Memory Performance In Adults Research Articles

Adolescent cannabinoid exposure permanently suppresses cortical oscillations in adult mice.

Regular marijuana use during adolescence, but not adulthood, may permanently impair cognition and increase the risk for psychiatric diseases, such as schizophrenia. Cortical oscillations are integral for cognitive processes and are abnormal in patients with schizophrenia. We test the hypothesis that adolescence is a sensitive period because of the active development of cortical oscillations and neuromodulatory systems that underlie them. The endocannabinoid system upon which marijuana acts is one such system. Here we test the prediction that adolescent cannabinoid exposure alters cortical oscillations in adults. Using in vitro local field potential, in vivo electrocorticogram recordings and cognitive behavioral testing in adult mice, we demonstrate that chronic adolescent, but not adult, cannabinoid exposure suppresses pharmacologically evoked cortical oscillations and impairs working memory performance in adults. The later-maturing prefrontal cortex is more sensitive to adolescent exposure than the earlier-maturing, primary somatosensory cortex. These data establish a link between chronic adolescent cannabinoid exposure and alterations in adult cortical network activity that underlie cognitive processes.

MEMORY IMPAIRMENTS IN ADULTS WITH DYSLEXIA

The aim of our study was to analyze the functioning of various aspects of memory in adults with developmental dys lexia, as compared to adults without developmental dyslexia. Our research involved a total of 180 adults, mostly students and university graduates from the Tri-City metropolitan region in north central Poland. The criterion group consisted of 93 adults with developmental dyslexia, while the control group consisted of 87 adults without developmental dyslexia. The results obtained confirm the assumption of a lower level of functioning of individuals with dyslexia in relation to phonemic analysis and phonemic awareness, phonological awareness and verbal working memory, visual working memory and perception in a task requiring the analysis and synthesis of details of a complex pattern, recalling data from the mental lexicon. The two groups did not differ in terms of working visuospatial memory (spatial span). These results are consistent with a majority of scientific reports on memory function ing in adults with developmental dyslexia. Our findings confirm the phonological deficit hypothesis, as the most profound disturbances were observed in phonological processing and verbal working memory. Moreover, our studies do not provide support for the compensation model of dyslexia, as diverse memory deficits persist into adulthood. However, adults with dyslexia were aware of their cognitive limitations in terms of memory.

Adolescent Exposure of JWH-018 “Spice” Produces Subtle Effects on Learning and Memory Performance in Adulthood

The active components associated with the bio-designer drugs known variously as “Spice” or “K2” have rapidly gained in popularity among recreational users, forcing the United States Drug Enforcement Administration to classify these compounds as Schedule I drugs in the Spring of 2011. However, although there is some information about many of the synthetic cannabinoids used in Spice products, little is known about the consequences of the main constituent, (1-pentyl-3-(1-naphthoyl)indole; JWH-018), on neuropsychological development or behavior. In the present experiment, adolescent rats were given repeated injections of either saline or 100 μg/kg of JWH-018. Once the animals were 75 days of age, they were trained using tasks with spatial components of various levels of difficulty and a spatial learning set task. On early trials with water maze tasks of varying difficulty, the JWH-018 treated rats were impaired relative to controls. However, by the end of each phase of testing, drug and control animals were comparable, although on probe trials the drug-treated animals spent significantly less time in the target quadrant. In addition, the performance of the drug-treated rats was inferior to that of the control animals on a learning set task, suggesting some difficulty in adapting their responses to changing task demands. The results suggest that chronic exposure to this potent cannabinoid CB1 receptor agonist during adolescence is capable of producing a variety of subtle changes affecting spatial learning and memory performance in adulthood, well after the drug exposure period.

Autobiographical memory in adults with autism spectrum disorder: The role of depressed mood, rumination, working memory and theory of mind

Autobiographical memory difficulties have been widely reported in adults with autism spectrum disorder (ASD). The aim of the current study was to explore the potential correlates of autobiographical memory performance (including depressed mood, rumination, working memory and theory of mind) in adults with ASD, relative to a group of typical adults matched for age, gender and IQ. Results demonstrated that the adults with ASD reported higher levels of depressed mood and rumination than the typical adults, and also received lower scores on measures of theory of mind and working memory. Correlational analysis suggested that theory of mind and working memory were associated with autobiographical memory performance in the adults with ASD, but no significant relationships were observed between autobiographical memory, depressed mood and rumination in this group. To explore these patterns further, two cases of adults with a dual diagnosis of ASD and depression are discussed. These participants present a profile in line with the idea that depressed mood and rumination do not have the same influence on autobiographical memory in adults with ASD as they do in typical adults.

