated this finding

• Depression could be linked with encoding deficits
• We are not aware of why the memory disruption occurs- thus dont know why the older memories are not affected

Question 28

Reed & Squire (1998)

Answer 28

Retrograde amnesia can be quite limited or very extensive, depending on whether the damage is restricted to the hippocampal formation or also involves additional temporal cortex

Question 29

The Consolidation theory

Squire and Alvarez (1995)

Answer 29

Consolidation of memory occurs when the cortico-connections to the hippocampus are strengthened
Memories become remote when the hippocampus is no longer engaged in consolidation

Question 30

Damage to hippocampus

Answer 30

Should only affect recent memories in consolidation, not remote memories as they are already consolidated.

Question 31

Issues with Consolidation Theory

Answer 31

• Unspecified period for consolidation to complete

- Unclear mechanism by which long-term consolidation occurs

Question 32

Cipolotti et al (2001)

Answer 32

Remote memory for facts impaired
Remote autobiographical memories were also severely affected
Impairment affected all periods of life

Question 33

Issues with Neuroimaging studies in Autobiographical memories

Answer 33

• Memories asked to recall are self selected

- Activity may become contaminated by this procedure which makes people rethink of their memories.

Question 34

Gilboa (2004)

Answer 34

Avoided self selected memories by asking friends and relatives to provide pictures relating to autobiographical events

Question 35

Restrospective Neuroimaging studies

Answer 35

• Both remote and recent memories triggered by personal photographs- at the hippocampus
• Remote memory activation tended to have a more widespread distribution relative to recent memories

Question 36

Multiple Trace Theory (MTT)

Nadel & Moscovitsch (1997

Answer 36

Dismissed that hippocampus has time limited role in memory
Re-encoding of older memories creates new hippocampal traces. As a result, incomplete hippocampal lesions will affect recent memories (few traces) more than remote memories (more traces) in a probabilistic manner.