Nathan Scott Rose

The ability to encode, retain and use information via working memory (WM) processes is critical for cognition, and declines in older adulthood, especially for those with Alzheimer’s disease and related dementias, but the neurocognitive mechanisms underlying these age-related declines remain unclear. We used time-resolved EEG decoding to track memory representations during a simple 1-back WM updating task in cognitively unimpaired older adults and younger adults (N=100). Older adults were characterized with cortical-thinning using structural MRI, plasma amyloid/tau-derived Alzheimer’s probability scores, APOE-ε4 status, and cognitive performance (NIH-Toolbox). Older adults performed well, but significantly worse than younger adults; this was not associated with age-differences in stimulus-evoked decoding, suggesting preserved encoding. Both groups showed transient delay-period decoding that returned to baseline by the late delay on average, consistent with passive, “activity-silent” WM maintenance. However, older adults showed elevated early/mid-delay decoding than young adults, and greater cortical thinning predicted more sustained late-delay decoding without any associated behavioral benefit. Rather than reflecting “compensatory” neural recruitment, older adults’ overactive delay-period decoding seems to indicate aberrant neurocognitive processing associated with an ADRD biomarker.

Age-related differences in working memory (WM) can be large, but the exact sources are unclear. We hypothesized that young adults outperform older adults on WM tasks because they use controlled attention processes to prioritize the maintenance of relevant information in WM in a proactive mode, whereas older adults tend to rely on the strength of familiarity signals to make memory decisions in a reactive mode. We used a WM task that cued participants to prioritize one item over others and presented repeated lure probes that cause errors when one is engaged in a reactive mode. Results showed that, relative to young adults with full attention available to use proactive control during the delays, older adults with full attention (and young adults with divided attention) during the delays had exaggerated error rates to repeated lure probes compared to control probes. When the amount of proactive interference was increased (by repeating stimuli across trials), older adults were able to engage in proactive control, and this eliminated their exaggerated error rate (while young adults with divided attention could not). These results provide evidence for a dual mechanisms of control account of age differences in WM. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Cognitive aging researchers have long reported "paradoxical" age differences in prospective memory (PM), with age deficits in laboratory settings and age benefits (or no deficits) in real-world settings. We propose a theoretical account that explains this "age-PM-paradox" as a consequence of both methodological factors and developmental changes in cognitive abilities and personality traits. To test this account, young and older adults performed a series of naturalistic PM tasks in the lab and real world. Age-related PM deficits were observed in both lab-based tasks where demands were implemented using virtual reality and in-person role-playing. In contrast, older adults performed equal to or better than young adults on both real-world tasks, where demands were implemented in participants' daily lives. Consistent with our proposed account, an index of these "paradoxical" effects was partially predicted by age-related differences in working memory, vigilance, agreeableness, and neuroticism, whose predictive utility varied across task settings.

Age deficits in working memory (WM) can be large, but the exact sources are unclear. We hypothesized that young adults outperform older adults on WM tasks because they use controlled attention processes to prioritize the maintenance of relevant information in WM in a proactive-mode, whereas older adults tend to rely on the strength of familiarity signals to make memory decisions in a reactive mode. We used a WM task that cued participants to prioritize one item over others, and presented repeated lure probes that cause errors when one is engaging a reactive mode. Results showed that, relative to young adults with full attention available to use proactive-control during the delays, older adults with full attention (and young adults with divided attention) during the delays had exaggerated error rates to repeated lure probes compared to control probes. When the amount of proactive interference was increased (by repeating stimuli across trials), older adults were able to engage proactive control and this eliminated their exaggerated error rate (while young adults with divided attention could not). These results provide evidence for a dual-mechanisms of control account of age differences in WM. Public Significance Statement:Age-deficits in working memory (WM) underlie older adults’ cognitive functioning. This study shows that age-deficits are largely due to older adults’ difficulties with focusing attention on relevant information and resisting interference from irrelevant information. Older adults relied on a reactive, familiarity-based mode-of-responding; however, with practice and feedback, they could learn to engage a proactive, maintenance-focused mode-of-processing and eliminate their age deficits. This study helps to explain age differences in WM, and identifies cognitive-training targets to improve older adults’ cognition.

Some theories propose that working memory (WM) involves the active deletion of irrelevant information, including items that were retained in WM, but are no

Working memory (WM) and long-term memory (LTM) tests have both overlapping and distinct neurocognitive processes. Hippocampal activity in fMRI studies–a hallmark of LTM–also occurs on WM tasks, typically during encoding or retrieval and sometimes (albeit rarely) through ‘late-delay’ periods. The Synaptic Theory of WM suggests that ‘activity-silent’ synaptic weights retain temporary, WM-relevant codes without sustained, elevated activity. The hippocampus temporarily retains item-context bindings during WM-delays that are typically ‘silent’ to fMRI, probably via oscillatory patterns of informational connectivity among task-relevant regions of cortex. Advancing WM theory will require modeling this dynamic interplay, as in the ‘Dynamic Processing Model of WM.

Switching one’s focus of attention between to-be-remembered information in working memory (WM) is critical for cognition, but the mechanisms by which this is accomplished are unclear. Some models suggest that passively retaining “latent” information outside of focal attention and returning it to the focus involves episodic long-term memory (LTM) retrieval processes even for delays of only a few seconds. We tested this hypothesis by examining performance on both a two-item, double-retrocue WM task (that oriented participants’ attention to the item that would be tested first and then to the item tested second on each trial) and subsequent LTM tests for the items from the initial WM task. We compared performance on these tests between older adults (a population with LTM deficits) and young adults with either full (Experiment 1) or divided (Experiment 2) attention during the WM delay periods. Retrocueing, aging, and divided attention all had significant effects on WM performance, but did not interact with or systematically affect subsequent LTM performance for item, location, or associative memory judgments made with either high or low confidence. These dissociations between WM and LTM suggest that retaining and reactivating an item outside of focal attention on this two-item, double-retrocue WM paradigm, which has shown neuroimaging, neurostimulation, and neurocomputational modeling evidence for latent WM, does not involve LTM retrieval processes; rather, the results are consistent with the Dynamic Processing Model of WM (Rose, 2020, Current Directions in Psychological Science).

Remembering intentions is critical for daily life, yet errors happen surprisingly often, even when there are fatal consequences, as in the “forgotten baby syndrome”. To study how people forget personally-important intentions, we took 192 students’ cell phones and attached an activity tracker to their clothes while they participated in an unrelated experiment in our lab. We examined how often students forgot to retrieve their cell phone (personally important task) and return the tracker (experimenter relevant task) when they left the lab, and whether it mattered if the instructions were explicitly encoded or not. Students only forgot the tracker 10-13% more often than their cell phone, and explicit instructions did not reduce forgetting; neither did longer, more distracting ongoing tasks. Between 60-70% of participants said the intention “popped into mind”. We suggest that PM intentions are “autonomically” encoded, yet even personally important tasks are forgotten at surprising rates.