• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 5
  • 2
  • 1
  • Tagged with
  • 9
  • 4
  • 4
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Joint time-frequency analysis and filtering of single trial event-related potentials

Gibson, Christopher January 2000 (has links)
The ongoing electrical activity of the brain is known as the electroencephalograph (EEG). Event related potentials (ERPs) are voltage deviations in the EEG elicited in association with stimuli. Their elicitation require cognitive processes such as response to a recognised stimulus. ERPs therefore provide clinical information by allowing an insight into neurological processes. The amplitude of an event-related potential is typically several times less than the background EEG. The background EEG has the effect of obscuring the ERP and therefore appropriate signal processing is required for its recovery. Traditionally ERPs are estimated using the synchronised averaging of several single trials or sweeps. This inhibits investigation of any trial-to-trial variation, which can prove valuable in understanding cognitive processes. An aim of this study was to develop wavelet-based techniques for the recovery of single trial ERPs from background EEG. A novel wavelet-based adaptive digital filtering method for ERPs has been developed. The method provides the ability to effectively estimate or recover single ERPs. The effectiveness of the method has been quantitatively evaluated and compared with other methods of ERP estimation. The ability to recover single sweep ERPs allowed the investigation of characteristics that are not possible using the conventional averaged estimation. The development of features of a cognitive ERP known as the contingent negative variation over a number of trials was investigated. The trend in variation enabled the identification of schizophrenic subjects using artificial intelligence methods. A new technique to investigate the phase dynamics of ERPs was developed. This was successfully applied, along with other techniques, to the investigation of independent component analysis (ICA) component activations in a visual spatial attention task. Two components with scalp projections that suggested that they may be sources within the visual cortex were investigated. The study showed that the two components were visual field selective and that their activation was both amplitude and phase modulated.
2

CLINICAL APPLICATIONS OF THE QUANTITATIVE ELECTROENCEPHALOGRAPH

Corradini, Paula L. 19 March 2014 (has links)
Clinical psychology is a discipline that assesses and treats individuals experiencing a variety of psychological disorders; including brain injuries. Employing neuroimaging tools can reveal biological correlates that have not been previously studied in detail. The quantitative electroencephalograph (QEEG) is a dynamic neuroimaging tool that allows for the measurement of brain activity. QEEG source localization analysis has provided additional construct validity for neuropsychological tests by revealing increased activation in the associated brain regions. In addition, differences in resting brain activity have been found depending on the severity of neuropsychological impairment. Finally, enhancement of memory in normal individuals is shown by applying a weak physiologically-patterned electromagnetic field over the left hemisphere. Therefore, by integrating the QEEG with elements of clinical psychology it is possible to provide construct validity to neuropsychological tests, show differences in brain activation depending on the severity of neuropsychological impairment, and study emerging therapeutic techniques that could enhance memory.
3

Cortisol Levels and Voltage Conditions of College Students

Steffens, Adriana 01 January 2015 (has links)
There is a limited research base on low voltage brain conditions, which are characterized by electrical activity being measured at below 20 microvolts. The purpose of this study was to examine the relationship between saliva cortisol levels and voltage using an EGG in a college student population. Illuminating this relationship is important to inform how low voltage conditions can affect daily memory and cognitive functioning of undergraduate college students that may be a result of stress. The college student population may be vulnerable to the low voltage condition because of stress from the transition between teenage and adult life and related social and academic pressures. Sapolsky's theory of stress, which hypothesized that high cortisol levels will manifest as a low voltage condition, guided this study. The sample included 60 undergraduate students recruited by flyers distributed on the campus of a liberal arts college. A multiple regression analysis was used to examine the relationship between explain the variables. Although no low voltage was found in this study sample, the study results contribute to positive social change by providing a better understanding for students and staff of brain functioning when exposed to chronic stress and encourage the implementation of programs for managing stress and prevention of stress before it reaches a chronic state and negatively impacts brain functioning.
4

Characterising Evoked Potential Signals using Wavelet Transform Singularity Detection.

