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  1. AU="Samira Mellah"
  2. AU="Al-Embideen S." AU="Al-Embideen S."
  3. AU="Kushiro, Tetsuo"
  4. AU="Spec, Andrej"
  5. AU="Salaniwal, Arul"
  6. AU="Epps, Chad A."
  7. AU=Brandt Ulrich
  8. AU="Kim, Hoyong"
  9. AU="Klas Bratteby"
  10. AU="Kim, Sae-Hoon"
  11. AU=Spivak Jerry L
  12. AU="Joel, Anjana"
  13. AU="Hill, William"
  14. AU="Ken M. Cadigan"
  15. AU="Lee, Hyun-Shik"
  16. AU="Martini, Denise"
  17. AU=Aziz Noreen M
  18. AU="Ho, Tony"
  19. AU=Barzilay Joshua I.
  20. AU="Ishizaka, Alessio"
  21. AU="Chao, Pei-Dawn Lee"
  22. AU="Rosa Gouveia"

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  1. Artikel ; Online: Latent patterns of task-related functional connectivity in relation to regions of hyperactivation in individuals at risk of Alzheimer’s disease

    Nick Corriveau-Lecavalier / M. Natasha Rajah / Samira Mellah / Sylvie Belleville

    NeuroImage: Clinical, Vol 30, Iss , Pp 102643- (2021)

    2021  

    Abstract: The goal of this study was to assess how task-related hyperactivation relates to brain network dysfunction and memory performance in individuals at risk of Alzheimer’s disease (AD). Eighty participants from the CIMA-Q cohort were included, of which 28 ... ...

    Abstract The goal of this study was to assess how task-related hyperactivation relates to brain network dysfunction and memory performance in individuals at risk of Alzheimer’s disease (AD). Eighty participants from the CIMA-Q cohort were included, of which 28 had subjective cognitive decline plus (SCD+), as they had memory complaints and worries in addition to a smaller hippocampal volume and/or an APOE4 allele, 26 had amnestic mild cognitive impairment (MCI) and 26 were healthy controls without memory complaints. Functional magnetic resonance imaging (fMRI) activation was measured during an object-location memory task. Seed-partial least square analyses (seed-PLS) were conducted in controls and in the SCD+/MCI groups to yield sets of orthogonal latent variables (LVs) assessing the triple association between: i) seed activity in brain regions found to be hyperactive in individuals at risk of AD (left hippocampus, left superior parietal lobule, right inferior temporal lobe), ii) latent patterns of whole-brain task-related activation, and iii) associative memory performance. Three LVs in the SCD+ and MCI groups (67.88% of total covariance explained) and two LVs in the controls (77.85% of total covariance explained) were significant. While controls and SCD+/MCI groups shared a common pattern of memory-related connectivity, patterns of hyperactivation-networks interactions were unique to the clinical groups. Interestingly, higher hippocampal connectivity was associated with poorer memory performance whereas higher neocortical connectivity predicted better memory performance in SCD+ and MCI groups. Our data provides empirical evidence that early dysfunction in brain activation and connectivity is present in the very early stages of AD and offers new insights on the relationship between functional brain alterations and memory performance.
    Schlagwörter Functional connectivity ; Hyperactivation ; Mild cognitive impairment ; Subjective cognitive decline ; Task-related fMRI ; Computer applications to medicine. Medical informatics ; R858-859.7 ; Neurology. Diseases of the nervous system ; RC346-429
    Thema/Rubrik (Code) 150
    Sprache Englisch
    Erscheinungsdatum 2021-01-01T00:00:00Z
    Verlag Elsevier
    Dokumenttyp Artikel ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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  2. Artikel ; Online: Evidence of parietal hyperactivation in individuals with mild cognitive impairment who progressed to dementia

    Nick Corriveau-Lecavalier / Samira Mellah / Francis Clément / Sylvie Belleville

    NeuroImage: Clinical, Vol 24, Iss , Pp - (2019)

    A longitudinal fMRI study

    2019  

    Abstract: Hyperactivation, which is defined as a higher level of activation in patients compared to cognitively unimpaired older adults (controls; CTL), might represent an early signature of Alzheimer's Disease (AD). The goal of this study was to assess the ... ...

