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Cheryl L Grady - One of the best experts on this subject based on the ideXlab platform.
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recollection and prior knowledge recruit the left angular gyrus during recognition
bioRxiv, 2019Co-Authors: Buddhika Bellana, N Ladykawojcik, S Lahan, Morris Moscovitch, Cheryl L GradyAbstract:Abstract The human angular gyrus (AG) is implicated in recollection, or our ability to retrieve detailed Memory Content from a specific study episode. Parallel work also highlights a key role of the AG in the representation of general knowledge and semantics. How these two lines of research converge remains unclear. The present fMRI experiment used a remember-know paradigm with famous and non-famous faces to test whether activity in the AG could be modulated by both task-specific recollection and general prior knowledge in the same participants. Increased BOLD activity in the left AG was observed during both recollection in the absence of prior knowledge (i.e., recollected > non-recollected or correctly rejected non-famous faces) and when prior knowledge was accessed in the absence of recollection (i.e., famous > non-famous correct rejections). This pattern was unique to the left AG, and was not present in any other regions of the lateral inferior parietal lobe. Furthermore, the response profile of the left AG was consistent with accounts of recollection strength. Recollection-related activity was greater for faces with longer exposures at encoding than those with shorter exposures and was greater for stimuli with prior knowledge than those without, despite prior knowledge being incidental to the recognition decision. Therefore, the left AG is recruited during the access of both task-specific recollection and general prior knowledge, with greater activity as the amount of retrieved information increases, irrespective of its episodic or semantic nature. Significance Statement The human angular gyrus (AG) is often implicated in our ability to remember past events. A separate line of research examining our ability to represent general knowledge has also highlighted the AG as a core region of interest. To reconcile these separate views of AG function, we used fMRI to test whether the human left AG was sensitive to remembering details from a specific study episode (i.e., recollection) or more general prior knowledge, within the same participants. Overall, activity in the left AG was sensitive to both recollection and prior knowledge, suggesting any complete functional account of the left AG during retrieval must consider its sensitivity to both kinds of mnemonic representations.
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influence of aging on the neural correlates of autobiographical episodic and semantic Memory retrieval
Journal of Cognitive Neuroscience, 2011Co-Authors: Marie Stlaurent, Herve Abdi, Hana Burianova, Cheryl L GradyAbstract:We used fMRI to assess the neural correlates of autobiographical, semantic, and episodic Memory retrieval in healthy young and older adults. Participants were tested with an event-related paradigm in which retrieval demand was the only factor varying between trials. A spatio-temporal partial least square analysis was conducted to identify the main patterns of activity characterizing the groups across conditions. We identified brain regions activated by all three Memory conditions relative to a control condition. This pattern was expressed equally in both age groups and replicated previous findings obtained in a separate group of younger adults. We also identified regions whose activity differentiated among the different Memory conditions. These patterns of differentiation were expressed less strongly in the older adults than in the young adults, a finding that was further confirmed by a barycentric discriminant analysis. This analysis showed an age-related dedifferentiation in autobiographical and episodic Memory tasks but not in the semantic Memory task or the control condition. These findings suggest that the activation of a common Memory retrieval network is maintained with age, whereas the specific aspects of brain activity that differ with Memory Content are more vulnerable and less selectively engaged in older adults. Our results provide a potential neural mechanism for the well-known age differences in episodic/autobiographical Memory, and preserved semantic Memory, observed when older adults are compared with younger adults.
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a common functional brain network for autobiographical episodic and semantic Memory retrieval
NeuroImage, 2010Co-Authors: Hana Burianova, Anthony R Mcintosh, Cheryl L GradyAbstract:The objective of this study was to delineate a common functional network that underlies autobiographical, episodic, and semantic Memory retrieval. We conducted an event-related fMRI study in which we utilized the same pictorial stimuli, but manipulated retrieval demands to extract autobiographical, episodic, or semantic memories. To assess this common network, we first examined the functional connectivity of regions identified by a previous analysis of task-related activity that were active across all three tasks. Three of these regions (left hippocampus, left lingual gyrus, and right caudate nucleus) appeared to share a common pattern of connectivity. This was confirmed in a subsequent functional connectivity analysis using these three regions as seeds. The results of this analysis showed that there was a pattern of functional connectivity that characterized all three seeds and that was common across the three retrieval conditions. Activity in inferior frontal and middle temporal cortex bilaterally, left temporoparietal junction, and anterior and posterior cingulate gyri was positively correlated with the seeds, whereas activity in posterior occipito-temporo-parietal regions was negatively correlated. These findings support the idea that a common neural network underlies the retrieval of declarative memories regardless of Memory Content. This proposed network consists of increased activity in regions that represent internal processes of Memory retrieval and decreased activity in regions that mediate attention to external stimuli.