Enhanced emotional interference on working memory performance in adults with ADHD

Objectives. Subjects with attention-deficit/hyperactivity disorder (ADHD) suffer from both executive dysfunction and deficits in emotion regulation. However, up to now, there has been no research demonstrating a clear impact of emotional dysregulation on cognitive performance in subjects with ADHD. Methods. Male and female adults with ADHD (n=39) and gender- and IQ-matched control subjects (n=40) performed an emotional working memory task (n-back task). In the background of the task, we presented neutral and negative stimuli varied in emotional saliency (negative pictures with low saliency, negative pictures with high saliency), but subjects were instructed to ignore these pictures and to process the working memory task as quickly and as accurately as possible. Results. Compared to control subjects, ADHD patients showed both a general working memory deficit and enhanced distractability by emotionally salient stimuli in terms of lower n-back performance accuracy. In particular, while controls showed impaired WM performance when presented with highly arousing negative background pictures, a comparable decrement was observed in the ADHD group already with lowly arousing pictures. Conclusions. Our results suggest that difficulties in suppressing attention towards emotionally laden stimuli might result from deficient executive control in ADHD.

Developmental differences in prefrontal activation during working memory maintenance and manipulation for different memory loads

The ability to keep information active in working memory is one of the cornerstones of cognitive development. Prior studies have demonstrated that regions which are important for working memory performance in adults, such as dorsolateral prefrontal cortex (DLPFC), ventrolateral prefrontal cortex (VLPFC), and superior parietal cortex, become increasingly engaged across school-aged development. The primary goal of the present functional MRI study was to investigate the involvement of these regions in the development of working memory manipulation relative to maintenance functions under different loads. We measured activation in DLPFC, VLPFC, and superior parietal cortex during the delay period of a verbal working memory task in 11-13-year-old children and young adults. We found evidence for age-related behavioral improvements in working memory and functional changes within DLPFC and VLPFC activation patterns. Although activation profiles of DLPFC and VLPFC were similar, group differences were most pronounced for right DLPFC. Consistent with prior studies, right DLPFC showed an interaction between age and condition (i.e. manipulation versus maintenance), specifically at the lower loads. This interaction was characterized by increased activation for manipulation relative to maintenance trials in adults compared to children. In contrast, we did not observe a significant age-dependent load sensitivity. These results suggest that age-related differences in the right DLPFC are specific to working memory manipulation and are not related to task difficulty and/or differences in short-term memory capacity.

Speaking, writing, and memory span in children: Output modality affects cognitive performance

Low‐level processes of children's written language production are cognitively more costly than those involved in speaking. This has been shown by French authors who compared oral and written memory span performance. The observed difficulties of children's, but not of adults' low‐level processes in writing may stem from graphomotoric as well as from orthographic inadequacies. We report on five experiments designed to replicate and expand the original results. First, the French results were successfully replicated for German third‐graders, and for university students. Then, the developmental changes of the cognitive costs of writing were examined during primary school, comparing the performance of second‐ and fourth‐graders. Next, we show that unpractised writing modes, which were experimentally induced, also lead to a decrease of memory performance in adults, which supports the assumption that a lack of graphomotoric automation is responsible for the observed effects in children. However, unpractised handwriting yields clearer results than unpractised typing. Lastly, we try to separate the influences of graphomotoric as opposed to orthographic difficulties by having the words composed through pointing on a “spelling board”. This attempt, however, has not been successful, probably because the pointing to letters introduced other low‐level costs. In sum, throughout the four years of primary school, German children show worse memory span performance in writing compared to oral recall, with an overall increase in both modalities. Thus, writing had not fully caught up with speaking regarding the implied cognitive costs by the end of primary school. Therefore, conclusions relate to the question of how to assess properly any kind of knowledge and abilities through language production.

