The Experts below are selected from a list of 63039 Experts worldwide ranked by ideXlab platform
Michael A. Kraut - One of the best experts on this subject based on the ideXlab platform.
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Common and differential electrophysiological mechanisms underlying Semantic Object memory retrieval probed by features presented in different stimulus types.
International Journal of Psychophysiology, 2016Co-Authors: Hsueh Sheng Chiang, Justin Eroh, Jeffrey S. Spence, Michael A. Motes, Mandy J. Maguire, Daniel C. Krawczyk, Matthew R. Brier, John Hart, Michael A. KrautAbstract:Abstract How the brain combines the neural representations of features that comprise an Object in order to activate a coherent Object memory is poorly understood, especially when the features are presented in different modalities (visual vs. auditory) and domains (verbal vs. nonverbal). We examined this question using three versions of a modified Semantic Object Retrieval Test, where Object memory was probed by a feature presented as a written word, a spoken word, or a picture, followed by a second feature always presented as a visual word. Participants indicated whether each feature pair elicited retrieval of the memory of a particular Object. Sixteen subjects completed one of the three versions (N = 48 in total) while their EEG were recorded simultaneously. We analyzed EEG data in four separate frequency bands (delta: 1–4 Hz, theta: 4–7 Hz; alpha: 8–12 Hz; beta: 13–19 Hz) using a multivariate data-driven approach. We found that alpha power time-locked to response was modulated by both cross-modality (visual vs. auditory) and cross-domain (verbal vs. nonverbal) probing of Semantic Object memory. In addition, retrieval trials showed greater changes in all frequency bands compared to non-retrieval trials across all stimulus types in both response-locked and stimulus-locked analyses, suggesting dissociable neural subcomponents involved in binding Object features to retrieve a memory. We conclude that these findings support both modality/domain-dependent and modality/domain-independent mechanisms during Semantic Object memory retrieval.
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Altered Neural Activity during Semantic Object Memory Retrieval in Amnestic Mild Cognitive Impairment as Measured by Event-Related Potentials
Journal of Alzheimer's disease : JAD, 2015Co-Authors: Hsueh Sheng Chiang, Justin Eroh, Jeffrey S. Spence, Michael A. Kraut, Raksha A. Mudar, Athula Pudhiyidath, Kyle B. Womack, C. Munro Cullum, Jeremy A. Tanner, John HartAbstract:Deficits in Semantic memory in individuals with amnestic mild cognitive impairment (aMCI) have been previously reported, but the underlying neurobiological mechanisms remain to be clarified. We examined event-related potentials (ERPs) associated with Semantic memory retrieval in 16 individuals with aMCI as compared to 17 normal controls using the Semantic Object Retrieval Task (EEG SORT). In this task, subjects judged whether pairs of words (Object features) elicited retrieval of an Object (retrieval trials) or not (non-retrieval trials). Behavioral findings revealed that aMCI subjects had lower accuracy scores and marginally longer reaction time compared to controls. We used a multivariate analytical technique (STAT-PCA) to investigate similarities and differences in ERPs between aMCI and control groups. STAT-PCA revealed a left fronto-temporal component starting at around 750 ms post-stimulus in both groups. However, unlike controls, aMCI subjects showed an increase in the frontal-parietal scalp potential that distinguished retrieval from non-retrieval trials between 950 and 1050 ms post-stimulus negatively correlated with the performance on the logical memory subtest of the Wechsler Memory Scale-III. Thus, individuals with aMCI were not only impaired in their behavioral performance on SORT relative to controls, but also displayed alteration in the corresponding ERPs. The altered neural activity in aMCI compared to controls suggests a more sustained and effortful search during Object memory retrieval, which may be a potential marker indicating disease processes at the pre-dementia stage.
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The Semantic Object Retrieval Test (SORT) in amnestic mild cognitive impairment.
