Week 10-Episodic memory processes across the adult lifespan

Question 1

What is the Component Process Model of Episodic Memory? (Moscovitch et al., 2016)

Answer 1

1. Perception Binding
    Sensory-to-medial temporal lobe (MTL)
   regions, including the hippocampus:
    Features > Objects > Contexts
    Sense of self as the experiencer
2. Temporary Maintenance
    Working memory Prefrontal cortex(PFC)-
   dependent
   -Helps with decision making
3. Long-term Maintenance
    Stabilisation
    Integration
    Hippocampus-cortex interactions
4. Retrieval
    Working memory “reconstruction”
   -Is a reinstatement off the perceptual phase

Question 2

What is the “WHAT” in Episodic Memory? (Gilboa & Moscovitch, 2021)

Answer 2

At encoding, multiple representations of the experienced event are created:
 Event-specific (has perceptual richness i.e., the here and now). depends on the occipital lobe and posterior hippocampus
 Event-general (“schemas” i.e., script of event), depends on the angular gyrus and ventromedial prefrontal cortex
 Abstract knowledge related to the experienced event (i.e., knowing what it may entail e.g., cultural celebrations) (lateral posterior cortex areas)

The relative dominance of one representation type over another at encoding/retrieval depends on:
 Availability of attentional resources
 Prior knowledge (stuck in a perceptually rich environment however)
 Current goal relevance
 (at retrieval) time since encoding (longer the time, the more schematic representation occurs i.e., a script of the moment)
 (at retrieval) type of retrieval cue

Question 3

Episodic Memory: What is meant by the “self” as the experiencer? (Simons et al., 2022)

Answer 3

Sense of self in the experienced event is associated with:
 First-person perspective

 Autonoetic consciousness (Tulving, 2001) (sense of self-awareness in a past episode)

 Awareness of one’s existence and identity in subjective time: self-continuity

 Mental time travel: re-experience (past) vs pre-experience (future)

 Appears late in the development (takes 6-7 years to develop due to cognitive control resources developing)

 Varies across individuals

Question 4

Ageing effects on episodic memory: What are binding deficits?

Answer 4

 The ability to remember item-item/item-context (i.e., multiple features in a scene) associations declines more sharply with age relative to memory for individual items (Castel & Craik, 2003; Old & Naveh-Benjamin, 2008; Troyer et al., 2011).

 Higher false alarm rate (i.e., poorer discrimination and recognition ability of a pair) on tasks probing memory for item-item/item-context associations (rather than individual items).

 False alarm rates are further increased in older adults when there is higher visual similarity among the to-be-remembered items (Stark & Stark, 2017). (this aging deficit in associative memory is due to a deficit in the perceptual stage)

Question 5

Ageing effects on Episodic Memory: What was found in the Binding/Discrimination Effects 1? (Stark & Stark, 2017)

Answer 5

 Participants: 26 younger adults (21- 38 years) and 28 older adults (59-84 years).

-Showing them multiple images with several features and asking if needs to be outside or inside

 The surprise memory test contained items identical to those studied, completely new items (novel foils) and new items similar to those studied (similar lures).

 Relative to younger adults, older adults show poorer mnemonic discrimination (the number of correct decisions) among both objects and scenes (which requires finer grained perceptual representations and the binding of these individual features)

-Both old and young great at recognising objects that are old

Question 6

Ageing effects on Episodic Memory: What was found in the Binding/Discrimination Effects 2? (Bouffard et al., 2024)

Answer 6

 Participants: 31 younger adults (19 ± 1.72 years) and 32 older adults (69.21 ± 4.04 years).

-Similar object distinct scene e.g., backpack with forest then beach etc.,

-Distinct object similar scene e.g., forest with torch then bacon etc.,

-Similar scene similar object

-3 types of judgements: Remember (know its been shown before), Know (knew item was presented but no recollection of the context it was presented in) and New (remember new details about the object)

-Presented an object and scene and asked participants if they had been presented together

 Recombined pair: both scene and object had been studied, but they were not paired together at study.

-When the objects are similar older adults performed more poorly with false alarms, but when it is a recombined pair, there was no difference between the young and old adults showing that older adults tend to rely on individual objects, distinct objects to base their memory representations.

Question 7

Ageing effects on episodic memory: What is functional neural dedifferation?

Answer 7

 Among older (relative to younger) adults, different types of visual stimuli (e.g., faces, places) evoke less differentiated patterns of brain activity (Bowman et al., 2019; Koen & Rugg, 2019), during both encoding and retrieval (Pauley et al., 2023) (i.e., similar activation for different things).

Older > Younger (Deng et al., 2021):
 Early visual cortex: less differentiated to various sensory features
 Anterior lateral temporal lobe (ATL): more differentiated to categorical features (i.e., semantic similarity) (i.e., older adults show more activation in this)

Older > Younger (Deng et al., 2021):
 Impaired memory representations in the early visual cortex and hippocampus
 Enhanced memory representations in the anterior lateral temporal lobe (ATL) (in regards to perception and retrieval, adults are better at differentiating the stimuli in regards to meaning).

