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Generalization of training to support the performance on new tasks—transfer—has been much studied. One hypothesis is that transfer occurs if overlapping neuronal circuits are engaged in both training and transfer tasks. Here, we investigated transfer effects in the domain of episodic memory by following 356 participants between 20 and 83 years who downloaded and used a smart phone application to practice the method of loci (MoL) over 3 months. We measured transfer of MoL training to three associative memory tasks with hypothesized neurocognitive overlap (binding in the hippocampus) with the trained task. Transfer tasks were administered at the beginning of training and when two specific proficiency levels in Loci training were reached. Results showed robust transfer effects across the age span at both levels. These results indicate that app-based strategy training can lead to enhancement of episodic memory beyond the specific training task, which may have clinical implementations.

Objectives: Episodic memory is age-sensitive but can be strengthened by targeted training interventions. The method of loci (MoL) is a classic mnemonic which if successfully implemented greatly improves memory performance. We developed and investigated the effects of a MoL training program implemented in a smart phone application (app) with the aim of studying usage of the application, training effect and its modifiability by age, predictors for MoL proficiency, transfer effects to a face-name memory task, and perceived benefit in everyday memory.

Method: A total of 359 adults participated. Instruction and training of the MoL, transfer test (face-name paired associates cued recall task), and surveys were performed in an in-house developed app.

Results: The app interested people across the adult life span. Older adults practiced the most, whereas younger and youngold participants showed the highest level of MoL proficiency. Level of proficiency was modulated by amount of practice, but in the oldest participants this effect was less pronounced. Greater self-rated health was associated with higher level of proficiency. No transfer effect was observed. Among those who answered the survey, about half expressed that MoL training had benefitted memory in their everyday life.

Discussion: App-based memory training in the MoL can be delivered successfully via an app across the adult life span. Level of performance reached in training is variable but generally high, and mainly influenced by amount of training and age of the participants. Our data suggest plasticity across the life span, but to a lesser degree for adults between 70 and 90 years.

Chemical intolerance is a surprisingly prevalent condition or affliction characterized by adverse reactions to low levels of chemical, often odorous stimulation. Sufferers often assume that their plight is due to an uncommon sensory acuteness, yet studies repeatedly fail to reveal altered detection thresholds. Here, we investigated whether self-reported chemical intolerance is associated with altered sensory sensitivity or response bias. The sensory acuity (sensitivity; A) and sensory decision rule (criterion; B) to n-butanol was assessed using the method of constant stimuli in 82 participants with different degrees of chemical intolerance (low to high). Higher self-reported chemical intolerance was associated with a lower criterion, but not with sensitivity.

A widely held view is that top-down modulation of sensory information relies on an amodal control network that acts through the thalamus to regulate incoming signals. Olfaction lacks a direct thalamic projection, which suggests that it may differ from other modalities in this regard. We investigated the late positive complex (LPC) amplitudes of event-related potentials (ERP) from 28 participants, elicited by intensity-matched olfactory, auditory and visual stimuli, during a condition of focused attention, a neutral condition, and a condition in which stimuli were to be actively ignored. Amplitudes were largest during the attend condition, lowest during the ignore condition, with the neutral condition in between. A Bayesian analysis resulted in strong evidence for similar effects of task across sensory modalities. We conclude that olfaction, despite its unique neural projections, does not differ from audition and vision in terms of task-dependent neural modulation of the LPC.

Prior studies have examined the magnitude of training and transfer effects after process-based training in early and late adulthood. However, little is known about how long-lasting these effects are. Here we investigate the degree of stability of training gains and transfer effects in younger and older adults 18 months after completion of executive process training, tapping updating, inhibition, and shifting. From the original sample, 24 out of 30 older participants, and 19 out of 29 young adults, returned for follow-up assessment at which the criterion and transfer tests from pre- and post-test were re-administered. The results demonstrated stability of training gains in the updating criterion task (Letter Memory Running Span), and in a near transfer updating task (Number Memory Running Span) for both age groups. The young adults improved performance in two complex working memory tasks immediately after training. These transfer effects did not survive across time. Our results provide evidence that executive process training has its greatest effect on transfer tasks with a substantial process overlap with the trained tasks: only those effects are maintained over an 18 month period in both early and late adulthood.

The study investigated the relationship between cognitive factors and gains in number recall following training in a number–consonant mnemonic in a sample of 112 older adults (M = 70.9 years). The cognitive factors examined included baseline episodic memory, working memory, processing speed, and verbal knowledge. In addition, predictors of maintenance of gains to a follow-up assessment, eight months later, were examined. Whereas working memory was a prominent predictor of baseline recall, the magnitude of gains in recall from pre- to post-test assessments were predicted by baseline episodic memory, processing speed, and verbal knowledge. Verbal knowledge was the only significant predictor of maintenance. Collectively, the results indicate the need to consider multiple factors to account for individual differences in memory plasticity. The potential contribution of additional factors to individual differences in memory plasticity is discussed.