Neonatal asphyxia and hyperthermia and cognitive deficits in adult rats: Role of iron

We compared effects of a critical neonatal anoxia, applied in Wistar rats at body temperatures of 33, 37 and 39 °C, on memory performance in adulthood. Because hyperthermic–anoxic neonates suffer from hyperferremia an additional group of rats, exposed to anoxia at 39 °C, was injected with deferoxamine, a chelator of iron. At the age of 4 and 12 months all rats were examined in hole board, typical maze and Morris maze. The memory was disturbed by neonatal anoxia at 39 °C. The disturbances were prevented by both the naturally reduced body temperature and by deferoxamine. In conclusion, neonatal hyperthermia induces iron-mediated, extremely delayed postanoxic cognitive disturbances in adulthood.

Environmental and tactile stimulation modulates the neonatal handling effect on adult rat spatial memory

Handling of rat pups promotes their adult cognitive performance. However, new data suggest that individual components of the handling procedure, like exposure to novelty or tactile stimulation, have distinct lasting effects on behaviour. In this study we examined the interaction of early novelty exposure with a varying amount of tactile stimulation on spatial recognition memory and corticosterone secretion of adult male and female rats. A split litter design was used and the experimental animals were also compared to animal facility reared controls. The experiment was conducted in two phases. In the first phase, we examined the effect of novel or home environment during the 15-min of neonatal handling, following 10 back-strokes. Tactile stimulation of 10 back-strokes combined with novelty exposure, enhanced novel arm discrimination in a Y-maze task in adult rats of both sexes compared to their siblings that stayed at home, as well as to the animal facility reared controls. In the second phase, additional back-stroking (total of 20 back-strokes) reduced the Y-maze performance of males neonatally exposed to novelty, while the same treatment enhanced the performance of their siblings that stayed at home. Basal corticosterone levels, determined 1 week post-Y-maze, were significantly increased only in the novelty exposed/10 back-stroked females compared to same sex non-handled controls. In contrast, 10 back-strokes combined with the home cage environment increased corticosterone in males. Increase to 20 back-strokes reversed the impact of neonatal environment on corticosterone levels.These data suggest that the nature and intensity of the individual components of a mild early life manipulation, like handling, are critical in modifying aspects of adult memory performance and basal adrenocortical function.

Moderators of and Mechanisms Underlying Stereotype Threat Effects on Older Adults' Memory Performance

Recent research has suggested that negative stereotypes about aging may have a detrimental influence on older adults' memory performance. This study sought to determine whether stereotype-based influences were moderated by age, education, and concerns about being stigmatized. Possible mechanisms underlying these influences on memory performance were also explored. The memory performance of adults aged 60 to 70 years and 71 to 82 years was examined under conditions designed to induce or eliminate stereotype threat. Threat was found to have a greater impact on performance in the young-old than in the old-old group, whereas the opposite was observed for the effects of stigma consciousness. In both cases, the effects were strongest for those with higher levels of education. Further analyses found little evidence in support of the mediating roles of affective responses or working memory. The only evidence of mediation was found with respect to recall predictions, suggesting a motivational basis of threat effects on performance. These findings highlight the specificity of stereotype threat effects in later adulthood as well as possible mechanisms underlying such effects.

Gestational Choline Supply Regulates Methylation of Histone H3, Expression of Histone Methyltransferases G9a (Kmt1c) and Suv39h1 (Kmt1a), and DNA Methylation of Their Genes in Rat Fetal Liver and Brain

Choline is an essential nutrient that, via its metabolite betaine, serves as a donor of methyl groups used in fetal development to establish the epigenetic DNA and histone methylation patterns. Supplementation with choline during embryonic days (E) 11-17 in rats improves memory performance in adulthood and protects against age-related memory decline, whereas choline deficiency impairs certain cognitive functions. We previously reported that global and gene-specific DNA methylation increased in choline-deficient fetal brain and liver, and these changes in DNA methylation correlated with an apparently compensatory up-regulation of the expression of DNA methyltransferase Dnmt1. In the current study, pregnant rats were fed a diet containing varying amounts of choline (mmol/kg: 0 (deficient), 8 (control), or 36 (supplemented)) during E11-17, and indices of histone methylation were assessed in liver and frontal cortex on E17. The mRNA and protein expression of histone methyltransferases G9a and Suv39h1 were directly related to the availability of choline. DNA methylation of the G9a and Suv39h1 genes was up-regulated by choline deficiency, suggesting that the expression of these enzymes is under negative control by methylation of their genes. The levels of H3K9Me2 and H3K27Me3, tags of transcriptionally repressed chromatin, were up-regulated by choline supplementation, whereas the levels of H3K4Me2, associated with active promoters, were highest in choline-deficient rats. These data show that maternal choline supply during pregnancy modifies fetal histone and DNA methylation, suggesting that a concerted epigenomic mechanism contributes to the long term developmental effects of varied choline intake in utero.

