Memory, Temporality and Subjective Experience

Semantic and episodic memory, collectively referred to as declarative memory, are crucial aspects of cognition, central to adaptation to our environment and identity, and subject to meaningful changes across the lifespan. Semantic memory refers to an individual’s general knowledge of the world, detached from its context of acquisition (e.g., “Sauna is very hot, steamy, and relaxing and is generally considered a Northern Europe tradition”), while episodic memory concerns the recollection of contextually specific events from one’s personal past (e.g., “I remember winning a dare of who could stay longest in the sauna. It was a Friday night and we celebrated with a large glass of cucumber water”). Although textbook descriptions suggest that semantic and episodic memory are associated with clearly distinct content and subjective experience, different patterns of change in ageing and in patients’ populations, and distinct brain activations in neuroimaging studies, data collected in recent years suggest a more complex pattern. First, several types of declarative memory do not easily fit into the standard semantic-episodic dichotomy, such as personal semantics (knowledge about our personal past; "I attend sauna therapy every Friday”). Second, a large proportion of existing data comes from indirect comparisons of semantic and episodic memory across different experiments. Third, there are a number of key methodological challenges when comparing them that are not often addressed, such as unmatched task difficulty and processing demands. The present research programme will address these challenges and develop new memory tests and experimental paradigms to reach a better understanding on how semantic and episodic memory differ in their representational content, in related subjective experience, and in neural substrates in young and older adults. Using a variety of behavioural, fMRI and EEG tasks, the research will break new ground in our understanding of these fundamental aspects of cognition. The experiments of axis 1 will provide an unparalleled understanding of the representational content of semantic and episodic memories, with tasks matched in response time and processing demands, to test whether both types of memory involve the same network of brain regions modulated by the richness of content being retrieved, as well as prior knowledge expertise. The studies of axis 2 will allow a unique insight into the subjective experience of semantic and episodic memory, while matching memory content as closely as possible. We hypothesise that, rather than revealing a dedicated brain centre for a specific type of awareness associated with episodic memory (i.e., mental time travel), these studies will be compatible with a component process model of declarative memory according to which, episodic memory retrieval relies to a greater extent than semantic retrieval on components processes related to self-referencing, perceptual imagery and temporal distancing. Finally, axis 3 will significantly increase our understanding of declarative memory in ageing under natural and ecological conditions, using new memory tests that we will share with the scientific community, allowing us to tease apart current hypotheses about age-related changes in memory.