McCooey, Conor Gerard, cmccooey@ieee.org January 2008 (has links)
This research set out to develop a novel technique to decompose Electroencephalograph (EEG) signal into sets of constituent peaks in order to better describe the underlying nature of these signals. It began with the question; can a localised, single stimulation of sensory nervous tissue in the body be detected in the brain? Flash Visual Evoked Potential (VEP) tests were carried out on 3 participants by presenting a flash and recording the response in the occipital region of the cortex. By focussing on analysis techniques that retain a perspective across different domains � temporal (time), spectral (frequency/scale) and epoch (multiple events) � useful information was detected across multiple domains, which is not possible in single domain transform techniques. A comprehensive set of algorithms to decompose evoked potential data into sets of peaks was developed and tested using wavelet transform singularity detection methods. The set of extracted peaks then forms the basis for a subsequent clustering analysis which identifies sets of localised peaks that contribute the most towards the standard evoked response. The technique is quite novel as no closely similar work in research has been identified. New and valuable insights into the nature of an evoked potential signal have been identified. Although the number of stimuli required to calculate an Evoked Potential response has not been reduced, the amount of data contributing to this response has been effectively reduced by 75%. Therefore better examination of a small subset of the evoked potential data is possible. Furthermore, the response has been meaningfully decomposed into a small number (circa 20) of constituent peaksets that are defined in terms of the peak shape (time location, peak width and peak height) and number of peaks within the peak set. The question of why some evoked potential components appear more strongly than others is probed by this technique. Delineation between individual peak sizes and how often they occur is for the first time possible and this representation helps to provide an understanding of how particular evoked potentials components are made up. A major advantage of this techniques is the there are no pre-conditions, constraints or limitations. These techniques are highly relevant to all evoked potential modalities and other brain signal response applications � such as in brain-computer interface applications. Overall, a novel evoked potential technique has been described and tested. The results provide new insights into the nature of evoked potential peaks with potential application across various evoked potential modalities.
5

Chaotic Modeling Of Electroencephalographic Signals With Application To Compression

Kavitha, V 12 1900 (has links) (PDF)
No description available.
6

The efficacy of the Berard Auditory Integration Training method for learners with attention difficulties / Hannelie Kemp

Kemp, Johanna Jacoba January 2010 (has links)
Research on the Berard Auditory Integration Training method has shown improvement in the regulation of attention, activity and impulsivity of children whose auditory system have been re-trained. Anecdotal reports have found improvements in sleeping patterns, balance, allergies, eyesight, eating patterns, depression and other seemingly unrelated physiological states. During the Auditory Integration Training (AIT) procedure dynamic music, with a wide range of frequencies, is processed through a system of filters in the AIT device. The volume and tone of the music is constantly and randomly modulated. The researcher explored Berard AIT as a possible intervention for learners between the ages of six and twelve years, who experienced problems with sustained attention and who have difficulty in shifting their attention from task to task. The aim was to investigate if Berard AIT method would enable the learner to stay calm, relaxed yet alert, with focused attention and thus concentration with appropriate reflection before action. An experimental quantative study, with a pretest-posttest control group design, was conducted to investigate the effect that Berard Auditory Integration Training has on learners with attention problems. Checklists and different measurements were conducted before the training started and repeated three months after the training was completed, to monitor if any change in the way that the learners pay attention, occurred the case group of ten learners was compared with ten learners in a control group who did not initially receive the intervention. Although the results of the post-tests varied amongst the learners, most learners in the experimental group experienced a statistical significant increase in attention control and a reduction in behavioural problems by the third month following the listening sessions. / Thesis (M.Ed.), North-West University, Vaal Triangle Campus, 2010
7

The efficacy of the Berard Auditory Integration Training method for learners with attention difficulties / Hannelie Kemp