Cognitive and behavioral neurology : official journal of the Society for Behavioral and Cognitive Neurology, 2007Co-Authors: Michael A. Kraut, Jeffery A. Pitcock, Barbara J. Cherry, Lindsey Vestal, Victor W. Henderson, Raksha Anand, John HartAbstract:Background Between 10% and 15% of patients with the amnestic variety of Mild Cognitive Impairment (MCI) convert to Alzheimer disease (AD) per year. Objective Characterize cognitive markers that may herald conversion from MCI to AD and directly assess Semantic memory in patients meeting criteria for amnestic MCI. Design Thirty-five amnestic MCI patients and 121 healthy aging controls enrolled at an Alzheimer Disease Center received a battery of standard neuropsychologic tests, and the Semantic Object Retrieval Test (SORT), a test that we have developed for the assessment of Semantic memory and subsequent name production, and that has been shown to be able to differentiate between normals and patients with AD. Results On the basis of normative data from the SORT, the MCI subjects could be divided into 2 groups: 10 patients (29%) with a significant Semantic impairment (SI+) and 25 without a Semantic memory deficit (SI−). There was a significant correlation between all SORT variables and performance on the Boston Naming Test. In this MCI population, significantly impaired SORT performance was associated with a relative decrease in performance on tests of frontal lobe functions, although disruption of thalamic-related processes cannot be excluded as an etiology for Semantic memory impairment. Conclusions The SORT is a specific test of Semantic memory, and is a sensitive measure of Semantic memory deficits in patients who otherwise meet criteria for amnestic MCI. Using this specific assessment tool, a significant number of MCI patients were found to have Semantic memory deficits. As these patients may be early in the course of possible progression toward dementia, the SORT or other tests of Semantic memory may provide important diagnostic or prognostic information in patients with MCI.
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The Semantic Object Retrieval Test (SORT) in normal aging and Alzheimer disease.
Cognitive and behavioral neurology : official journal of the Society for Behavioral and Cognitive Neurology, 2006Co-Authors: Michael A. Kraut, Jeffery A. Pitcock, Barbara J. Cherry, Lindsey Vestal, Victor W. Henderson, John HartAbstract:Objective To characterize performance on a test of Semantic Object retrieval (Semantic Object Retrieval Test-SORT) in healthy, elderly subjects and patients with Alzheimer disease (AD). Background Although the initial presentation of patients with AD often reflects impairment in delayed recall for verbally encoded memory, common complaints of patients with early AD are actually related to Semantic memory impairment. Design Thirty-eight AD patients and 121 healthy aging controls enrolled in an Alzheimer's Disease Center received a battery of standard neuropsychologic tests including the SORT. Results Compared with normal controls, AD patients had SORT memory impairments with significantly more false positive memory errors, fewer correctly produced names, and more substitutions in the name production aspect of the test. SORT had robust test-retest reliability in normals. Conclusions The SORT task provides a direct, specific assessment of Semantic memory, and has now been administered to 121 healthy, aging controls for normative ranges of performance, and to AD patients. The task detected Semantic memory deficits in approximately half of patients with mild-moderate AD, which is comparable to other studies assessing Semantic deficits in AD with less specific measures.
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Neural hybrid model of Semantic Object memory: implications from event-related timing using fMRI.
Journal of The International Neuropsychological Society, 2003Co-Authors: Michael A. Kraut, Jeffery A. Pitcock, Catherine G. Cusick, Vince D. Calhoun, John HartAbstract:Previous studies by our group have demonstrated fMRI signal changes and synchronized gamma rhythm EEG oscillations between thalamus and cortical regions as subjects recall Objects from visually presented features. Here, we extend this work by estimating the time course of fMRI signal changes in the cortical and subcortical regions found to exhibit evidence for task-related activation. Our results indicate that there are separate loci of signal changes in the thalamus (dorsomedial and pulvinar) that exhibit notable differences in times of onset, peak and return to baseline of signal changes. The signal changes in the pulvinar demonstrate the slowest transients of all the cortical and subcortical regions we examined. Evaluation of cortical regions demonstrated salient differences as well, with the signal changes in Brodmann area 6 (BA6) rising, peaking, and returning to baseline earlier than those detected in other regions. We conclude that BA6 mediates early designation or refinement of search criteria, and that the pulvinar may be involved in the binding of feature stimuli for an integrated Object memory. ( JINS , 2003, 9 , 1031–1040.)
Michael Beetz - One of the best experts on this subject based on the ideXlab platform.