Vladimir V Kulish - One of the best experts on this subject based on the ideXlab platform.
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analysis of the influence of Memory Content of auditory stimuli on the Memory Content of eeg signal
Oncotarget, 2016Co-Authors: Hamidreza Namazi, Reza Khosrowabadi, Jamal Hussaini, Shaghayegh Habibi, Ali Akhavan Farid, Vladimir V KulishAbstract:One of the major challenges in brain research is to relate the structural features of the auditory stimulus to structural features of Electroencephalogram (EEG) signal. Memory Content is an important feature of EEG signal and accordingly the brain. On the other hand, the Memory Content can also be considered in case of stimulus. Beside all works done on analysis of the effect of stimuli on human EEG and brain Memory, no work discussed about the stimulus Memory and also the relationship that may exist between the Memory Content of stimulus and the Memory Content of EEG signal. For this purpose we consider the Hurst exponent as the measure of Memory. This study reveals the plasticity of human EEG signals in relation to the auditory stimuli. For the first time we demonstrated that the Memory Content of an EEG signal shifts towards the Memory Content of the auditory stimulus used. The results of this analysis showed that an auditory stimulus with higher Memory Content causes a larger increment in the Memory Content of an EEG signal. For the verification of this result, we benefit from approximate entropy as indicator of time series randomness. The capability, observed in this research, can be further investigated in relation to human Memory.
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analysis of the influence of Memory Content of auditory stimuli on the Memory Content of eeg signal
Oncotarget, 2016Co-Authors: Hamidreza Namazi, Reza Khosrowabadi, Jamal Hussaini, Shaghayegh Habibi, Ali Akhavan Farid, Vladimir V KulishAbstract:// Hamidreza Namazi 1 , Reza Khosrowabadi 2,* , Jamal Hussaini 3,* , Shaghayegh Habibi 4,** , Ali Akhavan Farid 5,** and Vladimir V. Kulish 1 1 School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 2 Institute for Cognitive and Brain Science, Shahid Beheshti University, Tehran, Iran 3 Faculty of Medicine, Universiti Teknologi MARA, Sungai Buloh, Selangor, Malaysia 4 School of Medicine, Fasa University of Medical Sciences, Fasa, Iran 5 Faculty of Engineering and Technology, Multimedia University, Melaka, Malaysia * These authors have contributed equally to this work ** These authors have contributed equally to this work Correspondence to: Hamidreza Namazi, email: // Keywords : auditory stimulus, electroencephalogram (EEG) signal, Memory, Hurst exponent, approximate entropy Received : June 04, 2016 Accepted : July 29, 2016 Published : August 11, 2016 Abstract One of the major challenges in brain research is to relate the structural features of the auditory stimulus to structural features of Electroencephalogram (EEG) signal. Memory Content is an important feature of EEG signal and accordingly the brain. On the other hand, the Memory Content can also be considered in case of stimulus. Beside all works done on analysis of the effect of stimuli on human EEG and brain Memory, no work discussed about the stimulus Memory and also the relationship that may exist between the Memory Content of stimulus and the Memory Content of EEG signal. For this purpose we consider the Hurst exponent as the measure of Memory. This study reveals the plasticity of human EEG signals in relation to the auditory stimuli. For the first time we demonstrated that the Memory Content of an EEG signal shifts towards the Memory Content of the auditory stimulus used. The results of this analysis showed that an auditory stimulus with higher Memory Content causes a larger increment in the Memory Content of an EEG signal. For the verification of this result, we benefit from approximate entropy as indicator of time series randomness. The capability, observed in this research, can be further investigated in relation to human Memory.
Ryota Kanai - One of the best experts on this subject based on the ideXlab platform.
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parietal structure and function explain human variation in working Memory biases of visual attention
NeuroImage, 2014Co-Authors: David Soto, Pia Rotshtein, Ryota KanaiAbstract:Recent research indicates that human attention appears inadvertently biased by items that match the Contents of working Memory (WM). WM-biases can lead to attentional costs when the Memory Content matches goal-irrelevant items and to attentional benefits when it matches the sought target. Here we used functional and structural MRI data to determine the neural basis of human variation in WM biases. We asked whether human variation in WM-benefits and WM-costs merely reflects the process of attentional capture by the Contents of WM or whether variation in WM biases may be associated with distinct forms of cognitive control over internal WM signals based on selection goals. Human ability to use WM Contents to facilitate selection was positively correlated with gray matter volume in the left superior posterior parietal cortex (PPC), while the ability to overcome interference by WM-matching distracters was associated with the left inferior PPC in the anterior IPS. Functional activity in the left PPC, measured by functional MRI, also predicted the magnitude of WM-costs on selection. Both structure and function of left PPC mediate the expression of WM biases in human visual attention.
