Impact of working memory capacity on predominance of parietal over frontal P300 amplitude.

Working memory-related neural activity varies with task load, and these neural variations can be constrained by working memory capacity (WMC). For instance, some studies suggest that parietal and frontal P300 amplitudes, reflecting working memory functioning, vary differentially with task load and WMC. The present study explored whether the predominance of parietal over frontal P300 amplitude is related to WMC, and whether this relationship varies according to task load. Thirty-one adults aged 20-40 years performed a Sternberg task with two set sizes (2 vs. 6 items), during which event-related potentials were recorded. This allowed us to explore the P300 and estimate the magnitude of its parietal over frontal predominance, calculated as a parietal over frontal predominance index (PFPI). Participants also performed the Digit Span and alpha span tests, which were used to compute an independent index of WMC. Results revealed the classic parietal over frontal P300 predominance. They also indicated that the PFPI decreased as task load increased, owing mainly to an increase in frontal P300 amplitude. Interestingly, WMC was positively correlated with the PFPI, suggesting that individuals with greater WMC exhibited greater parietal over frontal predominance. These correlations did not vary across set sizes. Parietal over frontal predominance was reduced in individuals with lower WMC, who relied more on frontal neural resources. This frontal upregulation may have reflected the recruitment of supplementary attentional executive operations to compensate for less efficient working memory maintenance operations.

Involvement of executive control in neural capacity related to working memory in aging: an ERP P300 study.

Executive control could be involved in neural capacity, which corresponds to the modulation of neural activity with increased task difficulty. Thus, by exploring the P300-an electrophysiological correlate of working memory-we examined the role played by executive control in both the age-related decline in working memory and neural capacity in aging. Event-related potentials (ERPs) were recorded while younger and older participants performed a Sternberg task with two set sizes (2 vs. 6 items), allowing us to calculate a neural capacity index. Participants also completed two control tasks (Stroop and 3-back tests), which were used to calculate a composite executive control index. Results indicated that working memory performance decreased with aging and difficulty. At the neural level, results indicated that the P300 amplitude varied with aging and also with task difficulty. In the low difficulty condition, frontal P300 amplitude was higher for older than for younger adults, whereas in the high difficulty condition, the amplitude of frontal and parietal P300 did not differ between both age groups. Results also suggest that task difficulty led to a decrease in parietal amplitude in both age groups and to an increase in frontal amplitude in younger but not older adults. Both executive control and frontal neural capacity mediated the age-related variance in working memory for older adults. Moreover, executive control mediated the age-related variance in the frontal neural capacity of older adults. Thus, the present study suggests a model for older adults in which executive control deficits with advancing age lead to less efficient frontal recruitment to cope with task difficulty (neural capacity), which in turn has a negative impact on working memory functioning.

Brain tissue pulsatility mediates cognitive and electrophysiological changes in normal aging: Evidence from ultrasound tissue pulsatility imaging (TPI).

Aging is characterized by a cognitive decline of fluid abilities and is also associated with electrophysiological changes. The vascular hypothesis proposes that brain is sensitive to vascular dysfunction which may accelerate age-related brain modifications and thus explain age-related neurocognitive decline. To test this hypothesis, cognitive performance was measured in 39 healthy participants from 20 to 80 years, using tests assessing inhibition, fluid intelligence, attention and crystallized abilities. Brain functioning associated with attentional abilities was assessed by measuring the P3b ERP component elicited through an auditory oddball paradigm. To assess vascular health, we used an innovative measure of the pulsatility of deep brain tissue, due to variations in cerebral blood flow over the cardiac cycle. Results showed (1) a classical effect of age on fluid neurocognitive measures (inhibition, fluid intelligence, magnitude and latency of the P3b) but not on crystallized measures, (2) that brain pulsatility decreases with advancing age, (3) that brain pulsatility is positively correlated with fluid neurocognitive measures and (4) that brain pulsatility strongly mediated the age-related variance in cognitive performance and the magnitude of the P3b component. The mediating role of the brain pulsatility in age-related effect on neurocognitive measures supports the vascular hypothesis of cognitive aging.