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Semantic Object Maps for robotic housework - Representation, acquisition and use
IEEE International Conference on Intelligent Robots and Systems, 2012Co-Authors: Dejan Pangercic, Benjamin Pitzer, Moritz Tenorth, Michael BeetzAbstract:In this article we investigate the representation and acquisition of Semantic Objects Maps (SOMs) that can serve as information resources for autonomous service robots performing everyday manipulation tasks in kitchen environments. These maps provide the robot with information about its operation environment that enable it to perform fetch and place tasks more efficiently and reliably. To this end, the Semantic Object maps can answer queries such as the following ones: “What do parts of the kitchen look like?”, “How can a container be opened and closed?”, “Where do Objects of daily use belong?”, “What is inside of cupboards/drawers?”, etc. The Semantic Object maps presented in this article, which we call SOM+, extend the first generation of SOMs presented by Rusu et al. [1] in that the representation of SOM+ is designed more thoroughly and that SOM+ also include knowledge about the appearance and articulation of furniture Objects. Also, the acquisition methods for SOM+ substantially advance those developed in [1] in that SOM+ are acquired autonomously and with low-cost (Kinect) instead of very accurate (laser-based) 3D sensors. In addition, perception methods are more general and are demonstrated to work in different kitchen environments.
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Semantic Object Maps for Household Tasks
2012Co-Authors: Michael Beetz, Dejan Pangercic, Moritz Tenorth, Benjamin PitzerAbstract:We present the representation and acquisition of Semantic Objects maps (SOMs) that can serve as information resources for autonomous service robots performing everyday manipulation tasks in kitchen environments. These maps provide the robot with information about its operation environment that enable it to perform fetch and place tasks more efficiently and reliably. To this end, the Semantic Object maps can answer queries such as the following ones: “What do parts of the kitchen look like?”, “How can a container be opened and closed?”, “Where do Objects of daily use belong?”, “What is inside of cupboards/drawers?”, etc.
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IROS - Semantic Object Maps for robotic housework - representation, acquisition and use
2012 IEEE RSJ International Conference on Intelligent Robots and Systems, 2012Co-Authors: Dejan Pangercic, Benjamin Pitzer, Moritz Tenorth, Michael BeetzAbstract:In this article we investigate the representation and acquisition of Semantic Objects Maps (SOMs) that can serve as information resources for autonomous service robots performing everyday manipulation tasks in kitchen environments. These maps provide the robot with information about its operation environment that enable it to perform fetch and place tasks more efficiently and reliably. To this end, the Semantic Object maps can answer queries such as the following ones: “What do parts of the kitchen look like?”, “How can a container be opened and closed?”, “Where do Objects of daily use belong?”, “What is inside of cupboards/drawers?”, etc. The Semantic Object maps presented in this article, which we call SOM+, extend the first generation of SOMs presented by Rusu et al. [1] in that the representation of SOM+ is designed more thoroughly and that SOM+ also include knowledge about the appearance and articulation of furniture Objects. Also, the acquisition methods for SOM+ substantially advance those developed in [1] in that SOM+ are acquired autonomously and with low-cost (Kinect) instead of very accurate (laser-based) 3D sensors. In addition, perception methods are more general and are demonstrated to work in different kitchen environments.
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Semantic Object Search in Large-scale Indoor Environments
2011Co-Authors: Manabu Saito, Lars Kunze, Haseru Chen, Kei Okada, Masayuki Inaba, Michael BeetzAbstract:Many of today’s mobile robots are supposed to perform everyday manipulation tasks autonomously. However, in large-scale environments, a task-related Object might be out of the robot’s reach, that is, the Object is currently not perceivable by the robot. Hence, the robot first has to search for the Object in its environment before it can perform the task. In this paper, we present an approach for Object search in large-scale environments using different search strategies based on Semantic environment models. We demonstrate the feasibility of our approach by integrating it into a robot system and by conducting experiments where the robot is supposed to search for Objects within the context of fetch-and-delivery tasks within a multi-level building.
