Search results for "pattern recognition"
showing 10 items of 2301 documents
Multi-domain feature extraction for small event-related potentials through nonnegative multi-way array decomposition from low dense array EEG
2013
Non-negative Canonical Polyadic decomposition (NCPD) and non-negative Tucker decomposition (NTD) were compared for extracting the multi-domain feature of visual mismatch negativity (vMMN), a small event-related potential (ERP), for the cognitive research. Since signal-to-noise ratio in vMMN is low, NTD outperformed NCPD. Moreover, we proposed an approach to select the multi-domain feature of an ERP among all extracted features and discussed determination of numbers of extracted components in NCPD and NTD regarding the ERP context.
Exploring the switching of the focus of attention within working memory: A combined event-related potential and behavioral study.
2018
Abstract Working memory enables humans to maintain selected information for cognitive processes and ensures instant access to the memorized contents. Theories suggest that switching the focus of attention between items within working memory realizes the access. This is reflected in object-switching costs in response times when the item for the task processing is to be changed. Another correlate of attentional allocation in working memory is the P3a-component of the human event-related potential. The aim of this study was to demonstrate that switching of attention within working memory is a separable processing step. Participants completed a cued memory-updating task in which they were instr…
Distinct neural-behavioral correspondence within face processing and attention networks for the composite face effect
2022
The composite face effect (CFE) is recognized as a hallmark for holistic face processing, but our knowledge remains sparse about its cognitive and neural loci. Using functional magnetic resonance imaging with independent localizer and complete composite face task, we here investigated its neural-behavioral correspondence within face processing and attention networks. Complementing classical comparisons, we adopted a dimensional reduction approach to explore the core cognitive constructs of the behavioral CFE measurement. Our univariate analyses found an alignment effect in regions associated with both the extended face processing network and attention networks. Further representational simi…
pBrain: A novel pipeline for Parkinson related brain structure segmentation
2020
[EN] Parkinson is a very prevalent neurodegenerative disease impacting the life of millions of people worldwide. Although its cause remains unknown, its functional and structural analysis is fundamental to advance in the search of a cure or symptomatic treatment. The automatic segmentation of deep brain structures related to Parkinson's disease could be beneficial for the follow up and treatment planning. Unfortunately, there is not broadly available segmentation software to automatically measure Parkinson related structures. In this paper, we present a novel pipeline to segment three deep brain structures related to Parkinson's disease (substantia nigra, subthalamic nucleus and red nucleus…
Holistic face processing is induced by shape and texture.
2013
There is increasing evidence that shape and texture are integral parts of face identity. However, it is less clear whether face-specific processing mechanisms are triggered by face shape alone, or if texture might play an important role. We address this question by studying mechanisms involved in holistic face processing. Face stimuli were either full-color pictures of real faces (shape and texture) or line drawings of the same faces (shape without texture). In a change detection task subjects judged whether eyes and eyebrows in two otherwise identical, sequentially presented faces were different in size or not. Afterwards, subjects had to identify the just presented face among two distrac…
k-Nearest neighbour local linear prediction of scalp EEG activity during intermittent photic stimulation
2011
The characterization of the EEG response to photic stimulation (PS) is an important issue with significant clinical relevance. This study aims to quantify and map the complexity of the EEG during PS, where complexity is measured as the degree of unpredictability resulting from local linear prediction. EEG activity was recorded with eyes closed (EC) and eyes open (EO) during resting and PS at 5, 10, and 15. Hz in a group of 30 healthy subjects and in a case-report of a patient suffering from cerebral ischemia. The mean squared prediction error (MSPE) resulting from k-nearest neighbour local linear prediction was calculated in each condition as an index of EEG unpredictability. The linear or …
Reliability of Magnetoencephalography and High-Density Electroencephalography Resting-State Functional Connectivity Metrics
2019
Resting-state connectivity, for example, based on magnetoencephalography (MEG) or electroencephalography (EEG), is a widely used method for characterizing brain networks and a promising imaging biomarker. However, there is no established standard as to which method, modality, and analysis variant is preferable and there is only limited knowledge on the reproducibility, an important prerequisite for clinical application. We conducted an MEG-/ high-density (hd)-EEG-study on 22 young healthy adults, who were measured twice in a scan/rescan design after 7 – 2 days. Reliability of resting-state (15 min, eyes-closed) connectivity in source space was calculated via intraclass correlation coefficie…
Effects of masked repetition priming and orthographic neighborhood in visual recognition of words.
1996
Summay.-The role of orthographic neighborhood (neighborhood size and neighborhood Erequency) in visual-word recognition was analyzed using the masked repetition-priming paradigm. Specifically, we varied stimulus-onset asynchrony (33, 50, and 67 msec.) and type of prime (identical, unrelated, unprimed) in a lexical-decision task. Analyses show additive effects of repetition and stimulus-onset asynchrony. Further, the unrelated condition overestimated the repetition effects relative ro an unprimed condition. Fachtatory effects of neighborhood size and inhibitory effects of neighborhood frequency were also found. The results are interpreted in terms of current models of visual-word recognition…
Implicit memory functioning in schizophrenia: Explaining inconsistent findings of word stem completion tasks
2014
The definitive implicit memory profile of schizophrenia is yet to be clarified. Methodological differences between studies could be the reason for the inconsistent findings reported. In this study, we have examined implicit memory functioning using a word stem completion task. In addition, we have addressed methodological issues related with lexical and perceptual stimuli characteristics, and with the strategy used to calculate priming scores. Our data show similar performance values in schizophrenic patients and healthy controls. Furthermore, we have not detected significant differences in priming between the two groups, even when this parameter was calculated using three different procedu…
Perceptual priming in schizophrenia evaluated by word fragment and word stem completion
2011
Implicit memory seems to be preserved in schizophrenia as a whole, but dissociations between conceptual and perceptual tasks and between accuracy and reaction time measures have appeared. The present research has revealed some methodological limitations in many studies to date that are focused on the study of perceptual implicit memory in schizophrenic patients using accuracy measures. The review of these studies revealed that limitations are related to an inadequate definition of performance and priming measures, a lack of control over the characteristics of the stimuli, and the absence of information on the experimental procedures used in data collection. Moreover, the task used in these …