Age-Related Deficits in Component Processes of Working Memory

Department of Psychology, University of California, Berkeley, Berkeley, California, United States
Neuropsychology (Impact Factor: 3.27). 10/2007; 21(5):532-9. DOI: 10.1037/0894-4105.21.5.532
Source: PubMed


Working memory deficits in normal aging have been well documented, and studies suggest that high memory load plus the presence of distraction negatively impacts successful memory performance to a greater degree in older individuals. However, characterization of the component processes that are impaired by these task manipulations is not clear. In this behavioral study, younger and older subjects were tested with a delayed-recognition and recall task in which the encoding and delay period were both manipulated. During the encoding period, the subjects were presented with either a single letter or multiple letters at their predetermined forward letter span, and the delay period was either uninterrupted or interrupted with a visual distraction. There was an age-related impairment of working memory recognition accuracy only in the combination of high memory load and distraction. These results suggest that when working memory maintenance systems are taxed, faulty recognition processes may underlie cognitive aging deficits in healthy older individuals.

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Available from: Mark D'Esposito, Jan 07, 2015
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    • "Communication is more efficient in the presence of less noise (Shannon, 1948), whether that communication is between friends in a crowded room or between a radio transmitter and receiver tuned to a favorite station. As we age, we are faced with the likelihood that our cognitive faculties will decline (Gazzaley et al., 2007; Salthouse, 2010), our neural and behavioral response times will be slower and more variable (Salthouse, 2010), our memories less certain (Nyberg et al., 2012), and our attention less focused (Gazzaley et al., 2005). The neural noise hypothesis is an attempt to account for these age-related changes and states that, with aging, the effective signal-to-noise of neural communication diminishes (Cremer and Zeef, 1987). "
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    ABSTRACT: Aging is associated with performance decrements across multiple cognitive domains. The neural noise hypothesis, a dominant view of the basis of this decline, posits that aging is accompanied by an increase in spontaneous, noisy baseline neural activity. Here we analyze data from two different groups of human subjects: intracranial electrocorticography from 15 participants over a 38 year age range (15–53 years) and scalp EEG data from healthy younger (20–30 years) and older (60–70 years) adults to test the neural noise hypothesis from a 1/f noise perspective. Many natural phenomena, including electrophysiology, are characterized by 1/f noise. The defining characteristic of 1/f is that the power of the signal frequency content decreases rapidly as a function of the frequency (f) itself. The slope of this decay, the noise exponent (χ), is often <−1 for electrophysiological data and has been shown to approach white noise (defined as χ = 0) with increasing task difficulty. We observed, in both electrophysiological datasets, that aging is associated with a flatter (more noisy) 1/f power spectral density, even at rest, and that visual cortical 1/f noise statistically mediates age-related impairments in visual working memory. These results provide electrophysiological support for the neural noise hypothesis of aging.
    The Journal of Neuroscience : The Official Journal of the Society for Neuroscience 09/2015; 35(38):13257-13265. DOI:10.1523/JNEUROSCI.2332-14.2015 · 6.34 Impact Factor
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    • "Recent evidence have led several authors to suggest that such age-related decline in WM is mainly caused by changes in brain activity during information encoding (Friedman et al., 2007; Finnigan et al., 2011; Craik and Rose, 2012), especially when the encoding strategies are self-initiated, i.e., without specific instructions about how to encode information (Hashtroudi et al., 1989; Friedman et al., 2007; Craik and Rose, 2012). Moreover, differences in mnemonic capacities associated with normal aging are enhanced in tasks that impose high demands in cognitive abilities, such as those in which memory load is manipulated (Oberauer and Kliegl, 2001; Buckner, 2004; Gazzaley et al., 2007). "
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    ABSTRACT: Memory capacity suffers an age-related decline, which is supposed to be due to a generalized slowing of processing speed and to a reduced availability of processing resources. Information encoding in memory has been demonstrated to be very sensitive to age-related changes, especially when carried out through self-initiated strategies or under high cognitive demands. However, most ERP research on age-related changes in working memory (WM) has used tasks that preclude distinction between age-related changes in encoding and retrieval processes. Here, we used ERP recording and a delayed match to sample (DMS) task with two levels of memory load to assess age-related changes in electrical brain activity in young and old adults during successful information encoding in WM. Age-related decline was reflected in lower accuracy rates and longer reaction times in the DMS task. Beside, only old adults presented lower accuracy rates under high than low memory load conditions. However, effects of memory load on brain activity were independent of age and may indicate an increased need of processing after stimulus classification as reflected in larger mean voltages in high than low load conditions between 550 and 1000 ms post-stimulus for young and old adults. Regarding age-related effects on brain activity, results also revealed smaller P2 and P300 amplitudes that may signal the existence of an age dependent reduction in the processing resources available for stimulus evaluation and categorization. Additionally, P2 and N2 latencies were longer in old than in young participants. Furthermore, longer N2 latencies were related to greater accuracy rates on the DMS task, especially in old adults. These results suggest that age-related slowing of processing speed may be specific for target stimulus analysis and evaluation processes. Thus, old adults seem to improve their performance the longer they take to evaluate the stimulus they encode in visual WM.
    Frontiers in Aging Neuroscience 05/2015; 7. DOI:10.3389/fnagi.2015.00075 · 4.00 Impact Factor
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    • "Affective WM tasks are thus classical WM tasks that require the processing of affective stimuli (e.g., positive and negative pictures or words). Most interestingly, this system seems to show a different trajectory in the aging mind compared to classical WM functions and although WM deficits, in general, are typically cited as one of the principal cognitive indexes of pathological aging [8], studies about emotional effects in WM in dementia of Alzheimer's type (DAT) patients are only at the beginning. Consequently, here, we aimed to review a series of studies with DAT patients that show emotion modulation in WM performance during the active manipulation of affective tobe-remembered stimuli. "
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    ABSTRACT: A number of recent studies have reported that working memory does not seem to show typical age-related deficits in healthy older adults when emotional information is involved. Differently, studies about the short-term ability to encode and actively manipulate emotional information in dementia of Alzheimer's type are few and have yielded mixed results. Here, we review behavioural and neuroimaging evidence that points to a complex interaction between emotion modulation and working memory in Alzheimer's. In fact, depending on the function involved, patients may or may not show an emotional benefit in their working memory performance. In addition, this benefit is not always clearly biased (e.g., towards negative or positive information). We interpret this complex pattern of results as a consequence of the interaction between multiple factors including the severity of Alzheimer's disease, the nature of affective stimuli, and type of working memory task.
    International Journal of Alzheimer's Disease 02/2014; 2014:207698. DOI:10.1155/2014/207698
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