    Abstract Hyperactivation, which is defined as a higher level of activation in patients compared to cognitively unimpaired older adults (controls; CTL), might represent an early signature of Alzheimer's Disease (AD). The goal of this study was to assess the presence and location of hyperactivation in individuals with mild cognitive impairment (MCI) who were later diagnosed with dementia, examine how hyperactivation changes longitudinally, and whether it is related to time before dementia. Forty participants, 26 with MCI and 14 CTL were enrolled in the study. Magnetic resonance imaging was used to measure functional activation while participants encoded word-pairs as well as cortical thickness and regional brain volume at study entry (Y0) and two years later (Y2). Clinical follow-up was completed every two years following study entry to identify progressors (pMCI), that is, individuals who later received a diagnosis of dementia. Task-related activation was assessed in pMCI in both hippocampi and in regions showing greater cortical thinning from Y0 to Y2 compared to CTLs. Hyperactivation was found in pMCI individuals in the right supramarginal gyrus. Persons with pMCI also showed hypoactivation in the left hippocampus and left pars opercularis. Both hyper- and hypoactivation were present at Y0 and Y2 and did not change longitudinally. Activation was not associated with time before dementia diagnosis. Smaller volume and thinner cortical thickness were associated with shorter time to diagnosis in the left hippocampus and left pars opercularis. In conclusion, hyperactivation was found in individuals who later progressed to dementia, confirming that it might represent an early biomarker to identify individuals in the prodromal phase of AD and that its understanding could contribute to elucidate the key brain mechanisms that precede dementia. Keywords: Mild cognitive impairment, Alzheimer's disease, Task-related hyperactivation, Longitudinal fMRI, Episodic memory
    Schlagwörter Computer applications to medicine. Medical informatics ; R858-859.7 ; Neurology. Diseases of the nervous system ; RC346-429
    Thema/Rubrik (Code) 150
    Sprache Englisch
    Erscheinungsdatum 2019-01-01T00:00:00Z
    Verlag Elsevier
    Dokumenttyp Artikel ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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  3. Artikel ; Online: Neural correlates of resilience to the effects of hippocampal atrophy on memory

    Sylvie Belleville / Samira Mellah / Simon Cloutier / Thien Thanh Dang-Vu / Simon Duchesne / Samantha Maltezos / Natalie Phillips / Carol Hudon

    NeuroImage: Clinical, Vol 29, Iss , Pp 102526- (2021)

    2021  

    Abstract: Introduction: Cognitive reserve can be defined as a property of the brain that enables an individual to sustain cognitive performance in spite of age-related neural changes. This study uses brain imaging to identify which cognitive reserve mechanisms ... ...

    Abstract Introduction: Cognitive reserve can be defined as a property of the brain that enables an individual to sustain cognitive performance in spite of age-related neural changes. This study uses brain imaging to identify which cognitive reserve mechanisms protect against the detrimental effect of hippocampal atrophy on associative memory. Methods: The study included 108 older adults from the Quebec Consortium for the early identification of Alzheimer’s disease. They received a magnetic resonance imaging examination to measure memory-related activations and hippocampal volume. Participants also completed a reserve-proxy questionnaire, and received a comprehensive clinical assessment. Results: Higher scores on the reserve questionnaire were associated with more activation in the right inferior temporal and left occipital fusiform gyri. The activation of the right temporal gyrus moderated the relationship between the volume of the hippocampus and face-name memory. A smaller volume was associated with weaker memory in participants with lower activation, but not in those with greater activation. Discussion: Recruitment of the temporal lobe protects against the detrimental effect of hippocampal atrophy on associative memory and contributes to cognitive reserve.
    Schlagwörter Cognitive reserve ; Aging ; Subjective cognitive decline ; Mild cognitive impairment ; Hippocampal atrophy ; Associative memory ; Computer applications to medicine. Medical informatics ; R858-859.7 ; Neurology. Diseases of the nervous system ; RC346-429
    Thema/Rubrik (Code) 150
    Sprache Englisch
    Erscheinungsdatum 2021-01-01T00:00:00Z
    Verlag Elsevier
    Dokumenttyp Artikel ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

    Volltext online

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  4. Artikel ; Online: The pattern and loci of training-induced brain changes in healthy older adults are predicted by the nature of the intervention.

    Sylvie Belleville / Samira Mellah / Chloé de Boysson / Jean-Francois Demonet / Bianca Bier

    PLoS ONE, Vol 9, Iss 8, p e

    2014  Band 102710

    Abstract: There is enormous interest in designing training methods for reducing cognitive decline in healthy older adults. Because it is impaired with aging, multitasking has often been targeted and has been shown to be malleable with appropriate training. ... ...

    Abstract There is enormous interest in designing training methods for reducing cognitive decline in healthy older adults. Because it is impaired with aging, multitasking has often been targeted and has been shown to be malleable with appropriate training. Investigating the effects of cognitive training on functional brain activation might provide critical indication regarding the mechanisms that underlie those positive effects, as well as provide models for selecting appropriate training methods. The few studies that have looked at brain correlates of cognitive training indicate a variable pattern and location of brain changes--a result that might relate to differences in training formats. The goal of this study was to measure the neural substrates as a function of whether divided attentional training programs induced the use of alternative processes or whether it relied on repeated practice. Forty-eight older adults were randomly allocated to one of three training programs. In the single repeated training, participants practiced an alphanumeric equation and a visual detection task, each under focused attention. In the divided fixed training, participants practiced combining verification and detection by divided attention, with equal attention allocated to both tasks. In the divided variable training, participants completed the task by divided attention, but were taught to vary the attentional priority allocated to each task. Brain activation was measured with fMRI pre- and post-training while completing each task individually and the two tasks combined. The three training programs resulted in markedly different brain changes. Practice on individual tasks in the single repeated training resulted in reduced brain activation whereas divided variable training resulted in a larger recruitment of the right superior and middle frontal gyrus, a region that has been involved in multitasking. The type of training is a critical factor in determining the pattern of brain activation.
    Schlagwörter Medicine ; R ; Science ; Q
    Thema/Rubrik (Code) 796
    Sprache Englisch
    Erscheinungsdatum 2014-01-01T00:00:00Z
    Verlag Public Library of Science (PLoS)
    Dokumenttyp Artikel ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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