Viral Vector–mediated Delivery of Estrogen Receptor-α to the Hippocampus Improves Spatial Learning in Estrogen Receptor-α Knockout Mice

Estrogen, which influences both classical genomic and rapid membrane-associated signaling cascades, has been implicated in the regulation of hippocampal function, including spatial learning. Gene mutation studies suggest that estrogen effects are mediated by estrogen receptor-α (ER-α); however, because gonadal steroids influence the organization of the hippocampus during development, it has been difficult to distinguish developmental effects from those specific to adults. In this study we show that lentiviral delivery of the gene encoding ER-α to the hippocampus of adult ER-α-knockout (ER-αKO) mice restores hippocampal responsiveness to estrogen and rescues spatial learning. We propose that constitutive estrogen receptor activity is important for maintaining hippocampus-dependent memory function in adults.

Predictors of prospective memory in adults with traumatic brain injury

Previous studies have established that prospective memory is commonly affected following traumatic brain injury (TBI). This study examines whether demographic factors, injury severity and site, executive function, and metacognitive factors predict prospective memory performance in adults with TBI, using a cross-sectional multivariate correlational model. Prospective memory of 44 adults (mean age = 30 years) with severe TBI was measured by the Cambridge Prospective Memory Test (CAMPROMPT) time-based and event-based scores. Using stepwise multiple regression, the time-based score was predicted by the Controlled Oral Word Association Test (COWAT) Animals subtest score, length of post-traumatic amnesia (PTA) and use of note-taking on the CAMPROMPT. The event-based score was predicted by length of PTA and COWAT Animals score. Therefore, patients with longer periods of PTA and executive function impairment may be expected to display poorer prospective memory. Note-taking was associated with improved performance on time-based prospective memory tasks.

Episodic Memory in Adult Age and Effects of Sibship Size and Birth Order: Longitudinal Data

This study examined the effects of sibship size and birth order on episodic memory performance in adulthood and old age. Participants were 1,141 healthy individuals aged 35–80 years, who took part in a longitudinal project on age, health, and memory. Episodic memory measurements over a 5-year interval included tests of recognition (recognition of faces, family names, first names, and nouns) and tests of recall (free recall of sentences, free recall and cued recall of nouns, and recall of activities). Results showed significant effects for both recall and recognition, that is, the smaller the sibship size is for an individual and the earlier born, the better memory performance. These results demonstrate that the effects of sibship size and birth order previously shown in children and adolescents (Belmont and Marolla, Science 182:1096–1101, 1973; Zajonc and Markus, Psych Rev 82:74–88, 1975; Zajonc, Am Psychol 56:490–496, 2001) are robust over time and hold over a large adult range.

Environmental contaminants and learning and memory

A number of environmental contaminants are known to cause a reduction in IQ in children exposed prenatally or early in life. These effects are well documented for exposure to lead, methylmercury, polychlorinated biphenyls (PCBs), and cigarette smoke, all of which can reduce IQ by up to 5–7 IQ points. Similar effects may result from exposure to dioxins and some pesticides. In most or all of these situations there are also behavioral changes as a result of exposure, including shortened attention span and hyperactivity. Recent studies have shown that adverse effects of contaminants such as lead and cigarette smoke on IQ occur at lower levels of exposure than previously thought, and that the dose–response relationship is actually steeper at lower concentrations than what is seen at higher levels. While adults are not as sensitive as children, there is evidence for a rather selective loss of memory function in adults exposed to the same substances. Our group has attempted to determine the mechanisms whereby these effects occur using long-term potentiation (LTP), an electrophysiological measure known to be related to learning and memory, studied in rodent brain slices. We find that lead and PCBs both reduce LTP whether given during gestation and lactation or acutely applied to brain slices of unexposed animals. Surprisingly, these very different contaminants appear to have a similar mechanism of action, that being alteration of the activity of protein kinase C.

