Katharina Zinke

Working Memory Training and Transfer in Older Adults: Effects of Age, Baseline Performance, and Training Gains

Recent studies suggest that working memory training may benefit older adults; however, findings regarding training and transfer effects are mixed. The current study aimed to investigate the effects of a process-based training intervention in a diverse sample of older adults and explored possible moderators of training and transfer effects. For that purpose, 80 older adults (65-95 years) were assigned either to a training group that worked on visuospatial, verbal, and executive working memory tasks for 9 sessions over 3 weeks or to a control group. Performance on trained and transfer tasks was assessed in all participants before and after the training period, as well as at a 9-month follow-up. Analyses revealed significant training effects in all 3 training tasks in trained participants relative to controls, as well as near transfer to a verbal working memory task and far transfer to a fluid intelligence task. Encouragingly, all training effects and the transfer effect to verbal working memory were stable at the 9-month follow-up session. Further analyses revealed that training gains were predicted by baseline performance in training tasks and (to a lesser degree) by age. Gains in transfer tasks were predicted by age and by the amount of improvement in the trained tasks. These findings suggest that cognitive plasticity is preserved over a large range of old age and that even a rather short training regime can lead to (partly specific) training and transfer effects. However, baseline performance, age, and training gains moderate the amount of plasticity.

Potentials and limits of plasticity induced by working memory training in old-old age.

Background: Old-old age (80+ years) is associated with substantial cognitive decline. In this population, training-induced cognitive plasticity has rarely been studied. While earlier findings on strategy trainings suggested reduced training gains in old-old age, recent results of an extensive process-based working memory (WM) training have been more positive. Objective: Following up on previous research, the present study aimed at examining the effects of a short WM training in old-old adults and the influence of baseline WM capacity on training gains. Methods: A training group (mean age: 86.8 years) and a matched control group (mean age: 87.1 years) participated in the study. The WM training consisted of five tasks that were trained in each of 10 sessions. To evaluate possible transfer effects, executive functions were assessed with two tests before and after training. The training group was divided via median split in high- and low-capacity individuals to determine the influence of baseline WM capacity on training gains. Results: The training group improved in four of the trained tasks (medium-to-large effects). Training gains were significantly larger in the training group than in the control group in only two of those tasks. The training effects were mainly driven by the low-capacity individuals who improved in all trained tasks. No transfer effects were observed. Conclusions: These positive effects of a short WM training, particularly for low-capacity individuals, emphasize the potential for cognitive plasticity in old-old age. The absence of transfer effects may also point to its limits.

Plasticity of executive control through task switching training in adolescents

Research has shown that cognitive training can enhance performance in executive control tasks. The current study was designed to explore if executive control, specifically task switching, can be trained in adolescents, what particular aspects of executive control may underlie training and transfer effects, and if acute bouts of exercise directly prior to cognitive training enhance training effects. For that purpose, a task switching training was employed that has been shown to be effective in other age groups. A group of adolescents (10–14 years, n = 20) that received a three-session task switching training was compared to a group (n = 20) that received the same task switching training but who exercised on a stationary bike before each training session. Additionally, a no-contact and an exercise only control group were included (both ns = 20). Analyses indicated that both training groups significantly reduced their switching costs over the course of the training sessions for reaction times and error rates, respectively. Analyses indicated transfer to mixing costs in a task switching task that was similar to the one used in training. Far transfer was limited to a choice reaction time task and a tendency for faster reaction times in an updating task. Analyses revealed no additional effects of the exercise intervention. Findings thus indicate that executive control can be enhanced in adolescents through training and that updating may be of particular relevance for the effects of task switching training.