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knowrob map knowledge linked Semantic Object maps
IEEE-RAS International Conference on Humanoid Robots, 2010Co-Authors: Moritz Tenorth, Lars Kunze, Dominik Jain, Michael BeetzAbstract:Autonomous household robots are supposed to accomplish complex tasks like cleaning the dishes which involve both navigation and manipulation within the environment. For navigation, spatial information is mostly sufficient, but manipulation tasks raise the demand for deeper knowledge about Objects, such as their types, their functions, or the way how they can be used. We present KNOWROB-MAP, a system for building environment models for robots by combining spatial information about Objects in the environment with encyclopedic knowledge about the types and properties of Objects, with common-sense knowledge describing what the Objects can be used for, and with knowledge derived from observations of human activities by learning statistical relational models. In this paper, we describe the concept and implementation of KNOWROB-MAP and present several examples demonstrating the range of information the system can provide to autonomous robots.
John Hart - One of the best experts on this subject based on the ideXlab platform.
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Common and differential electrophysiological mechanisms underlying Semantic Object memory retrieval probed by features presented in different stimulus types.
International Journal of Psychophysiology, 2016Co-Authors: Hsueh Sheng Chiang, Justin Eroh, Jeffrey S. Spence, Michael A. Motes, Mandy J. Maguire, Daniel C. Krawczyk, Matthew R. Brier, John Hart, Michael A. KrautAbstract:Abstract How the brain combines the neural representations of features that comprise an Object in order to activate a coherent Object memory is poorly understood, especially when the features are presented in different modalities (visual vs. auditory) and domains (verbal vs. nonverbal). We examined this question using three versions of a modified Semantic Object Retrieval Test, where Object memory was probed by a feature presented as a written word, a spoken word, or a picture, followed by a second feature always presented as a visual word. Participants indicated whether each feature pair elicited retrieval of the memory of a particular Object. Sixteen subjects completed one of the three versions (N = 48 in total) while their EEG were recorded simultaneously. We analyzed EEG data in four separate frequency bands (delta: 1–4 Hz, theta: 4–7 Hz; alpha: 8–12 Hz; beta: 13–19 Hz) using a multivariate data-driven approach. We found that alpha power time-locked to response was modulated by both cross-modality (visual vs. auditory) and cross-domain (verbal vs. nonverbal) probing of Semantic Object memory. In addition, retrieval trials showed greater changes in all frequency bands compared to non-retrieval trials across all stimulus types in both response-locked and stimulus-locked analyses, suggesting dissociable neural subcomponents involved in binding Object features to retrieve a memory. We conclude that these findings support both modality/domain-dependent and modality/domain-independent mechanisms during Semantic Object memory retrieval.
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Altered Neural Activity during Semantic Object Memory Retrieval in Amnestic Mild Cognitive Impairment as Measured by Event-Related Potentials
Journal of Alzheimer's disease : JAD, 2015Co-Authors: Hsueh Sheng Chiang, Justin Eroh, Jeffrey S. Spence, Michael A. Kraut, Raksha A. Mudar, Athula Pudhiyidath, Kyle B. Womack, C. Munro Cullum, Jeremy A. Tanner, John HartAbstract:Deficits in Semantic memory in individuals with amnestic mild cognitive impairment (aMCI) have been previously reported, but the underlying neurobiological mechanisms remain to be clarified. We examined event-related potentials (ERPs) associated with Semantic memory retrieval in 16 individuals with aMCI as compared to 17 normal controls using the Semantic Object Retrieval Task (EEG SORT). In this task, subjects judged whether pairs of words (Object features) elicited retrieval of an Object (retrieval trials) or not (non-retrieval trials). Behavioral findings revealed that aMCI subjects had lower accuracy scores and marginally longer reaction time compared to controls. We used a multivariate analytical technique (STAT-PCA) to investigate similarities and differences in ERPs between aMCI and control groups. STAT-PCA revealed a left fronto-temporal component starting at around 750 ms post-stimulus in both groups. However, unlike controls, aMCI subjects showed an increase in the frontal-parietal scalp potential that distinguished retrieval from non-retrieval trials between 950 and 1050 ms post-stimulus negatively correlated with the performance on the logical memory subtest of the Wechsler Memory Scale-III. Thus, individuals with aMCI were not only impaired in their behavioral performance on SORT relative to controls, but also displayed alteration in the corresponding ERPs. The altered neural activity in aMCI compared to controls suggests a more sustained and effortful search during Object memory retrieval, which may be a potential marker indicating disease processes at the pre-dementia stage.
