Publications by authors named "Darlene Howard"

Relating individual differences in cognitive abilities to neural substrates in older adults is of significant scientific and clinical interest, but remains a major challenge. Previous functional magnetic resonance imaging (fMRI) studies of cognitive aging have mainly focused on the amplitude of fMRI response, which does not measure neuronal selectivity and has led to some conflicting findings. Here, using local regional heterogeneity analysis, or , a novel fMRI analysis technique developed to probe the sparseness of neuronal activations as an indirect measure of neuronal selectivity, we found that individual differences in two different cognitive functions, episodic memory and letter verbal fluency, are selectively related to -estimated neuronal selectivity at their corresponding brain regions (hippocampus and visual-word form area, respectively).

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Accumulating evidence suggests that physical activity improves explicit memory and executive cognitive functioning at the extreme ends of the lifespan (i.e., in older adults and children).

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Language learners must place unfamiliar words into categories, often with few explicit indicators about when and how that word can be used grammatically. Reeder, Newport, and Aslin (2013) showed that college students can learn grammatical form classes from an artificial language by relying solely on distributional information (i.e.

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Accumulating evidence shows a positive relationship between mindfulness and explicit cognitive functioning, i.e., that which occurs with conscious intent and awareness.

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As our society becomes more mobile and people reside farther away from their immediate families, competent decision-making has become critical for the older adults wishing to maintain their independence. However, very little is known about the relationship between residential choice and decision-making. Here we use the Balloon Analog Risk Task (BART) to examine risk-taking in two samples of older adults, one living in a retirement community and another living independently.

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There is currently some debate as to whether hippocampus mediates contextual cueing. In the present study, we examined contextual cueing in patients diagnosed with mild cognitive impairment (MCI) and healthy older adults, with the main goal of investigating the role of hippocampus in this form of learning. Amnestic MCI (aMCI) patients and healthy controls completed the contextual cueing task, in which they were asked to search for a target (a horizontal T) in an array of distractors (rotated L's).

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Recent studies have shown age-related deficits in learning subtle probabilistic sequential relationships. However, virtually all sequence learning studies have displayed successive events one at a time. Here we used a modified Triplets Learning Task to investigate if an age deficit occurs even when sequentially-presented predictive events remain in view simultaneously.

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Unlabelled: BACKGROUND/STUDY CONTEXT: Attention Restoration Theory (Kaplan, 1995, Journal of Environmental Psychology, 15, 169-182) suggests that exposure to nature improves attention. Berman, Jonides, and Kaplan (2008, Psychological Science, 19, 1207-1212) showed that simply viewing nature pictures improves executive attention in young adults. The present study is the first to investigate this Nature Effect in older adults.

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Objective: The primary objective was to determine whether age deficits in implicit sequence learning occur not only for second-order probabilistic regularities (event n - 2 predicts n), as reported earlier, but also for first-order regularities (event n - 1 predicts event n). A secondary goal was to determine whether age differences in learning vary with level of structure.

Method: Younger and older adults completed a nonmotor sequence learning task containing either a first- or second-order structure.

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Implicit sequence learning involves learning about dependencies in sequences of events without intent to learn or awareness of what has been learned. Sequence learning is related to striatal dopamine levels, striatal activation, and integrity of white matter connections. People with Parkinson's disease (PD) have degeneration of dopamine-producing neurons, leading to dopamine deficiency and therefore striatal deficits, and they have difficulties with sequencing, including complex language comprehension and postural stability.

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Implicit learning, the type of learning that occurs without intent to learn or awareness of what has been learned, has been thought to be insensitive to the effects of priming, but recent studies suggest this is not the case. One study found that learning in the serial reaction time (SRT) task was improved by nonconscious goal pursuit, primed via a word search task (Eitam et al. in Psychol Sci 19:261-267, 2008).

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Behavioral and neuroimaging evidence suggest that mindfulness exerts its salutary effects by disengaging habitual processes supported by subcortical regions and increasing effortful control processes supported by the frontal lobes. Here we investigated whether individual differences in dispositional mindfulness relate to performance on implicit sequence learning tasks in which optimal learning may in fact be impeded by the engagement of effortful control processes. We report results from two studies where participants completed a widely used questionnaire assessing mindfulness and one of two implicit sequence learning tasks.

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Purpose: To determine if older patients with breast cancer have cognitive impairment before systemic therapy.