Michael C Anderson - One of the best experts on this subject based on the ideXlab platform.
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suppressing unwanted memories reduces their unconscious influence via targeted cortical inhibition
Proceedings of the National Academy of Sciences of the United States of America, 2014Co-Authors: Pierre Gagnepain, Richard N Henson, Michael C AndersonAbstract:Suppressing retrieval of unwanted memories reduces their later conscious recall. It is widely believed, however, that suppressed memories can continue to exert strong unconscious effects that may compromise mental health. Here we show that excluding memories from awareness not only modulates medial temporal lobe regions involved in explicit retention, but also neocortical areas underlying unconscious expressions of Memory. Using repetition priming in visual perception as a model task, we found that excluding memories of visual objects from consciousness reduced their later indirect influence on perception, literally making the Content of suppressed memories harder for participants to see. Critically, effective connectivity and pattern similarity analysis revealed that suppression mechanisms mediated by the right middle frontal gyrus reduced activity in neocortical areas involved in perceiving objects and targeted the neural populations most activated by reminders. The degree of inhibitory modulation of the visual cortex while people were suppressing visual memories predicted, in a later perception test, the disruption in the neural markers of sensory Memory. These findings suggest a neurobiological model of how motivated forgetting affects the unconscious expression of Memory that may be generalized to other types of Memory Content. More generally, they suggest that the century-old assumption that suppression leaves unconscious memories intact should be reconsidered.
Hana Burianova - One of the best experts on this subject based on the ideXlab platform.
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influence of aging on the neural correlates of autobiographical episodic and semantic Memory retrieval
Journal of Cognitive Neuroscience, 2011Co-Authors: Marie Stlaurent, Herve Abdi, Hana Burianova, Cheryl L GradyAbstract:We used fMRI to assess the neural correlates of autobiographical, semantic, and episodic Memory retrieval in healthy young and older adults. Participants were tested with an event-related paradigm in which retrieval demand was the only factor varying between trials. A spatio-temporal partial least square analysis was conducted to identify the main patterns of activity characterizing the groups across conditions. We identified brain regions activated by all three Memory conditions relative to a control condition. This pattern was expressed equally in both age groups and replicated previous findings obtained in a separate group of younger adults. We also identified regions whose activity differentiated among the different Memory conditions. These patterns of differentiation were expressed less strongly in the older adults than in the young adults, a finding that was further confirmed by a barycentric discriminant analysis. This analysis showed an age-related dedifferentiation in autobiographical and episodic Memory tasks but not in the semantic Memory task or the control condition. These findings suggest that the activation of a common Memory retrieval network is maintained with age, whereas the specific aspects of brain activity that differ with Memory Content are more vulnerable and less selectively engaged in older adults. Our results provide a potential neural mechanism for the well-known age differences in episodic/autobiographical Memory, and preserved semantic Memory, observed when older adults are compared with younger adults.
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a common functional brain network for autobiographical episodic and semantic Memory retrieval
NeuroImage, 2010Co-Authors: Hana Burianova, Anthony R Mcintosh, Cheryl L GradyAbstract:The objective of this study was to delineate a common functional network that underlies autobiographical, episodic, and semantic Memory retrieval. We conducted an event-related fMRI study in which we utilized the same pictorial stimuli, but manipulated retrieval demands to extract autobiographical, episodic, or semantic memories. To assess this common network, we first examined the functional connectivity of regions identified by a previous analysis of task-related activity that were active across all three tasks. Three of these regions (left hippocampus, left lingual gyrus, and right caudate nucleus) appeared to share a common pattern of connectivity. This was confirmed in a subsequent functional connectivity analysis using these three regions as seeds. The results of this analysis showed that there was a pattern of functional connectivity that characterized all three seeds and that was common across the three retrieval conditions. Activity in inferior frontal and middle temporal cortex bilaterally, left temporoparietal junction, and anterior and posterior cingulate gyri was positively correlated with the seeds, whereas activity in posterior occipito-temporo-parietal regions was negatively correlated. These findings support the idea that a common neural network underlies the retrieval of declarative memories regardless of Memory Content. This proposed network consists of increased activity in regions that represent internal processes of Memory retrieval and decreased activity in regions that mediate attention to external stimuli.