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The Semantic Object Retrieval Test (SORT) in amnestic mild cognitive impairment.
Cognitive and behavioral neurology : official journal of the Society for Behavioral and Cognitive Neurology, 2007Co-Authors: Michael A. Kraut, Jeffery A. Pitcock, Barbara J. Cherry, Lindsey Vestal, Victor W. Henderson, Raksha Anand, John HartAbstract:Background Between 10% and 15% of patients with the amnestic variety of Mild Cognitive Impairment (MCI) convert to Alzheimer disease (AD) per year. Objective Characterize cognitive markers that may herald conversion from MCI to AD and directly assess Semantic memory in patients meeting criteria for amnestic MCI. Design Thirty-five amnestic MCI patients and 121 healthy aging controls enrolled at an Alzheimer Disease Center received a battery of standard neuropsychologic tests, and the Semantic Object Retrieval Test (SORT), a test that we have developed for the assessment of Semantic memory and subsequent name production, and that has been shown to be able to differentiate between normals and patients with AD. Results On the basis of normative data from the SORT, the MCI subjects could be divided into 2 groups: 10 patients (29%) with a significant Semantic impairment (SI+) and 25 without a Semantic memory deficit (SI−). There was a significant correlation between all SORT variables and performance on the Boston Naming Test. In this MCI population, significantly impaired SORT performance was associated with a relative decrease in performance on tests of frontal lobe functions, although disruption of thalamic-related processes cannot be excluded as an etiology for Semantic memory impairment. Conclusions The SORT is a specific test of Semantic memory, and is a sensitive measure of Semantic memory deficits in patients who otherwise meet criteria for amnestic MCI. Using this specific assessment tool, a significant number of MCI patients were found to have Semantic memory deficits. As these patients may be early in the course of possible progression toward dementia, the SORT or other tests of Semantic memory may provide important diagnostic or prognostic information in patients with MCI.
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The Semantic Object Retrieval Test (SORT) in normal aging and Alzheimer disease.
Cognitive and behavioral neurology : official journal of the Society for Behavioral and Cognitive Neurology, 2006Co-Authors: Michael A. Kraut, Jeffery A. Pitcock, Barbara J. Cherry, Lindsey Vestal, Victor W. Henderson, John HartAbstract:Objective To characterize performance on a test of Semantic Object retrieval (Semantic Object Retrieval Test-SORT) in healthy, elderly subjects and patients with Alzheimer disease (AD). Background Although the initial presentation of patients with AD often reflects impairment in delayed recall for verbally encoded memory, common complaints of patients with early AD are actually related to Semantic memory impairment. Design Thirty-eight AD patients and 121 healthy aging controls enrolled in an Alzheimer's Disease Center received a battery of standard neuropsychologic tests including the SORT. Results Compared with normal controls, AD patients had SORT memory impairments with significantly more false positive memory errors, fewer correctly produced names, and more substitutions in the name production aspect of the test. SORT had robust test-retest reliability in normals. Conclusions The SORT task provides a direct, specific assessment of Semantic memory, and has now been administered to 121 healthy, aging controls for normative ranges of performance, and to AD patients. The task detected Semantic memory deficits in approximately half of patients with mild-moderate AD, which is comparable to other studies assessing Semantic deficits in AD with less specific measures.
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Neural hybrid model of Semantic Object memory: implications from event-related timing using fMRI.
Journal of The International Neuropsychological Society, 2003Co-Authors: Michael A. Kraut, Jeffery A. Pitcock, Catherine G. Cusick, Vince D. Calhoun, John HartAbstract:Previous studies by our group have demonstrated fMRI signal changes and synchronized gamma rhythm EEG oscillations between thalamus and cortical regions as subjects recall Objects from visually presented features. Here, we extend this work by estimating the time course of fMRI signal changes in the cortical and subcortical regions found to exhibit evidence for task-related activation. Our results indicate that there are separate loci of signal changes in the thalamus (dorsomedial and pulvinar) that exhibit notable differences in times of onset, peak and return to baseline of signal changes. The signal changes in the pulvinar demonstrate the slowest transients of all the cortical and subcortical regions we examined. Evaluation of cortical regions demonstrated salient differences as well, with the signal changes in Brodmann area 6 (BA6) rising, peaking, and returning to baseline earlier than those detected in other regions. We conclude that BA6 mediates early designation or refinement of search criteria, and that the pulvinar may be involved in the binding of feature stimuli for an integrated Object memory. ( JINS , 2003, 9 , 1031–1040.)
