fMRI studies of associative encoding in young and elderly controls and mild Alzheimer's disease

Sperling, Reisa A.; Bates, Julianna F.; Chua, Elizabeth F.; Cocchiarella, Andrew; Rentz, D.; Rosen, Bruce R.; Schacter, Daniel L.; Albert, Marilyn

doi:10.1136/jnnp.74.1.44

Cited by 410 publications

(353 citation statements)

References 30 publications

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“…Participants were explicitly instructed to try to remember the name associated with each face, and to make a decision regarding whether they thought the name "fit" the face (i.e., "was a good name for that face") or not. This is a purely subjective decision, which has been shown to enhance associative encoding (Sperling et al, 2003a). The stimuli were arranged in a block design and each run consisted of three conditions: novel face-name pairs, repeated face-name pairs, and fixation.…”

Section: Mri Proceduresmentioning

confidence: 99%

Alterations in Memory Networks in Mild Cognitive Impairment and Alzheimer's Disease: An Independent Component Analysis

Celone¹,

Calhoun²,

Dickerson³

et al. 2006

J. Neurosci.

641

560

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Memory function is likely subserved by multiple distributed neural networks, which are disrupted by the pathophysiological process of Alzheimer's disease (AD). In this study, we used multivariate analytic techniques to investigate memory-related functional magnetic resonance imaging (fMRI) activity in 52 individuals across the continuum of normal aging, mild cognitive impairment (MCI), and mild AD. Independent component analyses revealed specific memory-related networks that activated or deactivated during an associative memory paradigm. Across all subjects, hippocampal activation and parietal deactivation demonstrated a strong reciprocal relationship. Furthermore, we found evidence of a nonlinear trajectory of fMRI activation across the continuum of impairment. Less impaired MCI subjects showed paradoxical hyperactivation in the hippocampus compared with controls, whereas more impaired MCI subjects demonstrated significant hypoactivation, similar to the levels observed in the mild AD subjects. We found a remarkably parallel curve in the pattern of memory-related deactivation in medial and lateral parietal regions with greater deactivation in less-impaired MCI and loss of deactivation in more impaired MCI and mild AD subjects. Interestingly, the failure of deactivation in these regions was also associated with increased positive activity in a neocortical attentional network in MCI and AD. Our findings suggest that loss of functional integrity of the hippocampal-based memory systems is directly related to alterations of neural activity in parietal regions seen over the course of MCI and AD. These data may also provide functional evidence of the interaction between neocortical and medial temporal lobe pathology in early AD.

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Section: Mri Proceduresmentioning

confidence: 99%

Alterations in Memory Networks in Mild Cognitive Impairment and Alzheimer's Disease: An Independent Component Analysis

Celone¹,

Calhoun²,

Dickerson³

et al. 2006

J. Neurosci.

641

560

View full text Add to dashboard Cite

show abstract

“…Such facts are based on studies using post-mortem examination 6 , structural imaging 7 , resting metabolism 8 and functional imaging [9][10][11][12][13][14] .…”

mentioning

confidence: 99%

Alzheimer's disease and implicit memory

Machado

Cunha

Minc

et al. 2009

Arq. Neuro-Psiquiatr.

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-Specific neuropsychiatric disorders, such as Alzheimer's disease (AD) affect some forms of memory while leaving others relatively intact. In this review, we investigate particularities of the relationship between explicit and implicit memories in AD. It was found that implicit memory is preserved in AD, irrespective of the task used; in other words, there was not interference from explicit memory. In addition, it was verified that is possible through implicit memory compensatory strategies such as, activities of daily living (ADL) to compensate for the explicit memory deficits. In this sense, cognitive rehabilitation (CR) demonstrates reasonable results in the process of compensation of explicit memory deficits. Concluding, the decline in explicit memory suggests that both systems are functionally independent even if the other is compromised. We expect that when explicit memory system is not involved in competition with the implicit system, the final effect of learning is better, because all of the implicit memory capacity is engaged in learning and not in competition with the explicit system. Key WoRDS: activities of daily living, Alzheimer's disease, cognitive rehabilitation, implicit memory. Doença de Alzheimer e memória implícitaResumo -Distúrbios neuropsiquiátricos específicos, tais como a doença de Alzheimer (DA), podem afetar algumas formas de memória enquanto deixam outros relativamente intactos. Nesta revisão, nós investigamos particularidades da relação entre as memórias explicita e implícita na DA. Foi verificado que a memória é preservada na DA, independente da tarefa usada; ou seja, não ocorre interferência da memória explícita. Além disso, foi verificado que é possível através de estratégias compensatórias de memória implícita, tais como, atividades da vida diária (AVD) compensar os déficits da memória explícita. Neste sentido, a reabilitação cognitiva (RC) demonstra resultados razoáveis no processo de compensação dos déficits da memória explicita. Concluindo, a queda na memória explícita sugere que ambos os sistemas são funcionalmente independentes mesmo que outro esteja comprometido. esperamos que quando o sistema de memória explícita não está envolvido em competição com o sistema implícito, o efeito final de aprendizagem é melhor, porque toda a capacidade da memória implícita está engajada na aprendizagem e não na competição com o sistema explícito. PALAVRAS-ChAVe: atividades da vida diária, doença de Alzheimer, memória implícita, reabilitação cognitiva.

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“…Measurements of brain activation with functional MRI (fMRI) show that activation patterns are different in people with AD compared with cognitively normal elderly, using activation paradigms such as visual saccades, visual and motor responses, semantic processing, angle discrimination, and memory. [45][46][47][48][49][50][51][52][53] All MR measurements discussed in this section are sensitive to a certain feature of AD pathology in people who are clinically diagnosed as AD. Autopsy studies, however, indicate that the pathology of AD precedes the clinical diagnosis of dementia, perhaps by decades.…”

mentioning

confidence: 99%

Quantitative magnetic resonance techniques as surrogate markers of Alzheimer’s disease

Kantarci

Jack

2004

Neurotherapeutics

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Summary: Recent advances in understanding the molecular biology of Alzheimer's disease (AD) offer the promise of useful therapeutic intervention in the foreseeable future. Hence, improved methods for early diagnosis and noninvasive surrogates of disease severity in AD have become more imperative. Various quantitative magnetic resonance (MR) techniques that measure the anatomic, biochemical, microstructural, functional, and blood-flow changes are being evaluated as possible surrogate measures of disease progression. Cross-sectional and longitudinal studies indicate that MR-based volume measurements are potential surrogates of disease progression in AD, starting from the preclinical stages. The validity of MR-based volumetry as a surrogate marker for therapeutic efficacy in AD remains to be tested in a positive disease-modifying drug trial. Recent development of amyloid imaging tracers for positron emission tomography has been a major breakthrough in the field of imaging markers for AD. Efforts to image plaques are also underway in MR imaging. As with indirect MR measures, these approaches of directly imaging the pathological substrate will need to undergo a validation process with longitudinal studies to prove their usefulness as surrogate markers in AD.

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fMRI studies of associative encoding in young and elderly controls and mild Alzheimer's disease

Cited by 410 publications

References 30 publications

Alterations in Memory Networks in Mild Cognitive Impairment and Alzheimer's Disease: An Independent Component Analysis

Alterations in Memory Networks in Mild Cognitive Impairment and Alzheimer's Disease: An Independent Component Analysis

Alzheimer's disease and implicit memory

Quantitative magnetic resonance techniques as surrogate markers of Alzheimer’s disease

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