Chapter 16 Flashcards
Describe why assessment is important in memory problems
Involves combining test results with info from other professionals + neuroimaging techniques.
B) Standardized test results allow the patient’s performance to be compared to healthy people using standardized norms
C) Contributes to the diagnosis of the clinical problem underlying the memory deficit
D) Important in communicating info about the patient to other professionals in a standardized way + patterns of strengths/weaknesses–>important in planning the treatment program.
E) The specification of the patient is essential for any publication + new discoveries can influence clinical practice.
Compare anterograde amnesia with retrograde amnesia
Anterograde–>problem in encoding, storing or retrieving ongoing information that can be used in the future (case of HM, CW & KI)
Retrograde–>refers to the loss of access to events that happened in the past, typically before the onset of the disease.
Describe amnesic syndrome + how it occurs
In its pure form, the amnesic syndrome involves grossly impaired episodic memory + with preserved working memory, semantic memory, implicit memory + intelligence.
Episodic memory allows individual, specific memories to be retrieved–> episodes are linked to the specific time + place of the experience
This associative link provides a way of specifying that particular experience + subsequently retrieving that memory
Loss of the capacity to link experiences to their spatial/temporal context would grossly disrupt subsequent recollection.
The same thing happens to rats with hippocampal lesions–> bad at making use of environmental context in a spatial learning task
Amnesic patients may have difficulty in imagining future activities but able to imagine the component experiences, but could not integrate them into a whole,
although the hippocampus plays a role in both episodic memory and the use of imagination to predict the future, these are best seen as separate functions.
Describe Huppert + Piercy study that compares amnesiacs to a control group on picture recognition
the performance of amnesic + control patients can be roughly equated by giving the amnesic patients longer to encode the pictures than the controls.
The study involved presenting pictures either once or twice on each of two successive days.
After the second day’s presentation, participants were shown a sequence of pictures + asked to say if they’d seen each picture.
If they recognized–>decide on which day that picture had been shown.
Amnesiac patients: more likely to say that items presented twice on day 1 had in fact been presented on day 2–> b/c the degree of familiarity was greater.
Control group: opposite pattern. More accurate in assigning items to day 1 if they had been presented twice–> 2 presentations = 2 chances of linking that picture to the day 1 context.
In the absence of episodic memory’s ability to link to context, amnesic patients had to rely on a general feeling of familiarity.
The same thing happened to answers to trivial pursuit questions e.g. what the favourite food of the comedian and film star was, Bob Hope.
Patients are able to recall the “fact,” but bad at recalling that they had just been given this info–>confused recency with the degree of familiarity.
Define source amnesia
Applied to the characteristic difficulty that amnesic patients experience in recollecting the source of a given memory.
Describe the Modal model of amnesia by Baddley (That was proven far too simple)
Model consistent with a contextual hypothesis
1) Assumes that the essence of episodic memory is the capacity to “glue” experiences to a specific context, which provides a contextual tag–>allows individual experiences to be retrieved.
2) Assumes that recall + recognition involves the same underlying storage processes with different constraints on subsequent retrieval.
3) Assumes that semantic memory represents the residue of many episodes + could be retrieved through a separate mechanism.
Testing Jon (Fargha-Khadem’s patient) convinced Baddeley that the modal model of amnesia was wrong, or far too simple.
Describe the case of Jon and how it goes against the modal model of amnesia
- Born prematurely–> anoxia + substantial damage to his hippocampus.
- Above-average intelligence
- Good semantic memory skills–> Jon’s knowledge of the world is excellent but takes longer than controls to acquire new facts
- Recognition was so well preserved and recall so impaired
Doors and People Test–>Separate measure for visual + verbal recall and recognition. Each of these components is assessed separately, then combined to give overall visual scores, overall verbal scores + combined recall versus recognition.
a) If episodic memory is impaired, semantic memory should have been impaired too since it is based on an accumulation of episodes; this was not the case
b) crystallized intelligence based on prior learning should have been impaired e.g. reduced vocabulary; this was not the case.
c) If recall and recognition involve essentially the same storage process, they both should have been impaired; this was not the case.