Growth Hormone Deficiency and Memory Functioning in Adults Visualized by Functional Magnetic Resonance Imaging

Cognitive functioning, especially memory performance, is known to be impaired in patients with childhood-onset growth hormone deficiency (CO-GHD), and growth hormone substitution has been found to counteract this memory impairment. Neuropsychological and functional magnetic resonance imagining (fMRI) data acquired during a working memory task in 13 childhood-onset GH-deficient patients were compared with 13 age, sex and education level matched healthy controls. Results demonstrated that there is no difference in the quality of the performance in the working memory task between GH-deficient patients and control subjects. However, memory speed was found to be subnormal in patients. Concerning mood, patients reported more complaints of fatigue, and less vigor. Imaging data showed that patients had increased activity in dorsolateral/ventrolateral prefrontal cortex, anterior cingulate cortex, parietal cortex, supplementary motor and motor cortex, as well as in the thalamus and precuneus area. Increasing task load was also associated with an increase in brain activity in similar areas in patients compared to control subjects. In conclusion, this fMRI study shows that GH-deficient patients have a subnormal memory speed, but no impaired quality of memory performance, which may be due to compensatory recruitment of dorsal prefrontal brain regions. These findings indicate that the GH-IGF-1 axis contributes to prefrontal functioning in patients with CO-GHD.

Current Awareness in NMR in Biomedicine

Current Awareness in NMR in Biomedicine

Utilization deficiency and working memory capacity in adult memory performance: not just for children anymore

In acquiring mnemonic strategies, children may demonstrate a utilization deficiency phase in which they successfully execute a strategy but it does not facilitate memory performance. The present experiment suggests that utilization deficiencies are not a developmental phenomenon per se, but rather a byproduct of diminished working memory capacity for any reason (i.e., maturation, knowledge base, context, individual differences, etc.). Adults performing a series of study-test memory trials using nonsense words exhibited characteristics of utilization deficiencies, with increased strategy use not contributing to increased memory performance. Furthermore, adults’ working memory capacity modified the effect. Implications of these findings for developmental models of strategy acquisition are discussed.

Attributions for Memory Performance in Adulthood: Age Differences and Mediation Effects

We examined age differences in attributions to internal (controllable and uncontrollable), external (uncontrollable), and unstable factors for performance on a free recall memory task in 149 young, middle-aged, and older adults. Attributions varied by age and by level of memory performance. Middle-aged and older adults rated internal, uncontrollable factors (ability and genes) as more influential for high performance than for low performance, and they were less likely than young adults to attribute low performance to these factors. Within age groups, only the older adults rated memory ability as more influential than strategy use, even though they were as likely as the other age groups to use a categorization strategy. Attributions to both internal controllable (strategy use) and uncontrollable (ability) factors as well as to health were associated with better memory performance. These attributions partially mediated the relationship between age and memory performance. Thus, attributions may provide some insight into sources of age differences in memory performance.

The involvement of executive functions in prospective memory performance of adults

The present study examines the relationship between prospective memory performance and executive functioning. The four phases of the prospective memory process—intention formation, intention retention, reinstantiation of the intention, and intention execution—are assumed to require different amounts of executive processing, most of which is demanded in the phases of intention formation and intention execution. At present, though, it is still unclear whether, and to what extent, prefrontal executive systems are involved in different kinds of prospective memory tasks, as some findings suggest that prospective memory might rather rely on nonstrategic processes that are unlikely to depend on prefrontal executive systems. Therefore, this study focuses on the following questions: (1) to what degree does executive functioning predict prospective memory performance in different standard prospective memory tasks and, furthermore, are certain executive measures better predictors than others; (2) are age‐related effects in different prospective memory measures due to individual differences in executive functioning; and (3) do age‐related differences in prospective memory exist that are not explained by individual differences in executive functioning. In a sample of 80 adults (20‐80 years), we applied four instruments to measure prospective memory: a traditional single‐task paradigm, two more complex tasks—one time‐based and one event‐based—and a highly complex multi‐task paradigm. We further assessed a broadly defined construct of executive functioning using several standard neuropsychological tests. Results showed that executive functioning did not predict performance in the simple single‐task paradigm. However, executive functioning, but not age, predicted performance in the two more complex standard tests of prospective remembering, and both executive functioning and age predicted performance in the most complex paradigm. In sum, the obtained data underline the assumption that frontal/ executive functions are related to prospective memory performance across a range of prospective paradigms. It also seems clear that age differences in prospective memory performance partially depend on age‐related individual differences in frontal/executive functions.