Changqun Xia - One of the best experts on this subject based on the ideXlab platform.
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Semantic Object Segmentation in Tagged Videos via Detection
IEEE transactions on pattern analysis and machine intelligence, 2017Co-Authors: Yu Zhang, Xiaowu Chen, Chen Wang, Changqun XiaAbstract:Semantic Object segmentation (SOS) is a challenging task in computer vision that aims to detect and segment all pixels of the Objects within predefined Semantic categories. In image-based SOS, many supervised models have been proposed and achieved impressive performances due to the rapid advances of well-annotated training images and machine learning theories. However, in video-based SOS it is often difficult to directly train a supervised model since most videos are weakly annotated by tags. To handle such tagged videos, this paper proposes a novel approach that adopts a segmentation-by-detection framework. In this framework, Object detection and segment proposals are first generated using the models pre-trained on still images, which provide useful cues to roughly localize the Semantic Objects. Based on these proposals, we propose an efficient algorithm to initialize Object tracks by solving a joint assignment problem. As such tracks provide rough spatiotemporal configurations of the Semantic Objects, a voting-based refinement algorithm is further proposed to improve their spatiotemporal consistency. Extensive experiments demonstrate that the proposed framework can robustly and effectively segment Semantic Objects in tagged videos, even when the image-based Object detectors provide inaccurate proposals. On various public benchmarks, the proposed approach obtains substantial improvements over the state-of-the-arts.
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Semantic Object segmentation via detection in weakly labeled video
Computer Vision and Pattern Recognition, 2015Co-Authors: Yu Zhang, Xiaowu Chen, Chen Wang, Changqun XiaAbstract:Semantic Object segmentation in video is an important step for large-scale multimedia analysis. In many cases, however, Semantic Objects are only tagged at video-level, making them difficult to be located and segmented. To address this problem, this paper proposes an approach to segment Semantic Objects in weakly labeled video via Object detection. In our approach, a novel video segmentation-by-detection framework is proposed, which first incorporates Object and region detectors pre-trained on still images to generate a set of detection and segmentation proposals. Based on the noisy proposals, several Object tracks are then initialized by solving a joint binary optimization problem with min-cost flow. As such tracks actually provide rough configurations of Semantic Objects, we thus refine the Object segmentation while preserving the spatiotemporal consistency by inferring the shape likelihoods of pixels from the statistical information of tracks. Experimental results on Youtube-Objects dataset and SegTrack v2 dataset demonstrate that our method outperforms state-of-the-arts and shows impressive results.
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CVPR - Semantic Object segmentation via detection in weakly labeled video
2015 IEEE Conference on Computer Vision and Pattern Recognition (CVPR), 2015Co-Authors: Yu Zhang, Xiaowu Chen, Chen Wang, Changqun XiaAbstract:Semantic Object segmentation in video is an important step for large-scale multimedia analysis. In many cases, however, Semantic Objects are only tagged at video-level, making them difficult to be located and segmented. To address this problem, this paper proposes an approach to segment Semantic Objects in weakly labeled video via Object detection. In our approach, a novel video segmentation-by-detection framework is proposed, which first incorporates Object and region detectors pre-trained on still images to generate a set of detection and segmentation proposals. Based on the noisy proposals, several Object tracks are then initialized by solving a joint binary optimization problem with min-cost flow. As such tracks actually provide rough configurations of Semantic Objects, we thus refine the Object segmentation while preserving the spatiotemporal consistency by inferring the shape likelihoods of pixels from the statistical information of tracks. Experimental results on Youtube-Objects dataset and SegTrack v2 dataset demonstrate that our method outperforms state-of-the-arts and shows impressive results.