Describe what neuroimaging & testing results discovered about Jon’s memory
- Considerable difficulty teaching Jon the distinction between remembering and knowing.
- When control participants made a remember judgment–> could describe their recollection
- Jon however, tried to form a visual image of the cards + if his image of the word was clear and bright–> categorized this as remembering.
- Jon was using a strength rather than a recollective criterion.
- The “remember” judgments are accompanied by a specific activation pattern that differs from that evoked by “know” responses. Jon proved to lack the remember component.
- Jon does have the capacity to recollect but has great difficulty in laying down their episodic memory traces
How is Jon different from other amnesiacs?
- Got his hippocampal damage at a very early age
- Damage is limited to the hippocampus but perirhinal and entorhinal cortices are entirely spared.
- The hippocampus is important for episodic memory, but familiarity-based recognition judgments are based on the adjacent perirhinal regions that are preserved
- Later studies on amnesiacs show that hippocampal volume had a minimal effect on memory for items, but a clear impact on context memory
- The greater the volume of the hippocampus, the better the memory of which word went with which scene
Define Consolidation + how it affects amnesia
- Memory traces are initially fragile + become more resistant to forgetting as time progresses
- It depends crucially on the hippocampus + related areas–>damage to this area interferes with the consolidation process.
- When learning is followed by a period of sleep, long-term retention is better than when remaining awake during that time
- The retention of information by amnesic patients was greatly enhanced if learning is immediately followed by their removal to a quiet, dim interference-free room.
- 4 densely amnesic patients + 6 controls attempted to remember a story 1 hour later.
- When the hour was spent in a darkened room, patients performed almost as well as controls.
- However, when the hour was filled with cognitive tasks, the patients remembered virtually nothing
- Amnesic patients are particularly susceptible to the disruption of the process of consolidation, particularly during the early stages.
Describe Dewar’s study with Mild cognitive impaired (MCI) patients
MCI patients and controls learned a list of words + were tested after a delay of 9 minutes (divided into 3), with interfering material presented during either the first, 2nd or 3rd part of the retention period.
Interference during the first stage caused more forgetting than in the later phases–>b/c the initial stages of consolidation are particularly vulnerable.
The process of hippocampal consolidation over this initial period –>operates at the cellular + subcellular level–> based on the mechanism of long-term potentiation (LTP)
What is retrograde amnesia?
Patients often suffer from both, however, the severity of anterograde is not highly correlated with the degree of retrograde amnesia, suggesting different origins
Problem with measuring retrograde amnesia–>the tester typically does not have control over the learning of the material to be recalled (learned many years ago)
Ribot’s law–>earlier memories are better preserved in those with retrograde amnesia + are more durable than those acquired more recently
What are some methods of testing retrograde amnesia + what are issues with them?
1) Scales testing degree of knowledge of news events or horse races is likely to vary substantially across patients + is continually ageing so needs constant revising and revalidating.
2) Requesting autobiographical recollections to probe the patient’s memory of their earlier life + cross-check with kin–> not very practical for lab studies + is time-consuming
Retrograde amnesia generally leads to impairment in autobiographical memory on both the personal + the semantic scales.
Personal semantic memory–> Factual knowledge about one’s own past.
Describe Autobiographical Memory Interview (AMI) by Kopelman, Wilson, and Baddeley
Involved asking people to remember factual questions that could be regarded as probing a form of personal semantic memory.
Some were remote (name of first school). Intermediate (first job), recent (last Christmas)
For each life period, had to recollect a specific personal event (winning a race at school)
Episodic recollections were rated in terms of amount + specificity of info retrieved.
The test was validated + found to be sensitive and reliable.
What is Alcoholic Korsakoff syndrome?
Patients have difficulty learning new information, although events from the past are recalled.
A tendency to invent material to fill memory blanks.
The most common cause is alcoholism, especially when this has resulted in a deficiency of vitamin B1.