Question 8

Ageing effects on episodic memory: What did Koen & Rugg (2019) find with functional neural dedifferation types?

Answer 8

-Younger adults tend to show a more differentiated response in object scene regions.

-Objects are less sensitive and responsive to older adults (attentuation)

-The object area doesn’t really change how it responds to the object in older adults but rather enhances and moves onto areas such as scenes or faces (broadening). There can be a combination of attenuation and broadening (i.e., less responsive to objects but enhances to scenes).

Question 9

Ageing effects on episodic memory: What is the impact of structural neural atrophy?

Answer 9

 Global cortical volume loss accounted for declines in visuospatial ability, processing speed and global memory from age 70+ years (Cox et al., 2021).

 Structural integrity of the hippocampus and parahippocampal gyrus is particularly predictive of superior episodic memory in older adults (60+ years), especially among males (Köhncke et al., 2021).

-Decrease in total cortical volume with age.

Question 10

Ageing effects on episodic memory: How does structure vs function differ? (Evangelista et al., 2021)

Answer 10

 Reduced activation in the DLPFC ROIs on a working memory task and reduced DLPFC greater neural integrity (i.e., surface area) were independently linked to poorer working memory performance.

-Measured levels of atrophy and activation in the dorsolateral prefrontal cortex during a working memory task

Question 11

Ageing effects on episodic memory: What are some neurochemical contributers?

Answer 11

 Greater noradrenergic (locus coeruleus, LC) integrity is linked to superior episodic memory ability (Dahl et al., 2023), while gray matter decay in LC predicts the transition from healthy ageing to mild cognitive impairment (MCI) (Tang et al., 2023).

 Greater dopaminergic (substantia nigra/ventral tegmental area) integrity is linked to superior working memory
ability (Dahl et al., 2023).

 Age-related declines in hippocampal neurogenesis are linked to changes in the organization of the cholinergic system with adverse effects on working memory performance (Kirshenbaum et al., 2023).

Question 12

Neurocognitive ageing: What is the link between maintenance, compensation and reserve? (Cabeza et al., 2018)

Answer 12

-These 3 components are thought to underpin the individual differences in episodic memory

Maintenance:
-Maintenance of neural resources and cognitive demands. This tends to change with things such as brain injuries however those who are better able to recruit will have a greater availability of neural repair processes i.e., counteracts
-These structures decline meaning greater demand of resources with older age but a decline in availability in neural repair

Compensation:
-As the demands rises, the individual should be able to recruit additional neural processes to successfully meet these demands
-As age increases, the ability to recruit additional mechanisms to compensate for cognitive decline also declines

Reserve:
-Accumulates additional neural resources to support those lost as one ages

Question 13

Neurocognitive ageing: Is episodic memory in older adults maintained? (Cabeza et al., 2018)

Answer 13

 Older adults with stable their episodic memory performance across time (“maintainers” [4 years panel a, 20 years,
panel b]) showed smaller reductions in hippocampal volume and in hippocampal activation level (on episodic memory tasks) relative to older adults with declining episodic memory performance (”decliners”).

-Essentially decliners have reduced activation in the hippocampus and a greater reduction in hippocampal volume.

Question 14

Neurocognitive ageing: How does upregulation help compensation? (Cabeza et al., 2018)

Answer 14

 On the same task, older adults show increased brain activity for similar performance levels (relative to younger adults)

-Ask task activity increases, so does neural resources (older adults plateau earlier)

-4-5 letters there’s no difference but with 7 theres a massive decrease with older adults and a decrease in DLPFC activation

Question 15

Neurocognitive ageing: How does selection help compensation? (Cabeza et al., 2018)

Answer 15

 Older adults engage in a process not recruited by younger adults, yet available to
them and used by them under other conditions.

-To do well, older adults draw on their semantic memory processes rather than episodic

Question 16

Neurocognitive ageing: How does reorganisation help compensation? (Cabeza et al., 2018)

Answer 16

 To respond to ageing-related decline, older adults may use and reorganise neural mechanisms not available to young adults

-Those older adults tend to recruit exactly the same neural substrates as younger adults (and these were low performers difficulty meeting task demands)

Question 17

Neurocognitive ageing: What is the role of education in reserves?

Answer 17

 Higher education does not seem to slow structural brain ageing rate, but is robustly (yet modestly) related to individual differences in brain atrophy (higher education = less atrophy) (Nyberg et al., 2021)

 Higher education is linked to cross-sectional indices of functional brain youth (i.e., patterns of functional network interactions relevant) (West et al., 2022)

Question 18

Neurocognitive ageing: What is the role of lifestyle factors in reserves?