Jeffrey S. Spence - One of the best experts on this subject based on the ideXlab platform.
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Common and differential electrophysiological mechanisms underlying Semantic Object memory retrieval probed by features presented in different stimulus types.
International Journal of Psychophysiology, 2016Co-Authors: Hsueh Sheng Chiang, Justin Eroh, Jeffrey S. Spence, Michael A. Motes, Mandy J. Maguire, Daniel C. Krawczyk, Matthew R. Brier, John Hart, Michael A. KrautAbstract:Abstract How the brain combines the neural representations of features that comprise an Object in order to activate a coherent Object memory is poorly understood, especially when the features are presented in different modalities (visual vs. auditory) and domains (verbal vs. nonverbal). We examined this question using three versions of a modified Semantic Object Retrieval Test, where Object memory was probed by a feature presented as a written word, a spoken word, or a picture, followed by a second feature always presented as a visual word. Participants indicated whether each feature pair elicited retrieval of the memory of a particular Object. Sixteen subjects completed one of the three versions (N = 48 in total) while their EEG were recorded simultaneously. We analyzed EEG data in four separate frequency bands (delta: 1–4 Hz, theta: 4–7 Hz; alpha: 8–12 Hz; beta: 13–19 Hz) using a multivariate data-driven approach. We found that alpha power time-locked to response was modulated by both cross-modality (visual vs. auditory) and cross-domain (verbal vs. nonverbal) probing of Semantic Object memory. In addition, retrieval trials showed greater changes in all frequency bands compared to non-retrieval trials across all stimulus types in both response-locked and stimulus-locked analyses, suggesting dissociable neural subcomponents involved in binding Object features to retrieve a memory. We conclude that these findings support both modality/domain-dependent and modality/domain-independent mechanisms during Semantic Object memory retrieval.
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Altered Neural Activity during Semantic Object Memory Retrieval in Amnestic Mild Cognitive Impairment as Measured by Event-Related Potentials
Journal of Alzheimer's disease : JAD, 2015Co-Authors: Hsueh Sheng Chiang, Justin Eroh, Jeffrey S. Spence, Michael A. Kraut, Raksha A. Mudar, Athula Pudhiyidath, Kyle B. Womack, C. Munro Cullum, Jeremy A. Tanner, John HartAbstract:Deficits in Semantic memory in individuals with amnestic mild cognitive impairment (aMCI) have been previously reported, but the underlying neurobiological mechanisms remain to be clarified. We examined event-related potentials (ERPs) associated with Semantic memory retrieval in 16 individuals with aMCI as compared to 17 normal controls using the Semantic Object Retrieval Task (EEG SORT). In this task, subjects judged whether pairs of words (Object features) elicited retrieval of an Object (retrieval trials) or not (non-retrieval trials). Behavioral findings revealed that aMCI subjects had lower accuracy scores and marginally longer reaction time compared to controls. We used a multivariate analytical technique (STAT-PCA) to investigate similarities and differences in ERPs between aMCI and control groups. STAT-PCA revealed a left fronto-temporal component starting at around 750 ms post-stimulus in both groups. However, unlike controls, aMCI subjects showed an increase in the frontal-parietal scalp potential that distinguished retrieval from non-retrieval trials between 950 and 1050 ms post-stimulus negatively correlated with the performance on the logical memory subtest of the Wechsler Memory Scale-III. Thus, individuals with aMCI were not only impaired in their behavioral performance on SORT relative to controls, but also displayed alteration in the corresponding ERPs. The altered neural activity in aMCI compared to controls suggests a more sustained and effortful search during Object memory retrieval, which may be a potential marker indicating disease processes at the pre-dementia stage.