Patients And Methods: Participants were patients with newly diagnosed nonmetastatic breast cancer and matched friend or community controls age > 60 years without prior systemic treatment, dementia, or neurologic disease. Participants completed surveys and a 55-minute battery of 17 neuropsychological tests.

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Differences in strategy use are thought to underlie age-related performance deficits on many learning and decision-making tasks. Recently, age-related differences in learning to make predictions were reported on the Triplets Prediction Task (TPT). Notably, deficits appeared early in training and continued with experience.

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There is a fairly consistent, albeit non-universal body of research documenting cognitive declines after cancer and its treatments. While few of these studies have included subjects aged 65 years and older, it is logical to expect that older patients are at risk of cognitive decline. Here, we use breast cancer as an exemplar disease for inquiry into the intersection of aging and cognitive effects of cancer and its therapies.

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It is often held that although explicit learning declines in the course of normal aging, implicit learning is relatively preserved. Here we summarize research from our group which leads us to argue that some forms of implicit learning do decline with adult age. In particular, we propose that there are age-related declines in implicit learning of probabilistic sequential relationships that occur across the adult lifespan, and that they reflect, at least in part, age-related striatal dysfunction.

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Abstract Implicit probabilistic sequence learning (IPSL) involves extracting statistical regularities from sequences of events without awareness, and is thought to underlie learning of language and behavioral repertoires of everyday life. We examined whether resting-state functional connectivity networks of the caudate predicted individual differences in IPSL performance measured on a separate day. Whole-brain connectivity maps of a bilateral dorsal caudate (DC) seed were created for each subject and examined for voxelwise correlations with sequence learning performance, as well as with overall response speed.

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It has been proposed that an impairment of procedural memory underlies a range of linguistic, cognitive and motor impairments observed in developmental dyslexia (DD). However, studies designed to test this hypothesis using the implicit sequence learning paradigm have yielded inconsistent results. A fundamental aspect of procedural learning is that it takes place over an extended time-period that may be divided into distinct stages based on both behavioural characteristics and neural correlates of performance.

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A number of studies have shown that information is remembered better when it is processed for its survival relevance than when it is processed for relevance to other, non-survival-related contexts. Here we conducted three experiments to investigate whether the survival advantage also occurs for healthy older adults. In Experiment 1, older and younger adults rated words for their relevance to a grassland survival or moving scenario and then completed an unexpected free recall test on the words.

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Objectives: Much of adaptive behavior relies on the ability to learn and generate predictions about relationships in the environment. Research on aging suggests both that there is an age deficit in the ability to learn sequential relationships and that this deficit in learning could underlie age differences reported in many decision-making tasks. This article introduces the Triplets Prediction Task (TPT) to investigate the learning of sequential relationships that underlies adaptive behavior.

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This study investigated the effects of a simultaneous memory load on implicit associative sequence learning using the Triplets Learning Task (TLT). Participants in the Simultaneous condition held a secondary task memory load during the TLT, while those in the Sequential condition also performed both tasks, but successively, rather than simultaneously. Thus, the Simultaneous condition had a memory load during the TLT, while the Sequential condition did not.

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Few studies have investigated how aging influences the neural basis of implicit associative learning, and available evidence is inconclusive. One emerging behavioral pattern is that age differences increase with practice, perhaps reflecting the involvement of different brain regions with training. Many studies report hippocampal involvement early on with learning becoming increasingly dependent on the caudate with practice.

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Background: During sentence processing we decode the sequential combination of words, phrases or sentences according to previously learned rules. The computational mechanisms and neural correlates of these rules are still much debated. Other key issue is whether sentence processing solely relies on language-specific mechanisms or is it also governed by domain-general principles.

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Objective: It is unclear whether implicit probabilistic learning, the acquisition of regularities without intent or explicit knowledge, declines with healthy aging.

Methods: Because age differences in previous work might reflect motor or rule learning deficits, we used the implicit Triplets Learning Task with reduced motor sequencing and non-rule-based associations. Fifteen young and 15 old adults responded only to the last event in a series of discrete 3-event sequences or triplets.

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Implicit learning, the non-conscious acquisition of sequential and spatial environmental regularities, underlies skills such as language, social intuition, or detecting a target in a complex scene. We examined relationships between a variation of the dopamine transporter (DAT1) gene (SLC6A3), which influences dopamine transporter expression in the striatum, and two forms of implicit learning that differ in the regularity to be learned and in striatal involvement. Participants, grouped as 9-repeat carriers or 10/10 homozygotes, completed the triplets learning task (TLT) and the spatial contextual cueing task (SCCT).

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