Kemp, Johanna Jacoba January 2010 (has links)
Research on the Berard Auditory Integration Training method has shown improvement in the regulation of attention, activity and impulsivity of children whose auditory system have been re-trained. Anecdotal reports have found improvements in sleeping patterns, balance, allergies, eyesight, eating patterns, depression and other seemingly unrelated physiological states. During the Auditory Integration Training (AIT) procedure dynamic music, with a wide range of frequencies, is processed through a system of filters in the AIT device. The volume and tone of the music is constantly and randomly modulated. The researcher explored Berard AIT as a possible intervention for learners between the ages of six and twelve years, who experienced problems with sustained attention and who have difficulty in shifting their attention from task to task. The aim was to investigate if Berard AIT method would enable the learner to stay calm, relaxed yet alert, with focused attention and thus concentration with appropriate reflection before action. An experimental quantative study, with a pretest-posttest control group design, was conducted to investigate the effect that Berard Auditory Integration Training has on learners with attention problems. Checklists and different measurements were conducted before the training started and repeated three months after the training was completed, to monitor if any change in the way that the learners pay attention, occurred the case group of ten learners was compared with ten learners in a control group who did not initially receive the intervention. Although the results of the post-tests varied amongst the learners, most learners in the experimental group experienced a statistical significant increase in attention control and a reduction in behavioural problems by the third month following the listening sessions. / Thesis (M.Ed.), North-West University, Vaal Triangle Campus, 2010
8

Biologická zpětná vazba v terapii / Biofeedback in therapy

Ticháček, Aleš January 2008 (has links)
Diploma thesis – the Biological feedback in therapy deals with electromyography (EMG), investigative techniques based on electromyography, myofeedback applications and intention controlled myofeedback (IMF therapy). Electromyography is described on principal and there are used electrodes presented. In investigative methods are mentioned their basic progress at investigation by the help of elektromyography. Next are present artifacts, which in the elektromyography signal values. For myofeedback I worked up basic study. Myofeedback is based principle in IMF therapy. The effect of IMF therapy was verified with synchronized signal electroencephalograph (EEG) and EMG. In concrete I worked with movement-related cortical potentials (MRCP) components and Bereitschaftspotential (BP). BP presents highlight component from MRCP and alone BP precluding fulfillment movement. It was tested on metering, that BP occur before executed movement. Idea IMF therapy is correct.
9

Analýza souvislostí mezi simultánně měřenými EEG a fMRI daty / Analysis of connections between simultaneous EEG and fMRI data

Labounek, René January 2012 (has links)
Electroencephalography and functional magnetic resonance are two different methods for measuring of neural activity. EEG signals have excellent time resolution, fMRI scans capture records of brain activity in excellent spatial resolution. It is assumed that the joint analysis can take advantage of both methods simultaneously. Statistical Parametric Mapping (SPM8) is freely available software which serves to automatic analysis of fMRI data estimated with general linear model. It is not possible to estimate automatic EEG–fMRI analysis with it. Therefore software EEG Regressor Builder was created during master thesis. It preprocesses EEG signals into EEG regressors which are loaded with program SPM8 where joint EEG–fMRI analysis is estimated in general linear model. EEG regressors consist of vectors of temporal changes in absolute or relative power values of EEG signal in the specified frequency bands from selected electrodes due to periods of fMRI acquisition of individual images. The software is tested on the simultaneous EEG-fMRI data of a visual oddball experiment. EEG regressors are calculated for temporal changes in absolute and relative EEG power values in three frequency bands of interest ( 8-12Hz, 12-20Hz a 20-30Hz) from the occipital electrodes (O1, O2 and Oz). Three types of test analyzes is performed. Data from three individuals is examined in the first. Accuracy of results is evaluated due to the possibilities of setting of calculation method of regressor. Group analysis of data from twenty-two healthy patients is performed in the second. Group EEG regressors analysis is realized in the third through the correlation matrix due to the specified type of power and frequency band outside of the general linear model.

Page generated in 0.0767 seconds