Children with high-functioning autism show a normal cortisol awakening response (CAR)

Individuals with high-functioning autism spectrum disorders (HFA) show difficulties in the ability to react to change. A recent study suggested that variations in the functioning of the hypothalamus-pituitary-adrenal axis, especially in one of its markers--the cortisol awakening response (CAR)--may be related to those difficulties in adolescents with Aspergers syndrome. The current study investigated the CAR in a younger sample with diagnoses from the whole autism spectrum: A group of children with HFA (N=15) was compared to a group of typically developing children (N=25). Findings suggest that the frequency of a CAR as well as the increase in cortisol levels from awakening to 30 min later were similar between groups, indicating that variations in the CAR in HFA may not be present early in life but only develop later in adolescence or may only occur in some diagnoses from the autism spectrum.

Visuospatial Short-Term Memory Explains Deficits in Tower Task Planning in High-Functioning Children with Autism Spectrum Disorder

Previous findings on planning abilities in individuals with high-functioning autism spectrum disorder (HFA) are inconsistent. Exploring possible reasons for these mixed findings, the current study investigated the involvement of memory in planning performance in 15 children with HFA and 17 typically developing controls. In addition to planning abilities (measured with the Tower of London), short-term memory and delayed recall for verbal as well as visuospatial material were assessed. Findings suggest that particularly reduced efficiency in visuospatial short-term memory is associated with Tower task planning deficits in children with HFA.

Time-Based Prospective Memory Performance and Time-Monitoring in Children with ADHD

The current study investigated prospective memory (PM) performance in children with attention deficit/hyperactivity disorder (ADHD) and controls and aimed at exploring possible underlying factors of PM performance. Twenty-two children with ADHD and 39 age- and ability-matched typically developing children performed a computerized time-based PM task. As predicted, children with ADHD had fewer correct PM responses than controls. Neither differences in overall ongoing task performance nor, remarkably, differences in overall frequency and accuracy of time monitoring were found. Exploratory analyses suggest that individual differences in time monitoring in the final interval before target times may be related to PM performance in ADHD.

Dissociating the contributions of slow-wave sleep and rapid eye movement sleep to emotional item and source memory.

Sleep benefits the consolidation of emotional memories, and this influence is commonly attributed to the rapid eye movement (REM) stage of sleep. However, the contributions of sleep stages to memory for an emotional episode may differ for the event per se (i.e., item memory), and the context in which it occurred (source memory). Here, we examined the effects of slow wave sleep (SWS) and REM sleep on the consolidation of emotionally negative and neutral item (picture recognition) and source memory (recall of picture-location and picture-frame color association) in humans. In Study 1, the participants (n=18) learned 48 negative and 48 neutral pictures which were presented at specific locations and preceded by colored frames that had to be associated with the picture. In a within-subject design, learning was either followed by a 3-h early-night SWS-rich or by a late-night REM sleep-rich retention interval, then retrieval was tested. Only after REM-rich sleep, and not after SWS-rich sleep, was there a significant emotional enhancement, i.e., a significantly superior retention of emotional over neutral pictures. On the other hand, after SWS-rich sleep the retention of picture-frame color associations was better than after REM-rich sleep. However, this benefit was observed only for neutral pictures; and it was completely absent for the emotional pictures. To examine whether this absent benefit reflected a suppressive effect of emotionality on associations of minor task relevance, in Study 2 we manipulated the relevance of the picture-frame color association by combining it with information about monetary reward, following otherwise comparable procedures. Here, rewarded picture-frame color associations were equally well retained over SWS-rich early sleep no matter if the frames were associated with emotional or neutral pictures. Results are consistent with the view that REM sleep favors the emotional enhancement of item memory whereas SWS appears to contribute primarily to the consolidation of context-color information associated with the item.