Episodic feeling-of-knowing relies on noncriterial recollection and familiarity: Evidence using an online remember-know procedure.

We examined the hypothesis that feeling-of-knowing judgments rely on recollection as well as on familiarity prompted by the cue presentation. A remember-know-no memory procedure was combined with the episodic FOK procedure employing a cue-target pair memory task. The magnitude of FOK judgments and FOK accuracy were examined as a function of recollection, familiarity, or the "no memory" option. Results showed that the proportion of R and K responses was similar. FOK accuracy and magnitude of FOK judgments were higher for R and K responses than for N responses. FOK accuracy related to R and K responses were above chance level, but FOK was not accurate in the "no memory" condition. Finally, both FOK magnitude and FOK accuracy were related more to recollection than to familiarity. These results support the hypothesis that both recollection and familiarity are determinants of the FOK process, although they suggest that recollection has a stronger influence.

Kinematic observation reduces effect of aging on episodic memory performance.

This study investigated the influence of kinematics observation (i.e., observing action from only the motion of the main joints of an actor) on episodic memory performance differences between young and older adults. To this end, 42 young (20-35 years) and 45 older (60-75 years) participants performed a free recall task in two different conditions: either after an encoding phase consisting of the visual presentation and reading of action verbs or after an encoding phase consisting of the visual presentation and naming of point-light displays of humans performing the same actions. Results showed a beneficial effect of point-light display encoding for both young and older participants but with a more pronounced benefit for the older participants compared to young adults. These findings are discussed in relation to the embodied view of memory which considers that memory is directly linked to the sensorimotor experiences and the environmental support hypothesis which postulates that elaborate processing can improve memory performance. In conclusion, kinematic observation could constitute an interesting potential intervention for supporting memory in older adults.

Working memory processing of traumatic material in women with posttraumatic stress disorder.

BACKGROUND: Posttraumatic stress disorder (PTSD) is associated with medial frontal and amygdala functional alterations during the processing of traumatic material and frontoparietal dysfunctions during working memory tasks. This functional magnetic resonance imaging (fMRI) study investigated the effects of trauma-related words processing on working memory in patients with PTSD. METHODS: We obtained fMRI scans during a 3-back task and an identity task on both neutral and trauma-related words in women with PTSD who had been sexually abused and in healthy, nonexposed pair-matched controls. RESULTS: Seventeen women with PTSD and 17 controls participated in the study. We found no behavioural working memory deficit for the PTSD group. In both tasks, deactivation of posterior parietal midline regions was more pronounced in patients than controls. Additionally, patients with PTSD recruited the left dorsolateral frontal sites to a greater extent during the processing of trauma-related material than neutral material. LIMITATIONS: This study included only women and did not include a trauma-exposed non-PTSD control group; the results may, therefore, have been influenced by sex or by effects specific to trauma exposure. CONCLUSION: Our results broadly confirm frontal and parietal functional variations in women with PTSD and suggest a compensatory nature of these variations with regard to the retreival of traumatic memories and global attentional deficits, respectively, during cognitively challenging tasks.

Influence of current physical exercise on the relationship between aging and episodic memory and fluid intelligence.

The present study examined the effects of current physical exercise and age on episodic memory and fluid intelligence, assessed with a free-recall task and the Culture Fair Intelligence Test (Cattell, 1963) respectively, while statistically controlling for other cognitive reserve factors (educational level, leisure activities, and vocabulary level). Two hundred and eight participants aged 20 to 85 participated in the study. Physical exercise level was indexed by weekly frequency over the last 12 months using self-reported measurement (from none to 4 times a week). Overall, results show a beneficial effect of physical exercise especially from a weekly practice of 2 times, and significant interaction between physical exercise and age on episodic memory and fluid intelligence capacities indicating a reduced effect of age in more physically active participants. These results reinforce the view that physical exercise is a strong and specific reserve factor that reduces decline in some cognitive functions during aging.

Metamemory mediates the protective effect of cognitive reserve on episodic memory during aging.

