Working Memory Capacity as a Predictor of Cognitive Training Efficacy in the Elderly Population

Aging is associated with a decline in a wide range of cognitive functions and working memory (WM) deterioration is considered a main factor contributing to this. Therefore, any attempt to counteract WM decline seems to have a potential benefit for older adults. However, determination of whether such methods like WM trainings are effective is a subject of a serious debate in the literature. Despite a substantial number of training studies and several meta-analyses, there is no agreement on the matter of their effectiveness. The other important and still not fully explored issue is the impact of the preexisting level of intellectual functioning on the training’s outcome. In our study we investigated the impact of WM training on variety of cognitive tasks performance among older adults and the impact of the initial WM capacity (WMC) on the training efficiency. 85 healthy older adults (55–81 years of age; 55 female, 30 males) received 5 weeks of training on adaptive dual N-back task (experimental group) or memory quiz (active controls). Cognitive performance was assessed before and after intervention with measures of WM, memory updating, inhibition, attention shifting, short-term memory (STM) and reasoning. We found post-intervention group independent improvements across all cognitive tests except for inhibition and STM. With multi-level analysis individual learning curves were modeled, which enabled examining of the intra-individual change in training and inter-individual differences in intra-individual changes. We observed a systematic and positive, but relatively small, learning trend with time. Moderator analyses with demographic characteristics as moderators showed no additional effects on learning curves. Only initial WMC level was a significant moderator of training effectiveness. Older adults with initially lower WMC improved less and reached lower levels of performance, compared to the group with higher WMC. Overall, our findings are in accordance with the research suggesting that post-training gains are within reach of older adults. Our data provide evidence supporting the presence of transfer after N-back training in older adults. More importantly, our findings suggest that it is more important to take into account an initial WMC level, rather than demographic characteristics when evaluating WM training in older adults

Combined Phase-Rate Coding by Persistently Active Neurons as a Mechanism for Maintaining Multiple Items in Working Memory in Humans

Maintaining multiple items in working memory (WM) is central to human behavior. Persistently active neurons are thought to be a mechanism to maintain WMs, but it remains unclear how such activity is coordinated when multiple items are kept in memory. We show that memoranda-selective persistently active neurons in the human medial temporal lobe phase lock to ongoing slow-frequency (1–7 Hz) oscillations during WM maintenance. The properties of phase locking are dependent on memory content and load. During high memory loads, the phase of the oscillatory activity to which neurons phase lock provides information about memory content not available in the firing rate of the neurons. We provide a computational model that reveals that inhibitory-feedback-mediated competition between multiple persistently active neurons reproduces this phenomenon. This work reveals a mechanism for the active maintenance of multiple items in WM that relies on persistently active neurons whose activation is orchestrated by oscillatory activity

Combined Phase-Rate Coding by Persistently Active Neurons as a Mechanism for Maintaining Multiple Items in Working Memory in Humans

Maintaining multiple items in working memory (WM) is central to human behavior. Persistently active neurons are thought to be a mechanism to maintain WMs, but it remains unclear how such activity is coordinated when multiple items are kept in memory. We show that memoranda-selective persistently active neurons in the human medial temporal lobe phase lock to ongoing slow-frequency (1–7 Hz) oscillations during WM maintenance. The properties of phase locking are dependent on memory content and load. During high memory loads, the phase of the oscillatory activity to which neurons phase lock provides information about memory content not available in the firing rate of the neurons. We provide a computational model that reveals that inhibitory-feedback-mediated competition between multiple persistently active neurons reproduces this phenomenon. This work reveals a mechanism for the active maintenance of multiple items in WM that relies on persistently active neurons whose activation is orchestrated by oscillatory activity

Not Just a Pot: Visual Episodic Memory in Cannabis Users and Polydrug Cannabis Users: ROC and ERP Preliminary Investigation

Background While research has consistently identified an association between long-term cannabis use and memory impairments, few studies have examined this relationship in a polydrug context (i.e., when combining cannabis with other substances).Aims: In this preliminary study, we used event-related potentials to examine the recognition process in a visual episodic memory task in cannabis users (CU) and cannabis polydrug users (PU). We hypothesized that CU and PU will have both–behavioral and psychophysiological–indicators of memory processes affected, compared to matched non-using controls with the PU expressing more severe changes.Methods 29 non-using controls (CG), 24 CU and 27 PU were enrolled into the study. All participants completed a visual learning recognition task while brain electrical activity was recorded. Event-related potentials were calculated for familiar (old) and new images from a signal recorded during a subsequent recognition test. We used receiver operating characteristic curves for behavioral data analysis.Results The groups did not differ in memory performance based on receiver operating characteristic method in accuracy and discriminability indicators nor mean reaction times for old/new images. The frontal old/new effect expected from prior research was observed for all participants, while a parietal old/new effect was not observed. While, the significant differences in the late parietal component (LPC) amplitude was observed between CG and PU but not between CG and CU nor CU and PU. Linear regression analysis was used to examine the mean amplitude of the LPC component as a predictor of memory performance accuracy indicator. LPC amplitude predicts recognition accuracy only in the CG.Conclusion The results showed alterations in recognition memory processing in CU and PU groups compared to CG, which were not manifested on the behavioral level, and were the most prominent in cannabis polydrug users. We interpret it as a manifestation of the cumulative effect of multiple drug usage in the PU group

