Search results for " processing"
showing 10 items of 7549 documents
Intra-individual gait patterns across different time-scales as revealed by means of a supervised learning model using kernel-based discriminant regre…
2017
Objective Traditionally, gait analysis has been centered on the idea of average behavior and normality. On one hand, clinical diagnoses and therapeutic interventions typically assume that average gait patterns remain constant over time. On the other hand, it is well known that all our movements are accompanied by a certain amount of variability, which does not allow us to make two identical steps. The purpose of this study was to examine changes in the intra-individual gait patterns across different time-scales (i.e., tens-of-mins, tens-of-hours). Methods Nine healthy subjects performed 15 gait trials at a self-selected speed on 6 sessions within one day (duration between two subsequent ses…
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…
Reproducibility of multiphase pseudo-continuous arterial spin labeling and the effect of post-processing analysis methods
2015
Arterial spin labeling (ASL) is an emerging MRI technique for non-invasive measurement of cerebral blood flow (CBF). Compared to invasive perfusion imaging modalities, ASL suffers from low sensitivity due to poor signal-to-noise ratio (SNR), susceptibility to motion artifacts and low spatial resolution, all of which limit its reliability. In this work, the effects of various state of the art image processing techniques for addressing these ASL limitations are investigated. A processing pipeline consisting of motion correction, ASL motion correction imprecision removal, temporal and spatial filtering, partial volume effect correction, and CBF quantification was developed and assessed. To fur…
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 …
Role of sensorimotor areas in early detection of motor errors: An EEG and TMS study
2019
Abstract Action execution is prone to errors and, while engaged in interaction, our brain is tuned to detect deviations from what one expects from other’s action. Prior research has shown that Event-Related-Potentials (ERPs) are specifically modulated by the observation of action mistakes interfering with goal achievement. However, in complex and modular actions, embedded motor errors do not necessarily produce an immediate effect on the global goal. Here we dissociate embedded motor goals from global action goals by asking subjects to observe familiar but untrained knotting actions. During knotting an embedded motor error (i.e. the rope is inserted top-down instead of bottom-up during the …
Evaluation of volumetric measurements on CBCT images using stafne bone cavities as an example
2015
Adisen, Mehmet Zahit/0000-0002-5493-8390; Yilmaz, Selmi/0000-0001-9546-6548; Yilmaz, Selmi/0000-0001-9546-6548; ATIL, Fethi/0000-0002-8286-4819 WOS: 000365269900009 PubMed: 26116844 Background: The aim of the present study is to evaluate the efficacy of CBCT in volume measuring using Stafne Bone Cavities (SBC) as an example. Material and Methods: The study was conducted with 14 subjects with SBC detected on panoramic radiographs. In order to evaluate lesions volumetric dimensions, CBCT images for each patient were captured. Files in Digital Imaging and Communications in Medicine (DICOM) format were transferred into a medical image processing program (ITK-SNAP 2.4.0) and volume in mm(3) of t…
Strange Attractors, Chaotic Behavior and Informational Aspects of Sleep EEG Data
1992
In order to perform a nonlinear dimensional analysis of the sleep EEG, we applied an algorithm proposed to calculate the correlation dimension D2 of different sleep stages. D2 characterizes the dynamics of the sleep EEG, estimates the degrees of freedom, and describes the complexity of the signal under study. An attempt is made to correlate dimensionality analysis and informational aspects of the sleep EEG. Information processing by the brain during different sleep stages of healthy subjects under the influence of lorazepam and in unmedicated acute schizophrenics is estimated.
Determination of Bolton tooth-size ratios by digitization, and comparison with the traditional method.
2005
The Bolton Index is one of the most useful calculations for precise orthodontic diagnosis as it shows if there is a correct ratio between dental proportions. However, at times, this calculation is not applied because it is a long and time-consuming procedure compared with digital methods. A new digital method for measuring tooth sizes and for calculating the Anterior (ABI) and the Overall (OBI) Bolton Index was tested on 100 sets of study dental casts of the permanent dentition in a Spanish sample and compared with the traditional method. The reproducibility of this digital method versus the traditional one was analysed to determine intra- and inter-examiner measurement errors by calculatin…
fMRI-activation patterns in the detection of concealed information rely on memory-related effects
2012
Recent research on potential applications of fMRI in the detection of concealed knowledge primarily ascribed the reported differences in hemodynamic response patterns to deception. This interpretation is challenged by the results of the present study. Participants were required to memorize probe and target items (a banknote and a playing card, each). Subsequently, these items were repeatedly presented along with eight irrelevant items in a modified Guilty Knowledge Test design and participants were instructed to simply acknowledge item presentation by pressing one button after each stimulus. Despite the absence of response monitoring demands and thus overt response conflicts, the experiment…
Covariations among fMRI, skin conductance, and behavioral data during processing of concealed information.
2007
Imaging techniques have been used to elucidate the neural correlates that underlie deception. The scientifically best understood paradigm for the detection of deception, however, the guilty knowledge test (GKT), was rarely used in imaging studies. By transferring a GKT‐paradigm to a functional magnetic resonance imaging (fMRI) study, while additionally quantifying reaction times and skin conductance responses (SCRs), this study aimed at identifying the neural correlates of the behavioral and electrodermal response pattern typically found in GKT examinations. Prior to MR scanning, subjects viewed two specific items (probes) and were instructed to hide their knowledge of these. Two other spec…