The present study investigated the impact of cognitive reserve on episodic memory and metamemory control during aging using a multidimensional index of cognitive reserve and a measure of metamemory control abilities. We tested the hypotheses that cognitive reserve may play a protective role against age-related differences in episodic memory and metamemory control and that metamemory control may mediate the effect of cognitive reserve on episodic memory during aging. Young and older adults carried out a readiness-recall task in which task difficulty was manipulated through a variation of the nature of the cue-target pair link (weak vs. strong semantic associates). Episodic memory was assessed through recall performance, and metamemory by a task difficulty index reflecting the ability to adjust study time to task difficulty. Results confirmed that older adults recall fewer words, indicating an age-related deficit in episodic memory, and that older adults adjust less to task difficulty, suggesting impaired metamemory control. Findings also showed that metamemory control moderates the age-related decline in episodic memory and that cognitive reserve plays a protective role against age-related deficits in episodic memory and metamemory control. In addition, metamemory abilities mediated the beneficial effect of cognitive reserve on episodic memory performance during aging. Hence, this study sheds new light on the mechanisms underlying the impact of cognitive reserve on cognitive aging, highlighting the role of metacognitive processes.

Two hemispheres for better memory in old age: role of executive functioning.

This experiment explored the functional significance of age-related hemispheric asymmetry reduction associated with episodic memory and the cognitive mechanisms that mediate this brain pattern. ERPs were recorded while young and older adults performed a word-stem cued-recall task. Results confirmed that the parietal old/new effect was of larger latency and reduced magnitude and less lateralized in the older group than the young group. Correlational and regression analyses indicated that the degree of laterality of brain activity determines the accuracy of memory performance and mediates age-related differences in memory performance among older participants. They also confirmed a cascade model in which the individual level of executive functioning of older adults mediates age-related differences in the degree of lateralization of brain activity, which in turn mediates age-related differences in memory performance.

Neural correlates of episodic memory change in increasing age: a longitudinal event-related potential study.

Using a longitudinal design, we examined whether event-related brain potentials (ERPs) correlates of successful episodic memory retrieval varied over a 4-year period according to the level of memory change. ERPs were recorded while participants performed a word-stem cued-recall task, and this procedure was repeated 4 years later. We compared the ERP old/new effect patterns of participants whose memory performance remained stable over time (stable group) with those of participants experiencing episodic memory decline (decline group). The pattern of change of the old/new effect differed between groups. At T1, the two groups exhibited the same pattern, with a positive frontal and parietal old/new effect. For the decline group, the old/new effect pattern did not change between T1 and T2. By contrast, for the stable group, the positive parietal old/new effect at T1 no longer appeared at T2, but a negative old/new effect was exhibited at frontal sites. This brain reorganization pattern could be a compensatory mechanism supporting strategic processes and allowing memory abilities to be maintained over time.

Effect of self-reported internal memory strategy use on age-related episodic and working memory decline: Contribution of control processes.

We explored whether control processes could account for age-related differences in internal strategy use, which in turn would contribute to episodic and working memory decline in aging. Young and older adults completed the internal strategy subscale of the Metamemory in Adulthood (MIA) questionnaire, a free-recall task (FRT), a reading span task (RST), and 3 executive control tasks (the Wisconsin Card Sorting Test, the Initial Letter Fluency Test, and the Digit Symbol Substitution Test) allowing us to calculate a composite index of control processes. Results indicated that both self-reported internal strategy use and control processes index accounted for a significant proportion of the age-related variance in the FRT and the RST. However, once the control processes index was controlled for, variance in both the FRT and RST explained by internal strategy use were significantly reduced. Additionally, age-related variance in internal strategy use was mediated by the control processes index. These results suggest a cascade model in which individual control level would mediate age-related differences in internal strategy use, which in turn would mediate age-related differences in episodic and working memory performance. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Protective role of educational level on episodic memory aging: an event-related potential study.

