Episodic Memory Encoding in Aging and Neuroimaging

Episodic memory encoding refers to the process by which experiences are transformed into stable neural representations that can later be recalled as events situated in time and place. In healthy ageing, this capacity often declines, reflecting alterations in hippocampal function, prefrontal control and large‐scale network dynamics. Neuroimaging modalities such as functional magnetic resonance imaging (fMRI) and functional near‐infrared spectroscopy (fNIRS) have been pivotal in revealing how older adults differ from younger counterparts in the recruitment and modulation of key brain circuits. Across studies, decreased deactivation of the default mode network (DMN), altered hippocampal–prefrontal connectivity and compensatory recruitment of ancillary regions have emerged as hallmarks of age‐related changes in encoding. Integrating these findings highlights both vulnerability and resilience in the ageing brain, with potential applications in early detection of pathological decline and the design of interventions to bolster memory performance.

Research from Nature Portfolio

Recent studies have provided evidence that individual differences in life-long learning and education shape patterns of brain activity during memory formation in older adults. One investigation employed task-based fMRI of visual memory encoding in a large cohort spanning cognitively normal to Alzheimer’s dementia, identifying a multivariate pattern of network engagement—featuring deactivation of the DMN alongside activation of inferior temporal regions including the fusiform gyrus—that moderates the impact of pathological load on performance. Personalised fMRI-derived “reserve scores” based on these patterns predict subsequent cognitive decline, underscoring the prognostic potential of encoding‐related activity. Another line of work has demonstrated that fNIRS can reliably track prefrontal, parietal and temporal cortical activation during paired‐associate tasks, with novel face-name encoding eliciting robust left dorsolateral prefrontal responses. These findings validate fNIRS as an accessible, non-invasive tool for monitoring early memory impairment and open avenues for scalable screening in ageing populations.

Episodic Memory Encoding in Aging and Neuroimaging publication trend

The graph below shows the total number of articles in episodic memory encoding in aging and neuroimaging across all publications each year (not limited to Nature Index journals).

Technical terms

Episodic memory encoding: The neural process of transforming and consolidating personal experiences into retrievable memory traces.

Default mode network (DMN): A set of interconnected brain regions typically more active at rest and deactivated during demanding cognitive tasks.

Cognitive reserve: The brain’s capacity to tolerate pathological changes through efficient or alternative network recruitment to maintain function.

Encoding/retrieval flip (E/R flip): A neural antagonism in which the same region shows opposite activation patterns during encoding versus retrieval phases of memory tasks.

Functional near-infrared spectroscopy (fNIRS): A non-invasive optical imaging technique that measures cortical haemodynamic responses associated with neural activity.

References

1. Cognitive reserve against Alzheimer’s pathology is linked to brain activity during memory formation. Nature Communications (2024).
2. Aging effects on the encoding/retrieval flip in associative memory: fMRI evidence from incidental contingency learning. Frontiers in Aging Neuroscience (2024).
3. The relationship between resting‐state amplitude fluctuations and memory‐related deactivations of the default mode network in young and older adults. Human Brain Mapping (2023).
4. fNIRS can robustly measure brain activity during memory encoding and retrieval in healthy subjects. Scientific Reports (2017).