Working Memory Training and Cortical Arousal in Healthy Older Adults: A Resting-State EEG Pilot Study

Parietal alpha and theta power predict cognitive training gains in middle-aged adults

Research on executive functions training shows inconsistent outcomes, with factors like age, baseline cognitive abilities, and personality traits implicated as predictive of training gains, while limited attention has been given to neurophysiological markers. Theta and alpha band power are linked to cognitive performance, suggesting a potential area for further study. This study aimed to determine whether relative theta and alpha power and their ratio could predict gains in updating and inhibition training beyond the practice effects (the order of training session). Forty healthy middle-aged adults (aged 49-65) were randomly assigned to either the cognitive training group (n = 20), or the communication skills (control) group (n = 20). Both groups completed the self-administered training sessions twice a week for 10 weeks, totaling to 20 sessions. Resting-state EEG data were recorded before the first session. Mixed-effects model analyses revealed that higher relative parietal alpha power positively predicted training performance, while theta power negatively predicted performance. Additionally, higher parietal alpha/theta ratio was associated with better training outcomes, while the frontal alpha/theta ratio did not demonstrate significant predictive value. Other EEG measures did not show additional predictive power beyond what was accounted for by the session effects. The findings imply that individuals with specific EEG pattern may change with cognitive training, making resting-state EEG a useful tool in tailoring interventions.

The arousal level of consciousness required for working memory performance: An anaesthesia study

Regarding the stage of arousal level required for working memory to function properly, limited studies have been conducted on changes in working memory performance when the arousal level of consciousness decreases. This study aimed to experimentally clarify the stages of consciousness necessary for optimal working memory function. In this experiment, the sedation levels were changed step-by-step using anaesthesia, and the performance accuracy during the execution of working memory was assessed using a dual-task paradigm. Participants were required to categorize and remember words in a specific target category. Categorization performance was measured across four different sedative phases: before anaesthesia (baseline), and deep, moderate and light stages of sedation. Short-delay recognition tasks were performed under these four sedative stages, followed by long-delay recognition tasks after participants recovered from sedation. The results of the short-delay recognition task showed that the performance was lowest at the deep stage. The performance of the moderate stage was lower than the baseline. In the long-delay recognition task, the performance under moderate sedation was lower than that under baseline and light sedation. In addition, the performance under light sedation was lower than that under baseline. These results suggest that task performance becomes difficult under half sedation and that transferring information to long-term memory is difficult even under one-quarter sedation.

The search for the relationship between female hormonal status, alpha oscillations, and aperiodic features of resting state EEG

Fluctuations in sex steroid levels during the menstrual cycle and the use of hormonal contraceptives have been linked to changes in cognitive function and emotions in females. Such variations may be mediated by overall brain activity and excitability. We aimed to investigate the impact of female hormonal status on resting state EEG (rsEEG) parameters, including periodic (individual alpha frequency, alpha power) and aperiodic (1/f slope) features. rsEEG was recorded in healthy females (mean age 26.4 ± 4.6 years), who were naturally cycling in the early follicular (n = 33) or mid-luteal phases (n = 35), or who used either oral contraceptives (n = 35) or hormonal intrauterine devices (n = 28). Salivary concentrations of estradiol, progesterone, and testosterone were measured. Contrary to previous findings, this study did not reveal significant differences in rsEEG parameters between groups or significant relationships with hormonal levels. Age emerged as a covariate negatively related to the median 1/f slope. Based on these findings, we found no significant evidence to suggest that the periodic (alpha power and peak frequency) or aperiodic activity patterns in the brain during the resting state differ between the groups of females under investigation.

Intermittent working memory training during adulthood protects against age-related long-term spatial reference memory decline in rats

Engagement in cognitive activity in adulthood is one of the factors that enable successful cognitive aging, both in humans and rodents. However, some studies emphasize that the beneficial effect on cognition of such an activity may reflect carry over from one test situation to another, including memory for procedural aspects of the behavioral tasks, and thus question whether this effect can be limited to the trained cognitive domain or whether it can be transferred to an untrained ones. In the current study, we assessed whether adulthood intermittent working memory training has beneficial effect on long-term memory of aged rats using two very different test situations. To this aim, rats trained in a delayed non-matching to position task in operant box at 3 and 15 months of age were tested in a place learning task in water maze when they were 24 months. The two tasks differ with regard to the cognitive domain but also in their spatial ability requirement and the nature of the reinforcer used. During the memory tests, accuracy of the platform search indicated age-related impairment only in the aged-untrained group. Thus, intermittent training during adult life in a task involving working memory protects aged animals from the deleterious effects of aging on spatial reference memory. This result highlights the long-term beneficial effects of training on a working memory task on an untrained cognitive domain.

EngAge - A metacognitive intervention to supplement working memory training: A feasibility study in older adults

Working Memory (WM) training has shown promise in supporting cognitive functioning in older adult populations, but effects that generalize beyond the trained task have been inconsistent. Targeting cognitive processes in isolation might be a limiting factor given that metacognitive and motivational factors have been shown to impact older adults' engagement with challenging cognitive activities, such as WM training. The current feasibility study implemented a novel metacognitive intervention in conjunction with WM training in older adults and examined its potential amplifying short- and long-term effects on cognitive and self-report outcomes as compared to WM or active control training alone. One-hundred and nineteen older adults completed a cognitive training over the course of 20 sessions at home. The cognitive training targeted either WM or general knowledge. In addition, one of the WM training groups completed a metacognitive program via group seminars. We tested for group differences in WM, inhibitory control, and episodic memory, and we assessed participants' perceived self-efficacy and everyday memory failures. At post-test, we replicated earlier work by demonstrating that participants who completed the WM intervention outperformed the active control group in non-trained WM measures, and to some extent, in inhibitory control. However, we found no evidence that the supplemental metacognitive program led to benefits over and above the WM intervention. Nonetheless, we conclude that our metacognitive program is a step in the right direction given the tentative long-term effects and participants' positive feedback, but more longitudinal data with larger sample sizes are needed to confirm these early findings.

EEG Frontal Asymmetry in Dysthymia, Major Depressive Disorder and Euthymic Bipolar Disorder

In the last few decades, the incidence of mood disorders skyrocketed worldwide and has brought an increasing human and economic burden. Depending on the main symptoms and their evolution across time, they can be classified in several clinical subgroups. A few psychobiological indices have been extensively investigated as promising markers of mood disorders. Among these, frontal asymmetry measured at rest with quantitative EEG has represented the main available marker in recent years. Only a few studies so far attempted to distinguish the features and differences among diagnostic types of mood disorders by using this index. The present study measured frontal EEG asymmetry during a 5-min resting state in three samples of patients with bipolar disorder in a Euthymic phase (EBD, n = 17), major depressive disorder (MDD, n = 25) and persistent depressive disorder (PDD, n = 21), once termed dysthymia. We aimed to test the hypothesis that MDD and PDD lack the typical leftward asymmetry exhibited by normal as well as EBD patients, and that PDD shows greater clinical and neurophysiological impairments than MDD. Clinical scales revealed no symptoms in EBD, and significant larger anxiety and depression scores in PDD than in MDD patients. Relative beta (i.e., beta/alpha ratio) EEG asymmetry was measured from lateral frontal sites and results revealed the typical greater left than right frontal beta activity in EBD, as well as a lack of asymmetry in both MDD and PDD. The last two groups also had lower bilateral frontal beta activity in comparison with the EBD group. Results concerning group differences were interpreted by taking into account both the clinical and the neurophysiological domains.