The aim of the present experiment was to investigate whether educational level could modulate the effect of aging on episodic memory and on the electrophysiological correlates of retrieval success. Participants were divided into four groups based on age (young vs. older) and educational level (high vs. low), with 14 participants in each group. Event-related potentials (ERP) were recorded while participants performed a word-stem cued-recall task. Age-related memory deficits were greater for the less educated individuals. Age differences in the ERP old/new effects were also modulated by the level of education. This study demonstrated that the effects of age on episodic memory and ERP correlates of retrieval success are smaller in participants with high educational levels than those with lower levels. These findings provide support for the reserve hypothesis and highlight the need to consider individual differences when studying cognitive and cerebral changes in aging.

Preserved subcortical volumes and cortical thickness in women with sexual abuse-related PTSD.

Posttraumatic stress disorder (PTSD) has been frequently associated with volumetric reductions of grey matter structures (e.g. hippocampus and anterior cingulate), but these results remain controversial, especially in female non-combat-related samples. The present study aimed at exploring whole-brain structures in women with sexual abuse-related PTSD on the basis of cortical and subcortical structure comparisons to a matched pair sample that was well-controlled. Seventeen young women who had experienced sexual abuse and who had a diagnosis of chronic PTSD based on the Clinician Administered PTSD Scale for DSM-IV and 17 healthy controls individually matched for age and years of education were consecutively recruited. Both groups underwent structural magnetic resonance imaging and psychiatric assessment of the main disorders according to Axis I of DSM-IV. The resulting scans were analyzed using automated cortical and subcortical volumetric quantifications. Compared with controls, PTSD subjects displayed normal global and regional brain volumes and cortical thicknesses. Our results indicate preserved subcortical volumes and cortical thickness in a sample of female survivors of sexual abuse with PTSD. The authors discuss potential differences between neural mechanisms of sexual abuse-related PTSD and war-related PTSD.

Differential protective role of control and representation against age-related memory decline.

Control and representation (Craik & Bialystok, 2006, 2008) could be considered as potential cognitive resources playing a protective role against age-related memory decline. The main objective of this study was to explore whether the protective role (passive vs. active) associated with these resources varies according to the characteristics of the memory task. Young and older adults' memory performance was assessed using a cued-recall and a recognition task. Control and representation were measured, using the Excluded Letter Fluency Test and the Mill Hill vocabulary test, respectively. The results revealed that both control and representation had a significant positive impact on performance in both memory tasks. However, in the cued-recall task, age interacted only with control and not with representation level. Memory performance in this task was correlated with the control measure only for the older adults, indicating that memory decline in this task is moderated by control level. By contrast, for the recognition task, results showed that age interacted only with representation, indicating that the association between representation and recognition performance was greater for the older than the younger adults. This suggests that age-related recognition decline is moderated by representation level. These results suggest that the role played by both control and representation as protective resources against age-related memory decline depends on the task features; control would have an active protective role for cued-recall tasks, which involve more self-initiated and strategic processes, whereas representation would play this active protective role in a recognition task, which is heavily dependent upon semantic processes. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Executive functioning and processing speed in age-related differences in memory: contribution of a coding task.

The aim of the present study was to examine executive dysfunctioning and decreased processing speed as potential mediators of age-related differences in episodic memory. We compared the performances of young and elderly adults in a free-recall task. Participants were also given tests to measure executive functions and perceptual processing speed and a coding task (the Digit Symbol Substitution Test, DSST). More precisely, we tested the hypothesis that executive functions would mediate the age-related differences observed in the free-recall task better than perceptual speed. We also tested the assumption that a coding task, assumed to involve both executive processes and perceptual speed, would be the best mediator of age-related differences in memory. Findings first confirmed that the DSST combines executive processes and perceptual speed. Secondly, they showed that executive functions are a significant mediator of age-related differences in memory, and that DSST performance is the best predictor.

Divided attention at encoding: effect on feeling-of-knowing.

This research investigated the effect of divided attention at encoding on feeling-of-knowing (FOK). Participants had to learn a 60 word-pair list under two experimental conditions, one with full attention (FA) and one with divided attention (DA). After that, they were administered episodic FOK tasks with a cued-recall phase, a FOK phase and a recognition phase. Our results showed that DA at encoding altered not only memory performance, but also FOK judgments and FOK accuracy. These findings throw some light on the central role of the quality of memory encoding to make accurate FOK judgments and provide new evidence supporting the relationship between memory and metamemory judgments.

