episodic memory processes Flashcards
component process of episodic memory (Moscovitch et al., 2016)
Formation of new episodic memory traces enters 4 stages: perceptual, temporary maintenance, long term and retrieval
component process of episodic memory (Moscovitch et al., 2016)- perception
- Perception: when you are perceiving your surroundings you bind together different perceptual features of the environment to a contextual representation
- Viewing that bound contextual representation with the sense of self- this is something from your life history
- Reason why you are forming these- need them for ongoing decision making and behaviour e.g. acting with people in your environment
- Binding of the different sensory and perceptual features as well as imbuing the experience with the sense of self happens in the posterior cortical areas associated with sensory processing
Binding happens in the hippocampus and medial temporal lobe structures
component process of episodic memory (Moscovitch et al., 2016)- temporary maintenance
Temporary maintenance: the perceptual representation is still frail, not all the bound perceptual representations will make it into the long term memory store, only those that are actively maintained for things such as ongoing social interactions
component process of episodic memory (Moscovitch et al., 2016)- long term maintenance
Long term maintenance: A subset of the bound mental perceptual representations will be integrated with your existing knowledge base as well as a record of past experiences (systems consolidation)
component process of episodic memory (Moscovitch et al., 2016)- retrieval
- Retrieval: at some pint in the future some of these memories will be retrieved e.g. involuntary or cued to retrieve these for example discussing a shared event or specific knowledge for an exam
- Process of retrieval is thought to actually reflect the reinstatement of the perceptual stage- reconstructing based on a mental representation of the past a specific moment from your past
Necessitates cognitive control resources- reconstruting a past episode is dependent on working memory resources
- Process of retrieval is thought to actually reflect the reinstatement of the perceptual stage- reconstructing based on a mental representation of the past a specific moment from your past
epsiodic memory- the what (Gilboa & Moscovitch, 2011)
- At encoding, multiple representations of the experienced event are created:
○ Event-specific: has perceptual richness, the experiential here and now (person in history)
§ Creation of this depends on interactions between posterior neocortical areas (visual processing in occipital lobe and posterior hippocampus)
○ Event-general (“schemas”)
§ Depend on the anterior hippocampus and the ventral medial prefrontal cortex which is relevant for the encoding of schematic information
§ Ventral medial prefrontal cortex and the lateral posterior cortex
○ Abstract knowledge related to the experienced event: general abstract knowledge for whatever new experience you will have e.g. knowing about how popular a specific cultural event will be
Interactions between anterior temporal lobe (semantic info), lateral posterior cortex and the posterior neocortical areas
the relative dominance of one representation over another at encoding/retrieval depends on…
○ Availability of attentional resources: encoding and retrieval requires attention
§ In situations where there is low availability of resources you are more likely to retrieve or encode more general memories
○ Prior knowledge: extent to which you have no prior knowledge you are confined to encoding perceptually specific representations
○ Current goal relevance: in some situations you may be more motivated to encode than retrieve episodically rich memories
○ (at retrieval) time since encoding: as memories age the more likely it is that you will retrieve a more schematic representation
§ Memories lose their perceptual specifity as they age
(at retrieval) type of retrieval cue: more specific a retrieval cue is the more likely you will be able to provide specific details from an event
episodic memory: the self as the experiencer (Simons et al., 2022)
- Sense of self in the experienced event
○ First-person perspective: retrieval is in the first person, a sense that it is your past
- Autonoetic consciousness (Tulving, 2001):
self awareness n a past episode
○ Awareness of one’s existence and identity in subjective time: self-continuity and identity
○ Mental time travel: re-experience (past) vs pre-experience (future) (delay of gratification e.g. the ability to pre experience the consequences of your actions to better self control)
○ Appears late in the development- around 6 or 7 years old- combination of being able to recall specific past details and also the development of cognitive control resources such as working memory
Varies across individuals and differences in sense of identity and to exert self control as a function of re experiencing the consequences of ones actions