Aging, also in the absence of pathological conditions, is associated with cognitivedecline, especially in so called fluid abilities, such as episodic memory andexecutive functions. Due to an ongoing demographic shift, a larger part of thepopulation will reach higher ages, and more people will be affected by age-relatedcognitive decline. Finding ways of counteracting this development have the potentialof having large benefits for both individuals and society. It has long beenknown that living in environments that are rich in terms of cognitive challengescan affect cognitive ability in old age. In this regard, intervention studies in whichthe amount of cognitive stimulation is manipulated can therefore generate insightsto the causality of such effects in specific cognitive functions. Cognitive trainingas means to counteract negative effects of aging on cognition has received a lot ofscientific interest in the last decades.This focus of this thesis is cognitive training interventions, which is studiedfrom several perspectives. In Study i, the aim was to investigate the extent towhich executive functions can be strengthened by training in younger and olderadults, and to which degree such training generalize to other measures of cognition.Although a large body of research has been investigating training of workingmemory and executive functions in recent years, the results are diverse, and fewhave been targeting executive functions broadly with training programs based ontheoretical models of executive functions. Study i showed that despite a broadtraining program targeting three executive functions (updating, shifting and inhibition),it did not lead to transfer beyond the very near in old adults. The youngerhowever showed transfer effects to measures of working memory.In Study ii, the focus was on studying how the effects survive across time.There is limited knowledge about long-term effects of process-based training andthe results showed that the training effect was stable after 1.5 years, while only thenearest transfer effect was still significant in both younger and older adults.Study iii focused on individual factors affecting gain and maintenance thereofin a sample of older individuals. We used a strategy-based intervention focusingon episodic memory performance with a number-consonant mnemonic which is amnemonic for memorizing digit-codes. A different set of predictors was observedfor baseline episodic memory performance and training gain. Those that are betteroff in terms of episodic memory performance, also gain more in the episodic memorycriterion task. Further, a higher rate of processing speed was also important.Lastly, better verbal knowledge also influence gain beyond the other factors. Theresults have both theoretical implications regarding how plastic cognitive functionsare, and practical, in terms of how to best design training programs.

Över hela världen blir vi äldre. År 2050 kommer en femtedel av jordens befolkningvara 60 år eller äldre, att jämföra med en knapp tiondel år 1950. Det är förstås enpositiv utveckling men en åldrande befolkning innebär också att vi står inför flerautmaningar. En sådan rör det kognitiva åldrandet. Vi vet att åldrande kan leda tillnedgång i vissa kognitiva förmågor, såsom det episodiska minnet samt exekutivafunktioner. Episodiskt minne är vår förmåga att komma ihåg upplevda händelserknutna till tid och rum. Exekutiva funktioner är ett begrepp som inbegriper vårförmåga att hålla en plan aktiv medan vi utför den, utan att distraheras av tankareller externa störningsmoment. Genom att studera effekter av träning hos yngreoch äldre vuxna på sådana kognitiva funktioner kan vi få kunskap om till vilkengrad de kan förbättras och om denna förbättringspotential är olika beroende påålder. Vi vet sedan tidigare att människor som under sin livstid lever ett kognitivtstimulerande liv också till viss del är skyddade mot nedgång i kognition underåldrandet. Träningsstudier kan ge kunskap om kausaliteten i sådana fynd.Studie i i denna avhandling behandlar träning av exekutiva funktioner föryngre och äldre vuxna. Träningsprogrammet konstruerades utefter en teoretiskmodell som beskriver exekutiva funktioner som bestående av förmågan att inhiberastörande stimuli eller överlärda responser, förmågan att uppdatera informationi arbetsminnet, och förmågan att skifta mellan att utföra olika uppgifter. Resultatenvisade att de yngre kunde generalisera träningseffekten också till otränadearbetsminnesuppgifter, medan de äldre endast visade förbättring på otränade uppgiftersom hade stora likheter med de tränade.I Studie ii undersöktes hur mycket av träningseffekterna som kvarstod ettoch ett halvt år efter träningen. Resultaten visade att både för yngre och äldreså kvarstod effekten på tränade uppgifter samt en av uppgifterna som hade stortöverlapp med träningsuppgifterna, för både unga och äldre.I Studie iii studerades ett strategibaserat träningsprogram för episodisktminne. Fokus låg på att undersöka vilka individuella kognitiva faktorer sompåverkar förbättring som följd av träning. Resultaten visade att de med högre förmågai kognitiv bearbetningshastighet samt verbal förmåga var de som hade bästförutsättningar för förbättring.Resultaten från dessa studier är av både teoretisk relevans i och med att deökar förståelsen för träningsbarheten av exekutiva funktioner, samt har praktiskrelevans för utformning av träningsprogram.

There is a growing body of research on the modifiability of executive functions in different stages of life. Previous studies demonstrate robust training effects but limited transfer in younger and particularly in older adults. The aim of the present study was to investigate whether a theoretically derived intervention for executive functioning, addressing several basic processes (updating, shifting, and inhibition), can induce transfer effects in early and late adulthood. Fifty-nine healthy adults, 29 young and 30 older adults, were randomly assigned to either training or no-contact control groups. The training groups received 15 sessions of executive process training for about 45 min/session during 5 weeks. A test battery including a criterion task and near, intermediate, and far transfer tasks was administered before and after training. Results showed pronounced age-equivalent gains on the criterion task. Near transfer was seen to non-trained updating and inhibition tasks for the young and older trained participants. However, only the young adults showed intermediate transfer to two complex working memory tasks. No far transfer effects were seen for either age group. These findings provide additional evidence for age-related constraints in the ability to generalize acquired executive skills, and specifically show that training of multiple executive processes is not sufficient to foster transfer beyond the very near in older adults.