Executive functioning and processing speed in age-related differences in time estimation: a comparison of young, old, and very old adults.

Age-related differences in time estimation were examined by comparing the temporal performance of young, young-old, and old-old adults, in relation to two major theories of cognitive aging: executive decline and cognitive slowing. We tested the hypothesis that processing speed and executive function are differentially involved in timing depending on the temporal task used. We also tested the assumption of greater age-related effects in time estimation in old-old participants. Participants performed two standard temporal tasks: duration production and duration reproduction. They also completed tests measuring executive function and processing speed. Findings supported the view that executive function is the best mediator of reproduction performance and inversely that processing speed is the best mediator of production performance. They also showed that young-old participants provide relatively accurate temporal judgments compared to old-old participants. These findings are discussed in terms of compensation mechanisms in aging.

Optimizing memory strategy use in young and older adults: The role of metamemory and internal strategy use.

We explored whether experiencing differential efficacy of reading and generation for memory in an initial learning trial led younger and older adults to improve recall of read items in a subsequent learning trial, leading to a reduction of the generation effect. In the first trial, generation improved the memory performance of both young and older adults. However, in Trial 2, the generation effect remained significant for older adults only, confirming that they did not change the way they processed read items, unlike the young adults. The older adults were also less spontaneously aware that generation led to better memory performance in the first trial, and, in contrast to the young adults, awareness did not result in a reduction of the generation effect. Moreover, the age-related differences in generation effect reduction were mediated by an independent measure of self-reported internal strategy use. However, when an appropriate environmental support was provided between both trials, older adults improved read items recall at the second trial as well as younger ones, leading to an elimination of the generation advantage for both groups. Environmental support reduced the implication of internal strategy use in the generation effect reduction, suggesting that age-related differences in the implementation of effective encoding processes in Trial 2 would be the consequence of a metamemory deficit, and reduced capacity to self-initiate internal strategies.

Aging, metamemory regulation and executive functioning.

In this chapter we deal with metamemory regulation processes and concentrate mainly on how they are related to learning in episodic memory. In recent years an increasing amount of the literature has emphasized conceptual similarities between metamemory regulation and executive-frontal functioning. Different data have also highlighted that age-related cognitive differences might, in many cases, be explained by the decline of executive-frontal functioning that accompanies aging. Thus, in the present chapter we evaluate the relationship of aging and metamemory regulation among the cognitive decline frontal hypothesis of aging. We focus specifically on two measures of metamemory regulation allowing evaluating monitoring and control processes: feeling-of-knowing (FOK) and capacity to adjust study strategies to task demand, respectively. After having presented evidence supporting the executive-frontal hypothesis of FOK, we present a series of experiments addressing the questions of age-related differences in metamemory monitoring and control, and of possible mediation of this age effect by the age-related decline in executive-frontal functioning. The findings support the ideas that the monitoring process of episodic memory FOK and the control process of adjusting study time to task difficulty are impaired in older adults. Moreover, these declines can be explained by the decline of executive-frontal functioning associated to aging. Finally, types of mechanisms pertaining to FOK monitoring and to adjustment control process on which executive-frontal functioning and aging may have an impact are discussed.

Rehearsal strategy use in Alzheimer's disease.

Memory strategy usage and awareness of memory performance are both crucial for memory rehabilitation. We explored Alzheimer's patients' ability to apply and control learning strategies and also their ability to predict the effect of these strategies on subsequent performance. In a rehearsal condition, participants were explicitly asked to overtly rehearse words and were given as long as they liked at study. In a control condition, participants read the words passively at a fixed presentation rate. In all groups, recall was superior in the rehearsal condition than in the reading condition. Alzheimer's patients showed different strategy usage. Overall, people with Alzheimer's disease spend longer studying to-be-remembered words under unpaced conditions, but they do not use this time to rehearse to the same extent as controls. We hypothesize that this failure to rehearse could be based on the inability to use effortful executive mechanisms involved during study.