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Accentuated Brain Responses During Semantic Object Memory Retrieval In Amnestic Mild Cognitive Impairment As Measured By Event-Related Potentials (P6.241)
Neurology, 2014Co-Authors: Hsueh Sheng Chiang, Justin Eroh, Jeffrey S. Spence, Raksha A. Mudar, Athula Pudhiyidath, Jeremy A. Tanner, Erin Venza, Audette Rackley, Kristin Martin-cook, Kyle B. WomackAbstract:ObjectIVE: To evaluate the effects of amnestic mild cognitive impairment (aMCI) on Semantic memory processing using event-related potentials (ERPs). BACKGROUND: Semantic memory deficits in MCI have been reported but the neurobiological mechanisms are less understood. We used ERPs to study electrophysiological changes underlying early deterioration in Semantic memory associated with aMCI. DESIGN/METHODS: EEG was recorded during subject performance of the Semantic Object Retrieval Task, a paradigm where subjects responded to pairs of words referring to particular Objects. Trials of “Retrieval” probed Object memory (e.g., humps and desert) whereas “NonRetrieval” did not (e.g., humps and mirror). Using a multivariate analytical technique (STAT-PCA), we analyzed ERPs from young adults (YA, N=12; mean age: 21.7 yr), normal aging adults (NA, N=12; mean age 67.7 yr; CDR=0; MMSE=29.3), and aMCI patients (N=12; mean age: 69.6 yr; CDR=0.5; MMSE=28.6) to investigate patterns related to normal aging and disease processes. RESULTS: NA subjects had slower reaction times (RT) than YA subjects (p = .004) but comparable accuracy. AMCI patients had similar RT compared to NA but lower accuracy (p = .006). ERP data (threshold of p = .001) showed a central parietal component contingent upon condition (potentials more negative in NonRetrieval than in Retrieval) starting around 700 ms post-stimulus across all groups. An age-related frontal-parietal component (potentials more positive in NonRetrieval than in Retrieval in the front) was observed between 800 and 900 ms post-stimulus in NA compared to YA. This frontal-parietal component increased significantly in amplitude around 1000 ms post-stimulus in aMCI compared to NA. CONCLUSIONS: Individuals with aMCI showed deteriorated Semantic memory performance with a different neurophysiological profile compared to YA and NA. The heightened neural activity in aMCI suggests greater effort in Object memory retrieval, a potential compensatory mechanism at a pre-dementia stage in response to disease processes. Study Supported by: Berman Laboratory for Learning and Memory; Alzheimer’s Association New Investigator Grant NIRG-11-173815; RGK Foundation; NIA Grant #1-P30-AG12300-16. Disclosure: Dr. Chiang has nothing to disclose. Dr. Mudar has nothing to disclose. Dr. Eroh has nothing to disclose. Dr. Spence has nothing to disclose. Dr. Pudhiyidath has nothing to disclose. Dr. Tanner has nothing to disclose. Dr. Venza has nothing to disclose. Dr. Rackley has nothing to disclose. Dr. Martin-Cook has nothing to disclose. Dr. Womack has received research support from Allon Pharmaceuticals. Dr. Bartz has nothing to disclose. Dr. Kraut has nothing to disclose. Dr. Hart has nothing to disclose.
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Threat as a Feature in Visual Semantic Object Memory
Human brain mapping, 2012Co-Authors: Clifford S. Calley, Jeffrey S. Spence, Michael A. Motes, Mandy J. Maguire, Raksha Anand, H. Sheng Chiang, Virginia I. Buhl, Hervé Abdi, Leonardo Estevez, Richard W. BriggsAbstract:Threatening stimuli have been found to modulate visual processes related to perception and attention. The present functional magnetic resonance imaging (fMRI) study investigated whether threat modulates visual Object recognition of man-made and naturally occurring categories of stimuli. Compared with nonthreatening pictures, threatening pictures of real items elicited larger fMRI BOLD signal changes in medial visual cortices extending inferiorly into the temporo-occipital (TO) ''what'' pathways. This region elicited greater signal changes for threatening items compared to nonthreatening from both the natural-occurring and man-made stimulus supraordinate categories, demonstrating a featural component to these visual processing areas. Two additional loci of signal changes within more lateral inferior TO areas (bilateral BA18 and 19 as well as the right ventral temporal lobe) were detected for a category-fea- ture interaction, with stronger responses to man-made (category) threatening (feature) stimuli than to nat- ural threats. The findings are discussed in terms of visual recognition of processing efficiently or rapidly groups of items that confer an advantage for survival. Hum Brain Mapp 00:000-000, 2012. V C 2012 Wiley