Ageing effects on episodic memory deficits- binding deficits Castel & Craik, 2003)
- The ability to remember item-item/item-context associations declines more sharply with age relative to memory for individual items (Castel & Craik, 2003; Old & Naveh-Benjamin, 2008; Troyer et al., 2011)
○ The ability to recall individual items tends to be relatively well preserved in ageing, the ability to recall associations of items particularly when the items are complex declines (associative memory)
Linked to the binding stage during perception and reconstructive stage during retrieval
Ageing effects on episodic memory deficits- binding deficits- higher false alarm rate
- Higher false alarm rate (i.e., poorer discrimination ability) on tasks probing memory for item-item/item-context associations (rather than individual items)
False alarm- incorrectly recognising a pair as being previously presented (false memories)
Ageing effects on episodic memory deficits- binding deficits- Stark & stark, 2017
- False alarm rates are further increased in older adults when there is higher visual similarity among the to-be-remembered items (Stark & Stark, 2017)
Have to make precise perceptual memory decisions with increasing similarity- ageing deficit in associative memory is likely related to a deficit in the perceptual stage
Ageing effects on episodic memory- binding/discrimination deficits (Stark & Stark et al., 2017)
- Participants: 26 younger adults (21- 38 years) and
- 28 older adults (59-84 years)
- Objects had multiple features
- Mnemonic similarity task participants are presented with both objects and scenes
- During encoding they have to make a judgement of whether that particular object is seen indoors or outdoors and if the scene is manmade
- Participants have to attend to the information without explicitly asking them to recall
- The surprise memory (participants told to not encode) 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 among both objects and scenes
Ageing effects on episodic memory- functional neural dedifferentiation
- 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)
Compared responses with regard to perceptual features e.g. places and faces with conceptual categorical categories e.g. outdoor and indoor
Older > Younger (Deng et al., 2021) in perception:
- Early visual cortex: less differentiated to various sensory features
- Anterior lateral temporal lobe (ATL): more differentiated to categorical features (i.e., semantic similarity)
Consistent with the idea that in ageing there is a shift from greater expertise in processing perceptual details to processing and focusing on meaning related details
- Anterior lateral temporal lobe (ATL): more differentiated to categorical features (i.e., semantic similarity)
Older > Younger (Deng et al., 2021) in retrieval:
- Impaired memory representations in the early visual cortex and hippocampus
- Consistent with the idea that the perceptual representations as they were retrieved were less differentiated in older adults and more distinct conceptual representations
- Enhanced memory representations in the anterior lateral temporal lobe (ATL)
Consistent with the idea that in both retrieval and perception older adults are able to differentiate the stimuli better with regards to their meaning
Ageing effects on episodic memory- functional neural differentiation types (Koen & Rugg, 2019)
- Younger adults tend to show in the object scene regions a more differentiated response, a greater response to the preferred stimulus to the non preferred stimulus relative to older adults
Can be explained by attenuation in response to the preferred stimulus compared to the non preferred stimulus
Ageing effects on episodic memory- structural neural atrophy (Kohncke et al., 2021)
- 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)
Ageing effects on episodic memory structure v function- Evangelista et al., 2021
Reduced activation in the DLPFC ROIs on a working memory task and reduced DLPFC neural integrity (i.e., surface area) were independently linked to poorer working memory performance
Ageing effects on episodic memory- neurochemical contributors
- 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 (rodents, Kirshenbaum et al., 2023)
Neurocognitive ageing- maintenance of episodic memory in older age- Cabeza et al., 2018
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”)
Neurocognitive ageing compensation by upregulation- Cabeza et al., 2018
On the same task, older adults show increased brain activity for similar performance levels (relative to younger adults)
Neurocognitive ageing- compensation by selection Cabeza et al., 2018
Older adults engage in a process not recruited by younger adults, yet available to them and used by them under other conditions
Neurocognitive ageing reserve: the role of education
- 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) (West et al., 2022)
