Relation of cognitive reserve and task performance to expression of regional covariance networks in an event-related fMRI study of nonverbal memory

Columbia University, New York, New York, United States
NeuroImage (Impact Factor: 6.36). 12/2003; 20(3):1723-33. DOI: 10.1016/j.neuroimage.2003.07.032
Source: PubMed


Cognitive reserve (CR) has been established as a mechanism that can explain individual differences in the clinical manifestation of neural changes associated with aging or neurodegenerative diseases. CR may represent individual differences in how tasks are processed (i.e., differences in the component processes), or in the underlying neural circuitry (of the component processes). CR may be a function of innate differences or differential life experiences. To investigate to what extent CR can account for individual differences in brain activation and task performance, we used fMRI to image healthy young individuals while performing a nonverbal memory task. We used IQ estimates as a proxy for CR. During both study and test phase of the task, we identified regional covariance patterns whose change in subject expression across two task conditions correlated with performance and CR. Common brain regions in both activation patterns were suggestive of a brain network previously found to underlie overt and covert shifts of spatial attention. After partialing out the influence of task performance variables, this network still showed an association with the CR, i.e., there were reserve-related physiological differences that presumably would persist were there no subject differences in task performance. This suggests that this network may represent a neural correlate of CR.

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Available from: Christian Habeck
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    • "Finally, task complexity is determined by the level of task difficulty relative to the expertise and abilities of the performer, known as " nominal task difficulty " according to Guadagnoli and Lee's Challenge Point Framework for motor learning [40]. In aging and disease states, declines in sensorimotor and cognitive functions may lead to reduced postural reserve [41] and cognitive reserve [42] creating overall greater demands for attention to the task. Interestingly, a recent review proposes that postural control in single and dual task conditions is influenced by a ratio of controlled (cognitive) to automatic processing that is determined by task difficulty [28]. "
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    ABSTRACT: The study of dual task interference has gained increasing attention in the literature for the past 35 years, with six MEDLINE citations in 1979 growing to 351 citations indexed in 2014 and a peak of 454 cited papers in 2013. Increasingly, researchers are examining dual task cost in individuals with pathology, including those with neurodegenerative diseases. While the influence of these papers has extended from the laboratory to the clinic, the field has evolved without clear definitions of commonly used terms and with extreme variations in experimental procedures. As a result, it is difficult to examine the interference literature as a single body of work. In this paper we present a new taxonomy for classifying cognitive-motor and motor-motor interference within the study of dual task behaviors that connects traditional concepts of learning and principles of motor control with current issues of multitasking analysis. As a first step in the process we provide an operational definition of dual task, distinguishing it from a complex single task. We present this new taxonomy, inclusive of both cognitive and motor modalities, as a working model; one that we hope will generate discussion and create a framework from which one can view previous studies and develop questions of interest.
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    • "This behavioral sparing may be mediated by high levels of education or IQ (Snowdon, Greiner, & Markesbery, 2000). Several neuroimaging studies have recently been conducted to examine the brain substrates supporting cognitive reserve (Habeck et al., 2003; Scarmeas et al., 2003). However the possible role played by education is still not determined. "

    Full-text · Dataset · Feb 2015
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    • "Several studies have tried to determine the anatomical and functional mechanisms/features underlying CR. These studies have provided evidence that CR contributes to modulate brain activity and effectiveness when executing cognitive tasks (Habeck et al., 2003; Scarmeas et al., 2003; Bartrés-Faz et al., 2009; Solé- Padullés et al., 2009; Stern et al., 2012). Results from these studies reveal that, in order to achieve a similar level of performance during cognitive tasks, participants with low CR show higher brain activation than participants with high CR. "
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    ABSTRACT: authors have contributed equally to this work. The proportion of elderly people in the population has increased rapidly in the last century and consequently "healthy aging" is expected to become a critical area of research in neuroscience. Evidence reveals how healthy aging depends on three main behavioral factors: social lifestyle, cognitive activity, and physical activity. In this study, we focused on the role of cognitive activity, concentrating specifically on educational and occupational attainment factors, which were considered two of the main pillars of cognitive reserve (CR). Twenty-one subjects with similar rates of social lifestyle, physical and cognitive activity were selected from a sample of 55 healthy adults. These subjects were divided into two groups according to their level of CR; one group comprised subjects with high CR (9 members) and the other one contained those with low CR (12 members). To evaluate the cortical brain connectivity network, all participants were recorded by Magnetoencephalography (MEG) while they performed a memory task (modified version of the Sternberg's Task). We then applied two algorithms [Phase Locking Value (PLV) and Phase Lag Index (PLI)] to study the dynamics of functional connectivity. In response to the same task, the subjects with lower CR presented higher functional connectivity than those with higher CR. These results may indicate that participants with low CR needed a greater "effort" than those with high CR to achieve the same level of cognitive performance. Therefore, we conclude that CR contributes to the modulation of the functional connectivity patterns of the aging brain.
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