Working Memory Load-related Theta Power Decreases in Dorsolateral Prefrontal Cortex Predict Individual Differences in Performance

Holding information in working memory (WM) is an active and effortful process that is accompanied by sustained load-dependent changes in oscillatory brain activity. These proportional power increases are often reported in EEG studies recording theta over frontal midline sites. Intracranial recordings, however, yield mixed results, depending on the brain area being recorded from. We recorded intracranial EEG with depth electrodes in 13 patients with epilepsy that were performing a Sternberg WM task. Here, we investigated patterns of theta power changes as a function of memory load during maintenance in three areas critical for WM: dorsolateral prefrontal cortex (DLPFC), dorsal ACC (dACC), and hippocampus. Theta frequency power in both hippocampus and dACC increased during maintenance. In contrast, theta frequency power in the DLPFC decreased during maintenance, and this decrease was proportional to memory load. Only the power decreases in DLPFC, but not the power increases in hippocampus and dACC, were predictive of behavior in a given trial. The extent of the load-related theta power decreases in the DLPFC in a given participant predicted a participant's RTs, revealing that DLPFC theta explains individual differences in WM ability between participants. Together, these data reveal a pattern of theta power decreases in the DLPFC that is predictive of behavior and that is opposite of that in other brain areas. This result suggests that theta band power changes serve different cognitive functions in different brain areas and specifically that theta power decreases in DLPFC have an important role in maintenance of information

Working Memory Load-related Theta Power Decreases in Dorsolateral Prefrontal Cortex Predict Individual Differences in Performance

Holding information in working memory (WM) is an active and effortful process that is accompanied by sustained load-dependent changes in oscillatory brain activity. These proportional power increases are often reported in EEG studies recording theta over frontal midline sites. Intracranial recordings, however, yield mixed results, depending on the brain area being recorded from. We recorded intracranial EEG with depth electrodes in 13 patients with epilepsy that were performing a Sternberg WM task. Here, we investigated patterns of theta power changes as a function of memory load during maintenance in three areas critical for WM: dorsolateral prefrontal cortex (DLPFC), dorsal ACC (dACC), and hippocampus. Theta frequency power in both hippocampus and dACC increased during maintenance. In contrast, theta frequency power in the DLPFC decreased during maintenance, and this decrease was proportional to memory load. Only the power decreases in DLPFC, but not the power increases in hippocampus and dACC, were predictive of behavior in a given trial. The extent of the load-related theta power decreases in the DLPFC in a given participant predicted a participant's RTs, revealing that DLPFC theta explains individual differences in WM ability between participants. Together, these data reveal a pattern of theta power decreases in the DLPFC that is predictive of behavior and that is opposite of that in other brain areas. This result suggests that theta band power changes serve different cognitive functions in different brain areas and specifically that theta power decreases in DLPFC have an important role in maintenance of information

Neural Signatures of Rational and Heuristic Choice Strategies: A Single Trial ERP Analysis

In multi-attribute choice, people use heuristics to simplify decision problems. We studied the use of heuristic and rational strategies and their electrophysiological correlates. Since previous work linked the P3 ERP component to attention and decision making, we were interested whether the amplitude of this component is associated with decision strategy use. To this end, we recorded EEG when participants performed a two-alternative choice task, where they could acquire decision cues in a sequential manner and use them to make choices. We classified participants’ choices as consistent with a rational Weighted Additive rule (WADD) or a simple heuristic Take The Best (TTB). Participants differed in their preference for WADD and TTB. Using a permutation-based single trial approach, we analyzed EEG responses to consecutive decision cues and their relation to the individual strategy preference. The preference for WADD over TTB was associated with overall higher signal amplitudes to decision cues in the P3 time window. Moreover, the preference for WADD was associated with similar P3 amplitudes to consecutive cues, whereas the preference for TTB was associated with substantial decreases in P3 amplitudes to consecutive cues. We also found that the preference for TTB was associated with enhanced N1 component to cues that discriminated decision alternatives, suggesting very early attention allocation to such cues by TTB users. Our results suggest that preference for either WADD or TTB has an early neural signature reflecting differences in attentional weighting of decision cues. In light of recent findings and hypotheses regarding P3, we interpret these results as indicating the involvement of catecholamine arousal systems in shaping predecisional information processing and strategy selection