The role of cue detection for prospective memory development across the lifespan

Behavioral findings suggest an inverted U-shaped pattern of prospective memory development across the lifespan. A key mechanism underlying this development is the ability to detect cues. We examined the influence of cue detection on prospective memory, combining behavioral and electrophysiological measures, in three age groups: adolescents (12-14 years), young (19-28 years), and old adults (66-77 years). Cue detection was manipulated by varying the distinctiveness (i.e., how easy it was to detect the cue based on color) of the prospective memory cue in a semantic judgment ongoing task. Behavioral results supported the pattern of an inverted U-shape with a pronounced prospective memory decrease in old adults. Adolescents and young adults showed a prospective memory specific modulation (larger amplitudes for the cues compared to other trials) already for the N1 component. No such specific modulation was evident in old adults for the early N1 component but only at the later P3b component. Adolescents showed differential modulations of the amplitude also for irrelevant information at the P3b, suggesting less efficient processing. In terms of conceptual implications, present findings underline the importance of cue detection for prospective remembering and reveal different developmental trajectories for cue detection. Our findings suggest that cue detection is not a unitary process but consists of multiple stages corresponding to several ERP components that differentially contribute to prospective memory performance across the lifespan. In adolescents resource allocation for detecting cues seemed successful initially but less efficient at later stages; whereas we found the opposite pattern for old adults.

Sleep Augments Training-Induced Improvement in Working Memory in Children and Adults

HighlightsOvernight sleep facilitates training‐induced improvements in working memory.Sleeping after an n‐back training increases the individuals optimum performance.Both adults and children profit from sleep, with a particular benefit in children. ABSTRACT Sleep plays an important role in forming procedural motor memories. Whether sleep plays a similar role for cognitive procedures related to working memory function, is not yet clear. Here we investigated if sleep enhances training‐induced improvements in working memory in children. Because children show more intense slow wave sleep (e.g., higher slow wave activity, more spindles) we expected sleep‐related improvements to be greater than in adults. Twenty‐four children (10–12 years) and 24 adults were trained on three sessions of an n‐back task comprising three runs of blocks (6 blocks with 20 responses each) presented in ascending levels of difficulty. The sessions were separated by ˜12 h. Between the training sessions, participants first spent a full night sleeping and then a normal day awake (evening groups) or vice versa (morning groups). We analyzed performance on the whole blocks and, to estimate the individuals optimum performance, on only the first 10 trials of each block. Results showed a distinct gain in training‐induced working memory performance with post‐training overnight sleep compared to wakefulness. The sleep‐induced gain was revealed only for performance on the first block‐halves and, in absolute terms, was closely comparable in children and adults. Taking differences in working memory performance into account sleep‐dependent gains expressed as percentages of baseline performance were, however, greater in children than in adults. The data thus indicate that sleep after training facilitates cognitive procedures related to executive control, i.e., the ability to operate sequences of events in working memory, with a particular benefit in developing populations.

Effects of Sleep on Word Pair Memory in Children – Separating Item and Source Memory Aspects

Word paired-associate learning is a well-established task to demonstrate sleep-dependent memory consolidation in adults as well as children. Sleep has also been proposed to benefit episodic features of memory, i.e., a memory for an event (item) bound into the spatiotemporal context it has been experienced in (source). We aimed to explore if sleep enhances word pair memory in children by strengthening the episodic features of the memory, in particular. Sixty-one children (8–12 years) studied two lists of word pairs with 1 h in between. Retrieval testing comprised cued recall of the target word of each word pair (item memory) and recalling in which list the word pair had appeared in (source memory). Retrieval was tested either after 1 h (short retention interval) or after 11 h, with this long retention interval covering either nocturnal sleep or daytime wakefulness. Compared with the wake interval, sleep enhanced separate recall of both word pairs and the lists per se, while recall of the combination of the word pair and the list it had appeared in remained unaffected by sleep. An additional comparison with adult controls (n = 37) suggested that item-source bound memory (combined recall of word pair and list) is generally diminished in children. Our results argue against the view that the sleep-induced enhancement in paired-associate learning in children is a consequence of sleep specifically enhancing the episodic features of the memory representation. On the contrary, sleep in children might strengthen item and source representations in isolation, while leaving the episodic memory representations (item-source binding) unaffected.