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Flashcards in CLOA - Explain how biological factors affect a cognitive process Deck (21):

Alzheimer's Disease

- a serious degenerative brain disease
- symptoms include memory impairment, difficulty speaking, attention problems, altered personality


what causes Alzheimer's?

- abnormal protein fragments that kill brain cells
- begins at the hippocampus
- amyloid plaques
- neurofibrillary tangles
- reduced metabolism in the hippocampus (Mosconi, 2005)


amyloid plaques

- caused by sticky deposits of amyloid-ß proteins that accumulate in the brain
- they damage axon and dendrite membranes
- plaques are formed from the degenerating axons and dendrites


neurofibrillary tangles

- accumulation of an abnormal form of tau protein
- structural support of neurons collapses
- tangles occur in the microtubules


tau protein

a component of the support structure of neurons


how does AD impair cognitive functions?

- degradation of the neurons in the brain
- leading to widespread atrophy (shrinking)


episodic memory

memory for events/personal experiences


semantic memory

general knowledge about the world, concepts, language


procedural memory

memory for the performance of particular actions


effect of AD on various types of memory

- Salthouse and Becker (1998): analyzed data from 180 AD patients and over 1000 normal elderly individuals, and found that AD primarily impaired episodic memory
- Hodges et al. (1994) measured semantic memory in AD patients with tasks (e.g. naming pictures of objects or animals) and found a steady decline in semantic
- procedural memory is also affected but to a lesser extent


Mosconi (2005) - Aim

To investigate early detection of Alzheimer’s


role of hippocampus

encoding and transferral of STM to LTM


Mosconi (2005) - Process

- Longitudinal study following a sample of 53 normal and healthy participants between 9 years and 24 years
- PET scans were used together with a computer program to measure hippocampus metabolism


Mosconi (2005) - Findings

participants showing early signs of reduced metabolism in the hippocampus associated with later development of AD


Mosconi (2005) - Conclusion

The hippocampus is a central part of memory processes and reduced metabolism may be a sign of AD



damage to brain tissue


how do lesions affect memory?

- manifests as memory loss
- demonstrates that different memories are stored in different areas of the brain

Main study: Scoville and Milner (1957)


Scoville and Milner (1957)

case study on Henry Molaison
- epileptic who had parts of his brain (including the hippocampus) removed
- his epilepsy was cured but he developed severe anterograde amnesia and partial retrograde amnesia
- intact STM but couldn't transfer semantic or episodic memories to the LTM
- his ability to store procedural memory in the LTM remains intact
- his memory prior to the surgery appears largely intact
- he has some capacity for working memory (could maintain short conversations)


what can be learned from HM's case?

- memory systems are highly specialized and complex
- hippocampus plays a critical role in transferral between STM and LTM
- however the hippocampus doesn't appear to be the site of permanent storage itself
- the fact that HM has deficits in some types of memories but not in other suggests that the brain has multiple memory systems located in different regions


relationship between HM's brain damage and his memory deficits

Corkin (1997)
- scanned HM's brain using MRI
- parts of the temporal lobes (including the hippocampus) was missing
- these parts are theorized to play an important role in the transferral of memories from STM to LTM
- as they are involved in specific neurotransmitter pathways (e.g. acetylcholine, which is associated with semantic and episodic memory)


what to write when asked: "Explain how 1 biological factor may affect 1 cognitive process"

- biological factor: Alzheimer's Disease; cognitive process: memory
- describe functions of the hippocampus
- explain hippocampus' role in memory formation and recall
- describe symptoms and effects of AD
- explain the causes of neurofibrillary tangles and amyloid plaques and their biological effects
- refer to Salthouse and Becker (1988) and Hodges et al (1994) for cognitive effects of AD

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