THE EFFECIVENESS OF COGNITIVE TRAININGS IN OLDER ADULTS – REVIEW

There is a gradual increase in the number of elderly people living in the world. Also, human aging is associated with a deterioration of cognitive processes, that touches multiple domains, including memory, attention, processing speed and cognitive control. For this reason, intervention programs that improve the intellectual functioning of older citizens became very popular. One of the broadly discussed approach aims to support the elderly’s functioning with the usage of cognitive trainings. Although, emerged training regimes are considered by some researchers to be effective, they are systematically criticized by others. Possible causes are due to a diversity of approaches to the training design itself, to the way it is applied, as well as to the training methodology. In terms of their utility, it is crucial to decide which interventions are effective, how strongly they affect behavior, and to what extent they actually transfer to everyday life of older participants. Especially the last attribute should be e  ential, considering participants’ well-being. Therefore, this article aims not only to systematize reports on improving the cognitive functioning of the elderly, but above all to draw attention to the increasingly perceptible problem of verification of the training effects of seniors. We would like to emphasize the need for implementation a stronger methodological unification of cognitive trainings, that allows a fair assessment of their impact on the quality of life of the participating seniors.Na świecie stopniowo wzrasta liczba osób dożywających sędziwego wieku. Jednocześnie wraz z wiekiem ulega pogorszeniu szereg procesów poznawczych, takich jak: pamięć, uwaga, szybkość przetwarzania informacji czy kontrola poznawcza. Z tego względu bardzo popularne stały się programy usprawniające zdolności intelektualne tej grupy. Jednym z szeroko dyskutowanych podejść jest wspomaganie funkcjonowania osób starszych z wykorzystaniem treningów poznawczych. Powstałe reżimy treningowe są przez część badaczy uznawane za skuteczne, przez innych zaś systematycznie krytykowane. Obserwujemy heterogeniczność podejść zarówno do samego treningu, jak i do metodologii badań. Z punktu widzenia ich użyteczności kluczowe jest natomiast rozstrzygnięcie, jakiego rodzaju interwencje są najbardziej skuteczne, jak szeroki mają zasięg i w jakim stopniu przekładają się na realne korzyści dla trenujących. Profitem powinna być przede wszystkim poprawa jakości codziennego życia. Dlatego niniejszy artykuł ma na celu nie tylko systematyzac   doniesień z dziedziny usprawniania funkcjonowania poznawczego osób starszych, lecz przede wszystkim zwrócenie uwagi na coraz bardziej odczuwalny problem weryfikacji efektywności treningów poznawczych seniorów. Pragniemy podkreślić potrzebę wprowadzenia silniejszej unifikacji metodologicznej interwencji poznawczych w celu umożliwienia rzetelnej oceny ich wpływu na jakość życia badanych seniorów. Na podstawie dokonanego przeglądu przedstawiamy sugestie dotyczące metodologii treningów

SKUTECZNOŚĆ TRENINGÓW POZNAWCZYCH W GRUPIE OSÓB STARSZYCH – PRZEGLĄD BADAŃ

Z wiekiem pogorszeniu ulega szereg procesów poznawczych, takich jak pamięć, uwaga, szybkość przetwarzania informacji czy kontrola poznawcza. Jednocześnie na świecie wzrasta stopniowo liczba osób, które dożywają sędziwego wieku. Z tego względu środowiska naukowe, polityczne czy nawet komercyjne firmy starają się stworzyć programy usprawniające zdolności intelektualne w tej grupie.Jednym z szeroko dyskutowanych podejść jest wspomaganie funkcjonowania osób starszych z użyciem treningów poznawczych. Powstałe reżimy treningowe są przez część badaczy uznawane za skuteczne, przez innych zaś systematycznie krytykowane. Spowodowane jest to różnorodnością podejść zarówno do samej konstrukcji treningu, sposobu jego aplikacji jak i metodologii badań. Natomiast, z punktu widzenia ich użyteczności kluczowe jest rozstrzygnięcie, jakiego rodzaju interwencji są najbardziej skuteczne, jak duży mają wpływ, i w jakim stopniu przekładają się na realne korzyści dla osób biorących w nich udział. Profitem powinna być przede wszystkim namacalna poprawa jakości codziennego życia. Z tego względu niniejszy artykuł ma na celu, nie tylko systematyzację doniesień z dziedziny usprawniania funkcjonowania poznawczego osób starszych, ale przede wszystkim zwrócenie uwagi na coraz bardziej odczuwalny problem weryfikacji efektów treningowych seniorów. Pragniemy także podkreślić potrzebę wprowadzenia silniejszej unifikacji metodologicznej badań treningów poznawczych w celu umożliwienia rzetelnej oceny ich wpływu na jakość życia badanych seniorów. Na podstawie dokonanego przeglądu formułujemy również wioski jakiego rodzaju elementy powinny w tego typu działaniach być uwzględnione