Working memory.

Henry H. Wheeler Jr Brain Imaging Center, Helen Wills Neuroscience Institute and the Department of Psychology, University of California, Berkeley, CA 94720-3190, USA.
Handbook of Clinical Neurology 01/2008; 88:237-47. DOI: 10.1016/S0072-9752(07)88011-0
Source: PubMed
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    ABSTRACT: Abstract Nearly 25 years ago, Mirsky and colleagues proposed a multiple-component model of attention. It was proposed that attention was characterized by several distinct elements that were organized into a system. A putative neuroanatomical substrate of this model of attention was proposed. This functional anatomy was primarily based upon inferences derived from brain lesion studies. Mirsky and colleagues developed a systematic clinical evaluation of this model by applying a group of neuropsychological tests. Since the introduction of what has been commonly referred to as the "Mirsky model," significant advances have been made in our understanding of brain-behavior relationships. This article applies current neuroscientific principles to "update" our understanding of attention and the "Mirsky model." We also demonstrate how the interpretation of neuropsychological tests can be modified according to principles of large-scale brain systems and patterns of brain network functional connectivity.
    Applied neuropsychology. Child. 02/2014;
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    ABSTRACT: PURPOSE: Temporal lobe epilepsy (TLE) has been considered to impair long-term memory, whilst not affecting working memory, but recent evidence suggests that working memory is compromised. Functional MRI (fMRI) studies demonstrate that working memory involves a bilateral frontoparietal network the activation of which is disrupted in hippocampal sclerosis (HS). A specific role of the hippocampus to deactivate during working memory has been proposed with this mechanism faulty in patients with HS. Structural correlates of disrupted working memory in HS have not been explored. METHODS: We studied 54 individuals with medically refractory TLE and unilateral HS (29 left) and 28 healthy controls. Subjects underwent 3T structural MRI, a visuospatial n-back fMRI paradigm and diffusion tensor imaging (DTI). Working memory capacity assessed by three span tasks (digit span backwards, gesture span, motor sequences) was combined with performance in the visuospatial paradigm to give a global working memory measure. Gray and white matter changes were investigated using voxel-based morphometry and voxel-based analysis of DTI, respectively. KEY FINDINGS: Individuals with left or right HS performed less well than healthy controls on all measures of working memory. fMRI demonstrated a bilateral frontoparietal network during the working memory task with reduced activation of the right parietal lobe in both patient groups. In left HS, gray matter loss was seen in the ipsilateral hippocampus and parietal lobe, with maintenance of the gray matter volume of the contralateral parietal lobe associated with better performance. White matter integrity within the frontoparietal network, in particular the superior longitudinal fasciculus and cingulum, and the contralateral temporal lobe, was associated with working memory performance. In right HS, gray matter loss was also seen in the ipsilateral hippocampus and parietal lobe. Working memory performance correlated with the gray matter volume of both frontal lobes and white matter integrity within the frontoparietal network and contralateral temporal lobe. SIGNIFICANCE: Our data provide further evidence that working memory is disrupted in HS and impaired integrity of both gray and white matter is seen in functionally relevant areas. We suggest this forms the structural basis of the impairment of working memory, indicating widespread and functionally significant structural changes in patients with apparently isolated HS.
    Epilepsia 04/2013; · 4.58 Impact Factor
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    ABSTRACT: Cognitive impairment and memory dysfunction following stroke diagnosis are common symptoms that significantly affect the survivors' quality of life. Stroke patients have a high potential to develop dementia within the first year of stroke onset. Currently, efforts are being exerted to assess stroke effects on the brain, particularly in the early stages. Numerous neuropsychological assessments are being used to evaluate and differentiate cognitive impairment and dementia following stroke. This article focuses on the role of available neuropsychological assessments in detection of dementia and memory loss after stroke. This review starts with stroke types and risk factors associated with dementia development, followed by a brief description of stroke diagnosis criteria and the effects of stroke on the brain that lead to cognitive impairment and end with memory loss. This review aims to combine available neuropsychological assessments to develop a post-stroke memory assessment (PSMA) scheme based on the most recognized and available studies. The proposed PSMA is expected to assess different types of memory functionalities that are related to different parts of the brain according to stroke location. An optimal therapeutic program that would help stroke patients enjoy additional years with higher quality of life is presented.
    Neuropsychiatric Disease and Treatment 01/2014; 10:1677-91. · 2.00 Impact Factor