Answer 18

 In older adults (64-87 years), higher engagement in physical and social activities is linked to reduced medial temporal lobe (MTL) atrophy over 7 years (Hotz et al., 2023).

 Current and retrospective physical activity levels are related to a younger looking brain (Dunas et al., 2017), which, in turn, is associated with superior cognitive ability (Cole et al., 2017).

 In older adulthood, higher physical fitness is associated with reduced gray matter decline in the temporal lobe and may also protect against future decline (Pani et al., 2022).

 Poorer cardiometabolic health is linked to greater decline in functional brain network organisation, including networks (e.g., default mode network, cingulo-opercular, fronto-parietal) relevant to episodic
working and working memory (Rashid et al., 2023; Soldan et al., 2021).

 Inflammatory diets (e.g., red meats, processed meats etc.,) are linked to greater risk for neurodegenerative disorders more later a decade later (Duggan et al., 2023).

Question 19

Neurocognitive ageing: What is the role of physical activity 1 in reserves? (Fraser et al., 2022)

Answer 19

 In middle age, increasing physical
activity is linked to reduced hippocampal loss in the future from the baseline to the 4 year follow up.

 The effect of increasing physical activity on hippocampal volume diminishes with time.

 In older age, increasing physical activity is not robustly linked to future hippocampal loss.

 Any effects (albeit non-robust) of increasing physical activity on hippocampal volume dissipate with time.

 Higher physical activity is linked to greater hippocampal volume/less atrophy among individuals at genetic risk for dementia.

Question 20

Neurocognitive ageing: What is the role of physical activity 2 in reserves? (Tarumi et al., 2022)

Answer 20

-Looked at aerobic exercise vs stretching

 Older adults assigned to a 1-year physical activity intervention show improvements in cognition (including working memory and episodic memory).

 No change in age-related structural brain decline.

 Cognitive improvements were linked to enhanced cardiorespiratory fitness (A).

 Region-specific changes like the right inferior parietal lobule in cortical thickness with changes in cardiorespiratory fitness (B).

Question 21

Neurocognitive ageing: What is the role of physical activity 3 in reserves? (Von Cederwald et al., 2023)

Answer 21

 An aerobic exercise intervention (vs stretching intervention) improves working memory performance, but only among the older adults with higher “brain reserve” (i.e., reduced white matter lesions).

Question 22

Neurocognitive ageing: What is the role of our diet in reserves? (Tsiknia et al., 2023)

Answer 22

 Higher Omega-3 intake in midlife is linked to greater white matter integrity in older adulthood (> 80 years) (A).

 The omega-3-white matter microstructural integrity links are stronger among individuals at genetic risk for dementia (B).

Question 23

What are modifiable risk factors for structural brain atrophy? Lancet commision (Walhovd et al., 2023)

Answer 23

-Late-life depression is one of the most influential correlations with brain atrophy and risk factors contributing to dementia which is modifiable

Question 24

How is depression a risk factor for alzheimers? Hypothesis 1 (Dafsari & Jessen, 2020; Hodes & Epperson, 2019)

Answer 24

• Depression is a risk factor for AD
• Positive relationship between length of depression diagnosis and AD risk.
• Genetic evidence that depression may be a cause of subsequent AD (Harerimana et
  al., 2022).
• Depression may be a risk factor for AD .among men only

Question 25

How is depression a risk factor for alzheimers? Hypothesis 2 (Dafsari & Jessen, 2020; Hodes & Epperson, 2019)

Answer 25

• Depression is an early sign or prodrome of dementia in AD
• Depressive symptoms in older adulthood, but not midlife predicted AD onset.
• The correlation between depression and AD is thus more likely to reflect a shared
  cause or the fact that depression is an early sign of AD.

Question 26

What is the link between depressive symptoms, personality and neurodegeneration? Tau Accumulation (Parent et al., 2022)

Answer 26

 In cognitively intact older adults, higher depressive symptoms and neuroticism, but lower conscientiousness are linked via locus coeruleus dysfunction to greater tau accumulation in the amygdala.

Question 27

What is the link between depression, depression treatment and dementia risk? (Yang et al., 2023)

Answer 27

 Higher risk for dementia among depressed individuals (A), particularly if their depression is on the rise (B).

 Lower dementia risk for treated (rather than untreated) depressed patients (A), particularly those treated with a combination of psychotherapy and pharmacotherapy (B).

Question 28

How does the external environment play a role in mental/brain health? (Ibanez et al., 2024)

Answer 28

 Among Aboriginal Australians, retrospective accounts of childhood trauma are linked to mood problems (depression, anxiety) and dementia risk (i.e., Alzheimer’s Disease diagnosis) in older adulthood (Radford et al., 2017).

 Experiencing 3 or more adverse events in childhood was linked to dementia risk among older Japanese adults (Tani et al., 2020).